[Android SQLite]數據存儲與訪問 - 外部存儲

接下來就到SD卡了吧 ^_^

不是所有的手機都有SD卡,但是Android系統本身提供了對SD卡很便捷的訪問方法

相關閱讀：

[Android SQLite]數據存儲與訪問 - 內部存儲 http://www.linuxidc.com/Linux/2011-12/50130.htm

[Android SQLite]數據存儲與訪問 - SharedPreferences http://www.linuxidc.com/Linux/2011-12/50131.htm

一般下載的數據都比較大就都放到SD卡了...具體原因,未知 哈哈

1. public class SD_Demo extends Activity implements OnClickListener  
2. {  
3.     private StringBuilder randomNumBersString = null;  
4.       
5.     private TextView displayView = null;  
6.       
7.     @Override  
8.     protected void onCreate(Bundle savedInstanceState)  
9.     {  
10.         super.onCreate(savedInstanceState);  
11.         setContentView(R.layout.main1);  
12.         setupViews();  
13.     }  
14.   
15.     private void setupViews()  
16.     {  
17.         displayView = (TextView) findViewById(R.id.display);  
18.         findViewById(R.id.random).setOnClickListener(this);  
19.         findViewById(R.id.write).setOnClickListener(this);  
20.         randomNumBersString = new StringBuilder();  
21.     }  
22.   
23.     @Override  
24.     public void onClick(View v)  
25.     {  
26.         switch (v.getId())  
27.         {  
28.             case R.id.random:  
29.                 for (int i = 0; i < 10; i++)  
30.                 {  
31.                     randomNumBersString.append(Math.random()+"\n");  
32.                 }  
33.                 displayView.setText(randomNumBersString.toString());  
34.                 break;  
35.                   
36.             case R.id.write:  
37.                 String fileName = "SdcardFile-"+System.currentTimeMillis()+".txt";;  
38.                 boolean sdCardExist = Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);   
39.                 File dir = null;  
40.                 if (sdCardExist)  
41.                 {  
42.                     dir = new File( Environment.getExternalStorageDirectory().toString() + File.separator + "123321");  
43.                     if (!dir.exists())  
44.                     {  
45.                         dir.mkdirs();  
46.                     }  
47.                 }  
48.                 if (dir.exists() && dir.canWrite())  
49.                 {  
50.                     File newFile = new File(dir.getAbsolutePath()+ "/" + fileName);  
51.                     FileOutputStream fos = null;  
52.                     try  
53.                     {  
54.                         newFile.createNewFile();  
55.                         if (newFile.exists() && newFile.canWrite())  
56.                         {  
57.                             fos = new FileOutputStream(newFile);  
58.                             fos.write(randomNumBersString.toString().getBytes());  
59.                             displayView.setText(String.format("%s文件寫入SD卡", fileName))   ;  
60.                         }  
61.                     } catch (IOException e)  
62.                     {  
63.                         e.printStackTrace();  
64.                     }finally  
65.                     {  
66.                         if (fos != null)  
67.                         {  
68.                             try  
69.                             {  
70.                                 fos.flush();  
71.                                 fos.close();  
72.                             } catch (IOException e)  
73.                             {  
74.                                 e.printStackTrace();  
75.                             }  
76.                         }  
77.                     }  
78.                 }  
79.                 break;  
80.         }  
81.     }  
82. }