Flink官方提供的sink服务可能满足不了我们的需要,此时可以开发自定义的sink,文本就来一起实战;
@Override
public void invoke(IN record) {
writer.write(record);
}
本次实战很简单:自定义sink,用于将数据写入MySQL,涉及的版本信息如下:
如果您不想写代码,整个系列的源码可在GitHub下载到,地址和链接信息如下表所示(https://github.com/zq2599/blog_demos):
名称 | 链接 | 备注 |
---|---|---|
项目主页 | 该项目在GitHub上的主页 | |
git仓库地址(https) | 该项目源码的仓库地址,https协议 | |
git仓库地址(ssh) | git@github.com:zq2599/blog_demos.git | 该项目源码的仓库地址,ssh协议 |
这个git项目中有多个文件夹,本章的应用在flinksinkdemo文件夹下,如下图红框所示:
请您将MySQL准备好,并执行以下sql,用于创建数据库flinkdemo和表student:
create database if not exists flinkdemo;
USE flinkdemo;
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(25) COLLATE utf8_bin DEFAULT NULL,
`age` int(10) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.11</version>
</dependency>
package com.bolingcavalry.customize;
public class Student {
private int id;
private String name;
private int age;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Student(String name, int age) {
this.name = name;
this.age = age;
}
}
package com.bolingcavalry.customize;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.functions.sink.RichSinkFunction;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReentrantLock;
public class MySQLSinkFunction extends RichSinkFunction<Student> {
PreparedStatement preparedStatement;
private Connection connection;
private ReentrantLock reentrantLock = new ReentrantLock();
@Override
public void open(Configuration parameters) throws Exception {
super.open(parameters);
//准备数据库相关实例
buildPreparedStatement();
}
@Override
public void close() throws Exception {
super.close();
try{
if(null!=preparedStatement) {
preparedStatement.close();
preparedStatement = null;
}
} catch(Exception e) {
e.printStackTrace();
}
try{
if(null!=connection) {
connection.close();
connection = null;
}
} catch(Exception e) {
e.printStackTrace();
}
}
@Override
public void invoke(Student value, Context context) throws Exception {
preparedStatement.setString(1, value.getName());
preparedStatement.setInt(2, value.getAge());
preparedStatement.executeUpdate();
}
/**
* 准备好connection和preparedStatement
* 获取mysql连接实例,考虑多线程同步,
* 不用synchronize是因为获取数据库连接是远程操作,耗时不确定
* @return
*/
private void buildPreparedStatement() {
if(null==connection) {
boolean hasLock = false;
try {
hasLock = reentrantLock.tryLock(10, TimeUnit.SECONDS);
if(hasLock) {
Class.forName("com.mysql.cj.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://192.168.50.43:3306/flinkdemo?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=UTC", "root", "123456");
}
if(null!=connection) {
preparedStatement = connection.prepareStatement("insert into student (name, age) values (?, ?)");
}
} catch (Exception e) {
//生产环境慎用
e.printStackTrace();
} finally {
if(hasLock) {
reentrantLock.unlock();
}
}
}
}
}
package com.bolingcavalry.customize;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import java.util.ArrayList;
import java.util.List;
public class StudentSink {
public static void main(String[] args) throws Exception {
final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
//并行度为1
env.setParallelism(1);
List<Student> list = new ArrayList<>();
list.add(new Student("aaa", 11));
list.add(new Student("bbb", 12));
list.add(new Student("ccc", 13));
list.add(new Student("ddd", 14));
list.add(new Student("eee", 15));
list.add(new Student("fff", 16));
env.fromCollection(list)
.addSink(new MySQLSinkFunction())
.disableChaining();
env.execute("sink demo : customize mysql obj");
}
}
至此,自定义sink的实战已经完成,希望本文能给您一些参考