HDFS的API操作

配置HADOOP_HOME和配置Path环境变量环境变量

 

创建一个Maven工程

 <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.8.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>2.7.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>2.7.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-hdfs</artifactId>
            <version>2.7.2</version>
        </dependency>

    </dependencies>

需要在项目的src/main/resources目录下，新建一个文件，命名为“log4j.properties”，在文件中填入

log4j.rootLogger=INFO, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/spring.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

创建测试类

/**
 * @author WGR
 * @create 2020/1/20 -- 15:05
 */
public class HDFSClient1 {

    public static void main(String[] args) throws URISyntaxException, IOException, InterruptedException {
        // 1 获取hdfs客户端对象
//        FileSystem fs = FileSystem.get(conf );
        Configuration configuration = new Configuration();
        FileSystem fileSystem = FileSystem.get(new URI("hdfs://hadoop002:9000"), configuration, "root");

        // 2 在hdfs上创建路径
        fileSystem.mkdirs(new Path("/0120/test/"));

        // 3 关闭资源
        fileSystem.close();

        System.out.println("over");
    }
}

 查看HDFS

[root@hadoop002 hadoop-2.7.2]# hadoop fs -ls -R /
drwxr-xr-x   - root supergroup          0 2020-01-20 15:12 /0120
drwxr-xr-x   - root supergroup          0 2020-01-20 15:12 /0120/test
-rw-r--r--   3 root supergroup       1366 2020-01-15 22:30 /README.txt
drwxr-xr-x   - root supergroup          0 2020-01-18 21:36 /tmp
drwxrwxrwt   - root supergroup          0 2020-01-18 21:36 /tmp/logs
drwxrwx---   - dr.who supergroup          0 2020-01-18 21:36 /tmp/logs/dr.who
drwxrwx---   - dr.who supergroup          0 2020-01-19 17:30 /tmp/logs/dr.who/logs
drwxrwx---   - dr.who supergroup          0 2020-01-18 21:46 /tmp/logs/dr.who/logs/application_1579060789521_0001
drwxrwx---   - dr.who supergroup          0 2020-01-18 21:46 /tmp/logs/dr.who/logs/application_1579060789521_0002
drwxrwx---   - dr.who supergroup          0 2020-01-18 21:47 /tmp/logs/dr.who/logs/application_1579060789521_0003
drwxrwx---   - dr.who supergroup          0 2020-01-18 21:46 /tmp/logs/dr.who/logs/application_1579060789521_0004
drwxrwx---   - dr.who supergroup          0 2020-01-19 17:34 /tmp/logs/dr.who/logs/application_1579060789521_0005
drwxrwx---   - dr.who supergroup          0 2020-01-19 17:30 /tmp/logs/dr.who/logs/application_1579060789521_0006
drwxrwx---   - dr.who supergroup          0 2020-01-19 17:36 /tmp/logs/dr.who/logs/application_1579060789521_0007
drwxrwx---   - dr.who supergroup          0 2020-01-19 17:43 /tmp/logs/dr.who/logs/application_1579060789521_0008
-rw-r--r--   3 root   supergroup   18284613 2020-01-15 12:11 /tools.jar
-rw-r--r--   3 root   supergroup         48 2020-01-15 12:05 /wc.input
drwxr-xr-x   - root   supergroup          0 2020-01-15 21:49 /wgr
drwxr-xr-x   - root   supergroup          0 2020-01-15 21:51 /wgr/test
-rwxrwxrwx   2 root   supergroup         15 2020-01-15 22:28 /wgr/test/kongming.txt
[root@hadoop002 hadoop-2.7.2]#

文件上传

 // 1 文件上传
    @Test
    public void testCopyFromLocalFile() throws IOException, InterruptedException, URISyntaxException{

        // 1 获取fs对象
        Configuration conf = new Configuration();
        conf.set("dfs.replication", "2");
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop002:9000"), conf , "root");

        // 2 执行上传API
        fs.copyFromLocalFile(new Path("C:\Users\asus\Desktop\2.txt"), new Path("/2.txt"));

        // 3 关闭资源
        fs.close();
    }

 文件下载

 // 2 文件下载
    @Test
    public void testCopyToLocalFile() throws IOException, InterruptedException, URISyntaxException{

        // 1 获取对象
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop002:9000"), conf , "root");

        // 2 执行下载操作
//        fs.copyToLocalFile(new Path("/banhua.txt"), new Path("e:/banhua.txt"));
        fs.copyToLocalFile(false, new Path("/2.txt"), new Path("e:/1111.txt"), true);

        // 3 关闭资源
        fs.close();
    }

文件删除

// 3 文件删除
    @Test
    public void testDelete() throws IOException, InterruptedException, URISyntaxException{

        // 1 获取对象
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop002:9000"), conf , "root");

        // 2 文件删除
        fs.delete(new Path("/0120"), true);

        // 3 关闭资源
        fs.close();
    }

 文件重改名的

 // 4 文件更名
    @Test
    public void testRename() throws IOException, InterruptedException, URISyntaxException{

        // 1 获取对象
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop002:9000"), conf , "root");

        // 2 执行更名操作
        fs.rename(new Path("/2.txt"), new Path("/111.txt"));

        // 3 关闭资源
        fs.close();
    }

 文件查看

// 5 文件详情查看
    @Test
    public void testListFiles() throws IOException, InterruptedException, URISyntaxException{

        // 1 获取对象
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop002:9000"), conf , "root");

        // 2 查看文件详情
        RemoteIterator<LocatedFileStatus> listFiles = fs.listFiles(new Path("/"), true);

        while(listFiles.hasNext()){
            LocatedFileStatus fileStatus = listFiles.next();

            // 查看文件名称、权限、长度、块信息
            System.out.println(fileStatus.getPath().getName());// 文件名称
            System.out.println(fileStatus.getPermission());// 文件权限
            System.out.println(fileStatus.getLen());// 文件长度

            BlockLocation[] blockLocations = fileStatus.getBlockLocations();

            for (BlockLocation blockLocation : blockLocations) {

                String[] hosts = blockLocation.getHosts();

                for (String host : hosts) {
                    System.out.println(host);
                }
            }

            System.out.println("------分割线--------");
        }

        // 3 关闭资源
        fs.close();
    }

111.txt
rw-r--r--
1773
hadoop003
hadoop004
------分割线--------
README.txt
rw-r--r--
1366
hadoop002
hadoop004
hadoop003
------分割线--------
tools.jar
rw-r--r--
18284613
hadoop002
hadoop004
hadoop003
------分割线--------
wc.input
rw-r--r--
48
hadoop003
hadoop002
hadoop004
------分割线--------
kongming.txt
rwxrwxrwx
15
hadoop004
hadoop003
------分割线--------

Process finished with exit code 0

文件查看

// 6 判断是文件还是文件夹
    @Test
    public void testListStatus() throws IOException, InterruptedException, URISyntaxException{

        // 1 获取对象
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(new URI("hdfs://hadoop002:9000"), conf , "root");

        // 2 判断操作
        FileStatus[] listStatus = fs.listStatus(new Path("/"));

        for (FileStatus fileStatus : listStatus) {

            if (fileStatus.isFile()) {
                // 文件
                System.out.println("f:"+fileStatus.getPath().getName());
            }else{
                // 文件夹
                System.out.println("d:"+fileStatus.getPath().getName());
            }
        }

        // 3 关闭资源
        fs.close();
    }

f:111.txt
f:README.txt
d:tmp
f:tools.jar
f:wc.input
d:wgr