公共代码参考（DisplayMetrics）

package com.fredric.util;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.WindowManager;

/*-
 * 屏幕交互类封装
 */

public class ScreenUtils {

    //获取屏幕宽度
    public static int getScreenWidth(Context context){
        WindowManager wm = (WindowManager) context  
                .getSystemService(Context.WINDOW_SERVICE);
        //DisplayMetrics提供关于现实的通用信息
        DisplayMetrics display = new DisplayMetrics();        
        //将当前窗口信息放置入display
        wm.getDefaultDisplay().getMetrics(display);        
        //返回绝对像素
        return display.widthPixels;  
    }
    
    //获取屏幕高度
    public static int getScreenHeight(Context context){
        
        WindowManager wm = (WindowManager) context  
                .getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics display = new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(display);
        return display.heightPixels;  
    }
    
    //截屏
    public static Bitmap getSnapShot(Activity activity){
        
        //decorView是window的最顶层view
        View view = activity.getWindow().getDecorView();
        //view组件的内容通过cache机制保存至bitmap
        //setDrawingCacheEnabled 开启cache
        //getDrawingCache 获取view的cache图片
        //buildDrawingCache 可不调用，若getDrawingCache调用时cache没有建立则调用
        //destoryDrawingCache 销毁cache，setDrawingCacheEnabled(false)也可销毁cache
        //cache若要更新则必须先销毁旧cache
        view.setDrawingCacheEnabled(true);
        
        Bitmap bp  = null;
        int width  = getScreenWidth(activity);  
        int height = getScreenHeight(activity);   
        bp = Bitmap.createBitmap(view.getDrawingCache(), 0, 0, width, height);  
        view.destroyDrawingCache();  
        return bp; 
    }
}