随时随地技术实战干货，获取项目源码、学习资料，请关注源代码社区公众号(ydmsq666)
SurfaceView与普通View还有一个重要区别：View的绘图必须在UI线程中进行，但SurfaceView不存在这个问题，因为它是由SurfaceHolder来完成的。所以对于View组件，如果绘图时间过长，会阻塞UI主线程，而SurfaceHolder则会启动新的线程去更新SurfaceView的绘制，不会阻塞UI线程。
下面的程序是通过SurfaceView绘制正玄曲线和余玄曲线的示例，代码如下：
Activity：
package com.home.showwave;import java.util.Timer;
import java.util.TimerTask;import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;
import android.view.View;public class ShowWaveActivity extends Activity {private SurfaceHolder holder;private SurfaceView surface;private Paint paint;private final int HEIGHT = 320;// 要绘制的曲线的水平宽度private final int WIDTH = 500;// 离屏幕左边界的起始距离private final int X_OFFSET = 5;// 初始化X坐标private int cx = X_OFFSET;// 实际的Y轴的位置private int centerY = HEIGHT / 2;private Timer timer = new Timer();private TimerTask task = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_show_wave);// 获得SurfaceView对象surface = (SurfaceView) findViewById(R.id.activity_show_wave_sv);// 初始化SurfaceHolder对象holder = surface.getHolder();paint = new Paint();paint.setColor(Color.GREEN);paint.setStrokeWidth(3);}public void click(final View v) {drawBackGround(holder);cx = X_OFFSET;if (task != null) {task.cancel();}task = new TimerTask() {@Overridepublic void run() {// 根据是正玄还是余玄和X坐标确定Y坐标int cy = v.getId() == R.id.activity_show_wave_btn_sin ? centerY- (int) (100 * Math.sin((cx - 5) * 2 * Math.PI / 150)): centerY- (int) (100 * Math.cos((cx - 5) * 2 * Math.PI/ 150));Canvas canvas = holder.lockCanvas(new Rect(cx, cy - 2, cx + 2,cy + 2));// 根据Ｘ，Ｙ坐标画点canvas.drawPoint(cx, cy, paint);cx++;// 超过指定宽度，线程取消，停止画曲线if (cx > WIDTH) {task.cancel();task = null;}// 提交修改holder.unlockCanvasAndPost(canvas);}};timer.schedule(task, 0, 30);holder.addCallback(new Callback() {@Overridepublic void surfaceChanged(SurfaceHolder holder, int format,int width, int height) {drawBackGround(holder);}@Overridepublic void surfaceCreated(SurfaceHolder holder) {}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {timer.cancel();}});}private void drawBackGround(SurfaceHolder holder) {Canvas canvas = holder.lockCanvas();// 绘制白色背景canvas.drawColor(Color.WHITE);Paint p = new Paint();p.setColor(Color.BLACK);p.setStrokeWidth(2);// 绘制坐标轴canvas.drawLine(X_OFFSET, centerY, WIDTH, centerY, p);canvas.drawLine(X_OFFSET, 40, X_OFFSET, HEIGHT, p);holder.unlockCanvasAndPost(canvas);holder.lockCanvas(new Rect(0, 0, 0, 0));holder.unlockCanvasAndPost(canvas);}
}
布局XML：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical" ><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:gravity="center_horizontal"android:orientation="horizontal" ><Buttonandroid:id="@+id/activity_show_wave_btn_sin"android:layout_width="wrap_content"android:layout_height="wrap_content"android:onClick="click"android:text="正玄曲线" /><Buttonandroid:id="@+id/activity_show_wave_btn_cos"android:layout_width="wrap_content"android:layout_height="wrap_content"android:onClick="click"android:text="余玄曲线" /></LinearLayout><SurfaceViewandroid:id="@+id/activity_show_wave_sv"android:layout_width="match_parent"android:layout_height="match_parent" /></LinearLayout>