Android--向SD卡读写数据

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1. // 向SD卡写入数据  
2.     private void writeSDcard(String str) {  
3.         try {  
4.             // 判断是否存在SD卡  
5.             if (Environment.getExternalStorageState().equals(  
6.                     Environment.MEDIA_MOUNTED)) {  
7.                 // 获取SD卡的目录  
8.                 File sdDire = Environment.getExternalStorageDirectory();  
9.                 FileOutputStream outFileStream = new FileOutputStream(  
10.                         sdDire.getCanonicalPath() + "/test.txt");  
11.                 outFileStream.write(str.getBytes());  
12.                 outFileStream.close();  
13.                 Toast.makeText(this, "数据保存到text.txt文件了", Toast.LENGTH_LONG)  
14.                         .show();  
15.             }  
16.         } catch (Exception e) {  
17.             e.printStackTrace();  
18.         }  
19.     }  
20.   
21.       
22.     // 从SD卡中读取数据  
23.     private void readSDcard() {  
24.         StringBuffer strsBuffer = new StringBuffer();  
25.         try {  
26.             // 判断是否存在SD  
27.             if (Environment.getExternalStorageState().equals(  
28.                     Environment.MEDIA_MOUNTED)) {  
29.                 File file = new File(Environment.getExternalStorageDirectory()  
30.                         .getCanonicalPath() + "/test.txt");  
31.                 // 判断是否存在该文件  
32.                 if (file.exists()) {  
33.                     // 打开文件输入流  
34.                     FileInputStream fileR = new FileInputStream(file);  
35.                     BufferedReader reads = new BufferedReader(  
36.                             new InputStreamReader(fileR));  
37.                     String st = null;  
38.                     while ((st = reads.readLine()) != null) {  
39.                         strsBuffer.append(st);  
40.                     }  
41.                     fileR.close();  
42.                 } else {  
43.                     Toast.makeText(this, "该目录下文件不存在", Toast.LENGTH_LONG).show();  
44.                 }  
45.             }  
46.         } catch (Exception e) {  
47.             e.printStackTrace();  
48.         }  
49.         Toast.makeText(this, "读取到的数据是：" + strsBuffer.toString() + "",  
50.                 Toast.LENGTH_LONG).show();  
51.     }  
52. }  

转载：http://blog.csdn.net/chaoyu168/article/details/50721480