import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import java.net.URI;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.FSDataInputStream;import org.apache.hadoop.fs.FSDataOutputStream;import org.apache.hadoop.fs.FileStatus;import org.apache.hadoop.fs.FileSystem;import org.apache.hadoop.fs.Path;import org.apache.hadoop.hdfs.DistributedFileSystem;import org.apache.hadoop.hdfs.protocol.DatanodeInfo;//利用JavaAPI来访问HDFS的文件与目录public class HDFSTest {    public static void main(String[] args) throws Exception {        try {            getHDFSNode();            makeDir();            writeToHDFS();            uploadToHdfs();            listHdfs();            readFromHdfs();            deleteFromHdfs();            deleteDir();        } catch (Exception e) {            e.printStackTrace();        } finally {            System.out.println("SUCCESS");        }    }    // HDFS集群上所有节点名称信息    public static void getHDFSNode() throws IOException {        Configuration conf = new Configuration();        FileSystem fs = FileSystem.get(URI.create("hdfs://localhost:9000/"),                conf);        DistributedFileSystem dfs = (DistributedFileSystem) fs;        DatanodeInfo[] dataNodeStats = dfs.getDataNodeStats();        for (int i = 0; i < dataNodeStats.length; i++) {            System.out.println("DataNode_" + i + "_Node:"                    + dataNodeStats[i].getHostName());        }    }    /** 遍历HDFS上的文件和目录 */    private static void listHdfs() throws FileNotFoundException, IOException {        Configuration conf = new Configuration();        FileSystem fs = FileSystem.get(URI.create("hdfs://localhost:9000/"),                conf);        FileStatus fileList[] = fs.listStatus(new Path("/"));        for (int i = 0; i < fileList.length; i++) {            System.out.println("name:" + fileList[i].getPath().getName()                    + "\t\tsize:" + fileList[i].getLen());        }        fs.close();    }    public static void writeToHDFS() throws IOException {        Configuration conf = new Configuration();        FileSystem fs = FileSystem.get(URI.create("hdfs://localhost:9000"),                conf);        Path path = new Path("/test/write");        FSDataOutputStream out = fs.create(path);        out.writeUTF("Hello HDFS!");        out.close();        fs.close();    }    // 创建HDFS目录    public static void makeDir() throws IOException {        Configuration conf = new Configuration();        FileSystem fs = FileSystem.get(URI.create("hdfs://localhost:9000"),                conf);        Path path = new Path("/test");        fs.mkdirs(path);        fs.close();    }    // 删除HDFS目录    public static void deleteDir() throws IOException {        Configuration conf = new Configuration();        FileSystem fs = FileSystem.get(conf);        Path path = new Path("/test");        fs.delete(path, true);        fs.close();    }    /** 上传文件到HDFS上去 */    private static void uploadToHdfs() throws FileNotFoundException,            IOException {        Configuration conf = new Configuration();        FileSystem fs = FileSystem.get(URI.create("hdfs://localhost:9000/"),                conf);        String localSrc = "/etc/profile";        String hdfsDst = "/profile";        Path src = new Path(localSrc);        Path dst = new Path(hdfsDst);        fs.copyFromLocalFile(src, dst);        fs.close();    }    /** 从HDFS上读取文件 */    private static void readFromHdfs() throws FileNotFoundException,            IOException {        Configuration conf = new Configuration();        FileSystem fs = FileSystem.get(URI.create("hdfs://localhost:9000/"),                conf);        String dst = "/profile";        FSDataInputStream hdfsInStream = fs.open(new Path(dst));        OutputStream out = new FileOutputStream("/home/manhua/profile");        byte[] ioBuffer = new byte[1024];        int readLen = hdfsInStream.read(ioBuffer);        if (fs.exists(new Path(dst))) {            while (-1 != readLen) {                out.write(ioBuffer, 0, readLen);                readLen = hdfsInStream.read(ioBuffer);            }            out.close();            hdfsInStream.close();            fs.close();        }    }    /** 从HDFS上删除文件 */    private static void deleteFromHdfs() throws FileNotFoundException,            IOException {        Configuration conf = new Configuration();        FileSystem fs = FileSystem.get(URI.create("hdfs://localhost:9000"),                conf);        String dst = "/profile";        fs.deleteOnExit(new Path(dst));        fs.close();    }}