hdfs的Java Api开发
1.创建maven工程并导入jar包
jdk使用1.8、maven3.x版本
pom.xml添加一下内容
<repositories>
<repository>
<id>cloudera</id>
<url>https://repository.cloudera.com/artifactory/cloudera-repos/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-client</artifactId>
<version>2.6.0-mr1-cdh5.14.2</version>
</dependency>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-common</artifactId>
<version>2.6.0-cdh5.14.2</version>
</dependency>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-hdfs</artifactId>
<version>2.6.0-cdh5.14.2</version>
</dependency>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-mapreduce-client-core</artifactId>
<version>2.6.0-cdh5.14.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/junit/junit -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.testng</groupId>
<artifactId>testng</artifactId>
<version>RELEASE</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.0</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
<!-- <verbal>true</verbal>-->
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.4.3</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<minimizeJar>true</minimizeJar>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
2.test目录下创建com.my.hdfs并在该包下创建HDFSOperate.java文件
2.1 创建文件夹
@Test
public void mkdirToHdfs() throws IOException {
Configuration configuration = new Configuration();
configuration.set("fs.defaultFS","hdfs://node01:8020");
FileSystem fileSystem = FileSystem.get(configuration);
fileSystem.mkdirs(new Path("/dir1"));//hdfs路径
fileSystem.close();
}
2.2文件上传
@Test
public void uploadFile() throws IOException {
Configuration configuration = new Configuration();
configuration.set("fs.defaultFS","hdfs://node01:8020");
FileSystem fileSystem = FileSystem.get(configuration);
fileSystem.copyFromLocalFile(new Path("file:///d:\\hello.txt")/**本地目录*/,new Path("hdfs://node01:8020/dir1")/**hdfs目录*/);
fileSystem.close();
}
2.3文件下载
@Test
public void downloadFile() throws IOException { Configuration configuration = new Configuration(); configuration.set("fs.defaultFS","hdfs://node01:8020"); FileSystem fileSystem = FileSystem.get(configuration); fileSystem.copyToLocalFile(new Path("hdfs://node01:8020/dir1/hello.txt")/**hdfs目录*/,new Path("file:///d:\\hello2.txt")/**本地目录*/); fileSystem.close(); }
2.4文件删除
@Test
public void deleteHDFS() throws IOException {
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://node01:8020");
FileSystem fs = FileSystem.get(conf);
fs.delete(new Path("/dir1/hello.txt"), true);
fs.close();
}
2.5重命名
@Test
public void renameDFS() throws IOException {
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://node01:8020");
FileSystem fs = FileSystem.get(conf);
fs.rename(new Path("/dir1/hello.txt"), new Path("/dir1/hello.md"));
fs.close();
}
2.6查看hdfs文件信息
@Test
public void testListFiles() throws IOException, InterruptedException, URISyntaxException{
// 1获取文件系统
Configuration configuration = new Configuration();
FileSystem fs = FileSystem.get(new URI("hdfs://node01:8020"), configuration);
// 2 获取文件详情
RemoteIterator<LocatedFileStatus> listFiles = fs.listFiles(new Path("/"), true);
while(listFiles.hasNext()){
LocatedFileStatus status = listFiles.next();
// 输出详情
// 文件名称
System.out.println(status.getPath().getName());
// 长度
System.out.println(status.getLen());
// 权限
System.out.println(status.getPermission());
// 分组
System.out.println(status.getGroup());
// 获取存储的块信息
BlockLocation[] blockLocations = status.getBlockLocations();
for (BlockLocation blockLocation : blockLocations) {
// 获取块存储的主机节点
String[] hosts = blockLocation.getHosts();
for (String host : hosts) {
System.out.println(host);
}
}
}
// 3 关闭资源
fs.close();
}
3.java API通过IO流操作hdfs文件
3.1 io流数据上传
@Test
public void putFileToHDFS() throws IOException, InterruptedException, URISyntaxException {
// 1 获取文件系统
Configuration configuration = new Configuration();
FileSystem fs = FileSystem.get(new URI("hdfs://node01:8020"), configuration);
// 2 创建输入流 不需要加file:///
FileInputStream fis = new FileInputStream(new File("e:\\helo.txt"));
// 3 获取输出流
FSDataOutputStream fos = fs.create(new Path("hdfs://node01:8020/outresult.txt"));
// 4 流对拷
IOUtils.copy(fis, fos);
// 5 关闭资源
IOUtils.closeQuietly(fos);
IOUtils.closeQuietly(fis);
fs.close();
}
3.2 io流数据下载
@Test
public void getFileFromHDFS() throws IOException {
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs:/[表情]de01:8020");
FileSystem fs = FileSystem.get(conf);
FSDataInputStream fis = fs.open(new Path("/dir1/hello.txt"));
FileOutputStream fos = new FileOutputStream("D:/hello_2.txt");
//filesystem关闭
IOUtils.copy(fis, fos);
IOUtils.closeQuietly(fis);
IOUtils.closeQuietly(fos);
fs.close();
}
3.3 hdfs小文件合并
/**
* 小文件合并
*/
@Test
public void mergeFile() throws URISyntaxException, IOException, InterruptedException {
//获取分布式文件系统hdfs
FileSystem fileSystem = FileSystem.get(new URI("hdfs://node01:8020"), new Configuration(), "hadoop");
FSDataOutputStream fsDataOutputStream = fileSystem.create(new Path("hdfs://node01:8020/bigfile.xml"));
//获取本地文件系统 localFileSystem
LocalFileSystem localFileSystem = FileSystem.getLocal(new Configuration());
//读取本地的文件
FileStatus[] fileStatuses = localFileSystem.listStatus(new Path("file:///D:smallFiles"));
for (FileStatus fileStatus : fileStatuses) {
//获取每一个本地的文件路径
Path path = fileStatus.getPath();
//读取本地小文件
FSDataInputStream fsDataInputStream = localFileSystem.open(path);
IOUtils.copy(fsDataInputStream,fsDataOutputStream);
IOUtils.closeQuietly(fsDataInputStream);
}
IOUtils.closeQuietly(fsDataOutputStream);
localFileSystem.close();
fileSystem.close();
//读取所有本地小文件，写入到hdfs的大文件里面去
}
