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Handler更新UI的幾種方法
handler使用Message
1.定義一個Handler
2.重寫消息處理函數
3.發送消息
//創建簡單的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);
}
}
//創建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.定義一個Handler(一般更新View)
Handler myHandler = new Handler() {
//2.重寫消息處理函數
public void handleMessage(Message msg) {
switch (msg.what) {
//判斷發送的消息
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.發送消息
Message message = new Message();
//發送消息與處理函數裏一致
message.what = TestHandler.GUIUPDATEIDENTIFIER;
//內部類調用外部類的變量
TestHandler.this.myHandler.sendMessage(message);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}
}
利用handler.post()更新UI
1.創建一個Handler 2.調用Handler.post(Runnable r)方法 3.Runnable運行在UI所在線程,所以可以直接調用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);
//創建一個Handler
mHandler = new Handler();
//調用Handler.post(Runnable r)方法
mHandler.post(new Runnable(){
@Override
public void run() {
//直接調用View.invalidate()，更新組件
myView.invalidate();
//延遲5毫秒後執行線程
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);
}
}
}
在線程裏直接更新UI
//在新線程裏更新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();
}
}
}
}
最後更新：2017-04-02 06:51:49