Android提高第三篇之SurfaceView与多线程的混搭

本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

         上一篇简单介绍了SurfaceView的基本使用，这次就介绍SurfaceView与多线程的混搭。SurfaceView与多线程混搭，是为了防止动画闪烁而实现的一种多线程应用。android的多线程用法与JAVA的多线程用法完全一样，本文不做多线程方面的介绍了。直接讲解SurfaceView与多线程的混合使用，即开一条线程专门读取图片，另外一条线程专门绘图。

        本文程序运行截图如下，左边是开单个线程读取并绘图，右边是开两个线程，一个专门读取图片，一个专门绘图：

对比一下，右边动画的帧速明显比左边的快，左右两者都没使用Thread.sleep()。为什么要开两个线程一个读一个画，而不去开两个线程像左边那样都“边读边画”呢？因为SurfaceView每次绘图都会锁定Canvas,也就是说同一片区域这次没画完下次就不能画，因此要提高动画播放的效率，就得开一条线程专门画图，开另外一条线程做预处理的工作。

main.xml的源码：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent" android:layout_height="fill_parent"android:orientation="vertical"><LinearLayout android:id="@+id/LinearLayout01"android:layout_width="wrap_content" android:layout_height="wrap_content"><Button android:id="@+id/Button01" android:layout_width="wrap_content"android:layout_height="wrap_content" android:text="单个独立线程"></Button><Button android:id="@+id/Button02" android:layout_width="wrap_content"android:layout_height="wrap_content" android:text="两个独立线程"></Button></LinearLayout><SurfaceView android:id="@+id/SurfaceView01"android:layout_width="fill_parent" android:layout_height="fill_parent"></SurfaceView></LinearLayout>

本文程序的源码：

 package com.testSurfaceView;import java.lang.reflect.Field;import java.util.ArrayList;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.Rect;import android.os.Bundle;import android.util.Log;import android.view.SurfaceHolder;import android.view.SurfaceView;import android.view.View;import android.widget.Button;public class testSurfaceView extends Activity {/** Called when the activity is first created. */Button btnSingleThread, btnDoubleThread;SurfaceView sfv;SurfaceHolder sfh;ArrayList<Integer> imgList = new ArrayList<Integer>();int imgWidth, imgHeight;Bitmap bitmap;//独立线程读取，独立线程绘图@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);btnSingleThread = (Button) this.findViewById(R.id.Button01);btnDoubleThread = (Button) this.findViewById(R.id.Button02);btnSingleThread.setOnClickListener(new ClickEvent());btnDoubleThread.setOnClickListener(new ClickEvent());sfv = (SurfaceView) this.findViewById(R.id.SurfaceView01);sfh = sfv.getHolder();sfh.addCallback(new MyCallBack());// 自动运行surfaceCreated以及surfaceChanged}class ClickEvent implements View.OnClickListener {@Overridepublic void onClick(View v) {if (v == btnSingleThread) {new Load_DrawImage(0, 0).start();//开一条线程读取并绘图} else if (v == btnDoubleThread) {new LoadImage().start();//开一条线程读取new DrawImage(imgWidth + 10, 0).start();//开一条线程绘图}}}class MyCallBack implements SurfaceHolder.Callback {@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {Log.i("Surface:", "Change");}@Overridepublic void surfaceCreated(SurfaceHolder holder) {Log.i("Surface:", "Create");// 用反射机制来获取资源中的图片ID和尺寸Field[] fields = R.drawable.class.getDeclaredFields();for (Field field : fields) {if (!"icon".equals(field.getName()))// 除了icon之外的图片{int index = 0;try {index = field.getInt(R.drawable.class);} catch (IllegalArgumentException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();}// 保存图片IDimgList.add(index);}}// 取得图像大小Bitmap bmImg = BitmapFactory.decodeResource(getResources(),imgList.get(0));imgWidth = bmImg.getWidth();imgHeight = bmImg.getHeight();}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {Log.i("Surface:", "Destroy");}}/* * 读取并显示图片的线程 */class Load_DrawImage extends Thread {int x, y;int imgIndex = 0;public Load_DrawImage(int x, int y) {this.x = x;this.y = y;}public void run() {while (true) {Canvas c = sfh.lockCanvas(new Rect(this.x, this.y, this.x+ imgWidth, this.y + imgHeight));Bitmap bmImg = BitmapFactory.decodeResource(getResources(),imgList.get(imgIndex));c.drawBitmap(bmImg, this.x, this.y, new Paint());imgIndex++;if (imgIndex == imgList.size())imgIndex = 0;sfh.unlockCanvasAndPost(c);// 更新屏幕显示内容}}};/* * 只负责绘图的线程 */class DrawImage extends Thread {int x, y;public DrawImage(int x, int y) {this.x = x;this.y = y;}public void run() {while (true) {if (bitmap != null) {//如果图像有效Canvas c = sfh.lockCanvas(new Rect(this.x, this.y, this.x+ imgWidth, this.y + imgHeight));c.drawBitmap(bitmap, this.x, this.y, new Paint());sfh.unlockCanvasAndPost(c);// 更新屏幕显示内容}}}};/* * 只负责读取图片的线程 */class LoadImage extends Thread {int imgIndex = 0;public void run() {while (true) {bitmap = BitmapFactory.decodeResource(getResources(),imgList.get(imgIndex));imgIndex++;if (imgIndex == imgList.size())//如果到尽头则重新读取imgIndex = 0;}}};}