Android开发总结之 --- 定时，读写文件

【一、定时】

Android中的Timer一般像下面这样写：



Timer timer = new Timer( );

TimerTask task = new TimerTask( ) {

public void run ( ) {

Message message = new Message( );

message.what = 1;

handler.sendMessage(message);

}

};

final Handler handler = new Handler( ) {

public void handleMessage(Message msg) {

switch (msg.what) {

case 1:

log.e("Timer","Timer");

update( );

break;

}

super.handleMessage(msg);

}

};

protected void onDestroy ( ) {

if (timer != null) {

timer.cancel( );

timer = null;

}

super.onDestroy( );

}

protected void onCreate (Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

this.setContentView(R.layout.main);

timer.schedule(task,1000,5000);

}

private Handler handler = new Handler( );

private Runnable runnable = new Runnable( ) {

public void run ( ) {

update( );

handler.postDelayed(this,1000);     //postDelayed(this,1000)方法安排一个Runnable对象到主线程队列中

}

};

handler.postDelayed(runnable,1000);         // 开始Timer

handler.removeCallbacks(runnable);           //停止Timer

【二、读写文件】

 //写文件在./data/data/com.tt/files/下面

   public voidwriteFileData(String fileName,String message){ 

       try{ 

        FileOutputStream fout =openFileOutput(fileName, MODE_PRIVATE);

        byte [] bytes = message.getBytes(); //可在此处进行转码设置

        fout.write(bytes); 

         fout.close(); 

        } 

       catch(Exception e){ 

        e.printStackTrace(); 

       } 

   }

//-------------------------------------------------------

//读文件在./data/data/com.tt/files/下面

   public String readFileData(String fileName){ 

        String res=""; 

        try{ 

         FileInputStream fin = openFileInput(fileName); 

         int length = fin.available(); 

         byte [] buffer = new byte[length]; 

         fin.read(buffer);     

         res = EncodingUtils.getString(buffer, "UTF-8"); 

         fin.close();     

        } 

        catch(Exception e){ 

         e.printStackTrace(); 

        } 

        return res; 

    }   

/** 
 * 描述：追加内容到文件末尾 
 * @author Administrator 
 * 
 */  
public class WriteStreamAppend {  
    /** 
     * 追加文件：使用FileOutputStream，在构造FileOutputStream时，把第二个参数设为true 
     *  
     * @param fileName 
     * @param content 
     */  
    public static void method1(String file, String conent) {  
        BufferedWriter out = null;  
        try {  
            out = new BufferedWriter(new OutputStreamWriter(  
                    new FileOutputStream(file, true)));  
            out.write(conent);  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            try {  
                out.close();  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
    }  
  
    /** 
     * 追加文件：使用FileWriter 
     *  
     * @param fileName 
     * @param content 
     */  
    public static void method2(String fileName, String content) {  
        try {  
            // 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  
            FileWriter writer = new FileWriter(fileName, true);  
            writer.write(content);  
            writer.close();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
  
    /** 
     * 追加文件：使用RandomAccessFile 
     *  
     * @param fileName 
     *            文件名 
     * @param content 
     *            追加的内容 
     */  
    public static void method3(String fileName, String content) {  
        try {  
            // 打开一个随机访问文件流，按读写方式  
            RandomAccessFile randomFile = new RandomAccessFile(fileName, "rw");  
            // 文件长度，字节数  
            long fileLength = randomFile.length();  
            // 将写文件指针移到文件尾。  
            randomFile.seek(fileLength);  
            randomFile.writeBytes(content);  
            randomFile.close();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
  
    public static void main(String[] args) {  
        System.out.println("start");  
        method1("c:/test.txt", "追加到文件的末尾");  
        System.out.println("end");  
    }  
  
}  

参考：

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

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