新建线程与UI线程间的通信

现在用一个实例来演示一下自己的新建线程与UI线程间的通信。

UI界面包含3个控件：

一个输入框，用来输入数字；

一个显示框，用来显示从2开始，到输入数字之间的所有质数；

一个按钮,点击后获取输入框输入的数字，交给新建线程处理，线程计算质数后把结果传给UI线程，UI线程显示结果到显示框。

XML如下：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <ScrollView
        android:id="@+id/scrollView1"
        android:layout_width="match_parent"
        android:layout_height="fill_parent" >

        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical"
            android:weightSum="5" >

            <TextView
                android:id="@+id/textView_for"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_weight="3"
                android:text="Large Text"
                android:textAppearance="?android:attr/textAppearanceLarge" />

            <EditText
                android:id="@+id/editText1_upper"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:ems="10"
                android:inputType="number" />

            <Button
                android:id="@+id/button_start_thread"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:onClick="cal"
                android:text="Button" />
        </LinearLayout>
    </ScrollView>

</RelativeLayout>

逻辑代码如下：

package com.example.mystudy;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class MyThreadTest extends Activity {
    static final String UPPER_NUM = "upper";
    static final String NUMS = "nums";
    TextView textView;
    EditText editText;
    MyThread myThread;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.button_and_textview);
        editText = (EditText) findViewById(R.id.editText1_upper);
        textView = (TextView) findViewById(R.id.textView_for);

        myThread = new MyThread();
        myThread.start();// 创建线程

    }

    public void cal(View v) {// 点击事件

        if (editText.getText().toString().equals("")) {
            textView.setText("");
            return;
        }
        Message message = new Message();
        Bundle bundle = new Bundle();
        bundle.putInt(UPPER_NUM, Integer.parseInt(editText.getText().toString()));// 将输入值发给新线程
        message.setData(bundle);
        message.what = 0x123;
        myThread.mHander.sendMessage(message);// 调用自己的线程中的hander来发送message,将消息放进线程的消息队列中等待hander处理

    }

    class MyThread extends Thread {
        public Handler mHander;// 本线程的hander

        @Override
        public void run() {
            Looper.prepare();// 创建本线程的looper
            mHander = new Handler() { // 实现自己的handler

                @Override
                public void handleMessage(Message msg) {
                    if (msg.what == 0x123) {// 计算质数
                        int upper = msg.getData().getInt(UPPER_NUM);
                        List<Integer> nums = new ArrayList<Integer>();
                        outer:
                        for (int i = 2; i <= upper; i++) {
                            for (int j = 2; j < Math.sqrt(i); j++) {
                                if (i != 2 && i % j == 0) {
                                    continue outer;
                                }
                            }
                            nums.add(i);
                        }

                        Message msg1 = new Message();
                        Bundle bundle = new Bundle();
                        bundle.putCharSequence(NUMS, nums.toString());
                        msg1.setData(bundle);
                        msg1.what = 0x124;
                        mainHandler.sendMessage(msg1);// 发送给主线程

                    }

                }

            };
            Looper.loop();// 启动looper
        }
    }

    Handler mainHandler = new Handler() {// UI线程的hander

        @Override
        public void handleMessage(Message msg) {
            if (msg.what == 0x124) {
                String nums = msg.getData().getCharSequence(NUMS, "no result").toString();
                textView.setText(nums.toString());
            }

        }

    };

}