家庭记账本小程序之java代码部分（java web基础版二）
1.数据库连接类
package com.wang.utils; import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement; public class DBUtils {
//数据库名
public static String db_url = "jdbc:mysql://localhost:3306/wang?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT";
public static String db_user = "root"; //用户名
public static String db_password = "123456"; //密码 public static Connection getConn () {
Connection conn = null;
try {
Class.forName("com.mysql.cj.jdbc.Driver");//加载驱动
conn = DriverManager.getConnection(db_url, db_user, db_password);//获取连接对象
} catch (Exception e) {
e.printStackTrace();
}
return conn;
} /**
* 关闭连接
* @param state
* @param conn
*/
public static void close (Statement state, Connection conn) {
if (state != null) {
try {
state.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
} /**
* 关闭连接
* @param rs
* @param state
* @param conn
*/
public static void close (ResultSet rs, Statement state, Connection conn) {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (state != null) {
try {
state.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
} }
DBUtils.java
2.实体类
package com.wang.pojo;
import java.math.BigDecimal;
public class HomeCost {
private int id;//id
private String name;//消费名称
private BigDecimal money;//消费金额
private String date;//消费日期
private BigDecimal sum;//累计消费
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public BigDecimal getMoney() {
return money;
}
public void setMoney(BigDecimal money) {
this.money = money;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public BigDecimal getSum() {
return sum;
}
public void setSum(BigDecimal sum) {
this.sum = sum;
}
@Override
public String toString() {
return "HomeCost [id=" + id + ", name=" + name + ", money=" + money + ", date=" + date + ", sum=" + sum + "]";
}
public HomeCost() {}
public HomeCost(String name, BigDecimal money) {
super();
this.name = name;
this.money = money;
}
public HomeCost(int id,String name,BigDecimal money, String date) {
super();
this.id=id;
this.name = name;
this.money=money;
this.date=date;
}
public HomeCost(int id, String name, BigDecimal money, String date, BigDecimal sum) {
super();
this.id = id;
this.name = name;
this.money = money;
this.date = date;
this.sum = sum;
}
}
HomeCost.java
3.持久化Dao层
package com.wang.dao; import java.math.BigDecimal;
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.wang.pojo.HomeCost;
import com.wang.utils.DBUtils; public class HomeCostDao { /**
* updatesql()用来执行 insert/update/delete语句
* @param sql 具体的sql语句
* @return 返回-1，说明执行失败；否则为影响数据条数
*/
public int updatesql(String sql) {
Connection conn = DBUtils.getConn();//获取连接对象
Statement state = null;
try {
state = conn.createStatement();
return state.executeUpdate(sql);
} catch (Exception e) {
e.printStackTrace();
} finally {
DBUtils.close(state, conn);
}
return -1;
} //添加
public int add(HomeCost homecost) {
//insert语句，形如insert into 表名(字段1，字段2) values('值1','值2');
String sql = "insert into home(name,money) values('"+ homecost.getName()
+ "','" + homecost.getMoney() + "')";
return updatesql(sql);
} //删除
public int delete (int id) {
//delete语句，形如delete from 表名 where id='值';
String sql = "delete from home where id='" + id + "'";
return updatesql(sql);
} //修改
public int update(HomeCost homecost) {
//update语句，形如update 表名 set 字段1 = '值1',字段2 = '值2'where id = '值3';
String sql = "update home set name='" + homecost.getName() + "', money='"
+ homecost.getMoney()+ "' where id='" + homecost.getId() + "'";
return updatesql(sql); } //查询
public List<HomeCost> query(String keyword) {
String sql = "select * from home WHERE name LIKE '%"+keyword+"%' OR money LIKE '%"+keyword
+"%'OR date LIKE '%"+keyword+ "%'";
List<HomeCost> list = new ArrayList<>();
Connection conn = DBUtils.getConn();
Statement state = null;
ResultSet rs = null;
try {
state = conn.createStatement();
rs = state.executeQuery(sql);
while (rs.next()) {
int id = rs.getInt("id");//获取查询结果中的id
String name = rs.getString("name");//获取查询结果中的name
BigDecimal money = rs.getBigDecimal("money");//获取查询结果中的money
String date = rs.getString("date");//获取查询结果中的date
HomeCost homeCost = new HomeCost(id,name,money,date);//调用构造方法赋值
list.add(homeCost);//添加到list集合中
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtils.close(rs, state, conn);
}
return list;
} //通过id找到某条信息
public HomeCost getHomeCostById(int id) {
String sql = "select * from home where id ='" + id + "'";
Connection conn = DBUtils.getConn();
Statement state = null;
ResultSet rs = null;
HomeCost homeCost = null;
try {
state = conn.createStatement();
rs = state.executeQuery(sql);
while (rs.next()) {
String name = rs.getString("name");
BigDecimal money = rs.getBigDecimal("money");
String date = rs.getString("date");
homeCost = new HomeCost(id,name,money,date);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
DBUtils.close(rs, state, conn);
}
return homeCost;
} /**
* 通过id计算该条消费记录累计消费金额
* @return BigDecimal类型money
*/
public BigDecimal queryMoneySum(int id) {
String sql = "select money from home where id <="+id;
BigDecimal sum = new BigDecimal("0.00");
Connection conn = DBUtils.getConn();
Statement state = null;
ResultSet rs = null;
try {
state = conn.createStatement();
rs = state.executeQuery(sql);
while (rs.next()) {
BigDecimal money = rs.getBigDecimal("money");
//sum是money累加值
sum = sum.add(money);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtils.close(rs, state, conn);
}
return sum;
} //获取全部数据
public List<HomeCost> list() {
String sql = "select * from home";
List<HomeCost> list = new ArrayList<>();
Connection conn = DBUtils.getConn();
Statement state = null;
ResultSet rs = null;
try {
state = conn.createStatement();
rs = state.executeQuery(sql);
HomeCost homeCost = null;
while (rs.next()) {
int id = rs.getInt("id");
BigDecimal sum = queryMoneySum(id);
String name = rs.getString("name");
BigDecimal money = rs.getBigDecimal("money");
String date = rs.getString("date");
homeCost = new HomeCost(id,name,money,date,sum);
list.add(homeCost);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBUtils.close(rs, state, conn);
}
return list;
} }
HomeCostDao.java
4.事务层Service层
package com.wang.service; import java.util.List; import com.wang.dao.HomeCostDao;
import com.wang.pojo.HomeCost; public class HomeCostService { HomeCostDao homeCostDao = new HomeCostDao(); //新增消费账单
public int add(HomeCost homecost) {
return homeCostDao.add(homecost);
} //删除消费账单
public int delete(int id) {
return homeCostDao.delete(id);
} //修改消费账单
public int update(HomeCost homecost) {
return homeCostDao.update(homecost);
} //关键字查询
public List<HomeCost> query(String keyword) {
return homeCostDao.query(keyword);
} //全部消费记录
public List<HomeCost> list() {
return homeCostDao.list();
} //由id查找某条消费记录
public HomeCost getHomeCostById(int id) {
return homeCostDao.getHomeCostById(id);
} }
HomeCostService.java
5.Web层Servlet层
Servlet创建方式：项目名右键new--Servlet,使用@WebServlet注解，省去配置web.xml的时间
package com.wang.web; import java.io.IOException;
import java.math.BigDecimal;
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.wang.pojo.HomeCost;
import com.wang.service.HomeCostService;
import com.wang.utils.WebUtils; /**
* 访问地址url:localhost:8080/homeCost/manager/homeCostServlet
* Servlet implementation class HomeCostServlet
*/
@WebServlet("/manager/homeCostServlet")
public class HomeCostServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private HomeCostService homeCostService = new HomeCostService(); protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
} protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String action = request.getParameter("action");
if("add".equals(action)) {
add(request, response);
}else if("delete".equals(action)) {
delete(request, response);
}else if("update".equals(action)) {
update(request, response);
}else if("list".equals(action)) {
list(request, response);
}else if("getHomeCostById".equals(action)) {
getHomeCostById(request, response);
}else if("query".equals(action)) {
query(request, response);
}
} //添加消费记录
protected void add(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取网页提交的参数
String name = request.getParameter("name");
BigDecimal money = WebUtils.bigdecimal(request.getParameter("money"), new BigDecimal(0.00));
//封装成类对象
HomeCost homeCost = new HomeCost(name,money);
//执行添加操作，返回1,添加成功，反之失败
if(homeCostService.add(homeCost) == 1) {
//页面重定向
response.sendRedirect(request.getContextPath()+"/manager/homeCostServlet?action=list");
}else {
//请求转发
request.setAttribute("msg", "添加失败，联系管理员");
request.setAttribute("homeCost", homeCost);
request.getRequestDispatcher("/cost_edit.jsp").forward(request, response);
}
}
//删除消费记录
protected void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取id
int id = WebUtils.parseInt(request.getParameter("id"), 0);
//执行删除操作，返回1,删除成功，反之失败
if (homeCostService.delete(id) == 1) {
//页面重定向
response.sendRedirect(request.getContextPath()+"/manager/homeCostServlet?action=list");
}else {
//请求转发
request.setAttribute("msg", "删除失败，联系管理员");
request.getRequestDispatcher("/manager/homeCostServlet?action=list").forward(request, response);
} }
//修改消费记录
protected void update(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取参数
int id = WebUtils.parseInt(request.getParameter("id"), 0);
String name = request.getParameter("name");
BigDecimal money = WebUtils.bigdecimal(request.getParameter("money"), new BigDecimal(0.00));
String date = request.getParameter("date");
//封装
HomeCost homeCost = new HomeCost(id,name,money,date);
//执行删除操作，返回1,修改成功，反之失败
if(homeCostService.update(homeCost) == 1) {
response.sendRedirect(request.getContextPath()+"/manager/homeCostServlet?action=list");
}else {
request.setAttribute("msg", "修改失败，联系管理员");
request.setAttribute("homeCost", homeCost);
request.getRequestDispatcher("/cost_edit.jsp").forward(request, response);
}
}
//查询全部消费记录
protected void list(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
List<HomeCost> homeCost = homeCostService.list();
request.setAttribute("homeCost", homeCost);
request.getRequestDispatcher("/manager.jsp").forward(request, response); }
//通过id查询该条消费记录
private void getHomeCostById(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int id = WebUtils.parseInt(request.getParameter("id"), 0);
HomeCost homeCost = homeCostService.getHomeCostById(id);
request.setAttribute("homeCost", homeCost);
request.getRequestDispatcher("/cost_edit.jsp").forward(request, response);
}
//通过关键词查询
protected void query(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String keyword=request.getParameter("keyword");
List<HomeCost> homeCost = homeCostService.query(keyword);
request.setAttribute("homeCost", homeCost);
request.getRequestDispatcher("/query.jsp").forward(request, response); } }
HomeCostServlet.java
6.工具类
package com.wang.utils;
import java.math.BigDecimal;
public class WebUtils {
//该类为工具类，封装常用的函数，catch类型转换异常，保障程序健壮性
/**
* String转BigDecimal发生异常返回默认值
* @param str 字符串
* @param defaultValue 默认值
* @return BigDecimal值
*/
public static BigDecimal bigdecimal(String str,BigDecimal defaultValue) {
try {
return new BigDecimal(str);
} catch (Exception e) {
//e.printStackTrace();
}
return defaultValue;
}
/**
* 字符串转int
* @param string 被转换的字符串
* @param defaultValue 默认值
* @return int
*/
public static int parseInt(String string,int defaultValue){
try {
return Integer.parseInt(string);
} catch (NumberFormatException e) {
//e.printStackTrace();
}
return defaultValue;
}
}
WebUtils.java
最终创建Web动态工程如下图：
**************************************************************************************************
注：需额外导入部分jar包，css样式，js文件，如下：
附下载链接（永久链）：
链接：https://pan.baidu.com/s/1XA99yVkFGCEeY0-9_5RAxg
提取码：jg0n
复制这段内容后打开百度网盘手机App，操作更方便哦
完整项目下载地址：
链接：https://pan.baidu.com/s/1AoVdFsq4eGvPehyFjVqIMw
提取码：5gvo
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