Android开发总结之 --- 定时，读写文件

【一、定时】

 1 Android中的Timer一般像下面这样写：
 2 
 3 
 4 
 5 Timer timer = new Timer( );
 6 
 7 TimerTask task = new TimerTask( ) {
 8 
 9 public void run ( ) {
10 
11 Message message = new Message( );
12 
13 message.what = 1;
14 
15 handler.sendMessage(message);
16 
17 }
18 
19 };
20 
21 final Handler handler = new Handler( ) {
22 
23 public void handleMessage(Message msg) {
24 
25 switch (msg.what) {
26 
27 case 1:
28 
29 log.e("Timer","Timer");
30 
31 update( );
32 
33 break;
34 
35 }
36 
37 super.handleMessage(msg);
38 
39 }
40 
41 };
42 
43 protected void onDestroy ( ) {
44 
45 if (timer != null) {
46 
47 timer.cancel( );
48 
49 timer = null;
50 
51 }
52 
53 super.onDestroy( );
54 
55 }
56 
57 protected void onCreate (Bundle savedInstanceState) {
58 
59 super.onCreate(savedInstanceState);
60 
61 this.setContentView(R.layout.main);
62 
63 timer.schedule(task,1000,5000);
64 
65 }

Timer

 1 private Handler handler = new Handler( );
 2 
 3 private Runnable runnable = new Runnable( ) {
 4 
 5 public void run ( ) {
 6 
 7 update( );
 8 
 9 handler.postDelayed(this,1000);     //postDelayed(this,1000)方法安排一个Runnable对象到主线程队列中
10 
11 }
12 
13 };
14 
15 handler.postDelayed(runnable,1000);         // 开始Timer
16 
17 handler.removeCallbacks(runnable);           //停止Timer

Runnable

【二、读写文件】

 1  //写文件在./data/data/com.tt/files/下面
 2 
 3    public voidwriteFileData(String fileName,String message){ 
 4 
 5        try{ 
 6 
 7         FileOutputStream fout =openFileOutput(fileName, MODE_PRIVATE);
 8 
 9         byte [] bytes = message.getBytes(); //可在此处进行转码设置
10 
11         fout.write(bytes); 
12 
13          fout.close(); 
14 
15         } 
16 
17        catch(Exception e){ 
18 
19         e.printStackTrace(); 
20 
21        } 
22 
23    }
24 
25 //-------------------------------------------------------
26 
27 //读文件在./data/data/com.tt/files/下面
28 
29    public String readFileData(String fileName){ 
30 
31         String res=""; 
32 
33         try{ 
34 
35          FileInputStream fin = openFileInput(fileName); 
36 
37          int length = fin.available(); 
38 
39          byte [] buffer = new byte[length]; 
40 
41          fin.read(buffer);     
42 
43          res = EncodingUtils.getString(buffer, "UTF-8"); 
44 
45          fin.close();     
46 
47         } 
48 
49         catch(Exception e){ 
50 
51          e.printStackTrace(); 
52 
53         } 
54 
55         return res; 
56 
57     }

读写

 1 /** 
 2  * 描述：追加内容到文件末尾 
 3  * @author Administrator 
 4  * 
 5  */  
 6 public class WriteStreamAppend {  
 7     /** 
 8      * 追加文件：使用FileOutputStream，在构造FileOutputStream时，把第二个参数设为true 
 9      *  
10      * @param fileName 
11      * @param content 
12      */  
13     public static void method1(String file, String conent) {  
14         BufferedWriter out = null;  
15         try {  
16             out = new BufferedWriter(new OutputStreamWriter(  
17                     new FileOutputStream(file, true)));  
18             out.write(conent);  
19         } catch (Exception e) {  
20             e.printStackTrace();  
21         } finally {  
22             try {  
23                 out.close();  
24             } catch (IOException e) {  
25                 e.printStackTrace();  
26             }  
27         }  
28     }  
29   
30     /** 
31      * 追加文件：使用FileWriter 
32      *  
33      * @param fileName 
34      * @param content 
35      */  
36     public static void method2(String fileName, String content) {  
37         try {  
38             // 打开一个写文件器，构造函数中的第二个参数true表示以追加形式写文件  
39             FileWriter writer = new FileWriter(fileName, true);  
40             writer.write(content);  
41             writer.close();  
42         } catch (IOException e) {  
43             e.printStackTrace();  
44         }  
45     }  
46   
47     /** 
48      * 追加文件：使用RandomAccessFile 
49      *  
50      * @param fileName 
51      *            文件名 
52      * @param content 
53      *            追加的内容 
54      */  
55     public static void method3(String fileName, String content) {  
56         try {  
57             // 打开一个随机访问文件流，按读写方式  
58             RandomAccessFile randomFile = new RandomAccessFile(fileName, "rw");  
59             // 文件长度，字节数  
60             long fileLength = randomFile.length();  
61             // 将写文件指针移到文件尾。  
62             randomFile.seek(fileLength);  
63             randomFile.writeBytes(content);  
64             randomFile.close();  
65         } catch (IOException e) {  
66             e.printStackTrace();  
67         }  
68     }  
69   
70     public static void main(String[] args) {  
71         System.out.println("start");  
72         method1("c:/test.txt", "追加到文件的末尾");  
73         System.out.println("end");  
74     }  
75   
76 }

ReadWriteFile

参考：

http://www.cnblogs.com/freeliver54/archive/2011/09/16/2178910.html

http://blog.csdn.net/jincf2011/article/details/6603916