java实现flink的sink mysql的两阶段提交 代码

下面是一个简单的 Java 代码示例，演示如何在 Flink 中实现 Sink MySQL 的两阶段提交。

首先，需要引入 Flink JDBC 连接器的依赖：

<dependency>
    <groupId>org.apache.flink</groupId>
    <artifactId>flink-jdbc_${scala.binary.version}</artifactId>
    <version>${flink.version}</version>
</dependency>

然后，创建一个 Transaction 类，实现两阶段提交协议的相关方法：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class Transaction {
    private final Connection conn;
    private Long transactionId;

    public Transaction(String url, String username, String password) throws SQLException {
        this.conn = DriverManager.getConnection(url, username, password);
    }

    public Long beginTransaction() throws SQLException {
        PreparedStatement stmt = conn.prepareStatement("START TRANSACTION");
        stmt.executeUpdate();
        stmt.close();
        this.transactionId = System.currentTimeMillis();
        return transactionId;
    }

    public boolean prepareTransaction(Long transactionId) throws SQLException {
        PreparedStatement stmt = conn.prepareStatement("PREPARE TRANSACTION ?");
        stmt.setLong(1, transactionId);
        boolean success = stmt.executeUpdate() == 1;
        stmt.close();
        return success;
    }

    public boolean commitTransaction(Long transactionId) throws SQLException {
        PreparedStatement stmt = conn.prepareStatement("COMMIT PREPARED ?");
        stmt.setLong(1, transactionId);
        boolean success = stmt.executeUpdate() == 1;
        stmt.close();
        return success;
    }

    public boolean rollbackTransaction(Long transactionId) throws SQLException {
        PreparedStatement stmt = conn.prepareStatement("ROLLBACK TO ?");
        stmt.setLong(1, transactionId);
        boolean success = stmt.executeUpdate() == 1;
        stmt.close();
        return success;
    }

    public void close() throws SQLException {
        conn.close();
    }
}

接下来，实现 Sink 函数，调用 Transaction 类实现两阶段提交协议的相关逻辑：

import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.functions.sink.RichSinkFunction;

import java.sql.SQLException;

public class MySQLTwoPhaseCommitSink extends RichSinkFunction<String> {
    private final String url;
    private final String username;
    private final String password;
    private Transaction transaction;

    public MySQLTwoPhaseCommitSink(String url, String username, String password) {
        this.url = url;
        this.username = username;
        this.password = password;
    }

    @Override
    public void open(Configuration parameters) throws Exception {
        super.open(parameters);
        transaction = new Transaction(url, username, password);
    }

    @Override
    public void close() throws Exception {
        super.close();
        transaction.close();
    }

    @Override
    public void invoke(String value, Context context) throws Exception {
        Long transactionId = transaction.beginTransaction();
        try {
            // 向 MySQL 数据库提交数据
            // ...

            boolean prepared = transaction.prepareTransaction(transactionId);
            if (prepared) {
                boolean committed = transaction.commitTransaction(transactionId);
                if (!committed) {
                    transaction.rollbackTransaction(transactionId);
                }
            } else {
                transaction.rollbackTransaction(transactionId);
            }
        } catch (SQLException e) {
            transaction.rollbackTransaction(transactionId);
        }
    }
}

最后，在 Flink 程序中使用以上实现的 Sink 函数：

DataStream<String> stream = ...;
MySQLTwoPhaseCommitSink sink = new MySQLTwoPhaseCommitSink("jdbc:mysql://localhost:3306/mydb", "user", "password");
stream.addSink(sink);