Handler理解
Android UI操作并不是线程安全的并且这些操作必须在UI线程中执行。常用的方法是利用Handler来实现UI线程的更新的。
package com.handler;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.drawable.Drawable;
import android.view.View;
public class TestView extends View {
float x = 40;
public TestView(Context context) {
super(context);
}
@Override
protected void onDraw(Canvas canvas) {
x+=5;
Paint mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setColor(Color.GREEN);
canvas.drawCircle(x, 100, 100, mPaint);
}
}
public class TestHandler extends Activity {
protected static final int GUIUPDATEIDENTIFIER = 0x101;
TestView myView = null;
Handler myHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case TestHandler.GUIUPDATEIDENTIFIER:
myView.invalidate();
break;
}
super.handleMessage(msg);
}
};
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
this.myBounceView = new BounceView(this);
this.setContentView(this.myBounceView);
new Thread(new TestThread()).start();
}
class TestThread implements Runnable {
public void run() {
while (!Thread.currentThread().isInterrupted()) {
Message message = new Message();
message.what = TestHandler.GUIUPDATEIDENTIFIER;
TestHandler.this.myHandler.sendMessage(message);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}
}
转载于:https://www.cnblogs.com/wzh206/archive/2010/05/15/1736329.html
总结
