Flink 是一個分布式計算引擎，能夠處理異步的工作流程，有助于解決不同數據源（例如：MySQL）之間的一致性問題，特別是在涉及多個數據源之間的復雜事務時。

MySQL 兩階段提交是在 Flink 中實現 ACID 事務的方法之一。操作系統中的基本思想是將對全局數據的修改拆分成不同的階段。每個階段都需要確認是否可以繼續進行。如果可以，就繼續；否則，中止整個過程。下面來具體了解 Flink 中的 MySQL 兩階段提交。

public class FlinkMySQLTwoPhaseCommitSinkFunction extends TwoPhaseCommitSinkFunction<T, Connection, Void> {
private static final long serialVersionUID = 1L;
private String driverName;
private String dbUrl;
private String query;
private String username;
private String password;
private PreparedStatement ps;
public FlinkMySQLTwoPhaseCommitSinkFunction(String driverName, String dbUrl, String username, String password, String query) {
super(new JdbcConnectionProvider<Connection>() {
private static final long serialVersionUID = 1L;
@Override
public Connection getConnection() throws SQLException {
try {
Class.forName(driverName);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
return DriverManager.getConnection(dbUrl, username, password);
}
}, new FlinkMySQLTwoPhaseCommitSinkFunction.PrepareStatementCallback(), new FlinkMySQLTwoPhaseCommitSinkFunction.CommitCallback(),
new FlinkMySQLTwoPhaseCommitSinkFunction.RollbackCallback());
this.driverName = driverName;
this.dbUrl = dbUrl;
this.username = username;
this.password = password;
this.query = query;
}
private static class PrepareStatementCallback implements SerializableFunction<Connection, PreparedStatement> {
private static final long serialVersionUID = 1L;
@Override
public PreparedStatement apply(Connection connection) throws Exception {
return connection.prepareStatement(query);
}
}
private static class CommitCallback implements SerializableConsumer<Connection> {
private static final long serialVersionUID = 1L;
@Override
public void accept(Connection connection) throws Exception {
connection.commit();
}
}
private static class RollbackCallback implements SerializableConsumer<Connection> {
private static final long serialVersionUID = 1L;
@Override
public void accept(Connection connection) throws Exception {
connection.rollback();
}
}
@Override
protected void invoke(Connection connection, T data, Context context) throws SQLException {
ps.setObject(1, data.getField(0));
ps.setObject(2, data.getField(1));
ps.executeUpdate();
}
public void setQuery(String query) {
this.query = query;
}
public void open(Configuration parameters) throws Exception {
ps = getConnection().prepareStatement(query);
}
public void close() throws Exception {
if (ps != null) {
ps.close();
}
super.close();
}
public static void main(String[] args) throws Exception {
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
env.setParallelism(2);
DataStreamSource<Tuple2<Integer, String>> source = env.fromElements(
Tuple2.of(1, "one"),
Tuple2.of(2, "two"));
String query = "INSERT INTO test (id, name) VALUES (?,?)";
FlinkMySQLTwoPhaseCommitSinkFunction sinkFunction = new FlinkMySQLTwoPhaseCommitSinkFunction("com.mysql.jdbc.Driver",
"jdbc:mysql://localhost:3306/test", "root", "123456", query);
sinkFunction.setQuery(query);
source.addSink(sinkFunction);
env.execute("Flink MySQL Two Phase Commit");
}
}

在上面的代碼中，實現了 Flink 平臺的 MySQL 兩階段提交。首先定義一個繼承了 TwoPhaseCommitSinkFunction 類的拓撲結構，然后在各個階段中實現了主要的操作。這種方法是實現 ACID 事務的其中一種方法，特別是在涉及到多個數據源的時候。