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','tom@163.com')";
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','tom@163.com')";
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。