Flink 自定义 Source 读取 MySQL 数据并更新状态 - 实战指南

要实现这个需求，首先需要自定义一个Flink的Source函数来读取MySQL中t_login_status表中read_status='0'的数据。然后，在读取数据完成后，将这些数据的read_status字段更新为'1'。\n\n以下是一个实现示例：\n\njava\nimport org.apache.flink.streaming.api.functions.source.SourceFunction;\nimport org.apache.flink.streaming.api.functions.source.SourceContext;\n\nimport java.sql.*;\n\npublic class MySQLSource implements SourceFunction<LoginStatus> {\n private String url;\n private String username;\n private String password;\n\n public MySQLSource(String url, String username, String password) {\n this.url = url;\n this.username = username;\n this.password = password;\n }\n\n @Override\n public void run(SourceContext<LoginStatus> sourceContext) throws Exception {\n Connection connection = null;\n PreparedStatement statement = null;\n ResultSet resultSet = null;\n\n try {\n connection = DriverManager.getConnection(url, username, password);\n statement = connection.prepareStatement("SELECT * FROM t_login_status WHERE read_status='0'");\n resultSet = statement.executeQuery();\n\n while (resultSet.next()) {\n int id = resultSet.getInt("id");\n String userId = resultSet.getString("user_id");\n int readStatus = resultSet.getInt("read_status");\n\n LoginStatus loginStatus = new LoginStatus(id, userId, readStatus);\n sourceContext.collect(loginStatus);\n }\n\n // 更新read_status为1\n updateReadStatus(connection);\n } finally {\n if (resultSet != null) {\n resultSet.close();\n }\n if (statement != null) {\n statement.close();\n }\n if (connection != null) {\n connection.close();\n }\n }\n }\n\n @Override\n public void cancel() {\n // 取消操作\n }\n\n private void updateReadStatus(Connection connection) throws SQLException {\n PreparedStatement updateStatement = connection.prepareStatement("UPDATE t_login_status SET read_status='1' WHERE read_status='0'");\n updateStatement.executeUpdate();\n updateStatement.close();\n }\n}\n\nclass LoginStatus {\n private int id;\n private String userId;\n private int readStatus;\n\n public LoginStatus(int id, String userId, int readStatus) {\n this.id = id;\n this.userId = userId;\n this.readStatus = readStatus;\n }\n\n // Getter和Setter方法省略\n}\n\n\n然后，在Flink程序中使用自定义的Source函数：\n\njava\nimport org.apache.flink.streaming.api.datastream.DataStream;\nimport org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;\n\npublic class Main {\n public static void main(String[] args) throws Exception {\n StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();\n\n String url = "jdbc:mysql://localhost:3306/db_name";\n String username = "root";\n String password = "password";\n\n MySQLSource source = new MySQLSource(url, username, password);\n DataStream<LoginStatus> dataStream = env.addSource(source);\n\n // 对读取到的数据进行处理，如打印出来\n dataStream.print();\n\n env.execute("Read MySQL Source");\n }\n}\n\n\n这样就可以实现自定义Flink Source读取MySQL中t_login_status表中read_status='0'的数据，并将其更新为'1'。