Android中利用线程更新UI（转）

handler使用Message

1.定义一个Handler

2.重写消息处理函数

3.发送消息

//创建简单的View
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 BounceView extends View {
float x = 40;

public BounceView(Context context) {
super(context);
}

@Override
protected void onDraw(Canvas canvas) {
x+=10;
Paint mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setColor(Color.GREEN);
canvas.drawCircle(x, 40, 40, mPaint);
}
}

//创建Activity
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.Window;

public class TestHandler extends Activity {
protected static final int GUIUPDATEIDENTIFIER = 0x101;

Thread myRefreshThread = null;
BounceView myBounceView = null;
//1.定义一个Handler(一般更新View)
Handler myHandler = new Handler() {
//2.重写消息处理函数
public void handleMessage(Message msg) {
switch (msg.what) {
//判断发送的消息
case TestHandler.GUIUPDATEIDENTIFIER:
//更新View
myBounceView.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 myThread()).start();
}

class myThread implements Runnable {
public void run() {
while (!Thread.currentThread().isInterrupted()) {
//3.发送消息
Message message = new Message();
//发送消息与处理函数里一致
message.what = TestHandler.GUIUPDATEIDENTIFIER;
//内部类调用外部类的变量
TestHandler.this.myHandler.sendMessage(message);

try {
Thread.sleep(100);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}
}

利用handler.post()更新UI

1.创建一个Handler 2.调用Handler.post(Runnable r)方法 3.Runnable运行在UI所在线程,所以可以直接调用View.invalidate()

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;

public class TestHandler extends Activity {
private MyView myView;
private Handler mHandler;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
myView = new MyView(this);
//创建一个Handler
mHandler = new Handler();
//调用Handler.post(Runnable r)方法
mHandler.post(new Runnable(){
@Override
public void run() {
//直接调用View.invalidate()，更新组件
myView.invalidate();
//延迟5毫秒后执行线程
mHandler.postDelayed(this, 5);
}
});
setContentView(myView);
}

class MyView extends View{
private float x = 0f;
public MyView(Context context) {
super(context);

}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
x+=1;
Paint mPaint = new Paint();
mPaint.setColor(Color.BLUE);
canvas.drawRect(x, 40, x+40, 80, mPaint);
}

}
}

在线程里直接更新UI

//在新线程里更新UI,可以直接使用postInvalidate()

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);

myView = new MyView(this);
this.setContentView(this.myView);
new Thread(new myThread()).start();
}

class myThread implements Runnable {
public void run() {
while (!Thread.currentThread().isInterrupted()) {
try {
//更新UI
myView.postInvalidate();
Thread.sleep(100);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}