android中使用Http下载文件并保存到本地SD卡

1 <uses-permission android:name="android.permission.INTERNET"></uses-permission>
2     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

 1 package com.vino.utils;
 2 
 3 import java.io.File;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.InputStream;
 7 import java.io.OutputStream;
 8 
 9 import android.os.Environment;
10 
11 public class FileUtils {
12 
13     private String SDPATH;  
14       
15     public String getSDPATH() {  
16         return SDPATH;  
17     }  
18     public FileUtils() {  
19         //得到当前外部存储设备的目录  
20         // /SDCARD  
21         SDPATH = Environment.getExternalStorageDirectory() + "/";  
22     }  
23     /** 
24      * 在SD卡上创建文件 
25      *  
26      * @throws IOException 
27      */  
28     public File creatSDFile(String fileName) throws IOException {  
29         File file = new File(SDPATH + fileName);  
30         file.createNewFile();  
31         return file;  
32     }  
33       
34     /** 
35      * 在SD卡上创建目录 
36      *  
37      * @param dirName 
38      */  
39     public File creatSDDir(String dirName) {  
40         File dir = new File(SDPATH + dirName);  
41         dir.mkdir();  
42         return dir;  
43     }  
44   
45     /** 
46      * 判断SD卡上的文件夹是否存在 
47      */  
48     public boolean isFileExist(String fileName){  
49         File file = new File(SDPATH + fileName);  
50         return file.exists();  
51     }  
52       
53     /** 
54      * 将一个InputStream里面的数据写入到SD卡中 
55      */  
56     public File write2SDFromInput(String path,String fileName,InputStream input){  
57         File file = null;  
58         OutputStream output = null;  
59         try{  
60             creatSDDir(path);  
61             file = creatSDFile(path + fileName);  
62             output = new FileOutputStream(file);  
63             byte buffer [] = new byte[4 * 1024];  
64             while((input.read(buffer)) != -1){  
65                 output.write(buffer);  
66             }  
67             output.flush();  
68         }  
69         catch(Exception e){  
70             e.printStackTrace();  
71         }  
72         finally{  
73             try{  
74                 output.close();  
75             }  
76             catch(Exception e){  
77                 e.printStackTrace();  
78             }  
79         }  
80         return file;  
81     }
82 }

 1 package com.vino.utils;
 2 
 3 import java.io.File;
 4 import java.io.IOException;
 5 import java.io.InputStream;
 6 import java.net.HttpURLConnection;
 7 import java.net.MalformedURLException;
 8 import java.net.URL;
 9 
10 public class HttpDownloader {
11 
12     private URL url=null;  
13     FileUtils fileUtils=new FileUtils();  
14     public int downfile(String urlStr,String path,String fileName)  
15     {  
16         if(fileUtils.isFileExist(path+fileName))  
17             {return 1;}  
18         else{  
19           
20         try {  
21             InputStream input=null;  
22             input = getInputStream(urlStr);  
23             File resultFile=fileUtils.write2SDFromInput(path, fileName, input);  
24             if(resultFile==null)  
25             {  
26                 return -1;  
27             }  
28         } catch (IOException e) {  
29             // TODO Auto-generated catch block  
30             e.printStackTrace();  
31         }  
32           
33         }  
34         return 0;  
35     }  
36   //由于得到一个InputStream对象是所有文件处理前必须的操作，所以将这个操作封装成了一个方法  
37        public InputStream getInputStream(String urlStr) throws IOException  
38        {       
39            InputStream is=null;  
40             try {  
41                 url=new URL(urlStr);  
42                 HttpURLConnection urlConn=(HttpURLConnection)url.openConnection();  
43                 is=urlConn.getInputStream();  
44                   
45             } catch (MalformedURLException e) {  
46                 // TODO Auto-generated catch block  
47                 e.printStackTrace();  
48             }  
49               
50             return is;  
51        } 
52 }

 1 package com.vino.download;
 2 
 3 import android.app.Activity;
 4 import android.os.Bundle;
 5 import android.view.Menu;
 6 import android.view.MenuItem;
 7 import android.view.View;
 8 import android.view.View.OnClickListener;
 9 import android.widget.Button;
10 
11 import com.vino.utils.HttpDownloader;
12 
13 public class MainActivity extends Activity {
14 
15     private Button button;
16     @Override
17     protected void onCreate(Bundle savedInstanceState) {
18         super.onCreate(savedInstanceState);
19         setContentView(R.layout.activity_main);
20         button = (Button)findViewById(R.id.button);
21         button.setOnClickListener(new DownloadListener());
22     }
23 
24     class DownloadListener implements OnClickListener{
25 
26         @Override
27         public void onClick(View arg0) {
28              
29              Thread thread = new Thread(){
30                  @Override
31                  public void run(){
32                      HttpDownloader httpDownLoader=new HttpDownloader();
33                      httpDownLoader.downfile("http://192.168.0.102:8080/data/data.txt", "data/", "data.txt");  
34 //使用Toast时相当于修改了UI,程序报错
35 //                     if(result==0)  
36 //                     {  
37 //                         Toast.makeText(MainActivity.this, "下载成功！", Toast.LENGTH_SHORT).show();  
38 //                     }  
39 //                     else if(result==1) {  
40 //                         Toast.makeText(MainActivity.this, "已有文件！", Toast.LENGTH_SHORT).show();  
41 //                   }  
42 //                     else if(result==-1){  
43 //                         Toast.makeText(MainActivity.this, "下载失败！", Toast.LENGTH_SHORT).show();  
44 //                     }
45                  }
46              };
47              thread.start();
48                
49         }
50         
51     }
52     @Override
53     public boolean onCreateOptionsMenu(Menu menu) {
54         // Inflate the menu; this adds items to the action bar if it is present.
55         getMenuInflater().inflate(R.menu.main, menu);
56         return true;
57     }
58 
59     @Override
60     public boolean onOptionsItemSelected(MenuItem item) {
61         // Handle action bar item clicks here. The action bar will
62         // automatically handle clicks on the Home/Up button, so long
63         // as you specify a parent activity in AndroidManifest.xml.
64         int id = item.getItemId();
65         if (id == R.id.action_settings) {
66             return true;
67         }
68         return super.onOptionsItemSelected(item);
69     }
70 }