主线程控制ProgressDialog的可见性

最新推荐文章于 2021-05-27 02:04:27 发布

原创最新推荐文章于 2021-05-27 02:04:27 发布 · 158 阅读

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#Android #FP #OS #thread

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本文介绍了一个使用Android中Looper和Handler实现线程间通信的例子。通过创建自定义的Activity，利用按钮触发后台线程任务，并将结果显示在界面上。文章详细展示了如何设置UI组件、初始化线程以及消息传递的过程。

貌似这个看起来比较合理:


package com.example;

import android.app.Activity;
import android.app.ProgressDialog;
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_8 extends Activity implements OnClickListener {
	private final int WC = LinearLayout.LayoutParams.WRAP_CONTENT;
	private final int FP = LinearLayout.LayoutParams.FILL_PARENT;
	private ProgressDialog progressDialog = null;
	private myThread th1;
	public TextView tv;
	private Button btn, btn2;
	private EventHandler h;

	public void onCreate(Bundle icicle) {
		super.onCreate(icicle);
		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:
			progressDialog = ProgressDialog.show(this, "please wait…",
					"Loading", true);
			//生成主线程的handle
			h = new EventHandler(Looper.myLooper());
			th1 = new myThread();
			th1.start();
			break;
		case 102:
			finish();
			break;
		}
	}

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

		@Override
		public void handleMessage(Message msg) {
			progressDialog.dismiss();
			setTitle((String) msg.obj);
		}
	}

	// ---------------------------------------
	class myThread extends Thread {
		@Override
		public void run() {
			try {
				sleep(6000); // 故意延遲
			} catch (Exception e) {
				e.printStackTrace();
			}
			String obj = "mainThread....";
			Message m = h.obtainMessage(1, 1, 1, obj);
			h.sendMessage(m);
		}
	}
}