Spring Boot整合Flink

软件版本:Spring Boot 2.1.6+Flink1.6.1+JDK1.8

程序主体：

@SpringBootApplication
public class HadesTmsApplication implements CommandLineRunner {

public static void main(String[] args) {
SpringApplication application = new SpringApplication(HadesTmsApplication.class);
application.setBannerMode(Banner.Mode.OFF);
application.run(args);
}

@Override
public void run(String... args) {
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
FlinkKafkaConsumer010 kafkaConsumer = new FlinkKafkaConsumer010<>("topic-name"), new SimpleStringSchema(), getProperties());
DataStream<String> dataStream = env.addSource(kafkaConsumer);
// 此处省略处理逻辑
dataStream.addSink(new MySink());

}

private Properties getProperties() {
Properties properties = new Properties();
properties.setProperty("bootstrap.servers", bootstrap_servers);
properties.setProperty("zookeeper.connect", zookeeper_connect);
properties.setProperty("group.id", group_id);
properties.setProperty("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
properties.setProperty("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
return properties;
}
}
说明一下：因为是非web项目，所以实现CommandLineRunner接口，重写run方法。在里面编写流处理逻辑。

如果在MySink中需要使用spring容器中的类，而MySink是一个普通的类，那么是无法访问到的。会引发空指针异常。可能有人想到了ApplicationContextAware这个接口，实现这个接口获取ApplicationContext，也即是：

@Component
public class ApplicationContextUtil implements ApplicationContextAware, Serializable {
private static final long serialVersionUID = -6454872090519042646L;
private static ApplicationContext applicationContext = null;

@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
if (ApplicationContextUtil.applicationContext == null) {
ApplicationContextUtil.applicationContext = applicationContext;
}
}

public static ApplicationContext getApplicationContext() {
return applicationContext;
}

//通过name获取 Bean.
public static Object getBean(String name) {
return getApplicationContext().getBean(name);
}

//通过class获取Bean.
public static <T> T getBean(Class<T> clazz) {
return getApplicationContext().getBean(clazz);
}

//通过name,以及Clazz返回指定的Bean
public static <T> T getBean(String name, Class<T> clazz) {
return getApplicationContext().getBean(name, clazz);
}
}
这种做法实际上在flink流处理中也是不可行的，在我之前的flink文章中 Flink读写系列之-读mysql并写入mysql 其中读和写阶段有一个open方法，这个方法专门用于进行初始化的，那么我们可以在这里进行spring bean的初始化。那么MySink改造后即为：

@EnableAutoConfiguration
@MapperScan(basePackages = {"com.xxx.bigdata.xxx.mapper"})
public class SimpleSink extends RichSinkFunction<String> {

TeacherInfoMapper teacherInfoMapper;

@Override
public void open(Configuration parameters) throws Exception {
super.open(parameters);
SpringApplication application = new SpringApplication(SimpleSink.class);
application.setBannerMode(Banner.Mode.OFF);
ApplicationContext context = application.run(new String[]{});
teacherInfoMapper = context.getBean(TeacherInfoMapper.class);
}

@Override
public void close() throws Exception {
super.close();
}

@Override
public void invoke(String value, Context context) throws Exception {
List<TeacherInfo> teacherInfoList = teacherInfoMapper.selectByPage(0, 100);
teacherInfoList.stream().forEach(teacherInfo -> System.out.println("teacherinfo:" + teacherInfo.getTeacherId() + "," + teacherInfo.getTimeBit() + "," + teacherInfo.getWeek()));
}
}
在invoke中就可以访问spring容器中的Mapper方法了。

pom如下：

<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.6.RELEASE</version>
<relativePath/> 
</parent>
<groupId>com.xxx.bigdata</groupId>
<artifactId>flink-project</artifactId>
<version>1.0.0</version>
<name>flink-project</name>
<packaging>jar</packaging>
<description>My project for Spring Boot</description>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<flink.version>1.6.1</flink.version>
<skipTests>true</skipTests>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>

<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<exclusions>
<exclusion>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.apache.flink</groupId>
<artifactId>flink-java</artifactId>
<version>${flink.version}</version>
</dependency>
<dependency>
<groupId>org.apache.flink</groupId>
<artifactId>flink-streaming-java_2.11</artifactId>
<version>${flink.version}</version>
</dependency>
<dependency>
<groupId>org.apache.flink</groupId>
<artifactId>flink-connector-kafka-0.10_2.11</artifactId>
<version>${flink.version}</version>
</dependency>
<dependency>
<groupId>com.cloudera</groupId>
<artifactId>ImpalaJDBC41</artifactId>
<version>2.6.4</version>
</dependency>
<dependency>
<groupId>com.zaxxer</groupId>
<artifactId>HikariCP</artifactId>
<version>3.2.0</version>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.1</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.47</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>

<build>
<sourceDirectory>src/main/java</sourceDirectory>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
<includes>
<include>application.properties</include>
<include>application-${package.environment}.properties</include>
</includes>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<skip>true</skip>
<mainClass>com.xxx.bigdata.xxx.Application</mainClass>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>

<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.5</version>
<configuration>
<configurationFile>${basedir}/src/main/resources/generatorConfig.xml</configurationFile>
<overwrite>true</overwrite>
<verbose>true</verbose>
</configuration>
<dependencies>
<dependency>
<groupId>com.cloudera</groupId>
<artifactId>ImpalaJDBC41</artifactId>
<version>2.6.4</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>

<profiles>

<profile>
<id>dev</id>
<properties>
<package.environment>dev</package.environment>
</properties>

<activation>
<activeByDefault>true</activeByDefault>
</activation>
</profile>

<profile>
<id>pre</id>
<properties>
<package.environment>pre</package.environment>
</properties>
</profile>

<profile>
<id>pro</id>
<properties>
<package.environment>pro</package.environment>
</properties>
</profile>
</profiles>

</project>
项目打包使用了默认的spring boot插件，配置了skip为true，如果不配置此项，打包后会多一个BOOT-INF目录，运行时会引起ClassNotFoundException等各种异常，比如KafkaStreming问题，甚至需要反转flink的类加载机制，由child-first变为parent-first(修改flink配置文件)等等。

遇到的问题：

1. java.lang.NoSuchMethodError: com.google.gson.GsonBuilder.setLenient()Lcom/google/gson/GsonBuilder
GsonBuilder类来自gson-xxx.jar包，而我在自己的项目中执行mvn dependency:tree并没有发现依赖这个包。莫非在flink运行时会使用自己lib库下的gson包，转而去flink的lib库下，发现flink-dist_2.11-1.6.1.jar里包含了gson-xxx包，但是打开这个包一看类中没有setLenient方法，于是在服务器上建立一个commlib，把gson-2.8.0.jar（包含setLenient方法）放进去，然后使用flink run提交时，指定classpath即可。

2.日志冲突

Caused by: java.lang.IllegalArgumentException: LoggerFactory is not a Logback LoggerContext but Logback is on the classpath. Either remove Logback or the competing implementation (class org.slf4j.impl.Log4jLoggerFactory loaded from file:/opt/flink-1.6.1/lib/slf4j-log4j12-1.7.7.jar). If you are using WebLogic you will need to add 'org.slf4j' to prefer-application-packages in WEB-INF/weblogic.xml: org.slf4j.impl.Log4jLoggerFactory

排除springboot中的日志即可：

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<exclusions>
<exclusion>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
</exclusion>
</exclusions>
</dependency>
3.flink run提交作业到yarn上时，如果需要指定classpath，则需要指定到确定的jar包，指定目录不可行。那么假如所有依赖包已经放置在目录中，拼接的shell可以这么写：

lib_classpath="";

for jar in `ls /home/hadoop/lib`
do
jar_suffix=${jar##*.}
if [ "$jar_suffix" = "jar" ]
then
jar_path=" --classpath file:///home/hadoop/lib/$jar "
lib_classpath=${lib_classpath}${jar_path}
else(http://www.my516.com)
echo "the jar file $jar it not legal jar file,skip appendig"
fi
done
拼接后的lib_classpath值如下效果：

--classpath file:///home/hadoop/lib/accessors-smart-1.2.jar --classpath file:///home/hadoop/lib/akka-actor_2.11-2.4.20.jar

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