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使用Apache Flink实现实时数据同步与清洗：MySQL和Oracle到目标MySQL的ETL流程

实现数据同步的ETL（抽取、转换、加载）过程通常涉及从源系统（如数据库、消息队列或文件）中抽取数据，进行必要的转换，然后将数据加载到目标系统（如另一个数据库或数据仓库）。在这里，我们将展示如何使用Apache Flink来实现一个从MySQL或Oracle数据库抽取数据并同步到另一个MySQL数据库的ETL过程。

• 1. 从源数据库(MySQL和Oracle)实时抽取数据。
• 2. 对数据进行清洗和转换。
• 3. 将转换后的数据写入目标数据库(MySQL)。
  

我们将使用Apache Flink来实现这个流程。Flink具有强大的数据流处理能力，适合处理实时数据同步和转换任务。

环境准备

• 确保MySQL和Oracle数据库运行**，并创建相应的表。
• 创建Spring Boot项目，并添加Flink、MySQL JDBC、和Oracle JDBC驱动的依赖。

第一步：创建源和目标数据库表

假设我们有以下三个表：

• source_mysql_table（MySQL中的源表）
• source_oracle_table（Oracle中的源表）
• target_table（目标MySQL表）

MySQL源表

CREATE DATABASE source_mysql_db;
USE source_mysql_db;CREATE TABLE source_mysql_table (id INT AUTO_INCREMENT PRIMARY KEY,user_id VARCHAR(255) NOT NULL,action VARCHAR(255) NOT NULL,timestamp VARCHAR(255) NOT NULL
);

Oracle源表

CREATE TABLE source_oracle_table (id NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,user_id VARCHAR2(255) NOT NULL,action VARCHAR2(255) NOT NULL,timestamp VARCHAR2(255) NOT NULL,PRIMARY KEY (id)
);

目标MySQL表

CREATE DATABASE target_db;
USE target_db;CREATE TABLE target_table (id INT AUTO_INCREMENT PRIMARY KEY,user_id VARCHAR(255) NOT NULL,action VARCHAR(255) NOT NULL,timestamp VARCHAR(255) NOT NULL
);

第二步：添加项目依赖

在pom.xml中添加Flink、MySQL和Oracle相关的依赖：

<dependencies><!-- Spring Boot dependencies --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><!-- Apache Flink dependencies --><dependency><groupId>org.apache.flink</groupId><artifactId>flink-streaming-java_2.12</artifactId><version>1.14.0</version></dependency><dependency><groupId>org.apache.flink</groupId><artifactId>flink-clients_2.12</artifactId><version>1.14.0</version></dependency><!-- MySQL JDBC driver --><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.23</version></dependency><!-- Oracle JDBC driver --><dependency><groupId>com.oracle.database.jdbc</groupId><artifactId>ojdbc8</artifactId><version>19.8.0.0</version></dependency>
</dependencies>

第三步：编写Flink ETL任务

创建一个Flink任务类来实现ETL逻辑。

创建一个POJO类表示数据结构

package com.example.flink;public class UserAction {private int id;private String userId;private String action;private String timestamp;// Getters and setterspublic int getId() {return id;}public void setId(int id) {this.id = id;}public String getUserId() {return userId;}public void setUserId(String userId) {this.userId = userId;}public String getAction() {return action;}public void setAction(String action) {this.action = action;}public String getTimestamp() {return timestamp;}public void setTimestamp(String timestamp) {this.timestamp = timestamp;}
}

编写Flink任务类

package com.example.flink;import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.common.functions.RichFlatMapFunction;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.source.SourceFunction;
import org.apache.flink.util.Collector;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;@Component
public class FlinkETLJob implements CommandLineRunner {@Overridepublic void run(String... args) throws Exception {final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();// 从MySQL读取数据DataStream<UserAction> mysqlDataStream = env.addSource(new MySQLSource());// 从Oracle读取数据DataStream<UserAction> oracleDataStream = env.addSource(new OracleSource());// 合并两个数据流DataStream<UserAction> mergedStream = mysqlDataStream.union(oracleDataStream);// 清洗和转换数据DataStream<UserAction> transformedStream = mergedStream.map(new MapFunction<UserAction, UserAction>() {@Overridepublic UserAction map(UserAction value) throws Exception {// 进行清洗和转换value.setAction(value.getAction().toUpperCase());return value;}});// 将数据写入目标MySQL数据库transformedStream.addSink(new MySQLSink());// 执行任务env.execute("Flink ETL Job");}public static class MySQLSource implements SourceFunction<UserAction> {private static final String JDBC_URL = "jdbc:mysql://localhost:3306/source_mysql_db";private static final String JDBC_USER = "source_user";private static final String JDBC_PASSWORD = "source_password";private volatile boolean isRunning = true;@Overridepublic void run(SourceContext<UserAction> ctx) throws Exception {try (Connection connection = DriverManager.getConnection(JDBC_URL, JDBC_USER, JDBC_PASSWORD)) {while (isRunning) {String sql = "SELECT * FROM source_mysql_table";try (PreparedStatement statement = connection.prepareStatement(sql);ResultSet resultSet = statement.executeQuery()) {while (resultSet.next()) {UserAction userAction = new UserAction();userAction.setId(resultSet.getInt("id"));userAction.setUserId(resultSet.getString("user_id"));userAction.setAction(resultSet.getString("action"));userAction.setTimestamp(resultSet.getString("timestamp"));ctx.collect(userAction);}}Thread.sleep(5000); // 模拟实时数据流，每5秒查询一次}}}@Overridepublic void cancel() {isRunning = false;}}public static class OracleSource implements SourceFunction<UserAction> {private static final String JDBC_URL = "jdbc:oracle:thin:@localhost:1521:orcl";private static final String JDBC_USER = "source_user";private static final String JDBC_PASSWORD = "source_password";private volatile boolean isRunning = true;@Overridepublic void run(SourceContext<UserAction> ctx) throws Exception {try (Connection connection = DriverManager.getConnection(JDBC_URL, JDBC_USER, JDBC_PASSWORD)) {while (isRunning) {String sql = "SELECT * FROM source_oracle_table";try (PreparedStatement statement = connection.prepareStatement(sql);ResultSet resultSet = statement.executeQuery()) {while (resultSet.next()) {UserAction userAction = new UserAction();userAction.setId(resultSet.getInt("id"));userAction.setUserId(resultSet.getString("user_id"));userAction.setAction(resultSet.getString("action"));userAction.setTimestamp(resultSet.getString("timestamp"));ctx.collect(userAction);}}Thread.sleep(5000); // 模拟实时数据流，每5秒查询一次}}}@Overridepublic void cancel() {isRunning = false;}}public static class MySQLSink extends RichFlatMapFunction<UserAction, Void> {private static final String JDBC_URL = "jdbc:mysql://localhost:3306/target_db";private static final String JDBC_USER = "target_user";private static final String JDBC_PASSWORD = "target_password";private transient Connection connection;private transient PreparedStatement statement;@Overridepublic void open(Configuration parameters) throws Exception {super.open(parameters);connection = DriverManager.getConnection(JDBC_URL, JDBC_USER, JDBC_PASSWORD);String sql = "INSERT INTO target_table (user_id, action, timestamp) VALUES (?, ?, ?)";statement = connection.prepareStatement(sql);}@Overridepublic void flatMap(UserAction value, Collector<Void> out) throws Exception {statement.setString(1, value.getUserId());statement.setString(2, value.getAction());statement.setString(3, value.getTimestamp());statement.executeUpdate();}@Overridepublic void close() throws Exception {super.close();if (statement != null) {statement.close();}if (connection != null) {connection.close();}}}
}

第四步：配置Spring Boot

在application.properties中添加必要的配置：

# Spring Boot configuration
server.port=8080

第五步：运行和测试

• 启动MySQL和Oracle数据库：确保你的源和目标数据库已经运行，并且创建了相应的数据库和表。
• 启动Spring Boot应用：启动Spring Boot应用程序，会自动运行Flink ETL任务。
• 测试Flink ETL任务：插入一些数据到源数据库的表中，验证数据是否同步到目标数据库的表中。

总结

通过上述步骤，你可以在Spring Boot项目中集成Flink并实现实时数据同步和ETL流程。这个示例展示了如何从MySQL和Oracle源数据库实时抽取数据，进行数据清洗和转换，并将结果加载到目标MySQL数据库中。根据你的具体需求，你可以扩展和修改这个示例，处理更复杂的数据转换和加载逻辑。