来源: 互联网  发布时间: 2014-02-18

创建文件不可写的解决办法

有时候你在ddms中可以看见创建了一个文件用file = new File( getFilesDir() + "/file.txt"); 
但是呢它是只读的 这时候你会发现-rw------- ，那怎么才能写呢

1.file = new File( getFilesDir() + "/file.txt"); 

 openFileOutput("file.txt", MODE_PRIVATE)

2.如果你已经确定他已经创建了 只是只读的 不能写那你可以哟偶那个

FileWriter fWriter; 
try { 
    fWriter = new FileWriter(file, true); 
    fWriter.write("hello"); 
    fWriter.close(); 
} catch (IOException e) { 
    // log error 
} 

    

    来源: 互联网  发布时间: 2014-02-18

ViewFlipper Animation 使用
ViewFlipper

[功能]
1. ViewFlipper 可以包含多个View 且View之间的切换有Animation  比如：渐变效果


[代码]
1. 创建包含ViewFlipper 的main.xml 还包含2个Button 用于各个View切换

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    >
	<Button
	android:id="@+id/previousButton"  
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="Previous"
    />
    <Button
	android:id="@+id/nextButton"  
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="Next"
    />
    </LinearLayout>
<ViewFlipper  
	android:id="@+id/flipper"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:gravity="center"
    >
</ViewFlipper>
</LinearLayout>

2. 设定 Animation 效果

flipper = (ViewFlipper) findViewById(R.id.flipper);
flipper.setInAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_in));
flipper.setOutAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_out));

3. 在 ViewFlipper  里面增加各种View

flipper.addView(addTextByText("HelloAndroid"));
        flipper.addView(addImageById(R.drawable.beijing_003_mb5ucom));
        flipper.addView(addTextByText("eoe.Android"));
        flipper.addView(addImageById(R.drawable.beijing_004_mb5ucom));
        flipper.addView(addTextByText("Gryphone"));

ublic View addTextByText(String text){
    		TextView tv = new TextView(this);
    		tv.setText(text);
    		tv.setGravity(1);
    		return tv;
    }
    
    public View addImageById(int id){
		ImageView iv = new ImageView(this);
		iv.setImageResource(id);
		
		return iv;
    }

4. View 切换
* 下一个View

flipper.showNext();

* 上一个View

flipper.showPrevious();

现释出所有代码!

over.

    

    来源: 互联网  发布时间: 2014-02-18

AsyncTask 和Timer同时使用

package com.example.test; 
 
import java.net.URL; 
import java.util.Timer; 
import java.util.TimerTask; 
 
import javax.xml.parsers.SAXParser; 
import javax.xml.parsers.SAXParserFactory; 
 
import org.xml.sax.InputSource; 
import org.xml.sax.XMLReader; 
 
import android.app.Activity; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.os.Handler; 
import android.util.Log; 
 
public class MyXmlPoller extends Activity { 
 
    private Handler handler = new Handler(); 
 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main); 
 
        new Timer().schedule(new MyTimerTask(), 0, 1000); 
    } 
 
    private class MyAsyncTask extends AsyncTask<Integer, Integer, MyData> { 
 
        protected MyData doInBackground(Integer... counter) { 
            MyData myData = new MyData(); 
 
            try { 
                URL url = new URL("http://www.example.com/my.xml"); 
                SAXParserFactory spf = SAXParserFactory.newInstance(); 
                SAXParser sp = spf.newSAXParser(); 
 
                XMLReader xr = sp.getXMLReader(); 
 
                MySAXHandler mySAXHandler = new Handler(); 
                xr.setContentHandler(mySAXHandler); 
 
                xr.parse(new InputSource(url.openStream())); 
 
                myData = mySAXHandler.getParsedData(); 
 
                return myData; 
 
            } catch (Exception e) { 
                Log.e("!!!!!!!!!! MyAsyncTask doInBackground error", e.getMessage(), e); 
                return myData; 
            } 
 
        } 
 
        protected void onPostExecute(MyData myData) { 
            Log.d("+++++++++++++ MyAsyncTask onPostExecute", myData.toString()); 
        } 
    } // MyAsyncTask 
 
   private Handler mHandler = new Handler();  
 
public class MyTimerTask extends TimerTask { 
    public void run() { 
        mHandler.post( 
            new Runnable() {  
                public void run() {  
                    new MyAsyncTask().execute(""); 
                }  
            };      
        ) 
    } 
} } 

 在这里呢一定要注意TimerTask要运行在Handler中。

 

当然上面的代码也可以如下变化

URL url = new URL("http://www.example.com/my.xml"); 
            SAXParserFactory spf = SAXParserFactory.newInstance(); 
            SAXParser sp = spf.newSAXParser(); 
 
            XMLReader xr = sp.getXMLReader(); 
 
            MyHandler myHandler = new MyHandler(); 
            xr.setContentHandler(myHandler); 

 

将上面的放在onPreExecute() method 中。

http://developer.android.com/intl/fr/reference/android/os/Looper.html