Android开发之UI更新交互机制与实例解析

android开发过程中，经常需要更新UI的状态和文案等。这是就需要对UI进行 更新。在android中更新UI一般有三种方法，handler机制、RunOnUiThread方法以及AsyncTask异步类方法等

本文下面就这三种方法进行了演示和代码实现.

a.Handler机制通过使用消息机制来实现

b.RunOnUiThread方法是通过运行UI线程来达到更新UI的目的

c.AsyncTask是异步类，通过异步更新来更新UI

效果图如下：

    

    

（1）Java功能实现代码如下：

package com.czm.updateui;

import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.R.integer;
import android.app.Activity;
import android.graphics.Color;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

public class UpdateUIActivity extends Activity {

    private Button btnHandler;
    private Button btnRunOnUiThread;
    private Button btnAsyncTask;
    private TextView tvHandler;
    private TextView tvOnUiThread;
    private TextView tvProgress;
    private Handler uiHandler;
    private ProgressBar progressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.update_ui);
        initViews();
        setListeners();
    }
    private void initViews(){
        btnHandler = (Button) findViewById(R.id.btnHandler);
        btnRunOnUiThread = (Button) findViewById(R.id.btnRunOnUiThread);
        btnAsyncTask = (Button)findViewById(R.id.btnAsyncTask);
        tvHandler = (TextView) findViewById(R.id.tvText1);
        tvOnUiThread = (TextView)findViewById(R.id.tvText2);
        tvProgress = (TextView)findViewById(R.id.tvText3);
        progressBar = (ProgressBar)findViewById(R.id.progressBar);
    }
    private void setListeners(){
        uiHandler = new Handler(){

            @Override
            public void handleMessage(Message msg) {
                // TODO Auto-generated method stub
                super.handleMessage(msg);
                Bundle bundle = msg.getData();
                String text = bundle.getString("handler_text");
                String color = bundle.getString("handler_color");

                tvHandler.setText(text);
                tvHandler.setBackgroundColor(Color.BLUE);

            }

        };
        //通过Handler机制来更新UI
        btnHandler.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new Thread(){

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub
                        Message msg =new Message();
                        Bundle bundle = new Bundle();
                        bundle.putString("handler_text", "我是由Handler更新UI后的文案");
                        bundle.putString("handler_color", "#0000FF");
                        msg.setData(bundle);
                        //uiHandler.sendMessageDelayed(msg, 2000);
                        uiHandler.sendMessage(msg);
                    }

                }.start();
            }
        });

        //通过RunOnUiThread来更新UI
        btnRunOnUiThread.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                runOnUiThread(new Runnable() {

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub
                        tvOnUiThread.setText("我是由runOnUiThread更新UI后的文案");
                        tvOnUiThread.setBackgroundColor(Color.RED);

                    }
                });
            }
        });
        //通过AsyncTask 异步任务来更新UI
        btnAsyncTask.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new MyAsyncTask().execute(0);
            }
        });
    }

    private class MyAsyncTask extends AsyncTask<Integer, Integer, Integer>{

        @Override
        protected void onPostExecute(Integer result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            tvProgress.setText("加载完成...100%");
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            // TODO Auto-generated method stub
            super.onProgressUpdate(values);
            progressBar.setProgress((int)(values[0]));
            tvProgress.setText("加载中..."+values[0]+"%");
        }

        @Override
        protected Integer doInBackground(Integer... params) {
            // TODO Auto-generated method stub
            Integer timer = 0;
            while(timer <=100){
                try {
                    publishProgress(timer);
                    timer ++;
                    Thread.sleep(40);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            return null;
        }

    }

}

（2）对应的UI布局xml文件代码：

<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:orientation="vertical"
    android:gravity="center_horizontal"
    tools:context=".UpdateUIActivity" >
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >"
        <Button
        android:id="@+id/btnHandler"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Handler" />
    <Button
        android:id="@+id/btnRunOnUiThread"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="runOnUiThread" />
    <Button
        android:id="@+id/btnAsyncTask"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="AsyncTask" />
    </LinearLayout>

    <TextView
        android:id="@+id/tvText1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="Handler来更新UI"
        android:padding="3dp"
        android:textColor="#FFF"
        android:background="#666666"
        android:textSize="20dp" />
    <TextView
        android:id="@+id/tvText2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:text="RunOnUiThread来更新UI"
        android:padding="3dp"
        android:textColor="#FFF"
        android:background="#666666"
        android:textSize="20dp" />

    <ProgressBar android:id="@+id/progressBar"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="fill_parent"
        android:layout_height="25dp"
        android:progressDrawable="@drawable/progressbar"
        android:max="100"
        android:progress="0"
        android:layout_marginLeft="5dp"
        android:layout_marginRight="5dp"
        android:layout_marginTop="10dp"
         />
    <TextView
        android:id="@+id/tvText3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="准备加载...0%"
        android:textSize="20dp" />

</LinearLayout>