為什麼InputStream skip() 沒有跑到我想要的位置再download~~ 請高手指教:)

1. package com.example.download1;
   
2. 
   
3. import java.io.File;
   
4. import java.io.FileOutputStream;
   
5. import java.io.InputStream;
   
6. import java.net.URL;
   
7. import java.net.URLConnection;
   
8. 
   
9. import android.app.Activity;
   
10. import android.app.Dialog;
    
11. import android.app.ProgressDialog;
    
12. 
    
13. 
    
14. import android.os.AsyncTask;
    
15. import android.os.Bundle;
    
16. import android.os.Environment;
    
17. import android.util.Log;
    
18. import android.view.View;
    
19. import android.view.View.OnClickListener;
    
20. import android.widget.Button;
    
21. 
    
22. 
    
23. 
    
24. public class MainActivity extends Activity {
    
25.         public static final int DIALOG_DOWNLOAD_PROGRESS = 0;
    
26.     private Button startBtn;
    
27.     private ProgressDialog mProgressDialog;
    
28.    
    
29.    
    
30.     /** Called when the activity is first created. */
    
31.     @Override
    
32.     public void onCreate(Bundle savedInstanceState) {
    
33.         super.onCreate(savedInstanceState);
    
34.         setContentView(R.layout.activity_main);
    
35.         checkAndCreateDirectory("/timecoolfree/");
    
36.         
    
37.         startBtn = (Button)findViewById(R.id.button1);
    
38.         startBtn.setOnClickListener(new OnClickListener(){
    
39.             public void onClick(View v) {
    
40.               startDownload();
    
41.             }
    
42.         });
    
43.     }
    
44.     public void textz(long total,int count){
    
45. }
    
46.     public void checkAndCreateDirectory(String dirName){
    
47.         File new_dir = new File( Environment.getExternalStorageDirectory() + dirName );
    
48.         new_dir.getName();
    
49.         
    
50.         if( !new_dir.exists() ){
    
51.             new_dir.mkdirs();
    
52.         }
    
53.     }
    
54.    
    
55.     private void startDownload() {
    
56.         String url = "http://k007.kiwi6.com/hotlink/2ppi39j9w3/0430b.mp3";
    
57.         new DownloadFileAsync().execute(url);
    
58.     }
    
59.     @Override
    
60.     protected Dialog onCreateDialog(int id) {
    
61.    return mProgressDialog;      
    
62.     }
    
63. 
    
64. class DownloadFileAsync extends AsyncTask<String, String, String> {
    
65.    
    
66. @Override
    
67. protected void onPreExecute() {
    
68.   super.onPreExecute();
    
69. // showDialog(DIALOG_DOWNLOAD_PROGRESS);
    
70.   
    
71. }
    
72. 
    
73. @Override
    
74. protected String doInBackground(String... aurl) {
    
75. 
    
76.   long aaa= 2000000;
    
77.   URL url = null;
    
78.   InputStream inputa = null;
    
79. try {
    
80.          FileOutputStream output = new FileOutputStream("/sdcard/timecoolfree/0430b.mp3");
    
81. url = new URL(aurl[0]);
    
82. URLConnection conexion = url.openConnection();
    
83. inputa = conexion.getInputStream();
    
84. 
    
85. inputa.skip(2000000);
    
86.          
    
87.          Log.d("aaaa", ""+inputa.skip(aaa));
    
88. 
    
89. byte data[] = new byte[1024];
    
90. long total = 0;
    
91. int count;
    
92. 
    
93.   while ((count = inputa.read(data)) >0) {
    
94.    total += count;
    
95.    output.write(data, 0, count);
    
96. 
    
97.   }
    
98. 
    
99.   output.flush();
    
100.   output.close();
     
101.   inputa.close();
     
102. 
     
103. 
     
104.   
     
105.   
     
106.   
     
107.   
     
108.   }catch (Exception e) {}
     
109. 
     
110. return null;
     
111. 
     
112. }
     
113. protected void onProgressUpdate(String... progress) {
     
114.    Log.d("ANDRO_ASYNC",progress[0]);
     
115. }
     
116. 
     
117. @Override
     
118. protected void onPostExecute(String unused) {
     
119. 
     
120. }
     
121. }
     
122. 
     
123. }
     
124.        
     

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請高手幫幫我

这是API中对skip方法的描述。你可以查看一下它返回的实际跳过字节数。

做下载的话，建议使用 RandomAccessFile 它里面有一个方法 seek() 可以设置文件的指针位置