Hadoop1.2.0开发笔记（八）

public class WordCount extends Configured implements Tool{ public static class Map extends Mapper 
    
     {  
    private 
    final 
    static IntWritable one = 
    new IntWritable(1 
    );  
    private Text word = 
    new 
     Text();  
    public 
    void 
     map(Object key, Text value, Context context )  
    throws 
     IOException, InterruptedException { StringTokenizer itr = 
    new 
     StringTokenizer(value.toString()); String str= 
    null 
    ;  
    while 
     (itr.hasMoreTokens()) { str= 
    itr.nextToken(); word.set(str); context.write(word, one); } } }  
    public 
    static 
    class Reduce 
    extends Reducer 
     
      {  
     private IntWritable result = 
     new 
      IntWritable();  
     public 
     void reduce(Text key, Iterable 
      
       values, Context context)  
      throws 
       IOException, InterruptedException {  
      int sum = 0 
      ;  
      for 
       (IntWritable val : values) { sum += 
       val.get(); } result.set(sum); context.write(key, result); } } @Override  
      public 
      int run(String[] args) 
      throws 
       Exception {  
      // 
       TODO Auto-generated method stub 
       File jarFile = EJob.createTempJar("bin" 
      ); EJob.addClasspath("/usr/hadoop/conf" 
      ); ClassLoader classLoader = 
       EJob.getClassLoader(); Thread.currentThread().setContextClassLoader(classLoader);  
      / 
       创建一个job，起个名字以便跟踪查看任务执行情况 * 
      */ 
       Job job = 
      new 
       Job(getConf()); ((JobConf) job.getConfiguration()).setJar(jarFile.toString());  
      / 
       * 当在hadoop集群上运行作业时，需要把代码打包成一个jar文件（hadoop会在集群分发这个文件）， * 通过job的setJarByClass设置一个类，hadoop根据这个类找到所在的jar文件 * 
      */ 
       job.setJarByClass(WordCount. 
      class 
      ); job.setJobName("wordcount" 
      );  
      / 
       * 设置map和reduce函数的输入类型，这里没有代码是因为我们使用默认的TextInputFormat，针对文本文件，按行将文本文件切割成 * InputSplits, 并用 LineRecordReader 将 InputSplit 解析成 
        
        */ 
        / 
         设置map和reduce函数的输出键和输出值类型 * 
        */ 
         job.setOutputKeyClass(Text. 
        class 
        ); job.setOutputValueClass(IntWritable. 
        class 
        );  
        / 
         设置要使用的map、combiner、reduce类型 * 
        */ 
         job.setMapperClass(Map. 
        class 
        ); job.setCombinerClass(Reduce. 
        class 
        ); job.setReducerClass(Reduce. 
        class 
        );  
        / 
         设置输入和输出路径 * 
        */ 
         FileInputFormat.addInputPath(job,  
        new Path(args[0 
        ])); FileOutputFormat.setOutputPath(job,  
        new Path(args[1 
        ]));  
        / 
         提交作业并等待它完成 * 
        */ 
        // 
        System.exit(job.waitForCompletion(true) ? 0 : 1); 
        return job.waitForCompletion( 
        true) ? 0 : 1 
        ; }  
        / 
         *  
        @param 
         args *  
        @throws 
         Exception  
        */ 
        public 
        static 
        void main(String[] args) 
        throws 
         Exception {  
        // 
         TODO Auto-generated method stub  
        // 
        hdfs/localhost:9000 String[] arg={"/test/input","/test/output" 
        };  
        int ret=ToolRunner.run( 
        new 
         WordCount(), arg);  
        // 
        int ret2=ToolRunner.run(conf, tool, args); 
         System.exit(ret); } } 
        
      
     
   

 public class EJob { // To declare global field private static List 
   
     classPath = 
    new ArrayList 
     
     ();  
     // 
      To declare method 
     public 
     static File createTempJar(String root) 
     throws 
      IOException {  
     if (! 
     new 
      File(root).exists()) {  
     return 
     null 
     ; } Manifest manifest = 
     new 
      Manifest(); manifest.getMainAttributes().putValue("Manifest-Version", "1.0" 
     );  
     final File jarFile = File.createTempFile("EJob-", ".jar", 
     new 
      File( System.getProperty("java.io.tmpdir" 
     ))); Runtime.getRuntime().addShutdownHook( 
     new 
      Thread() {  
     public 
     void 
      run() { jarFile.delete(); } }); JarOutputStream out = 
     new 
      JarOutputStream(  
     new 
      FileOutputStream(jarFile), manifest); createTempJarInner(out,  
     new File(root), "" 
     ); out.flush(); out.close();  
     return 
      jarFile; }  
     private 
     static 
     void 
      createTempJarInner(JarOutputStream out, File f, String base)  
     throws 
      IOException {  
     if 
      (f.isDirectory()) { File[] fl = 
      f.listFiles();  
     if (base.length() > 0 
     ) { base = base + "/" 
     ; }  
     for ( 
     int i = 0; i < fl.length; i++ 
     ) { createTempJarInner(out, fl[i], base + 
      fl[i].getName()); } }  
     else 
      { out.putNextEntry( 
     new 
      JarEntry(base)); FileInputStream in = 
     new 
      FileInputStream(f);  
     byte[] buffer = 
     new 
     byte[1024 
     ];  
     int n = 
      in.read(buffer);  
     while (n != -1 
     ) { out.write(buffer, 0 
     , n); n = 
      in.read(buffer); } in.close(); } }  
     public 
     static 
      ClassLoader getClassLoader() { ClassLoader parent = 
      Thread.currentThread().getContextClassLoader();  
     if (parent == 
     null 
     ) { parent = EJob. 
     class 
     .getClassLoader(); }  
     if (parent == 
     null 
     ) { parent = 
      ClassLoader.getSystemClassLoader(); }  
     return 
     new URLClassLoader(classPath.toArray( 
     new URL[0 
     ]), parent); }  
     public 
     static 
     void 
      addClasspath(String component) {  
     if ((component != 
     null) && (component.length() > 0 
     )) {  
     try 
      { File f = 
     new 
      File(component);  
     if 
      (f.exists()) { URL key = 
      f.getCanonicalFile().toURL();  
     if (! 
     classPath.contains(key)) { classPath.add(key); } } }  
     catch 
      (IOException e) { } } } }