通过 FlinkCDC 实现 MySQL 数据库、表的实时变化监控，这里只把变化打印了出来，后面会实现如何再写入其他 MySQL 库中；

1、开启 MySQL 的 binlog

在 my.cnf 中开启 binlog，我这里指定了 test 库，然后重启 MySQL

server.id=1
log-bin=mysql-bin
binlog-do-db=test

2、在 MySQL 中创建测试库和表

mysql> create database test;
mysql> create table user_info(id int unsigned not null auto_increment primary key, username varchar(60), sex tinyint(1), nickname varchar(60), addr varchar(255))ENGINE=InnoDB default charset=utf8mb4;

3、Flink 代码

在 IDEA 中新建工程 flinkcdc

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.zsoft.flinkcdc</groupId><artifactId>flinkcdc</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><flink.version>1.13.1</flink.version></properties><dependencies><!-- FlinkCDC DataStream 方式 --><dependency><groupId>org.apache.flink</groupId><artifactId>flink-java</artifactId><version>${flink.version}</version></dependency><dependency><groupId>org.apache.flink</groupId><artifactId>flink-streaming-java_2.12</artifactId><version>${flink.version}</version></dependency><dependency><groupId>org.apache.flink</groupId><artifactId>flink-clients_2.12</artifactId><version>${flink.version}</version></dependency><dependency><groupId>org.apache.hadoop</groupId><artifactId>hadoop-client</artifactId><version>3.1.3</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.22</version></dependency><dependency><groupId>com.alibaba.ververica</groupId><artifactId>flink-connector-mysql-cdc</artifactId><version>1.4.0</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.75</version></dependency></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-assembly-plugin</artifactId><version>3.0.0</version><configuration><descriptorRefs><descriptorRef>jar-with-dependencies</descriptorRef></descriptorRefs></configuration><executions><execution><id>make-assembly</id><phase>package</phase><goals><goal>single</goal></goals></execution></executions></plugin></plugins></build></project>

resources/log4j.properties

log4j.rootLogger=warn,stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n

反序列化类：

com/zsoft/flinkcdc/MyDeserializationSchema.java

package com.zsoft.flinkcdc;import com.alibaba.fastjson.JSONObject;
import com.alibaba.ververica.cdc.debezium.DebeziumDeserializationSchema;
import io.debezium.data.Envelope;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.util.Collector;
import org.apache.kafka.connect.data.Field;
import org.apache.kafka.connect.data.Struct;
import org.apache.kafka.connect.source.SourceRecord;public class MyDeserializationSchema implements DebeziumDeserializationSchema<String> {@Overridepublic void deserialize(SourceRecord sourceRecord, Collector<String> collector) throws Exception {Struct valueStruct = (Struct) sourceRecord.value();Struct sourceStruct = valueStruct.getStruct("source");// 获取数据库的名称String database = sourceStruct.getString("db");// 获取表名String table = sourceStruct.getString("table");// 获取类型( c -> insert, u -> update)String type = Envelope.operationFor(sourceRecord).toString().toLowerCase();if(type.equals("create")){type = "insert";}JSONObject jsonObj = new JSONObject();jsonObj.put("database",database);jsonObj.put("table", table);jsonObj.put("type", type);// 获取数据 dataStruct afterStruct = valueStruct.getStruct("after");JSONObject dataJsonObj = new JSONObject();if(afterStruct != null) {for(Field field : afterStruct.schema().fields()) {String fieldName = field.name();Object fieldValue = afterStruct.get(field);dataJsonObj.put(fieldName, fieldValue);}}jsonObj.put("data", dataJsonObj);collector.collect(jsonObj.toJSONString());}@Overridepublic TypeInformation<String> getProducedType() {return TypeInformation.of(String.class);}
}

主类：

com/zsoft/flinkcdc/FlinkCdcDataStream.java

package com.zsoft.flinkcdc;import com.alibaba.ververica.cdc.connectors.mysql.MySQLSource;
import com.alibaba.ververica.cdc.connectors.mysql.table.StartupOptions;
import com.alibaba.ververica.cdc.debezium.StringDebeziumDeserializationSchema;
import org.apache.flink.api.common.restartstrategy.RestartStrategies;
import org.apache.flink.runtime.state.filesystem.FsStateBackend;
import org.apache.flink.streaming.api.CheckpointingMode;
import org.apache.flink.streaming.api.datastream.DataStreamSource;
import org.apache.flink.streaming.api.environment.CheckpointConfig;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.source.SourceFunction;import java.util.Properties;public class FlinkCdcDataStream {public static void main(String[] args) throws Exception {// TODO 1. 准备流处理环境StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();env.setParallelism(1);// TODO 2. 开启检查点// 2.1 开启 Checkpointenv.enableCheckpointing(5000L, CheckpointingMode.EXACTLY_ONCE);// 2.2 设置超时时间env.getCheckpointConfig().setCheckpointTimeout(60000);// 2.3 指定从 CK 自动重启策略env.setRestartStrategy(RestartStrategies.fixedDelayRestart(1, 6000L));// 2.4 设置任务关闭时候保留最后一次 CK 数据env.getCheckpointConfig().enableExternalizedCheckpoints(CheckpointConfig.ExternalizedCheckpointCleanup.RETAIN_ON_CANCELLATION);// 2.5 设置状态后端env.setStateBackend(new FsStateBackend("hdfs://s1:8020/flinkCDC_DS"));// 2.6 设置访问 HDFS 的用户名System.setProperty("HADOOP_USER_NAME", "hadoop");// TODO 3. 创建 Flink-MySQL-CDC 的 SourceProperties props = new Properties();props.setProperty("scan.startup.mode", "initial");SourceFunction<String> sourceFunction = MySQLSource.<String>builder().hostname("s1").port(3306).username("root").password("123456").databaseList("test").tableList("test.user_info").startupOptions(StartupOptions.earliest()).debeziumProperties(props).deserializer(new MyDeserializationSchema()).build();// TODO 4. 使用 CDC Source 从 MySQL 读取数据DataStreamSource<String> mysqlDS = env.addSource(sourceFunction).setParallelism(1);// TODO 5. 打印输出mysqlDS.print();// TODO 6. 执行任务env.execute();}
}

4、打包运行

在 IDEA 中打包项目 package

将生成的 flinkcdc-1.0-SNAPSHOT-jar-with-dependencies.jar 通过 Flink 的 webUI 上传

在 Flink 的 WebUI 中上传 jar 包

Submit New Job 页面点击 + Add New 按钮

上传后的 jar 包下填入：

• Entry Class：com.zsoft.flinkcdc.FlinkCdcDataStream
• Parallelism：1
• Program Arguments：
• Savepoint Path：

点击 ”Submit“ 提交应用

5、测试

此时在 MySQL 中插入如下数据：

mysql> insert into user_info values(null, 'zhangsan', 1, 'zhs','beijing');

mysql> insert into user_info values(null, 'lisi', 1, 'ls','shanghai');

mysql> insert into user_info values(null, 'wangwu', 1, 'ww','wangwu');

在 Flink 的 webUI 中 Task Managers 中点击项目，在 Stdout 中有输出日志：

{"database":"test","data":{"sex":1,"nickname":"zhs","id":1,"addr":"beijing","username":"zhangsan"},"type":"insert","table":"user_info"}
{"database":"test","data":{"sex":1,"nickname":"ls","id":2,"addr":"shanghai","username":"lisi"},"type":"insert","table":"user_info"}
{"database":"test","data":{"sex":1,"nickname":"ww","id":3,"addr":"wangwu","username":"wangwu"},"type":"insert","table":"user_info"}