如何查看 JDBC / MySQL 的 TRANSACTION_REPEATABLE_READ 操作？

我的计算机上当前运行 MySQL 服务器 (5.7.16)，并且此服务器上名为“Sakila”的数据库中有此示例行：

mysql> SELECT * FROM actor WHERE last_name = 'tugay';
+----------+------------+-----------+---------------------+
| actor_id | first_name | last_name | last_update         |
+----------+------------+-----------+---------------------+
|      201 | koray      | tugay     | 2017-06-11 21:42:08 |
+----------+------------+-----------+---------------------+

这是 JDBC 返回的 MySQL 服务器事务隔离级别：

public static void main(String[] args) throws SQLException, InterruptedException {
    final Connection connection = getConnection("jdbc:mysql://localhost:3306/sakila", "root", "root");
    System.out.println(connection.getTransactionIsolation()); // Prints 4!
    connection.close();
}

where 4这是常数TRANSACTION_REPEATABLE_READ这是有记录的 https://docs.oracle.com/javase/7/docs/api/java/sql/Connection.html#TRANSACTION_REPEATABLE_READ如下：

int TRANSACTION_REPEATABLE_READ  = 4;
A constant indicating that dirty reads are prevented. 
This level prohibits a transaction from reading a row with uncommitted changes in it.

我想看到这种行为，所以我有两个主要方法，第一个是：

import java.sql.*;

import static java.sql.DriverManager.*;

public class Foo {

    public static void main(String[] args) throws SQLException, InterruptedException {
        final Connection connection = getConnection("jdbc:mysql://localhost:3306/sakila", "root", "root");
        connection.setAutoCommit(false);

        final Statement statement = connection.createStatement();
        statement.executeUpdate("UPDATE actor SET first_name = 'ALTERED' WHERE first_name = 'koray'");

        System.out.println("Sleeping!");

        // Here I am expecting MySQL to lock the Row so no other Connection
        // can read data from it. This row will be updated, so unless the transaction is 
        // either commited or rolled back, the read data will be 'dirty'.
        Thread.sleep(5000);

        connection.commit();
        connection.close();
    }
}

如您所见，交易是not在自动提交模式下，我锁定该行 5 秒。当这个进程处于睡眠状态时，我也不断运行以下代码：

public class Bar {

    public static void main(String[] args) throws SQLException, InterruptedException {
        final Connection connection = getConnection("jdbc:mysql://localhost:3306/sakila", "root", "root");
        connection.setAutoCommit(false);

        final Statement statement = connection.createStatement();
        final ResultSet resultSet = statement.executeQuery("SELECT * FROM actor WHERE last_name = 'tugay'");

        resultSet.next();
        System.out.println(resultSet.getString("first_name"));

        connection.close();
    }
}

但即使我在控制台中看到“睡眠”文本，只要我在 Bar 中运行 main 方法，我就会看到类似的值

koray
koray
koray
ALTERED

我的期望是永远见不到科雷因为这是一个“脏数据”，第一个 java 进程应该锁定该行。

我缺少什么以及如何锁定这一行？

您应该再次阅读定义：

该级别禁止事务读取未提交的行 其中的变化。

ALTERED 是脏数据，因为它没有提交。科雷是正确的。酒吧禁止看到“ALTERED”。只要交易未提交，您就会一直看到“koray”。