Handler的使用

package com.example.wang.testapp2;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import java.util.Random;


public class TestActivity6 extends AppCompatActivity {

    TextView tv_3,tv_5;
    TextView tv_4,tv_6;

    Button bt_4,bt_5,bt_3;

    //定义 Handler,Handler在子线程里发消息，在主线程里处理消息，所以需要定义为全局变量

    Handler h=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            //处理消息
            if (msg.what==1)
            {
                String m=msg.obj.toString();

                tv_5.setText(tv_5.getText()+" "+m);
            }
            if (msg.what==2)
            {
                tv_5.setText(tv_5.getText()+" 空消息");
            }
        }
    };

    int i=10;
    Handler hl=new Handler()
    {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);



            switch (msg.what)
            {
                case 1:

                    if (i==20)
                    {
                        bt_3.setEnabled(false);
                        bt_5.setEnabled(false);
                        return;
                    }
                    i++;
                    tv_6.setText(i + "");

                    //发送
                    hl.sendEmptyMessageDelayed(1, 1000);
                    hl.removeMessages(2);

                    bt_3.setEnabled(false);
                    bt_4.setEnabled(true);
                    bt_5.setEnabled(true);

                    break;

                case 2:
                    if (i==1)
                    {
                        bt_4.setEnabled(false);
                        bt_5.setEnabled(false);
                        return;
                    }
                    i--;
                    tv_6.setText(i + "");

                    //发送
                    hl.sendEmptyMessageDelayed(2, 1000);

                    hl.removeMessages(1);
                    bt_3.setEnabled(true);
                    bt_4.setEnabled(false);
                    bt_5.setEnabled(true);

                    break;

                case  3:

                    hl.removeMessages(1);
                    hl.removeMessages(2);
                    bt_3.setEnabled(true);
                    bt_4.setEnabled(true);
                    bt_5.setEnabled(false);
                    break;
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test6);

        tv_3=(TextView)findViewById(R.id.tv_3);
        tv_4=(TextView)findViewById(R.id.tv_4);
        tv_5=(TextView)findViewById(R.id.tv_5);
        tv_6=(TextView)findViewById(R.id.tv_6);

        bt_4=(Button)findViewById(R.id.bt_4);

        bt_5=(Button)findViewById(R.id.bt_5);

        bt_3=(Button)findViewById(R.id.bt_3);


        bt_5.setEnabled(false);
    }

    public void bt3_OnClick(View v)
    {
        switch (v.getId())
        {
            case R.id.bt_3:

                //发送增加的消息
                hl.sendEmptyMessage(1);
                break;

            case R.id.bt_4:

                //发送减少的消息
                hl.sendEmptyMessage(2);

                break;
            case R.id.bt_5:

                //发送暂停的消息
                hl.sendEmptyMessage(3);

                break;
                //default:
        }
    }

    public void bt2_OnClick(View v)
    {
        //启动线程
        new Thread(){
            @Override
            public void run() {

                //发送消息

                //1-创建Message
                Message m=Message.obtain();
                m.what=1;
                m.obj="新信息1";

                //2-发送即时消息
                h.sendMessage(m);

                //发送延时消息
                m=Message.obtain();
                m.what=1;
                m.obj="新消息2";
                h.sendMessageDelayed(m,2000);

                //发送空消息
                h.sendEmptyMessage(2);

                //发送延时空消息
                h.sendEmptyMessageDelayed(2,3000);
            }
        }.start();
    }



    public void  bt1_OnClick(View v) {
        //创建子线程1

        new Thread() {

            @Override
            public void run() {

                for (int i = 0; i < 10; i++)
                {
                    try {
                        //暂停一下，时间随机
                        Thread.sleep(new Random().nextInt(2000));
                    } catch (Exception e) {}

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            tv_3.setText(tv_3.getText()+" 北京");
                        }
                    });


                }
                  runOnUiThread(new Runnable() {
                      @Override
                      public void run() {
                          Toast.makeText(TestActivity6.this,  "北京 循环结束", Toast.LENGTH_SHORT).show();
                      }
                  });
            }

        }.start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < 10; i++)
                {
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            tv_4.setText(tv_4.getText()+" 上海");
                        }
                    });

                    try {
                        //暂停一下，时间随机
                        Thread.sleep(new Random().nextInt(2000));
                    } catch (Exception e) {}
                }
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(TestActivity6.this, "上海 循环结束", Toast.LENGTH_SHORT).show();
                    }
                });
            }
        }).start();
    }

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.wang.testapp2.TestActivity6"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="北京"
        android:id="@+id/tv_3"/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="上海"
        android:id="@+id/tv_4"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="启动"
        android:onClick="bt1_OnClick"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_5"
        android:text="接收的消息"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="发消息"
        android:onClick="bt2_OnClick"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_6"
        android:text="10"
        android:layout_gravity="center"/>

        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="增加"
            android:onClick="bt3_OnClick"
            android:id="@+id/bt_3"/>
        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="减少"
            android:onClick="bt3_OnClick"
            android:id="@+id/bt_4"/>
        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="暂停"
            android:onClick="bt3_OnClick"
            android:id="@+id/bt_5"/>



</LinearLayout>