详解android进行异步更新UI的四种方式

大家都知道由于性能要求，android要求只能在ui线程中更新ui，要想在其他线程中更新ui，我大致总结了4种方式，欢迎补充纠正：

1. 使用handler消息传递机制；
2. 使用asynctask异步任务；
3. 使用runonuithread(action)方法；
4. 使用handler的post(runnabel r)方法；

下面分别使用四种方式来更新一个textview。

1.使用handler消息传递机制

package com.example.runonuithreadtest;

import android.app.activity;
import android.os.bundle;
import android.os.handler;
import android.widget.textview;

public class mainactivity extends activity {
 
 private textview tv;
 
 handler handler = new handler()
 {
  public void handlemessage(android.os.message msg) {
   if(msg.what==0x123)
   {
    tv.settext("更新后的textview");
   }
  };
 };
 
 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_main);
  tv = (textview) findviewbyid(r.id.tv);
  new mythread().start();
 }
 class mythread extends thread
 {
  @override
  public void run() {
   //延迟两秒更新
   try {
    thread.sleep(2000);
   } catch (interruptedexception e) {
    // todo auto-generated catch block
    e.printstacktrace();
   }
   handler.sendemptymessage(0x123);
  }
 }
}

2. 使用asynctask异步任务

注：更新ui的操作只能在onpostexecute(string result)方法中。

package com.example.runonuithreadtest;

import android.app.activity;
import android.os.asynctask;
import android.os.bundle;
import android.widget.textview;

public class mainactivity extends activity {
 
 private textview tv;
 
 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_main);
  tv = (textview) findviewbyid(r.id.tv);
  new yibu().execute();
 }
 class yibu extends asynctask<string, string, string>
 {

  @override
  protected string doinbackground(string... params) {
   try {
    thread.sleep(2000);
   } catch (interruptedexception e) {
    // todo auto-generated catch block
    e.printstacktrace();
   }
   return null;
  }
  @override
  protected void onpostexecute(string result) {
   // todo auto-generated method stub
   tv.settext("更新后的textview");
  }
  
 }
}

3. 使用runonuithread(action)方法

package com.example.runonuithreadtest;

import android.app.activity;
import android.os.bundle;
import android.widget.textview;

public class mainactivity extends activity {
 
 private textview tv;
 
 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_main);
  tv = (textview) findviewbyid(r.id.tv);
  new mythread().start();
 }
 class mythread extends thread
 {
  @override
  public void run() {
   runonuithread(new runnable() {
    
    @override
    public void run() {
     // todo auto-generated method stub
      try {
       //延迟两秒更新
       thread.sleep(2000);
      } catch (interruptedexception e) {
       e.printstacktrace();
      }
      tv.settext("更新后的textview");
    }
   });
  }
 }
}

4. 使用handler的post(runnabel r)方法

package com.example.runonuithreadtest;

import android.app.activity;
import android.os.bundle;
import android.os.handler;
import android.widget.textview;

public class mainactivity extends activity {
 
 private textview tv;
 
 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_main);
  tv = (textview) findviewbyid(r.id.tv);
  handler handler = new handler();
  handler.post(new runnable(){
   @override
   public void run() {
    try {
     //延迟两秒更新
     thread.sleep(2000);
    } catch (interruptedexception e) {
     e.printstacktrace();
    }
    tv.settext("更新后的textview");
   }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。