Android屏幕截图有很多方式这里只使用其中一种截图
主要是读取/dev/graphics/fb0,进行转换，复杂点就在如何把读取的数据进行转换。
可以参考一下这篇文章：http://blog.chinaaet.com/detail/28298
下面给出程序代码

/**
 * ScreenShotFb.java
 * 版权所有(C) 2014
 * 创建者:cuiran 2014-4-3 下午4:55:23
 */
package com.ghyf.mplay.util;


import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import com.ghyf.mplay.value.ConstantValue;



import android.app.Activity;
import android.graphics.Bitmap;

import android.graphics.PixelFormat;
import android.util.DisplayMetrics;
import android.view.Display;

/**
 * FrameBuffer中获取Android屏幕截图 
 * @author cuiran
 * @version 1.0.0
 */
public class ScreenShotFb {

    private static final String TAG="ScreenShotFb";
    
    final static String FB0FILE1 = "/dev/graphics/fb0";

    static File fbFile;
      //程序入口  
    public static  void shoot(){  
         try {  
             /************ 创建锁对象 ************/
                final Object lock = new Object();
                
                synchronized (lock) {
                    long start=System.currentTimeMillis();
                    Bitmap bitmap=getScreenShotBitmap();
                    long end=System.currentTimeMillis();
                    LogUtil.i(TAG, "getScreenShotBitmap time is :"+(end-start)+" ms");
                    String filePath= ConstantValue.ROOT_SDCARD_DIR+"/s.png";
//                  String filePath= ConstantValue.ROOT_SDCARD_DIR+"/screens/"+System.currentTimeMillis()+".png";
                    ScreenShotFb.savePic(bitmap,filePath);  
                }
         }catch (Exception e) {  
            LogUtil.e(TAG, "Exception error",e);
         }  
    
    
    }  
     //保存到sdcard  
    public static void savePic(Bitmap b,String strFileName){  
        FileOutputStream fos = null;  
        try {  
            fos = new FileOutputStream(strFileName);  
            if (null != fos)  
            {  
                b.compress(Bitmap.CompressFormat.PNG, 50, fos);  
                fos.flush();  
                fos.close();  
            }  
        } catch (FileNotFoundException e) {  
            LogUtil.e(TAG, "FileNotFoundException error",e);
        } catch (IOException e) {  
            LogUtil.e(TAG, "IOException error",e);
        }  
        
        LogUtil.i(TAG, "savePic success");
    }  
    
     public static void init(Activity activity){  
        
            try {
            
                DisplayMetrics dm = new DisplayMetrics();
                Display display = activity.getWindowManager().getDefaultDisplay();
                display.getMetrics(dm);
                screenWidth = dm.widthPixels; // 屏幕宽（像素，如：480px）
                screenHeight = dm.heightPixels; // 屏幕高（像素，如：800p）
                int pixelformat = display.getPixelFormat();
                PixelFormat localPixelFormat1 = new PixelFormat();
                PixelFormat.getPixelFormatInfo(pixelformat, localPixelFormat1);
                int deepth = localPixelFormat1.bytesPerPixel;// 位深
                LogUtil.i(TAG, "deepth="+deepth);
                piex = new byte[screenHeight * screenWidth*deepth] ;// 像素
                colors = new int[screenHeight * screenWidth];
                
                
                
            }catch(Exception e){
                LogUtil.e(TAG, "Exception error",e);
            }
     }
     static DataInputStream dStream=null;
     static byte[] piex=null;
     static int[] colors =null;
     static int screenWidth;
     static int screenHeight;
     
    public static synchronized Bitmap getScreenShotBitmap() {
        FileInputStream buf = null;
        try {
            fbFile = new File(FB0FILE1);
            buf = new FileInputStream(fbFile);// 读取文件内容
            dStream=new DataInputStream(buf);
            dStream.readFully(piex);
            dStream.close();
            // 将rgb转为色值
              for(int i=0;i<piex.length;i+=2)
                {
                  colors[i/2]= (int)0xff000000 +
                            (int) (((piex[i+1]) << (16))&0x00f80000)+
                            (int) (((piex[i+1]) << 13)&0x0000e000)+
                            (int) (((piex[i]) << 5)&0x00001A00)+
                            (int) (((piex[i]) << 3)&0x000000f8);
                }

           // 得到屏幕bitmap
            return Bitmap.createBitmap(colors, screenWidth, screenHeight,
                        Bitmap.Config.RGB_565);
            
        } catch (FileNotFoundException e) {
            LogUtil.e(TAG, "FileNotFoundException error",e);
        } catch (IOException e) {
            LogUtil.e(TAG, "IOException error",e);
        }catch (Exception e) {
            LogUtil.e(TAG, "Exception error",e);
        }  
        finally {
            if(buf!=null){
                try {
                    buf.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
        return null;
    }
  
}

调用时候需要先init 然后在shoot
看到很多朋友咨询得到的数据花屏和数组越界
这里跟设备的设备的位深和像素有关 需要修改这些代码。
// 将rgb转为色值
for(int i=0;i<piex.length;i+=2) {
colors[i/2]= (int)0xff000000 +
(int) (((piex[i+1]) << (16))&0x00f80000)+
(int) (((piex[i+1]) << 13)&0x0000e000)+
(int) (((piex[i]) << 5)&0x00001A00)+
(int) (((piex[i]) << 3)&0x000000f8);
}