Handle-postDelayed 延遲操作

今天在工作的時候，遇到了一個方法，是關於Handle來實現延時操作的，自己寫了一個小demo，學習總結如下

xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <RelativeLayout
        android:id="@+id/abc"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:padding="30dp" >

        <RelativeLayout
            android:id="@+id/ll"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="20dp" >

            <TextView
                android:id="@+id/tv_time"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:background="@drawable/select"
                android:text="time"
                android:textColor="#ffffff"
                android:textSize="30dp" />

            <TextView
                android:id="@+id/tv_click"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentRight="true"
                android:background="@drawable/select"
                android:text="click"
                android:textColor="#ffffff"
                android:textSize="30dp" />
        </RelativeLayout>

        <TextView
            android:id="@+id/tv_run"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/ll"
            android:layout_centerHorizontal="true"
            android:background="@drawable/select"
            android:padding="20dp"
            android:text="wait...."
            android:textColor="#ffffff"
            android:textSize="30dp" />

        <Button
            android:id="@+id/bt1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/tv_run"
            android:src="@drawable/select"
            android:text="start"
            android:textColor="#ff0000" />

        <Button
            android:id="@+id/bt2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/tv_run"
            android:layout_centerHorizontal="true"
            android:src="@drawable/select"
            android:text="stop"
            android:textColor="#ff0000" />

        <Button
            android:id="@+id/bt3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:layout_below="@+id/tv_run"
            android:src="@drawable/select"
            android:text="clear"
            android:textColor="#ff0000" />
    </RelativeLayout>

</LinearLayout>

java如下

package com.example.alert;

import android.R.integer;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;

import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

public class HeadSetActivity extends Activity {
    private TextView tv_time;
    private TextView tv_click;
    private TextView tv_run;
    private Button button1;
    private Button button2;
    private Button button3;
    private int time = 0;
    private boolean time_begin = true;
    private int click = 0;
    //創建消息隊列
     private Handler uiHandle = new Handler(){  
            public void handleMessage(Message msg) {  
                switch(msg.what){  
                //實現計時器功能
                case 1: 
                    time++;
                    tv_time.setText("time:"+time);
                    uiHandle.sendEmptyMessageDelayed(1, 1000);  
                    break;  
                default: break;  
                }  
            }  
        };
        //開啟一個線程
        private Runnable runnable = new Runnable() {
            
            @Override
            public void run() {
                // TODO Auto-generated method stub
                tv_run.setText("runnable is start|time="+time);
            }
        };
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv_time = (TextView)findViewById(R.id.tv_time);
        tv_click = (TextView)findViewById(R.id.tv_click);
        tv_run = (TextView)findViewById(R.id.tv_run);
        button1 = (Button) findViewById(R.id.bt1);
        button2 = (Button) findViewById(R.id.bt2);
        button3 = (Button) findViewById(R.id.bt3);
        //啟動計時器以及runnable延時操作
        button1.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                //啟動activity1
                if (time_begin) {
                    uiHandle.sendEmptyMessageDelayed(1, 1000);
                    tv_run.setText("runnable wait begin|time="+time);
                    time_begin = false;
                }
                click++;
                tv_click.setText("click:"+click);
                
                uiHandle.postDelayed(runnable,4000);
            }
                    
        
        });
//移除runnable延時操作        
button2.setOnClickListener(new OnClickListener() {
    
    @Override
    public void onClick(View arg0) {
        // TODO Auto-generated method stub
        uiHandle.removeCallbacks(runnable);
        tv_run.setText("runnable is clear|time ="+time);
        
    }
});
//清除消息隊列的所有操作
button3.setOnClickListener(new OnClickListener() {
    
    @Override
    public void onClick(View arg0) {
        // TODO Auto-generated method stub
        uiHandle.removeMessages(1);
        tv_click.setText("click");
        tv_run.setText("wait...");
        tv_time.setText("time");
        uiHandle.removeCallbacks(runnable);
        time_begin = true;
        time = 0;
        click = 0;
    }
});
    }

}

我們看下如下的演示結果

從上面的演示結果我們可以得出關於postDelayed 的知識點總結

1.這個方法是用來延時執行一個動作的

2.多次執行這個動作，並不會移除之前仍然處於延時等待狀態的動作

3.如果想要結束處於等待執行中的動作，我們可以主動調用

uiHandle.removeCallbacks(runnable);