SpringBoot集成Hadoop

        SpringBoot集成Hadoop，相关配置过程如下。默认在Linux下已经装好Hadoop集群（Hadoop-2.8.5）。

一、集成HDFS

1、主要application.properties配置

#hdfs
hdfs.url=hdfs://192.168.2.5:9000
hdfs.username=root
hdfs.replication=2
hdfs.blocksize=67108864

2、主要pom.xml配置

<dependencies>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-web</artifactId>
		<exclusions>
			<exclusion>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-starter-logging</artifactId>
			</exclusion>
		</exclusions>
	</dependency>
	<!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-common -->
	<dependency>
		<groupId>org.apache.hadoop</groupId>
		<artifactId>hadoop-common</artifactId>
		<version>2.8.5</version>
	</dependency>
	<!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-hdfs -->
	<dependency>
		<groupId>org.apache.hadoop</groupId>
		<artifactId>hadoop-hdfs</artifactId>
		<version>2.8.5</version>
	</dependency>
	<!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-client -->
	<dependency>
		<groupId>org.apache.hadoop</groupId>
		<artifactId>hadoop-client</artifactId>
		<version>2.8.5</version>
	</dependency>
	<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
	<dependency>
		<groupId>com.alibaba</groupId>
		<artifactId>fastjson</artifactId>
		<version>1.2.44</version>
	</dependency>
	<!-- https://mvnrepository.com/artifact/io.springfox/springfox-swagger2 -->
	<dependency>
		<groupId>io.springfox</groupId>
		<artifactId>springfox-swagger2</artifactId>
		<version>2.9.2</version>
	</dependency>
	<!-- https://mvnrepository.com/artifact/io.springfox/springfox-swagger-ui -->
	<dependency>
		<groupId>io.springfox</groupId>
		<artifactId>springfox-swagger-ui</artifactId>
		<version>2.9.2</version>
	</dependency>
	<!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
	<dependency>
		<groupId>com.google.guava</groupId>
		<artifactId>guava</artifactId>
		<version>27.0.1-jre</version>
	</dependency>
</dependencies>

完成其他相关配置和代码。

3、Windows下环境变量设置

        在Windows下启动程序，请求HDFS报以下错误：

java.io.FileNotFoundException: java.io.FileNotFoundException: HADOOP_HOME and hadoop.home.dir are unset.

        Windows下Java集成HADOOP，需要用到winutils.exe。提示缺少HADOOP_HOME或hadoop.home.dir相关配置。从https://github.com/steveloughran/winutils下载相关库，与本集群hadoop-2.8.5最接近的库为hadoop-2.8.3，下载hadoop-2.8.3到本地磁盘。通过设置Windows环境变量或在程序中设置hadoop.home.dir解决。

（1）设置Windows环境变量

设置Windows环境变量HADOOP_HOME=D:\soft\hadoop\winutils\hadoop-2.8.3

（2）程序中设置hadoop.home.dir

在程序初始化Hadoop Configuration之前添加以下代码设置环境变量

//Windows设置hadoop.home.dir
System.setProperty("hadoop.home.dir","D:\\soft\\hadoop\\winutils\\hadoop-2.8.3");