android 异步任务的一个后台方法本质是开启一个线程完成耗时操作，其他onPostExecute方法和onPreExecute方法运行在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加载方式现在总结如下：

1、异步加载界面效果如下:

关键代码如下所示：

/**	 * 异步任务给列表加载数据	 */	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对应的

loading=findViewById(R.id.ll_rublish_sms_info_loading);

布局文件如下：

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="数据加载中,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>

通过如上代码即可实现上述效果。

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("扫描完成！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("扫描完成！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();								//获得设备上所有应用的签名				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();					}

该逻辑处理对应的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，可以实现动态加载数据的效果。

实现自定义对话框的布局：

<?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>

实现动态扫描并加载数据的整个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目录			 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("扫描完成！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("扫描完成！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();								//获得设备上所有应用的签名				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目录	 */	private void copyVirusDB(){ new AsyncTask<Void,Void,Void>(){			@Override			protected Void doInBackground(Void... params) {				//获得要拷贝到目的地的文件				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();					}	}