Java web实现综合查询+SQL语句拼接

首先展示图形界：

界面比较简单，但麻雀虽小五脏俱全。因为数据库只有六种数据类型，所以最多添加六个查询框。

测试以下问题： 删除方式是从上往下开始的，如果删除之后会有问题。（后续改进ing）

若干个并且，或，不含在一起执行如果顺序不对会报错（sql语句拼接执行有问题）。

如果还有问题，敬请指正。

sql语句的拼接推荐（如果有更好的请忽略，可以先看一看拼接的方法再实现方法，不要一上来就抱住一团慢慢啃，例如我。。。嘿嘿）：

http://codingdict.com/article/6952

废话不多说，上代码：

Bean 层（基础层）：

 public class Bean {

     private String name;
     private String sex;
     private String minzu;
     private String zhucetime;
     private String age;
     private String mianmao;
     private String fuwuleibie;
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getSex() {
         return sex;
     }
     public void setSex(String sex) {
         this.sex = sex;
     }
     public String getMinzu() {
         return minzu;
     }
     public void setMinzu(String minzu) {
         this.minzu = minzu;
     }
     public String getZhucetime() {
         return zhucetime;
     }
     public void setZhucetime(String zhucetime) {
         this.zhucetime = zhucetime;
     }
     public String getAge() {
         return age;
     }
     public void setAge(String age) {
         this.age = age;
     }
     public String getMianmao() {
         return mianmao;
     }
     public void setMianmao(String mianmao) {
         this.mianmao = mianmao;
     }
     public String getFuwuleibie() {
         return fuwuleibie;
     }
     public void setFuwuleibie(String fuwuleibie) {
         this.fuwuleibie = fuwuleibie;
     }
     public Bean(String name, String sex, String minzu, String zhucetime, String age, String mianmao,
             String fuwuleibie) {
         super();
         this.name = name;
         this.sex = sex;
         this.minzu = minzu;
         this.zhucetime = zhucetime;
         this.age = age;
         this.mianmao = mianmao;
         this.fuwuleibie = fuwuleibie;
     }
     public Bean() {
         // TODO Auto-generated constructor stub
     }
       

DBUtil层 emm。。。关闭的方法有点多，但是使用的就只有一个，懒得删除了   ：

 package com.DBUtil;

 import java.beans.Statement;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;

 public class DBUtil {
     public static String db_url="jdbc:mysql://localhost:3306/db_database01?serverTimezone=UTC&characterEncoding=UTF-8&allowPublicKeyRetrieval=true&useSSL=false";
     public static String db_user="root";
     public static String db_password="101032";
     public static Connection getConn()  {
         Connection conn=null;
         try {
             Class.forName("com.mysql.cj.jdbc.Driver");
             try {
                 conn=DriverManager.getConnection(db_url, db_user, db_password);
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             System.out.println("驱动链接加载成功！");
         } catch (ClassNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         return conn;

     }

     public static void close(Statement state,Connection conn) {
         if(state!=null) {
             try {
                 ((Connection) state).close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }

         }
         if(conn!=null) {
             try {
                 conn.close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
     }

     public static void close(PreparedStatement state,Connection conn) {
         if(state!=null) {
             try {
                 ((Connection) state).close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }

         }
         if(conn!=null) {
             try {
                 conn.close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
     }

     public static void close(ResultSet rs,Statement state,Connection conn) {
         if(rs!=null) {
             try {
                 rs.close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         if(state!=null) {
             try {
                 ((Connection) state).close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         if(conn!=null) {
             try {
                 conn.close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
     }

     @SuppressWarnings("static-access")
     public static void main(String[] args) throws SQLException {
         DBUtil dbu=new DBUtil();
         dbu.getConn();
     }

     public static void close(java.sql.Statement state, Connection conn) {
         // TODO Auto-generated method stub
         if(state!=null)
         {
             try {
                 state.close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         if(conn!=null) {
             try {
                 conn.close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
     }
 }

Dao层（由于是之前的程序基础上改写的，有点乱，就该查询来说无用的程序比较多）：

在多条件查询的方法当中sql语句不是在Dao层生成的，而是在Servlet 层拼接好之后传递过来的。

 import java.sql.Connection;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.List;

 import com.Bean.Bean;
 import com.DBUtil.DBUtil;

 public class Dao {

     //遍历
         public static List<Bean> show() {
             List<Bean>list =new ArrayList<>();
             Connection conn=DBUtil.getConn();
             String sql="select * from tb_qingnian";
             Statement pstmt = null;
             try {
                 pstmt = conn.createStatement();
                 ResultSet rs=pstmt.executeQuery(sql);
                 Bean use=null;
                 while(rs.next()) {
                     String name=rs.getString("name");
                     String sex=rs.getString("sex");
                     String minzu=rs.getString("minzu");
                     String zhucetime=rs.getString("zhucetime");
                     String age=rs.getString("age");
                     String mianmao=rs.getString("mianmao");
                     String fuwuleibie=rs.getString("fuwuleibie");
                     use=new Bean(name,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
                     list.add(use);
                 }
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstmt, conn);
                 }

             return list;
             }

         //添加
         public static boolean insert(Bean e) {
             System.out.println("添加中");
             String sql="insert into tb_qingnian(name,sex,minzu,zhucetime,age,mianmao,fuwuleibie) values('"+e.getName()+"','"+e.getSex()+"','"+e.getMinzu()+"','"+e.getZhucetime()+"','"+e.getAge()+"','"+e.getMianmao()+"','"+e.getFuwuleibie()+"')";
             Connection conn=DBUtil.getConn();
             Statement state=null;

             try {
                 state= conn.createStatement();
                 state.executeUpdate(sql);
             } catch (SQLException e1) {
                 // TODO Auto-generated catch block
                 e1.printStackTrace();
             }
             finally {
                 DBUtil.close(state, conn);
             }
             return false;

         }

         //修改
         public static boolean update(Bean e) {
             System.out.println("修改中");
             String sql="update tb_qingnian set sex='"+e.getSex()+"',mianmao='"+e.getMianmao()+"',fuwuleibie='"+e.getFuwuleibie()+"'   where name='"+e.getName()+"' ";
             Connection conn=DBUtil.getConn();
             Statement pstm=null;
             try {
                 pstm=conn.createStatement();
                 pstm.executeUpdate(sql);
             } catch (SQLException e1) {
                 // TODO Auto-generated catch block

                 e1.printStackTrace();
             }finally{
                 DBUtil.close(pstm, conn);
                 }
             return false;

         }

         //删除 按照姓名
         public static boolean delete(String name) {
             String sql="delete from tb_qingnian where name='"+name+"'"  ;
             Connection conn=DBUtil.getConn();
             Statement pstm=null;
             try {
                 pstm=conn.createStatement();
                 pstm.executeUpdate(sql);
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstm, conn);
             }

             return false;
         }

         //按姓名查询 可模糊查询
         public static List<Bean> search(String info) {
             List<Bean>list =new ArrayList<>();
             Connection conn=DBUtil.getConn();
             String sql="select * from tb_qingnian where name like'%"+info+"%'";
             Statement pstmt = null;
             try {
                 pstmt = conn.createStatement();
                 ResultSet rs=pstmt.executeQuery(sql);
                 Bean use=null;
                 while(rs.next()) {
                     String name1=rs.getString("name");
                     String sex=rs.getString("sex");
                     String minzu=rs.getString("minzu");
                     String zhucetime=rs.getString("zhucetime");
                     String age=rs.getString("age");
                     String mianmao=rs.getString("mianmao");
                     String fuwuleibie=rs.getString("fuwuleibie");
                     use=new Bean(name1,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
                     list.add(use);
                 }
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstmt, conn);
                 }

             return list;

         }

         //多条件综合查询 代码执行   使用list进行遍历操作
         public static List<Bean> searchs(String sql) {
             List<Bean>list =new ArrayList<>();
             Connection conn=DBUtil.getConn();
             //String sql="select * from tb_qingnian where name like'%"+info+"%'";
             Statement pstmt = null;
             try {
                 pstmt = conn.createStatement();
                 ResultSet rs=pstmt.executeQuery(sql);
                 Bean use=null;
                 while(rs.next()) {
                     String name1=rs.getString("name");
                     String sex=rs.getString("sex");
                     String minzu=rs.getString("minzu");
                     String zhucetime=rs.getString("zhucetime");
                     String age=rs.getString("age");
                     String mianmao=rs.getString("mianmao");
                     String fuwuleibie=rs.getString("fuwuleibie");
                     use=new Bean(name1,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
                     list.add(use);
                 }
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstmt, conn);
                 }

             return list;

         }

          //性别
         public static List<Bean> search1(String info) {
             List<Bean>list =new ArrayList<>();
             Connection conn=DBUtil.getConn();
             String sql="select * from tb_qingnian where sex like'%"+info+"%'";
             Statement pstmt = null;
             try {
                 pstmt = conn.createStatement();
                 ResultSet rs=pstmt.executeQuery(sql);
                 Bean use=null;
                 while(rs.next()) {
                     String name1=rs.getString("name");
                     String sex=rs.getString("sex");
                     String minzu=rs.getString("minzu");
                     String zhucetime=rs.getString("zhucetime");
                     String age=rs.getString("age");
                     String mianmao=rs.getString("mianmao");
                     String fuwuleibie=rs.getString("fuwuleibie");
                     use=new Bean(name1,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
                     list.add(use);
                 }
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstmt, conn);
                 }

             return list;
         }
         //民族
         public static List<Bean> search2(String info) {
             List<Bean>list =new ArrayList<>();
             Connection conn=DBUtil.getConn();
             String sql="select * from tb_qingnian where minzu like'%"+info+"%'";
             Statement pstmt = null;
             try {
                 pstmt = conn.createStatement();
                 ResultSet rs=pstmt.executeQuery(sql);
                 Bean use=null;
                 while(rs.next()) {
                     String name1=rs.getString("name");
                     String sex=rs.getString("sex");
                     String minzu=rs.getString("minzu");
                     String zhucetime=rs.getString("zhucetime");
                     String age=rs.getString("age");
                     String mianmao=rs.getString("mianmao");
                     String fuwuleibie=rs.getString("fuwuleibie");
                     use=new Bean(name1,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
                     list.add(use);
                 }
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstmt, conn);
                 }

             return list;
         }
         //政治面貌
         public static List<Bean> search3(String info) {
             List<Bean>list =new ArrayList<>();
             Connection conn=DBUtil.getConn();
             String sql="select * from tb_qingnian where mianmao like'%"+info+"%'";
             Statement pstmt = null;
             try {
                 pstmt = conn.createStatement();
                 ResultSet rs=pstmt.executeQuery(sql);
                 Bean use=null;
                 while(rs.next()) {
                     String name1=rs.getString("name");
                     String sex=rs.getString("sex");
                     String minzu=rs.getString("minzu");
                     String zhucetime=rs.getString("zhucetime");
                     String age=rs.getString("age");
                     String mianmao=rs.getString("mianmao");
                     String fuwuleibie=rs.getString("fuwuleibie");
                     use=new Bean(name1,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
                     list.add(use);
                 }
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstmt, conn);
                 }

             return list;
         }
         //服务类别
         public static List<Bean> search4(String info) {
             List<Bean>list =new ArrayList<>();
             Connection conn=DBUtil.getConn();
             String sql="select * from tb_qingnian where fuwuleibie like'%"+info+"%'";
             Statement pstmt = null;
             try {
                 pstmt = conn.createStatement();
                 ResultSet rs=pstmt.executeQuery(sql);
                 Bean use=null;
                 while(rs.next()) {
                     String name1=rs.getString("name");
                     String sex=rs.getString("sex");
                     String minzu=rs.getString("minzu");
                     String zhucetime=rs.getString("zhucetime");
                     String age=rs.getString("age");
                     String mianmao=rs.getString("mianmao");
                     String fuwuleibie=rs.getString("fuwuleibie");
                     use=new Bean(name1,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
                     list.add(use);
                 }
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstmt, conn);
                 }

             return list;
         }
         //注册时间
         public static List<Bean> search5(String info) {
             List<Bean>list =new ArrayList<>();
             Connection conn=DBUtil.getConn();
             String sql="select * from tb_qingnian where zhucetime like'%"+info+"%'";
             Statement pstmt = null;
             try {
                 pstmt = conn.createStatement();
                 ResultSet rs=pstmt.executeQuery(sql);
                 Bean use=null;
                 while(rs.next()) {
                     String name1=rs.getString("name");
                     String sex=rs.getString("sex");
                     String minzu=rs.getString("minzu");
                     String zhucetime=rs.getString("zhucetime");
                     String age=rs.getString("age");
                     String mianmao=rs.getString("mianmao");
                     String fuwuleibie=rs.getString("fuwuleibie");
                     use=new Bean(name1,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
                     list.add(use);
                 }
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally {
                 DBUtil.close(pstmt, conn);
                 }

             return list;
         }

         public static void main(String[] args) {
             Bean e=new Bean("李","男","汉","2015-02-10","24","党员","志愿者");
             insert(e);
             List<Bean> list =show();
             for(int i=0;i<list.size();i++) {
                 Bean s=list.get(i);
                 System.out.println(s.getName());
             }
             String a="李四";
             //delete(a);
         }

 }

Servlet 层   通过jsp传递过来的参数来拼接sql语句 然后执行sql语句（前面的查询通过了Service 层来传递，就该方法直接调用了Dao层的方法），查询信息：

 package com.Servlet;

 import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 import java.util.List;

 import javax.servlet.ServletException;
 import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import com.Bean.Bean;
 import com.Dao.Dao;

 /**
  * Servlet implementation class Servlet
  */
 @WebServlet("/Servlet")
 public class Servlet extends HttpServlet {
     private static final long serialVersionUID = 1L;
     //创建service层
     Service service=new Service();

 protected void service(HttpServletRequest req,HttpServletResponse resp) throws ServletException, IOException {
         //通过method 传递参数获取需要调用的方法
         req.setCharacterEncoding("utf-8");
         String method=req.getParameter("method");
         if("insert".equalsIgnoreCase(method)) {
             insert(req,resp);
         }else if("update".equals(method)) {
             update(req,resp);
         }else if("delete".equals(method)) {
             Delete(req,resp);
         }
         else if("show".equals(method)) {
             show(req,resp);
           }
         else if("search".equals(method)) {
             search(req,resp);
         }
         else if("searchs".equals(method)) {
             searchs(req,resp);
         }
         }

 // 多条件并发式查询
    private void searchs(HttpServletRequest req, HttpServletResponse resp) {
     // TODO Auto-generated method stub
     // TODO Auto-generated method stub
             try {
                 req.setCharacterEncoding("utf-8");
             } catch (UnsupportedEncodingException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }

             String type1=req.getParameter("type1");   //获取查找的信息的参数 如 姓名，性别等
             String type2=req.getParameter("type2");
             String type3=req.getParameter("type3");
             String type4=req.getParameter("type4");
             String type5=req.getParameter("type5");
             String type6=req.getParameter("type6");
             String sql="select * from tb_qingnian where 1=1 ";  //最基础的sql语句，在此基础上进行拼接

             String SearchBox1=req.getParameter("SearchBox1");   //获取需要查找的信息

             String method1=req.getParameter("method1");   //获取查找的方式  模糊查找或者精确查找
             String method2=req.getParameter("method2");
             String method3=req.getParameter("method3");
             String method4=req.getParameter("method4");
             String method5=req.getParameter("method5");
             String method6=req.getParameter("method6");

             String con2=req.getParameter("con2");    //获取与前一个条件的关系  与  and  或 or 非  not
             String con3=req.getParameter("con3");
             String con4=req.getParameter("con4");
             String con5=req.getParameter("con5");
             String con6=req.getParameter("con6");
             System.out.println(con2);
             System.out.println(con3);
             System.out.println(con4);
             System.out.println(con5);
             System.out.println(con6);

             //sql语句的拼接操作
             //1
             if(type1!=null) {

                 if(!SearchBox1.equals("")&&SearchBox1!=null) {
                     if(method1.equals("mohu"))
                     {
                         sql=sql+"and "+type1+" like '%"+SearchBox1+"%'";}
                     else {
                     sql=sql+"and "+type1+"='"+SearchBox1+"'";
                     }
                 }
             }
             System.out.println(sql);
             //
             if(type2!=null) {
                 String SearchBox2=req.getParameter("SearchBox2");
                 System.out.println(SearchBox2);
                 if(!SearchBox2.equals("")&&SearchBox2!=null) {
                     if(method2.equals("mohu"))
                     {
                         sql=sql+" "+con2+" "+type2+" like '%"+SearchBox2+"%'";}
                     else {
                     sql=sql+" "+con2+" "+type2+"='"+SearchBox2+"'";
                     }
                 }
             }
             System.out.println(sql);
             //
             if(type3!=null) {
                 String SearchBox3=req.getParameter("SearchBox3");
                 System.out.println(SearchBox3);
                 if(!SearchBox3.equals("")&&SearchBox3!=null) {
                     if(method3.equals("mohu"))
                     {
                         sql=sql+" "+con3+" "+type3+" like '%"+SearchBox3+"%'";}
                     else {
                     sql=sql+" "+con3+" "+type3+"='"+SearchBox3+"'";
                     }
                 }
             }
             //
             if(type4!=null) {

                 String SearchBox4=req.getParameter("SearchBox4");
                 System.out.println(SearchBox4);
                 if(!SearchBox4.equals("")&&SearchBox4!=null) {
                     if(method4.equals("mohu"))
                     {
                         sql=sql+" "+con4+" "+type4+" like '%"+SearchBox4+"%'";}
                     else {
                     sql=sql+" "+con4+" "+type4+"='"+SearchBox4+"'";
                     }
                 }
             }
             //
             if(type5!=null) {
                 String SearchBox5=req.getParameter("SearchBox5");
                 System.out.println(SearchBox5);
                 if(!SearchBox5.equals("")&&SearchBox5!=null) {
                     if(method5.equals("mohu"))
                     {
                         sql=sql+" "+con5+" "+type5+" like '%"+SearchBox5+"%'";}
                     else {
                     sql=sql+" "+con5+" "+type5+"='"+SearchBox5+"'";
                     }
                 }
             }

             //
             if(type6!=null) {
                 String SearchBox6=req.getParameter("SearchBox6");
                 System.out.println(SearchBox6);
                 if(!SearchBox6.equals("")&&SearchBox6!=null) {
                     if(method6.equals("mohu"))
                     {
                         sql=sql+" "+con6+" "+type6+" like '%"+SearchBox6+"%'";}
                     else {
                     sql=sql+" "+con6+" "+type6+"='"+SearchBox6+"'";
                     }
                 }
             }

             List<Bean> list=Dao.searchs(sql);
             if(!list.isEmpty()) {
             req.setAttribute("list", list);

             try {
                 req.getRequestDispatcher("show.jsp").forward(req, resp);
             } catch (ServletException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             }else {
                 try {
                     req.getRequestDispatcher("error.jsp").forward(req, resp);
                 } catch (ServletException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }
 }

 // 查询信息
 private void search(HttpServletRequest req, HttpServletResponse resp) {
     // TODO Auto-generated method stub
     try {
         req.setCharacterEncoding("utf-8");
     } catch (UnsupportedEncodingException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }
     String info=req.getParameter("name");
     String search=req.getParameter("search");
     //按姓名查找
     if(search.equals("name")) {
         List<Bean> list=service.search(info);
         req.setAttribute("list", list);
     }
     //按性别查询
     else if(search.equals("sex")) {
         List<Bean> list=service.search1(info);
         req.setAttribute("list", list);
     }
     //按民族查询
     else if(search.equals("minzu")) {
         List<Bean> list=service.search2(info);
         req.setAttribute("list", list);
     }
     //按政治面貌查询
     else if(search.equals("mianmao")) {
         List<Bean> list=service.search3(info);
         req.setAttribute("list", list);
     }
     //按服务类别查询 可模糊查询
     else if(search.equals("fuwuleibie")) {
         List<Bean> list=service.search4(info);
         req.setAttribute("list", list);
     }
     //按注册时间查询 可模糊查询
     else if(search.equals("zhucetime")) {
         List<Bean> list=service.search5(info);
         req.setAttribute("list", list);
     }

     try {
         req.getRequestDispatcher("show.jsp").forward(req, resp);
     } catch (ServletException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }

 }

   //遍历数据库
 private void show(HttpServletRequest req, HttpServletResponse resp) {
     // TODO Auto-generated method stub
     try {
         req.setCharacterEncoding("utf-8");
     } catch (UnsupportedEncodingException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }
     List<Bean> list= service.show();
     req.setAttribute("list", list);
     try {
         req.getRequestDispatcher("show.jsp").forward(req, resp);
     } catch (ServletException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }

 }
    //删除信息
 private void Delete(HttpServletRequest req, HttpServletResponse resp) {
     // TODO Auto-generated method stub
     try {
         req.setCharacterEncoding("utf-8");
     } catch (UnsupportedEncodingException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }
     String name=req.getParameter("name");
     System.out.println(name);
     service.delete(name);
     try {
         req.getRequestDispatcher("main.jsp").forward(req, resp);
     } catch (ServletException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }

 }

 private void update(HttpServletRequest req, HttpServletResponse resp) {
     // TODO Auto-generated method stub
     try {
         req.setCharacterEncoding("utf-8");
     } catch (UnsupportedEncodingException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }
     String name=req.getParameter("name");
     String sex=req.getParameter("sex");
     String mianmao=req.getParameter("mianmao");
     //多个选项，变化为String类型存储
     String[] list=req.getParameterValues("fuwuleibie");
     String fuwuleibie="";
     for(int i=0;i<list.length;i++) {
         fuwuleibie+=list[i];
         if(i!=list.length-1) {
             fuwuleibie+="，";
         }
     }

     Bean use=new Bean(name,sex,"","","",mianmao,fuwuleibie);
     System.out.println(use.getSex());
     System.out.println("servlet 修改");
     service.update(use);
     try {
         req.getRequestDispatcher("Servlet?method=show").forward(req, resp);
     } catch (ServletException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
     }

 }

 private void insert(HttpServletRequest req, HttpServletResponse resp) {
     // TODO Auto-generated method stub
         try {
             req.setCharacterEncoding("utf-8");
         } catch (UnsupportedEncodingException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         String name=req.getParameter("name");
         String sex=req.getParameter("sex");
         String minzu=req.getParameter("minzu");
         String zhucetime=req.getParameter("zhucetime");
         String age=req.getParameter("age");
         String mianmao=req.getParameter("mianmao");
         String[] list=req.getParameterValues("fuwuleibie");
         String fuwuleibie="";
         for(int i=0;i<list.length;i++) {
             fuwuleibie+=list[i];
             if(i!=list.length-1) {
                 fuwuleibie+="，";
             }
         }
         System.out.println(fuwuleibie);
         Bean e=new Bean(name,sex,minzu,zhucetime,age,mianmao,fuwuleibie);
         if(service.insert(e)) {
             try {
                 req.setAttribute("message","添加成功");
                 req.getRequestDispatcher("Servlet?method=show").forward(req, resp);
             } catch (ServletException e1) {
                 // TODO Auto-generated catch block
                 e1.printStackTrace();
             } catch (IOException e1) {
                 // TODO Auto-generated catch block
                 e1.printStackTrace();
             }
         }else {
             try {

                 req.setAttribute("message", "添加重复,请重新输入");
                 req.getRequestDispatcher("insert.jsp").forward(req, resp);
             } catch (ServletException e1) {
                 // TODO Auto-generated catch block
                 e1.printStackTrace();
             } catch (IOException e1) {
                 // TODO Auto-generated catch block
                 e1.printStackTrace();
             }
         }
 }

 }

jsp界面：

对于 应且 或者 不含的三个条件的选择框的 value 值 直接设置为了  “and”  “or”    “and  not ”，在拼接时可以直接获取值进行拼接

查找界面:

 <%@ page language="java" contentType="text/html; charset=UTF-8"
     pageEncoding="UTF-8"%>
 <!DOCTYPE html>
 <html>
 <head>
 <meta charset="UTF-8">
 <title>Insert title here</title>
 </head>
 <body>

 <div align="center">
 <!--              &#43: + &#45 : -   -->
             <button onclick="insert_row()" type="button" >&#43</button>
             <button onclick="deleteRow(this)" type="button" >&#45</button>
     <form action="Servlet?method=searchs" method="post">
         <table name="tbl" id="tbl">
             <tr>
                 <td>
                     <select id="type1" name="type1">
                         <option value="name">姓名</option>
                         <option value="minzu">民族</option>
                         <option value="sex">性别</option>
                         <option value="mianmu">政治面目</option>
                         <option value="fuwuleibie">服务类别</option>
                         <option value="zhucetime">注册时间</option>
                     </select>
                     <input type="text" id="SearchBox1" name="SearchBox1">
                     <select id="method1"  name="method1">
                         <option value="jingque">精确</option>
                         <option value="mohu">模糊</option>
                     </select>

 <!--                     <select id="con"  name="con"> -->
 <!--                         <option value="and">并且</option> -->
 <!--                         <option value="or">或者</option> -->
 <!--                         <option value="no">不含</option> -->
 <!--                     </select> -->

                 </td>
             </tr>
         </table>

         <div id="SearchButton">
             <button id="Button" type="submit" >查询</button>
         </div>
        <div>
                <a href="Servlet?method=show">信息浏览</a>
          </div>
      </form>
 </div>
 </body>
 <script type="text/javascript">
     var i=1;
     var first=1;
     function insert_row(){
         if(i<6){
         i++;
         R=tbl.insertRow(); //insertRow() 方法用于在表格中的指定位置插入一个新行。
         C=R.insertCell();  //insertCell() 方法用于在 HTML 表的一行的指定位置插入一个空的 <td> 元素。
          C.innerHTML =
             "<select id='con"+i+"'  name='con"+i+"'>"+
             "<option value='and'>并且</option>"+
             "<option value='or'>或者</option>"+
             "<option value=' and  not'>不含</option>"+
         "</select>"+
         "<select id='type"+i+"' name='type"+i+"'>"+
          "<option value='name' >姓名</option>"+
          "<option value='sex' >性别</option>"+
          "<option value='age'>年龄</option>"+
          "<option value='mianmao'>政治面目</option>"+
          "<option value='zhucetime'>注册时间</option>"+
          "<option value='fuwuleibie'>服务类别</option>"+
          "</select>"+"&nbsp;<input id='SearchBox"+i+"' name='SearchBox"+i+"' />"+
          "<select id='method"+i+"' name='method"+i+"'>"+
             "<option value='jingque'>精确</option>"+
             "<option value='mohu'>模糊</option>"+
           "</select>"
         }else{
             alert("查询条件冲突！");
         }

     }

     function deleteRow(obj){
         if(i>1){
          alert("确定删除一行吗？");
          tbl.deleteRow(obj.parentElement.parentElement.rowIndex);

          i--;
         }
     }

 </script>

 </body>
 </html>

显示界面    (需要用到list 遍历，需要 jstl.jar)：

可能会有收费，多找找总会有免费的。（万能的度娘在上见证，总会找到的。 。嘿嘿）

 <%@ page language="java" contentType="text/html; charset=utf-8"
     pageEncoding="utf-8"%>
     <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
 <!DOCTYPE html>
 <html>
 <head>
 <meta charset="utf-8">
 <title>遍历志愿者信息</title>
 </head>
 <body>
 <div align="center">
 <h1>志愿者信息浏览：</h1>
 <a href="indexfind.jsp">返回</a>
 <form action="Servlet?method=show" method="post" onsubmit="return check()">
 <table>
 <tr>
 <td>姓名</td>
 <td>性别</td>
 <td>民族</td>
 <td>注册时间</td>
 <td>年龄</td>
 <td>面貌</td>
 <td>服务类别</td>
  <td align="center" colspan="2">操作</td>
 </tr>
 <c:forEach items="${list}" var="item">
 <tr>
  <td>${item.name}</td>
  <td>${item.sex}</td>
  <td>${item.minzu}</td>
  <td>${item.zhucetime}</td>
  <td>${item.age}</td>
  <td>${item.mianmao}</td>
  <td>${item.fuwuleibie}</td>
  <td><a href="update.jsp?name=${item.name}&sex=${item.sex}&mianmao=${item.mianmao}&fuwuleibie=${item.fuwuleibie}">修改</a></td>
 <!--  <td><a href="javaScript:if(confirm('确定删除吗?')){location.href='Servlet?method=delete'}">删除</a></td>  -->
 <%-- <td><a href="javaScript:if(confirm('确定删除吗?')){location.href='delete.jsp'?name=${item.name}}">删除</a></td>  --%>
 <td> <a href="delete.jsp?minzu=${item.minzu}&zhucetime=${item.zhucetime}&age=${item.age}&name=${item.name}&sex=${item.sex}&mianmao=${item.mianmao}&fuwuleibie=${item.fuwuleibie}">删除</a>
 </tr>
 </c:forEach>
 </table>
 </form>
 </div>

如果没有查找到信息会跳转到一个提示界面。

 <%@ page language="java" contentType="text/html; charset=UTF-8"
     pageEncoding="UTF-8"%>
 <!DOCTYPE html>
 <html>
 <head>
 <meta charset="UTF-8">
 <title>错误信息展示</title>
 </head>
 <body>
 <div align="center">
 <a href="indexfind.jsp">返回</a>
 <div>
 <h3>未找到查询信息</h3>
 </div>
 </div>
 </body>
 </html>

package com.Servlet;
import java.io.IOException;import java.io.UnsupportedEncodingException;import java.util.List;
import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;
import com.Bean.Bean;import com.Dao.Dao;

/** * Servlet implementation class Servlet */@WebServlet("/Servlet")public class Servlet extends HttpServlet {private static final long serialVersionUID = 1L;    //创建service层Service service=new Service();protected void service(HttpServletRequest req,HttpServletResponse resp) throws ServletException, IOException {//通过method 传递参数获取需要调用的方法req.setCharacterEncoding("utf-8");String method=req.getParameter("method");if("insert".equalsIgnoreCase(method)) {insert(req,resp);}else if("update".equals(method)) {update(req,resp);}else if("delete".equals(method)) {Delete(req,resp);}else if("show".equals(method)) {show(req,resp);  }else if("search".equals(method)) {search(req,resp);}else if("searchs".equals(method)) {searchs(req,resp);}}
// 多条件并发式查询   private void searchs(HttpServletRequest req, HttpServletResponse resp) {// TODO Auto-generated method stub// TODO Auto-generated method stubtry {req.setCharacterEncoding("utf-8");} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();}String type1=req.getParameter("type1");   //获取查找的信息的参数 如 姓名，性别等String type2=req.getParameter("type2");String type3=req.getParameter("type3");String type4=req.getParameter("type4");String type5=req.getParameter("type5");String type6=req.getParameter("type6");String sql="select * from tb_qingnian where 1=1 ";  //最基础的sql语句，在此基础上进行拼接
String SearchBox1=req.getParameter("SearchBox1");   //获取需要查找的信息String method1=req.getParameter("method1");   //获取查找的方式  模糊查找或者精确查找String method2=req.getParameter("method2"); String method3=req.getParameter("method3");String method4=req.getParameter("method4");String method5=req.getParameter("method5");String method6=req.getParameter("method6");String con2=req.getParameter("con2");    //获取与前一个条件的关系  与  and  或 or 非  notString con3=req.getParameter("con3");     String con4=req.getParameter("con4");String con5=req.getParameter("con5");String con6=req.getParameter("con6");System.out.println(con2);System.out.println(con3);System.out.println(con4);System.out.println(con5);System.out.println(con6);
//sql语句的拼接操作//1  if(type1!=null) {
if(!SearchBox1.equals("")&&SearchBox1!=null) {if(method1.equals("mohu")){sql=sql+"and "+type1+" like '%"+SearchBox1+"%'";}else {sql=sql+"and "+type1+"='"+SearchBox1+"'";}}}System.out.println(sql);//2if(type2!=null) {String SearchBox2=req.getParameter("SearchBox2");System.out.println(SearchBox2);if(!SearchBox2.equals("")&&SearchBox2!=null) {if(method2.equals("mohu")){sql=sql+" "+con2+" "+type2+" like '%"+SearchBox2+"%'";}else {sql=sql+" "+con2+" "+type2+"='"+SearchBox2+"'";}}}System.out.println(sql);//3if(type3!=null) {String SearchBox3=req.getParameter("SearchBox3");System.out.println(SearchBox3);if(!SearchBox3.equals("")&&SearchBox3!=null) {if(method3.equals("mohu")){sql=sql+" "+con3+" "+type3+" like '%"+SearchBox3+"%'";}else {sql=sql+" "+con3+" "+type3+"='"+SearchBox3+"'";}}}//4if(type4!=null) {String SearchBox4=req.getParameter("SearchBox4");System.out.println(SearchBox4);if(!SearchBox4.equals("")&&SearchBox4!=null) {if(method4.equals("mohu")){sql=sql+" "+con4+" "+type4+" like '%"+SearchBox4+"%'";}else {sql=sql+" "+con4+" "+type4+"='"+SearchBox4+"'";}}}//5if(type5!=null) {String SearchBox5=req.getParameter("SearchBox5");System.out.println(SearchBox5);if(!SearchBox5.equals("")&&SearchBox5!=null) {if(method5.equals("mohu")){sql=sql+" "+con5+" "+type5+" like '%"+SearchBox5+"%'";}else {sql=sql+" "+con5+" "+type5+"='"+SearchBox5+"'";}}}//6if(type6!=null) {String SearchBox6=req.getParameter("SearchBox6");System.out.println(SearchBox6);if(!SearchBox6.equals("")&&SearchBox6!=null) {if(method6.equals("mohu")){sql=sql+" "+con6+" "+type6+" like '%"+SearchBox6+"%'";}else {sql=sql+" "+con6+" "+type6+"='"+SearchBox6+"'";}}}List<Bean> list=Dao.searchs(sql);if(!list.isEmpty()) {req.setAttribute("list", list);try {req.getRequestDispatcher("show.jsp").forward(req, resp);} catch (ServletException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}else {try {req.getRequestDispatcher("error.jsp").forward(req, resp);} catch (ServletException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}

// 查询信息private void search(HttpServletRequest req, HttpServletResponse resp) {// TODO Auto-generated method stubtry {req.setCharacterEncoding("utf-8");} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();}String info=req.getParameter("name");String search=req.getParameter("search");//按姓名查找if(search.equals("name")) {List<Bean> list=service.search(info);req.setAttribute("list", list);}//按性别查询else if(search.equals("sex")) {List<Bean> list=service.search1(info);req.setAttribute("list", list);}//按民族查询else if(search.equals("minzu")) {List<Bean> list=service.search2(info);req.setAttribute("list", list);}//按政治面貌查询else if(search.equals("mianmao")) {List<Bean> list=service.search3(info);req.setAttribute("list", list);}//按服务类别查询 可模糊查询else if(search.equals("fuwuleibie")) {List<Bean> list=service.search4(info);req.setAttribute("list", list);}//按注册时间查询 可模糊查询else if(search.equals("zhucetime")) {List<Bean> list=service.search5(info);req.setAttribute("list", list);}try {req.getRequestDispatcher("show.jsp").forward(req, resp);} catch (ServletException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}
  //遍历数据库private void show(HttpServletRequest req, HttpServletResponse resp) {// TODO Auto-generated method stubtry {req.setCharacterEncoding("utf-8");} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();}List<Bean> list= service.show();req.setAttribute("list", list);try {req.getRequestDispatcher("show.jsp").forward(req, resp);} catch (ServletException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}   //删除信息private void Delete(HttpServletRequest req, HttpServletResponse resp) {// TODO Auto-generated method stubtry {req.setCharacterEncoding("utf-8");} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();}String name=req.getParameter("name");System.out.println(name);service.delete(name);try {req.getRequestDispatcher("main.jsp").forward(req, resp);} catch (ServletException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}
private void update(HttpServletRequest req, HttpServletResponse resp) {// TODO Auto-generated method stubtry {req.setCharacterEncoding("utf-8");} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();}String name=req.getParameter("name");String sex=req.getParameter("sex");String mianmao=req.getParameter("mianmao");//多个选项，变化为String类型存储String[] list=req.getParameterValues("fuwuleibie");String fuwuleibie="";for(int i=0;i<list.length;i++) {fuwuleibie+=list[i];if(i!=list.length-1) {fuwuleibie+="，";}}Bean use=new Bean(name,sex,"","","",mianmao,fuwuleibie);System.out.println(use.getSex());System.out.println("servlet 修改");service.update(use);try {req.getRequestDispatcher("Servlet?method=show").forward(req, resp);} catch (ServletException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}
private void insert(HttpServletRequest req, HttpServletResponse resp) {// TODO Auto-generated method stubtry {req.setCharacterEncoding("utf-8");} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();}String name=req.getParameter("name");String sex=req.getParameter("sex");String minzu=req.getParameter("minzu");String zhucetime=req.getParameter("zhucetime");String age=req.getParameter("age");String mianmao=req.getParameter("mianmao");String[] list=req.getParameterValues("fuwuleibie");String fuwuleibie="";for(int i=0;i<list.length;i++) {fuwuleibie+=list[i];if(i!=list.length-1) {fuwuleibie+="，";}}System.out.println(fuwuleibie);Bean e=new Bean(name,sex,minzu,zhucetime,age,mianmao,fuwuleibie);if(service.insert(e)) {try {req.setAttribute("message","添加成功");req.getRequestDispatcher("Servlet?method=show").forward(req, resp);} catch (ServletException e1) {// TODO Auto-generated catch blocke1.printStackTrace();} catch (IOException e1) {// TODO Auto-generated catch blocke1.printStackTrace();}}else {try {req.setAttribute("message", "添加重复,请重新输入");  req.getRequestDispatcher("insert.jsp").forward(req, resp);} catch (ServletException e1) {// TODO Auto-generated catch blocke1.printStackTrace();} catch (IOException e1) {// TODO Auto-generated catch blocke1.printStackTrace();}}}  
}