Android 之JDBC

JDBC(Java DataBase Connectivity)是使用 Java 存取数据库系统的标准解决方案，它将不同数据库间各自差异API与标准 SQL语句分开看待，实现数据库无关的 Java操作接口。

JDBC程序访问数据库的步骤 

步骤一：加载JDBC驱动程序:Class.forName("com.mysql.jdbc.Driver");Oracle10g：oracle.jdbc.driver.OracleDriver;MySQL5：com.mysql.jdbc.Driver;SQLServer2005：com.microsoft.sqlserver.jdbc.SQLServerDriver

步骤二：提供连接参数:URL,USERNAME, PASSWORD:不同数据库产品的连接URL不同

Oracle10g：jdbc:oracle:thin:@主机名:端口:数据库SID

jdbc:oracle:thin:@localhost:1521:ORCL

MySQL5：jdbc:mysql://主机名:端口/数据库名

jdbc:mysql://localhost:3306/test       

SQLServer2005：jdbc:sqlserver://主机名:端口:DatabaseName=库名

jdbc:sqlserver://localhost:1433:DatabaseName=BookDB

步骤三：建立一个数据库的连接:connection=DriverManager.getConnection(URL,USERNAME, PASSWORD);

步骤四：创建一个statement:preparedStatement=connection.prepareStatement(sql);

步骤五：执行SQL语句:result=preparedStatement.executeUpdate();

步骤六：处理结果:flag=result>0?true:false;return flag;

步骤七：关闭JDBC对象:if(resultSet!=null){resultSet.close();}if(preparedStatement!=null){preparedStatement.close();}if(connection!=null){connection.close();}

 package com.jdbc.dbUtils;
 
 import java.lang.reflect.Field;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 import com.jdbc.dbUtils.dormain.UserInfo;
 
 public class JDBCutils {
 
     private final String USERNAME="root";
     private final String PASSWORD="admin";
     private final String DRIVER="com.mysql.jdbc.Driver";
     private final String URL="jdbc:mysql://localhost:3306/mydb";
 
     private Connection connection;
     private PreparedStatement preparedStatement;
     private ResultSet resultSet;
 
     public JDBCutils() {
         try {
             Class.forName(DRIVER);//注册驱动
             System.out.println("成功注册驱动");
 
         } catch (Exception e) {
             // TODO: handle exception
         }
     }
 
     public Connection getConnection(){
         try {
             connection=DriverManager.getConnection(URL,USERNAME, PASSWORD);
         } catch (Exception e) {
             // TODO: handle exception
             e.printStackTrace();
         }
         return connection;
     }
     //增删改
     public boolean updateByPreparedStatement(String sql,List<Object> params)throws SQLException {
         boolean flag=false;
         int result=-;//执行增删改操作的时候所影响的行数
         int index=;//占位符的第一个位置
         preparedStatement=connection.prepareStatement(sql);
         if(params!=null&&!params.isEmpty()){
             for (int i = ; i < params.size(); i++) {
                 preparedStatement.setObject(index++, params.get(i));
             }
         }
         result=preparedStatement.executeUpdate();
         flag=result>?true:false;
         return flag;
     }
     //查询 返回单条记录
     public Map<String,Object> findSimpleResult(String sql,List<Object> params) throws SQLException{
         Map<String,Object> map=new HashMap<String,Object>();
         int index=;//占位符的第一个位置
         preparedStatement=connection.prepareStatement(sql);
         if(params!=null&&!params.isEmpty()){
             for (int i = ; i < params.size(); i++) {
                 preparedStatement.setObject(index++, params.get(i));
             }
         }
         resultSet=preparedStatement.executeQuery();
         ResultSetMetaData resultSetMetaData=resultSet.getMetaData();
         int col_len=resultSetMetaData.getColumnCount();//得到数据库表的列
         while(resultSet.next()){
             for (int i = ; i < col_len; i++) {
                 String col_name=resultSetMetaData.getColumnName(i+);
                 Object col_val=resultSet.getObject(col_name);
                 if(col_val==null){
                     col_val="";
                 }
                 map.put(col_name,col_val);
             }
         }
         return map;
 
     }
     //查询 返回多条记录
     public List<Map<String,Object>> findMultiResult(String sql,List<Object> params) throws SQLException{
         List<Map<String,Object>> list=new ArrayList<Map<String,Object>>();
         int index=;//占位符的第一个位置
         preparedStatement=connection.prepareStatement(sql);
         if(params!=null&&!params.isEmpty()){
             for (int i = ; i < params.size(); i++) {
                 preparedStatement.setObject(index++, params.get(i));
             }
         }
         resultSet=preparedStatement.executeQuery();
         ResultSetMetaData resultSetMetaData=resultSet.getMetaData();
         int col_len=resultSetMetaData.getColumnCount();//得到数据库表的列名
         while(resultSet.next()){
             Map<String,Object>map=new HashMap<String,Object>();
             for (int i = ; i < col_len; i++) {
                 String col_name=resultSetMetaData.getColumnName(i+);
                 Object col_val=resultSet.getObject(col_name);
                 if(col_val==null){
                     col_val="";
                 }
                 map.put(col_name,col_val);
             }
             list.add(map);
         }
         return list;
 
     }
     //jdbc的封装也可以采用反射机制
     public <T> T findSimpReflectResult(String sql,List<Object> params,Class<T> cls) throws Exception{
         T resObj=null;
         int index=;//占位符的第一个位置
         preparedStatement=connection.prepareStatement(sql);
         if(params!=null&&!params.isEmpty()){
             for (int i = ; i < params.size(); i++) {
                 preparedStatement.setObject(index++, params.get(i));
             }
         }
         resultSet=preparedStatement.executeQuery();
         ResultSetMetaData resultSetMetaData=resultSet.getMetaData();
         int col_len=resultSetMetaData.getColumnCount();//得到数据库表的列名
         while(resultSet.next()){
             resObj=cls.newInstance();//通过反射机制创建实例
             for (int i = ; i < col_len; i++) {
                 String col_name=resultSetMetaData.getColumnName(i+);
                 Object col_val=resultSet.getObject(col_name);
                 if(col_val==null){
                     col_val="";
                 }
                 Field field=cls.getDeclaredField(col_name);
                 field.setAccessible(true);//打开访问javabean的私有权限
                 field.set(resObj, col_val);
             }
         }
         return resObj;
     }
     public <T> List<T> findMultiReflectResult(String sql,List<Object> params,Class<T> cls) throws Exception{
         List<T> list=new ArrayList<T>();
         int index=;//占位符的第一个位置
         preparedStatement=connection.prepareStatement(sql);
         if(params!=null&&!params.isEmpty()){
             for (int i = ; i < params.size(); i++) {
                 preparedStatement.setObject(index++, params.get(i));
             }
         }
         resultSet=preparedStatement.executeQuery();
         ResultSetMetaData resultSetMetaData=resultSet.getMetaData();
         int col_len=resultSetMetaData.getColumnCount();//得到数据库表的列名
         while(resultSet.next()){
             T resObj=cls.newInstance();//通过反射机制创建实例
             for (int i = ; i < col_len; i++) {
                 String col_name=resultSetMetaData.getColumnName(i+);
                 Object col_val=resultSet.getObject(col_name);
                 if(col_val==null){
                     col_val="";
                 }
                 Field field=cls.getDeclaredField(col_name);
                 field.setAccessible(true);//打开访问javabean的私有权限
                 field.set(resObj, col_val);
             }
             list.add(resObj);
         }
         return list;
     }
     public void releaseConnection() throws SQLException{
         if(resultSet!=null){
             resultSet.close();
         }
         if(preparedStatement!=null){
             preparedStatement.close();
         }
         if(connection!=null){
             connection.close();
         }
     }
     public static void main(String[] args) throws Exception {
         // TODO Auto-generated method stub
         JDBCutils jdbc=new JDBCutils();
         jdbc.getConnection();
         List<Object> params=new ArrayList<Object>();
 
         /*    params.add("fjf");
         params.add("123");
         params.add("fanjingfang");
         String sql="insert into userinfo(username,password,realname)values(?,?,?)";
         boolean flag=jdbc.updateByPreparedStatement(sql, params);
         System.out.println(flag);
         params.add(1);
         String sql="select * from userinfo where id=?";
         Map<String,Object> m=jdbc.findSimpleResult(sql, params);
         System.out.println(m);*/
 
         /*String sql2="select * from userinfo ";
         List<Map<String,Object>> list=jdbc.findMultiResult(sql2, null);
         System.out.println(list);*/
 
     /*    params.add(1);
         String sql3="select * from userinfo where id=? ";
         UserInfo u=jdbc.findSimpReflectResult(sql3, params,UserInfo.class);
         System.out.println(u);*/
 
         String sql4="select * from userinfo ";
         List<UserInfo> list=jdbc.findMultiReflectResult(sql4, null,UserInfo.class);
         System.out.println(list);
     }
 
 }