Looper物件之角色(Demo 3)

这个例子是为了更进一步的理解Demo2 
这个例子跟Demo2只是有些小的改动,大家可以对比的看下 

package com.example.Looper_03;

import android.app.Activity;
import android.content.Context;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

public class Looper_03 extends Activity implements OnClickListener {
    private final int WC = LinearLayout.LayoutParams.WRAP_CONTENT;
    private final int FP = LinearLayout.LayoutParams.FILL_PARENT;
    public TextView tv;
    private myThread t;
    private Button btn, btn2;
    EventHandler h;
    Context ctx;

    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        ctx = this;
        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.VERTICAL);
        btn = new Button(this);
        btn.setId(101);
        btn.setBackgroundResource(R.drawable.icon);
        btn.setText("test looper");
        btn.setOnClickListener(this);
        LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(100, 50);
        param.topMargin = 10;
        layout.addView(btn, param);
        btn2 = new Button(this);
        btn2.setId(102);
        btn2.setBackgroundResource(R.drawable.icon);
        btn2.setText("exit");
        btn2.setOnClickListener(this);
        layout.addView(btn2, param);
        tv = new TextView(this);
        tv.setTextColor(Color.WHITE);
        tv.setText("");
        LinearLayout.LayoutParams param2 = new LinearLayout.LayoutParams(FP, WC);
        param2.topMargin = 10;
        layout.addView(tv, param2);
        setContentView(layout);
    }

    public void onClick(View v) {
        switch (v.getId()) {
        case 101:
            // 此h是屬於main線程的(用來存取主線程的MessageQueue)
            //h = new EventHandler(Looper.myLooper());//@

            //或者可以写成这样;
            h = new EventHandler();

            t = new myThread();
            t.start();
            break;
        case 102:
            finish();
            break;
        }
    }

    //或者可以写成这样;
    public class EventHandler extends Handler {
        @Override
        public void handleMessage(Message msg) {
            ((Activity) ctx).setTitle((String) msg.obj);
        }
    }

    // ------------------------------------------------
    /*public class EventHandler extends Handler {//@
        public EventHandler(Looper looper) {
            super(looper);
        }

        @Override
        public void handleMessage(Message msg) {
            ((Activity) ctx).setTitle((String) msg.obj);
        }
    }*/

    // ------------------------------------------------------
    class myThread extends Thread {
        public void run() {
            String obj = "from myThread";
            Message m = h.obtainMessage(1, 1, 1, obj);
            //这里还是通过主线程的handler来传送消息
            //所以还是由主线程的Looper来接受消息
            h.sendMessage(m);
        }
    }
}
// ------------------------------------------------------

• Looper_3.rar (24.4 KB)
• 下载次数: 5