[大数据]连载No2之Hadoop文件增删改查API使用

除了命令行之外,还可以通过API操作文件的操作

导入 share/hadoop/common/lib 下面jar到工程

先打开与 hadoop连接配置,

Configuration conf = new Configuration();conf.set("fs.defaultFS", "localhost:9000");FileSystem fs = FileSystem.get(conf);

查看hdfs目录列表

 public void ls() throws Exception {
   Path path = new Path("/user");   FileStatus[] status = fs.listStatus(path);   for(FileStatus s : status) {      System.out.println(s.getPath());      System.out.println(s.getAccessTime());      System.out.println(s.getLen());      System.out.println(s.getBlockSize());   }}

创建文件夹

public void mkdir() throws Exception {   Path path = new Path("/user/dir");   Boolean flag = fs.mkdirs(path);   if(flag) {      System.out.println("mkdir /user/dir success~~");   }}

上传文件

public void put() throws Exception {   Path path = new Path("/user/aaa.txt");   FSDataOutputStream out = fs.create(path);   IOUtils.copyBytes(new FileInputStream(new File("/Users/wlx/test/my.text")), out, conf);}

小文件上传

public void putsmall() throws Exception {   //小文件上传   Path path = new Path("/user/bigfile");   SequenceFile.Writer write = new SequenceFile.Writer(fs, conf, path, Text.class, Text.class);   File[] files = new File("D:/HDFS/").listFiles();   for(File f : files) {      write.append(new Text(f.getName()), new Text(FileUtils.readFileToString(f)));   }   write.close();}

大文件上传

public void getsmall() throws Exception {   Path path = new Path("/user/bigfile");   SequenceFile.Reader reader = new SequenceFile.Reader(fs, path, conf);   Text key = new Text();   Text val = new Text();   while(reader.next(key, val)) {      System.out.println("111");      System.out.println(key.toString());      System.out.println(val.toString());   }}

删除文件

public void del() throws Exception {   Path path = new Path("/user/aaa.txt");   fs.delete(path, true);}