JDBC编程之事务处理

当插入数据遇到唯一性约束时，数据插入失败，如下列操作，插入tbl_user成功，但是插入tbl_address失败，因为id为1已经存在。

package com.djx.jdbc;

import java.sql.DriverManager;
import java.sql.SQLException;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;

public class TransactionTest {
	
	public static Connection getConnection() {
		Connection conn=null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn=(Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/jsp_db?autoReconnect=true&useSSL=false","root","1234");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}
	
	public static void insertTbUserData() {
		Connection conn=getConnection();
		String sql="insert into tbl_user(id,name,password,email) values(10,'Tom','1234','[email protected]')";
		int count;
		try {
			Statement statement=(Statement)conn.createStatement();
			count = statement.executeUpdate(sql);
			System.out.println("向用户表中插入"+count+"条记录");
		    statement.close();
		    conn.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	
	public static void insertTbAddressData() {
		Connection conn=getConnection();
		String sql="insert into tbl_address(id,city,country,user_id) values(1,'深圳','中国',10)";
		int count;
		try {
			Statement statement=(Statement)conn.createStatement();
			count = statement.executeUpdate(sql);
			System.out.println("向用户表中插入"+count+"条记录");
		    statement.close();
		    conn.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		insertTbUserData();
		insertTbAddressData();
	}

}

利用事务回滚就可以防止错误的插入，如下代码

package com.djx.jdbc;

import java.sql.DriverManager;
import java.sql.SQLException;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;

public class TransactionTest {
	
	public static Connection getConnection() {
		Connection conn=null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn=(Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/jsp_db?autoReconnect=true&useSSL=false","root","1234");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}
	
	public static void insertTbUserData(Connection conn) throws SQLException {
		
		String sql="insert into tbl_user(id,name,password,email) values(10,'Tom','1234','[email protected]')";
		int count;
			Statement statement=(Statement)conn.createStatement();
			count = statement.executeUpdate(sql);
			System.out.println("向用户表中插入"+count+"条记录");
		    statement.close();
	}
	
	public static void insertTbAddressData(Connection conn) throws SQLException{
		
		String sql="insert into tbl_address(id,city,country,user_id) values(1,'深圳','中国',10)";
		int count;
		
			Statement statement=(Statement)conn.createStatement();
			count = statement.executeUpdate(sql);
			System.out.println("向用户表中插入"+count+"条记录");
		    statement.close();
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Connection conn=null;
		try {
			conn=getConnection();
			conn.setAutoCommit(false);
			insertTbUserData(conn);
			insertTbAddressData(conn);
			conn.commit();//提交事务
		} catch (SQLException e) {
			System.out.println("======捕获到SQL异常======");
			e.printStackTrace();
			try {
				conn.rollback();//事务回滚
				System.out.println("======事务回滚成功======");
			} catch (Exception e2) {
				// TODO: handle exception
				e2.printStackTrace();
			}
			}
		finally {
			try {
				if (conn!=null) {
					conn.close();
				}
				
			} catch (Exception e3) {
				// TODO: handle exception
			}
		}
	}
}

利用事务回滚，如果下面插入错误，则上面插入也将不成功。