21天学习android开发教程之SurfaceView与多线程的混搭

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：

<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 android:id="@+id/button02" android:layout_width="wrap_content" 
            android:layout_height="wrap_content" android:text="两个独立线程">
    
    <surfaceview android:id="@+id/surfaceview01" 
        android:layout_width="fill_parent" android:layout_height="fill_parent">

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 imglist = new arraylist();
    int imgwidth, imgheight;
    bitmap bitmap;//独立线程读取，独立线程绘图

    @override
    public 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 {

        @override
        public 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 {

        @override
        public void surfacechanged(surfaceholder holder, int format, int width,
                int height) {
            log.i("surface:", "change");

        }

        @override
        public 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 block
                        e.printstacktrace();
                    } catch (illegalaccessexception e) {
                        // todo auto-generated catch block
                        e.printstacktrace();
                    }
                    // 保存图片id
                    imglist.add(index);
                }
            }
            // 取得图像大小
            bitmap bmimg = bitmapfactory.decoderesource(getresources(),
                    imglist.get(0));
            imgwidth = bmimg.getwidth();
            imgheight = bmimg.getheight();
        }

        @override
        public 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;
            }
        }
    };
}

以上就是本文的全部内容，希望对大家学习android软件编程有所帮助。