mysql数据库行级锁的使用

Posted 2020-08-05 梦见舟

项目上的另外一个需求是：

在做统计的时候需要将当前表锁定不能更新当前表记录

直接上代码

package com.robert.RedisTest;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Calendar;
import java.util.concurrent.TimeUnit;

public class JDBCCountLockTest {
    
    private static String jdbcUrl = "jdbc:mysql://localhost:3306/test";
    private static String username = "test";
    private static String password = "test";
    
    public static void main(String[] args) {
        
        new Thread(new Runnable(){
            public void run(){                    
                try {
                    Class.forName("com.mysql.jdbc.Driver");
                    Connection connection = DriverManager.getConnection(jdbcUrl,username,password);
                    connection.setAutoCommit(false);
                    Statement st = connection.createStatement();
                    st.executeQuery("select count(1) num from table_name where mobile_phone = ‘13651969037‘ and rule_id=‘39‘ for update");
                    TimeUnit.SECONDS.sleep(5);
                    connection.commit();
                    System.out.println("Thread 1 commit "+Calendar.getInstance().getTime());
                } catch (ClassNotFoundException e) {
                    e.printStackTrace();
                } catch (SQLException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
        
        new Thread(new Runnable(){
            public void run(){                    
                try {
                    Class.forName("com.mysql.jdbc.Driver");
                    Connection connection = DriverManager.getConnection(jdbcUrl,username,password);
                    connection.setAutoCommit(false);
                    Statement st = connection.createStatement();
                    TimeUnit.SECONDS.sleep(1);
                    st.executeQuery("select * from table_name where id=4139 for update");
                    System.out.println("Thread 2 executeQuery finish "+Calendar.getInstance().getTime());
                    String update_sql_1 = "update table_name set rule_id=‘40‘  where id = ‘4139‘";
                    st.executeUpdate(update_sql_1);
                    System.out.println("Thread 2 executeUpdate finish "+Calendar.getInstance().getTime());
                    connection.commit();
                } catch (ClassNotFoundException e) {
                    e.printStackTrace();
                } catch (SQLException e) {
                    e.printStackTrace();
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}

在Thread 2中 先sleep 1s

保证了Thread 1先执行

然后在Thread 1执行结束之后，Thread 2才能执行更新操作。

执行结果如下：

Thread 1 commit Thu Sep 01 15:58:51 CST 2016
Thread 2 executeQuery finish Thu Sep 01 15:58:51 CST 2016
Thread 2 executeUpdate finish Thu Sep 01 15:58:51 CST 2016