android异步任务载入数据界面实现

android 异步任务的一个后台方法本质是开启一个线程完毕耗时操作，其它onPostExecute方法和onPreExecute方法执行在UI主线程用于更新UI界面。为了提高用户体验常见的异步任务载入方式如今总结例如以下：

1、异步载入界面效果例如以下:


关键代码例如以下所看到的：

/**
	 * 异步任务给列表载入数据
	 */
	private void fillData(){
		new AsyncTask<Void,Void,Void>(){
			
			@Override
			protected void onPreExecute() {
				loading.setVisibility(View.VISIBLE);
				super.onPreExecute();
			}

			@Override
			protected void onPostExecute(Void result) {
				loading.setVisibility(View.INVISIBLE);
				//刷新界面列表数据
				if(mAdapter==null){
					mAdapter=new RubishSmsInfosAdapter();
					mRubishSms.setAdapter(mAdapter);
					
				}else{
					
					mAdapter.notifyDataSetChanged();
				}
				super.onPostExecute(result);
			}

			@Override
			protected Void doInBackground(Void... params) {
				if(mInfos==null){
					mInfos=mRubishSmsInfoDao.findInfosbyPage(maxNum, offset);
				}else{
					
					mInfos.addAll(mRubishSmsInfoDao.findInfosbyPage(maxNum, offset));
				}
				
				try {
					
					Thread.sleep(2000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				return null;
			}
			
		}.execute();
		
	}



loading相应的
loading=findViewById(R.id.ll_rublish_sms_info_loading);


布局文件例如以下：

activity_rubish_sms.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:orientation="vertical" >

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="100" >

        <LinearLayout
            android:layout_gravity="center"
            android:id="@+id/ll_rublish_sms_info_loading"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:visibility="invisible" >

            <ProgressBar
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />

            <TextView
                android:gravity="center"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="数据载入中,请稍后..."
                android:textSize="13sp" />
        </LinearLayout>
    </FrameLayout>

    <ListView
        android:id="@+id/lv_rubish_sms_content"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
    </ListView>

</LinearLayout>


通过如上代码就可以实现上述效果。


2、利用对话框实现


实现效果图：







异步任务实现 逻辑代码：


/**
	 * 扫描病毒 并动态显示在界面
	 */
	private void scanVirus(){
		new AsyncTask<Void,Object, Void>() {
			List<VirusApp> apps=new ArrayList<VirusApp>();
			String desc=null;
			Dialog dialog=new Dialog(KillVirusActivity.this);
			View viewKilling=View.inflate(KillVirusActivity.this,R.layout.killing_dialog,null);
			@Override
			protected void onPreExecute() {
				mKillVirusResult.setText("正在扫描中，请稍等...");
				dialog.setCancelable(false);
				dialog.setContentView(viewKilling);
				dialog.show();
				pm=getPackageManager();
			 packageInfos=pm.getInstalledPackages(PackageManager.GET_UNINSTALLED_PACKAGES|PackageManager.GET_SIGNATURES);
			// progressBar.setMax(packageInfos.size());
				super.onPreExecute();
			}

			@Override
			protected void onPostExecute(Void result) {
				dialog.dismiss();
				if(apps.size()>0){
					mKillVirusResult.setTextColor(Color.RED);
					mKillVirusResult.setText("扫描完毕！发现病毒"+apps.size()+"个"+","+"请及时清理");
					
					for(final VirusApp app:apps){
						//有病毒
						View view=View.inflate(KillVirusActivity.this,R.layout.app_virus_info_item,null);
						view.setClickable(true);
						view.setOnClickListener(new OnClickListener() {
							
							@Override
							public void onClick(View v) {
								//卸载程序
								Intent intent = new Intent();
								intent.setAction("android.intent.action.DELETE");
								intent.addCategory(Intent.CATEGORY_DEFAULT);
								intent.setData(Uri.parse("package:"
										+ app.getmAppVirusName()));
								startActivity(intent);
								
							}
						});
						
						ImageView appIcon=(ImageView) view.findViewById(R.id.iv_app_icon);
						TextView appName=(TextView) view.findViewById(R.id.tv_app_name);
						TextView appDesc=(TextView)view.findViewById(R.id.tv_app_virus_desc);
						
						
						appIcon.setBackground(app.getmAppVirusIcon());
						appName.setText(app.getmAppVirusName());
						appDesc.setText(app.getmAPPVirusDesc());
						
						mContainer.addView(view);
					}
					
					
				}else if(apps.size()==0){
					mKillVirusResult.setText("扫描完毕！恭喜没有发现病毒。");
					
				}
				
				
				super.onPostExecute(result);
			}

			@Override
			protected Void doInBackground(Void... params) {
				int total=0;
				//获得数据库操作对象
				VirusDao virusDao=new VirusDao();
				
				//获得设备上全部应用的签名
				for(PackageInfo info:packageInfos){
					 total++;
					
				Signature[] signature=info.signatures;
				try {
					String md5=Md5Util.encode(signature[0].toString());
					 desc=virusDao.findVirus(md5);
						Log.i("杀毒MD5<<<", md5);
						 desc=virusDao.findVirus(md5);
				} catch (Exception e) {
					// TODO: handle exception
				}
				//Log.i("杀毒<<<", (signature[0]).toString());
				//签名用MD5编码获得MD5加密后的应用的签名信息
				
				//Log.i("杀毒MD5<<<", md5);
				//查询本地病毒签名数据库
			// desc=virusDao.findVirus(md5);
			 if(desc!=null){//查询到病毒
				
				 VirusApp app=new VirusApp();
				 //获得应用的图标
				Drawable drawable=pm.getApplicationIcon(info.applicationInfo);
				app.setmAppVirusIcon(drawable);
				 //获得应用名
				String appName=(String) pm.getApplicationLabel(info.applicationInfo);
				app.setmAppVirusName(appName);
				 //获得该应用的病毒描写叙述
				 app.setmAPPVirusDesc(desc);
				 apps.add(app);
				 app=null;
				 //publishProgress(total,app);
			 }else{
				 Log.i("杀毒MD5<<<","不是病毒"+total);
			 }
				}
				//progressBar.setProgress(total);
				
				try {
					Thread.sleep(200);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				return null;
			}

			

			
			
		}.execute();
		
		
	}
	
该逻辑处理相应的activity布局界面：


<?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:orientation="vertical" >

    <TextView
        android:layout_width="match_parent"
        android:layout_height="35dp"
        android:background="@drawable/ll_title_bg"
        android:gravity="center"
        android:text="手机病毒查杀" />

    <TextView
        android:id="@+id/tv_kill_virus_result"
        android:layout_width="match_parent"
        android:layout_height="125dp"
        android:gravity="center"
        android:background="@drawable/ll_title_bg" />
	
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <LinearLayout
           <span style="color:#ff0000;"> android:id="@+id/ll_container"</span>
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical" >
        </LinearLayout>
    </ScrollView>

</LinearLayout>
该界面有一个线性布局容器，能够实现动态载入数据的效果。







实现自己定义对话框的布局：


<?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:orientation="vertical" >

    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="病毒扫描中..."
        android:textSize="15sp" />

</LinearLayout>


实现动态扫描并载入数据的整个Activity代码:


package com.example.yqqmobilesafe;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.Dialog;
import android.content.Intent;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.Signature;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.example.yqqmobilesafe.db.dao.VirusDao;
import com.example.yqqmobilesafe.domain.VirusApp;
import com.example.yqqmobilesafe.utils.CopyFileToSystem;
import com.example.yqqmobilesafe.utils.Md5Util;
//本地病毒查杀
public class KillVirusActivity extends Activity {
private LinearLayout<span style="color:#ff0000;"> mContainer</span>;
private TextView mKillVirusResult;
private PackageManager pm;
private ProgressBar progressBar;
private List<PackageInfo> packageInfos;
	public KillVirusActivity() {
		
	}
	@Override
		protected void onCreate(Bundle savedInstanceState) {
			setContentView(R.layout.activity_kill_virus);
			<span style="color:#ff0000;">mContainer</span>=(LinearLayout) this.findViewById(R.id.ll_container);
			mKillVirusResult=(TextView) this.findViewById(R.id.tv_kill_virus_result);
			//progressBar=(ProgressBar) this.findViewById(R.id.pb_scanning_virus);
			copyVirusDB();//拷贝本地病毒签名到系统文件夹
			 scanVirus();
			super.onCreate(savedInstanceState);
		}
	/**
	 * 扫描病毒 并动态显示在界面
	 */
	private void scanVirus(){
		new AsyncTask<Void,Object, Void>() {
			List<VirusApp> apps=new ArrayList<VirusApp>();
			String desc=null;
			Dialog dialog=new Dialog(KillVirusActivity.this);
			View viewKilling=View.inflate(KillVirusActivity.this,R.layout.killing_dialog,null);
			@Override
			protected void onPreExecute() {
				mKillVirusResult.setText("正在扫描中。请稍等...");
				dialog.setCancelable(false);
				dialog.setContentView(viewKilling);
				dialog.show();
				pm=getPackageManager();
			 packageInfos=pm.getInstalledPackages(PackageManager.GET_UNINSTALLED_PACKAGES|PackageManager.GET_SIGNATURES);
			// progressBar.setMax(packageInfos.size());
				super.onPreExecute();
			}

			@Override
			protected void onPostExecute(Void result) {
				dialog.dismiss();
				if(apps.size()>0){
					mKillVirusResult.setTextColor(Color.RED);
					mKillVirusResult.setText("扫描完毕！
发现病毒"+apps.size()+"个"+","+"请及时清理");
					
					for(final VirusApp app:apps){
						//有病毒
						View view=View.inflate(KillVirusActivity.this,R.layout.app_virus_info_item,null);
						view.setClickable(true);
						view.setOnClickListener(new OnClickListener() {
							
							@Override
							public void onClick(View v) {
								//卸载程序
								Intent intent = new Intent();
								intent.setAction("android.intent.action.DELETE");
								intent.addCategory(Intent.CATEGORY_DEFAULT);
								intent.setData(Uri.parse("package:"
										+ app.getmAppVirusName()));
								startActivity(intent);
								
							}
						});
						
						ImageView appIcon=(ImageView) view.findViewById(R.id.iv_app_icon);
						TextView appName=(TextView) view.findViewById(R.id.tv_app_name);
						TextView appDesc=(TextView)view.findViewById(R.id.tv_app_virus_desc);
						
						
						appIcon.setBackground(app.getmAppVirusIcon());
						appName.setText(app.getmAppVirusName());
						appDesc.setText(app.getmAPPVirusDesc());
						
						<span style="color:#ff0000;">mContainer.addView(view);</span>
					}
					
					
				}else if(apps.size()==0){
					mKillVirusResult.setText("扫描完毕！恭喜没有发现病毒！
");
					
				}
				
				
				super.onPostExecute(result);
			}

			@Override
			protected Void doInBackground(Void... params) {
				int total=0;
				//获得数据库操作对象
				VirusDao virusDao=new VirusDao();
				
				//获得设备上全部应用的签名
				for(PackageInfo info:packageInfos){
					 total++;
					
				Signature[] signature=info.signatures;
				try {
					String md5=Md5Util.encode(signature[0].toString());
					 desc=virusDao.findVirus(md5);
						Log.i("杀毒MD5<<<", md5);
						 desc=virusDao.findVirus(md5);
				} catch (Exception e) {
					// TODO: handle exception
				}
				//Log.i("杀毒<<<", (signature[0]).toString());
				//签名用MD5编码获得MD5加密后的应用的签名信息
				
				//Log.i("杀毒MD5<<<", md5);
				//查询本地病毒签名数据库
			// desc=virusDao.findVirus(md5);
			 if(desc!=null){//查询到病毒
				
				 VirusApp app=new VirusApp();
				 //获得应用的图标
				Drawable drawable=pm.getApplicationIcon(info.applicationInfo);
				app.setmAppVirusIcon(drawable);
				 //获得应用名
				String appName=(String) pm.getApplicationLabel(info.applicationInfo);
				app.setmAppVirusName(appName);
				 //获得该应用的病毒描写叙述
				 app.setmAPPVirusDesc(desc);
				 apps.add(app);
				 app=null;
				 //publishProgress(total,app);
			 }else{
				 Log.i("杀毒MD5<<<","不是病毒"+total);
			 }
				}
				//progressBar.setProgress(total);
				
				try {
					Thread.sleep(200);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				return null;
			}

			

			
			
		}.execute();
		
		
	}
	
	/**
	 * 拷贝本地病毒库数据库到app文件夹
	 */
	private void copyVirusDB(){
		new AsyncTask<Void,Void,Void>(){

			@Override
			protected Void doInBackground(Void... params) {
				//获得要复制到目的地的文件
				File file=new File(getFilesDir(),"antivirus.db");
				if(file.exists()&&file.length()>0){
					
				}else{
					//获得文件输入流
					InputStream is=null;
					try {
						is=getResources().getAssets().open("antivirus.db");
						CopyFileToSystem.copyFile(is, file.getAbsolutePath());
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					
				}
				return null;
			}
			
			
		}.execute();
		
		
	}
	
}









   




        

	      

	    

	  

	  

	    
      
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          原文地址：https://www.cnblogs.com/zfyouxi/p/5302759.html