HDFS简单编程实例：文件合并

 1 package mergeFile;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintStream;
 5 import java.net.URI;
 6 
 7 import org.apache.hadoop.conf.Configuration;
 8 import org.apache.hadoop.fs.FSDataInputStream;
 9 import org.apache.hadoop.fs.FSDataOutputStream;
10 import org.apache.hadoop.fs.FileStatus;
11 import org.apache.hadoop.fs.FileSystem;
12 import org.apache.hadoop.fs.Path;
13 import org.apache.hadoop.fs.PathFilter;
14 
15 
16 class myPathFilter implements PathFilter{  //过滤掉文件名满足特定条件的文件
17     String reg = null;
18     myPathFilter(String reg){
19         this.reg = reg;
20     }
21     public boolean accept(Path path) {
22         if(!(path.toString().matches(reg)))
23             return true;
24         return false;
25     }
26     
27 }
28 
29 public class merge {
30     Path inputPath = null;  //待合并的文件所在的目录的路径
31     Path outputPath = null; //输出文件的路径
32     public merge(String input, String output){
33         this.inputPath = new Path(input);
34         this.outputPath = new Path(output);
35     }
36     public void doMerge() throws IOException{
37         Configuration conf = new Configuration();
38         conf.set("fs.defaultFS","hdfs://localhost:9000" );
39         conf.set("fs.hdfs.impl", "org.apache.hadoop.hdfs.DistributedFileSystem");
40         
41         FileSystem fsSource = FileSystem.get(URI.create(inputPath.toString()),conf);
42         FileSystem fsDst = FileSystem.get(URI.create(outputPath.toString()),conf);
43         
44         FileStatus[] sourceStatus = fsSource.listStatus(inputPath, new myPathFilter(".*\\.abc"));   //过滤掉目录中后缀为.abc的文件
45         FSDataOutputStream fsdos = fsDst.create(outputPath);
46         
47         //下面分别读取过滤之后的每个文件的内容，并输出到同一个文件中
48         for(FileStatus sta:sourceStatus){
49             System.out.println("路径: " + sta.getPath() + "   文件大小: " + sta.getLen() + "   权限: " + sta.getPermission() + "  内容: ");
50             FSDataInputStream fsdis = fsSource.open(sta.getPath());
51             byte[] data = new byte[1024];
52             int read = -1;
53             PrintStream ps = new PrintStream(System.out);
54             while((read = fsdis.read(data)) > 0){
55                 ps.write(data, 0, read);
56                 fsdos.write(data, 0, read);
57             }
58         }
59         fsdos.close();
60     }
61     public static void main(String args[]) throws IOException{
62         merge merge = new merge("hdfs://localhost:9000/user/hadoop/", "hdfs://localhost:9000/user/hadoop/merge.txt");
63         merge.doMerge();
64     }
65 }