Android逐条加载ListView，实现动画更新

 Android逐条加载ListView，实现动画更新

 

在Android应用中，如果ListView或是GridView里面的数据比较多的时候，加载会比较费时间，特别是里面有图片的时候，需要花费的时间就更长，这样就会出现一个长时间的等待黑屏界面，这样有时会给用户造成一种错觉，就是这个程序已经“死”了，，，

对于这个问题可以的一个方法是，添加一个ProgressDialog，显示正在处理的窗口，等待加载完之后再关闭这个窗口，

但是这样等所有的数据加载完之后，就是特别突然的显示， 这样用户体验也不佳，

以前看Android优化大师的时候，打开进程管理的时候，它是前面显示正在加载的ProgressDialog，然后也可以看到后台的数据正在逐条加载，这样给人的感觉就好很多，现在就是要做这个效果~~~~

 

主要实现的思路是这样的，新建一个线程，然后在线程里面获取已经安装的程序，再逐条把这些程序(数据)添加到缓冲数组中，再发送一个消息，更新显示ListView的内容，当线程中所有的数据已经加载完的时候，再把ProgressDialog关掉，总的完成效果如下：

 

程序源代码

 

 

package com.sf.test;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.app.ProgressDialog;import android.content.Context;import android.content.Intent;import android.content.pm.PackageManager;import android.content.pm.ResolveInfo;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.KeyEvent;import android.widget.ArrayAdapter;import android.widget.ListView;/** * @author Yao.GUET * blog: http://blog.csdn.net/Yao_GUET * 实现动态加载一个ListView */public class ProcessorBarTest extends Activity {public static final int MSG_UPDATE_LIST = 18;private ListView mApps;private Context mContext;private List<String> mAppList;private ProgressDialog dialog;@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);setContentView(R.layout.processorbar_test);// ListView 列表 mAppsmApps = (ListView)findViewById(R.id.lvProcessbar);mContext = this;mAppList = new ArrayList<String>();// 设置正在处理窗口dialog = new ProgressDialog(mContext);dialog.setIcon(R.drawable.icon);dialog.setTitle("ProgressDialog");dialog.setMessage("Please wait while loading application list...");dialog.setCancelable(false);dialog.show();// 开始动态加载线程mThreadLoadApps.start();}private Thread mThreadLoadApps = new Thread(){@Overridepublic void run() {int i = 0;// TODO Auto-generated method stub// 获取已经安装程序列表PackageManager pm = mContext.getPackageManager();Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);// 逐项添加程序，并发送消息更新ListView列表。for (i=0; i<list.size(); i++) {mAppList.add(list.get(i).loadLabel(pm).toString());handler.sendEmptyMessage(MSG_UPDATE_LIST);}// 关闭正在处理窗口dialog.dismiss();}};private Handler handler = new Handler(){@Overridepublic void handleMessage(Message msg) {// TODO Auto-generated method stubswitch (msg.what) {case MSG_UPDATE_LIST:// 更新应用程序列表mApps.setAdapter(new ArrayAdapter(mContext, android.R.layout.simple_list_item_1, mAppList));break;}super.handleMessage(msg);}};} 

 

后面发现有效率更高的方法，其实不用每次更新一项都需要构建一个Adapter的，，，

把Adapter和一个List<?>绑定在一起之后，可以直接改变List<?>的内容，然后再使用Adapter的数据集更新通知，即可改变ListView的内容，所以后面改了一下源码变成这个样子，，，

package com.Yao_GUET.test;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.app.ProgressDialog;import android.content.Context;import android.content.Intent;import android.content.pm.PackageManager;import android.content.pm.ResolveInfo;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.AdapterView;import android.widget.ArrayAdapter;import android.widget.ListView;/** * @author Yao.GUET * blog: http://blog.csdn.net/Yao_GUET * 实现动态加载一个ListView */public class ProcessorBarTest extends Activity {public static final int MSG_UPDATE_LIST = 18;private ListView mApps;private Context mContext;private List<String> mAppList;private ProgressDialog dialog;private ArrayAdapter mAdapter;private boolean mIsLoaded = false;@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);setContentView(R.layout.processorbar_test);// ListView 列表 mAppsmApps = (ListView)findViewById(R.id.lvProcessbar);mContext = this;mAppList = new ArrayList<String>();mAdapter = new ArrayAdapter(mContext, android.R.layout.simple_list_item_1, mAppList);mApps.setAdapter(mAdapter);// 设置正在处理窗口dialog = new ProgressDialog(mContext);dialog.setIcon(R.drawable.icon);dialog.setTitle("ProgressDialog");dialog.setMessage("Please wait while loading application list...");dialog.setCancelable(false);dialog.show();// 开始动态加载线程mThreadLoadApps.start();mApps.setOnItemClickListener(new AdapterView.OnItemClickListener(){public void onItemClick(AdapterView<?> parent, View v, int position,long id) {// TODO Auto-generated method stubmAppList.remove(position);mAdapter.notifyDataSetChanged();}});// 获取已经安装程序列表PackageManager pm = mContext.getPackageManager();Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);// 逐项添加程序，并发送消息更新ListView列表。for (int i=0; i<list.size(); i++) {mAppList.add(list.get(i).loadLabel(pm).toString());mAdapter.notifyDataSetChanged();}mIsLoaded = true;}private Thread mThreadLoadApps = new Thread(){@Overridepublic void run() {int i = 0;// TODO Auto-generated method stubwhile (!mIsLoaded) {try {sleep(100);} catch (InterruptedException e) {e.printStackTrace();}}// 关闭正在处理窗口dialog.dismiss();}};} 

 

2011－12－06更新，根据hb24775179 朋友的提示，第二个确实是不能达到效果的，

因为获取程序列表的操作放到UI线程里面，所以结果是当获取完程序列表的时候，都会显示progress dialog，这样反而不能达到效果了，

所以把获取程序列表的部分提取出来入放到子线程中处理，代码如下

package com.progress;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.app.ProgressDialog;import android.content.Context;import android.content.Intent;import android.content.pm.PackageManager;import android.content.pm.ResolveInfo;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.AdapterView;import android.widget.ArrayAdapter;import android.widget.ListView;/**  * @author Yao.GUET  * blog: http://blog.csdn.net/Yao_GUET  * 实现动态加载一个ListView  */  public class ListViewTestActivity extends Activity {  public static final int MSG_DISMISS_PROGRESS_DIALOG = 17;    public static final int MSG_UPDATE_LIST = 18;          private ListView mApps;      private Context mContext;      private List<String> mAppList;      private ProgressDialog dialog;      private ArrayAdapter mAdapter;      private boolean mIsLoaded = false;            @Override      protected void onCreate(Bundle savedInstanceState) {          // TODO Auto-generated method stub           super.onCreate(savedInstanceState);          setContentView(R.layout.main);                    // ListView 列表 mApps           mApps = (ListView)findViewById(R.id.lvProcessbar);          mContext = this;          mAppList = new ArrayList<String>();          mAdapter = new ArrayAdapter(mContext,                   android.R.layout.simple_list_item_1, mAppList);          mApps.setAdapter(mAdapter);                    // 设置正在处理窗口           dialog = new ProgressDialog(mContext);          dialog.setIcon(R.drawable.icon);          dialog.setTitle("ProgressDialog");          dialog.setMessage("Please wait while loading application list...");          dialog.setCancelable(false);          dialog.show();                    // 开始动态加载线程           mThreadObtainApps.start();                  mApps.setOnItemClickListener(new AdapterView.OnItemClickListener(){              public void onItemClick(AdapterView<?> parent, View v, int position,                      long id) {                  // TODO Auto-generated method stub                   mAppList.remove(position);                  mAdapter.notifyDataSetChanged();              }                        });      }        private Handler mHandler = new Handler() {@Overridepublic void handleMessage(Message msg) {// TODO Auto-generated method stubswitch (msg.what) {case MSG_UPDATE_LIST:mAdapter.notifyDataSetChanged(); break;case MSG_DISMISS_PROGRESS_DIALOG:// 关闭正在处理窗口               dialog.dismiss();            break;        default:        break;}super.handleMessage(msg);}        };        private Thread mThreadObtainApps = new Thread() {    @Override    public void run() {    // 获取已经安装程序列表               PackageManager pm = mContext.getPackageManager();              Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);              mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);              List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);                            // 逐项添加程序，并发送消息更新ListView列表。               for (int i=0; i<list.size(); i++) {                  mAppList.add(list.get(i).loadLabel(pm).toString());                list.get(i).loadIcon(pm);                mHandler.sendEmptyMessage(MSG_UPDATE_LIST);            }              mHandler.sendEmptyMessage(MSG_DISMISS_PROGRESS_DIALOG);    }    };}