我截图出现黑屏的原因是在Activity中用到了SurfaceView控件，在XML布局中的控件可以完整的显示出来但是有surfaceView的时候就出现黑屏了。具体原因我想的是因为在surfaceView中用线程不停的绘图，操作太频繁了，原来那种方法没有办法截出来。在surfaceView中绘图的原理：

用另外一个Canvas对象不停的把要画到surfaceView中的对象画到这个额外的canvas中，再声明一个Bitmap bitmap对象，注意这个bitmap不是你画在surfaceView中的对象，而是你的目标对象，就是需要截的图。你只需要这样：Canvas canvas=new Canvas（bitmap），接着用canvas.drawBitmap(curBitmap, 0, 0, null),你就可以把当前的的要画的到SurfaceView保存到bitmap中，然后把bitmap保存出来就可以了。PS：这只是截出来SurfaceView中图像，如果想截取背景图片，可以把surfaceView设置为透明。网上有很多种方法，这里就不介绍了。

贴出网上可以运行的代码：

menu.xml:

< xml version="1.0" encoding="utf-8" >

Element.java

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;

public class Element {
private float mX;
private float mY;

private Bitmap mBitmap;

public Element(Resources res, int x, int y) {
mBitmap = BitmapFactory.decodeStream(new BufferedInputStream(res.openRawResource(R.drawable.icon)));
mX = x - mBitmap.getWidth() / 2;
mY = y - mBitmap.getHeight() / 2;
}

public void doDraw(Canvas canvas) {
canvas.drawBitmap(mBitmap, mX, mY, null);
}
}

Panel.java

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Environment;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class Panel extends SurfaceView implements SurfaceHolder.Callback
{

public static float mWidth;
public static float mHeight;

private ViewThread mThread;
private ArrayList mElements = new ArrayList();
private int mElementNumber = 0;

private Paint mPaint = new Paint();
private String mScreenshotPath = Environment.getExternalStorageDirectory()
+ "/droidnova";

public Panel(Context context)
{
super(context);
getHolder().addCallback(this);
mThread = new ViewThread(this);
mPaint.setColor(Color.WHITE);
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height)
{
mWidth = width;
mHeight = height;
}

@Override
public void surfaceCreated(SurfaceHolder holder)
{
if (!mThread.isAlive())
{
mThread = new ViewThread(this);
mThread.setRunning(true);
mThread.start();
}
}

@Override
public void surfaceDestroyed(SurfaceHolder holder)
{
if (mThread.isAlive())
{
mThread.setRunning(false);
}
}

@Override
public boolean onTouchEvent(MotionEvent event)
{
synchronized (mElements)
{
mElements.add(new Element(getResources(), (int) event.getX(),
(int) event.getY()));
mElementNumber = mElements.size();
}
return super.onTouchEvent(event);
}