Android 自定义 ListView 上下拉动“刷新最新”和“加载更多”歌曲列表
2014-07-09 16:46
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本文内容
环境测试数据项目结构演示参考资料下载Demo
环境
Windows2008R264位EclipseADTV22.6.2，Android4.4.3SAMSUNGGT-I9008L，AndroidOS2.2.2测试数据
本演示的歌曲信息，共有20条，包括歌手名、歌曲名、时长、缩略图，为了简单起见都存在本地，你当然也可以通过网络获得。同时，当下拉刷新最新或上拉加载更多时，为了简单，20条歌曲信息是取模运算循环使用的。packagecom.my.android.app.data;
importcom.my.android.app.R;
publicclassTestData{publicstaticString[]title=newString[]{"SomeoneLikeYou","SpaceBound","StrangerInMoscow","LoveTheWayYouLie",
"KhwajaMereKhwaja","AllMyDays","LifeForRent",
"LoveToSeeYouCry","TheGood,TheBadAndTheUgly",
"Showmethemeaning","SomeoneLikeYou","SpaceBound",
"StrangerInMoscow","LoveTheWayYouLie","KhwajaMereKhwaja",
"AllMyDays","LifeForRent","LoveToSeeYouCry",
"TheGood,TheBadAndTheUgly","Showmethemeaning"};
publicstaticString[]artist=newString[]{"Adele","Eminem","MichaelJackson","Rihanna","ARRehman","AlexiMurdoch",
"Dido","EnriqueIglesias","EnnioMorricone","BackstreetBoys",
"Adele","Eminem","MichaelJackson","Rihanna","ARRehman",
"AlexiMurdoch","Dido","EnriqueIglesias","EnnioMorricone",
"BackstreetBoys"};
publicstaticint[]thumb=newint[]{R.drawable.adele,R.drawable.eminem,R.drawable.mj,R.drawable.rihanna,
R.drawable.arrehman,R.drawable.alexi_murdoch,R.drawable.dido,
R.drawable.enrique,R.drawable.ennio,R.drawable.backstreet_boys,
R.drawable.adele,R.drawable.eminem,R.drawable.mj,
R.drawable.rihanna,R.drawable.arrehman,R.drawable.alexi_murdoch,
R.drawable.dido,R.drawable.enrique,R.drawable.ennio,
R.drawable.backstreet_boys};
publicstaticString[]duration=newString[]{"4:47","4:38","5:44","4:23","6:58","4:47","3:41","4:07","2:42","3:56","4:47",
"4:38","5:44","4:23","6:58","4:47","3:41","4:07","2:42",
"3:56"};
}
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项目结构
图1项目结构
com.my.android.app.activit包，是主程序和三个演示的界面后台；
com.my.android.app.activit.data包，是测试数据；
com.my.android.app.activit.view包，是实现下拉上拉“刷新最新”和“加载更多”。
演示
本程序主界面，如图2所示。包含三个演示，“example1：SimplePushandPull”是上拉下拉刷新最新和加载更多的演示，刷新或加载的内容只是当前时间而已；“example2：CustomMusicList”是显示歌曲列表。当点击第三个按钮“Combineexample1and2”时，就是本文想要达到的效果，如图3所示。
初始状态为图3左边，加载20个音乐；
当用手指向下拉动时，获得最新的10个，如图3中间所示；
当向上拉动时，加载之前的10个，如图3右边所示。
图2主程序
图3本文想要达到的效果：下拉或上拉，刷新最新或加载更多的歌曲列表
刚开始，若想实现这个功能，着实不易，主要是没思路。疑问在于，如何实现下拉和上拉？如何显示歌曲列表？又如何刷新最近、加载更多的歌曲列表？可你要是研究一下本程序前面的两个演示：example1和example2，这两个示例在网上很容易找到，那么，以上所有的问题，都迎刃而解了。
图4简单的下拉或上拉，刷新最新或加载更多
图4演示的核心代码如下所示：
packagecom.my.android.app.activity;
importjava.util.ArrayList;
importjava.util.Date;
importandroid.annotation.SuppressLint;
importandroid.app.Activity;
importandroid.os.Bundle;
importandroid.os.Handler;
importandroid.os.Message;
//importandroid.util.Log;
importandroid.view.View;
importandroid.widget.AdapterView;
importandroid.widget.AdapterView.OnItemClickListener;
importandroid.widget.ArrayAdapter;
importandroid.widget.RelativeLayout;
importandroid.widget.Toast;
importcom.my.android.app.R;
importcom.my.android.app.view.PushPullList;
importcom.my.android.app.view.PushPullListListener;
@SuppressLint("HandlerLeak")publicclassPushPullListTestextendsActivityimplementsPushPullListListener{PushPullListlist;
ArrayList<String>data;
ArrayAdapter<String>adapter;
//刷新控件状态
Handlerhandler=newHandler(){@Override
publicvoidhandleMessage(Messagemsg){if(msg.what==0){//刷新最新adapter.notifyDataSetChanged();
list.doneRefresh();
Toast.makeText(PushPullListTest.this,
"新加载"+msg.arg1+"条数据!",Toast.LENGTH_LONG).show();
}elseif(msg.what==1){//加载更多adapter.notifyDataSetChanged();
list.doneMore();
}else{super.handleMessage(msg);
}
}
};
@Override
protectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pushpulllist);
//添加自定义控件
list=newPushPullList(this);
RelativeLayoutroot=(RelativeLayout)findViewById(R.id.root_a);
root.addView(list);
data=newArrayList<String>();
for(inti=1;i<10;++i){data.add(newDate().toLocaleString());
}
adapter=newArrayAdapter<String>(this,
android.R.layout.simple_expandable_list_item_1,data);
list.setAdapter(adapter);
list.setOnItemClickListener(newOnItemClickListener(){@Override
publicvoidonItemClick(AdapterView<?>arg0,Viewarg1,intarg2,
longarg3){Toast.makeText(PushPullListTest.this,data.get(arg2-1),
Toast.LENGTH_LONG).show();
//Log.i("",data.get(arg2-1));}
});
list.setDoMoreWhenBottom(false);//滚动到低端的时候不自己加载更多
list.setOnRefreshListener(this);//刷新最新的监听
list.setOnMoreListener(this);//加载更多的监听
}
@Override
publicbooleanonRefreshOrMore(PushPullListdynamicListView,
booleanisRefresh){if(isRefresh){newThread(r_refresh).start();
}else{newThread(r_more).start();
}
returnfalse;
}
//刷新最新，插入前边
Runnabler_refresh=newRunnable(){@Override
publicvoidrun(){//下拉，刷新最新
ArrayList<String>temp=newArrayList<String>();
for(inti=0;i<3;++i){temp.add(0,newDate().toLocaleString());
try{Thread.sleep(1000);
}catch(InterruptedExceptione){e.printStackTrace();
}
}
synchronized(data){data.addAll(0,temp);
}
Messagemessage=newMessage();
message.what=0;
message.arg1=temp.size();
handler.sendMessage(message);
}
};
//加载更多，插入末尾
Runnabler_more=newRunnable(){@Override
publicvoidrun(){//上拉，加载更多
ArrayList<String>temp=newArrayList<String>();
for(inti=0;i<3;++i){temp.add(newDate().toLocaleString());
try{Thread.sleep(1000);
}catch(InterruptedExceptione){e.printStackTrace();
}
}
synchronized(data){data.addAll(temp);
}
handler.sendEmptyMessage(1);
}
};
}
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图4主要是自定义了一个Listview，并继承android.widget.AbsListView.OnScrollListener接口，至于如何定义PushPullListListener和PushPullList，请自行下载源代码，这样就能实现上拉或下拉功能。通过上面代码，你就能了解基本的运行情况。
[align=left]onCreate方法，创建一个自定义ListView——PushPullList，并添加到页面，然后创建一个Adapter，用list.setAdapter设置该Adaper；[/align]
[align=left]onRefreshOrMore方法，是分别利用两个线程，下拉或上拉后，刷新最新或加载更多。[/align]
图5歌曲列表
图5核心代码如下所示：
packagecom.my.android.app.activity;
importjava.util.ArrayList;
importjava.util.HashMap;
importjava.util.List;
importjava.util.Map;
importandroid.app.Activity;
importandroid.os.Bundle;
importandroid.view.View;
importandroid.widget.AdapterView;
importandroid.widget.AdapterView.OnItemClickListener;
importandroid.widget.AdapterView.OnItemSelectedListener;
importandroid.widget.ListView;
importandroid.widget.SimpleAdapter;
importandroid.widget.Toast;
importcom.my.android.app.data.TestData;
importcom.my.android.app.R;
publicclassCustomListTestextendsActivity{ListViewlist;
@Override
publicvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);
setContentView(R.layout.activity_customlist);
//创建一个List集合，List集合的元素是Map
List<Map<String,Object>>listItems=newArrayList<Map<String,Object>>();
for(inti=0;i<TestData.artist.length;i++){Map<String,Object>listItem=newHashMap<String,Object>();
listItem.put("thumb",TestData.thumb[i]);listItem.put("artist",TestData.artist[i]);listItem.put("title",TestData.title[i]);listItem.put("duration",TestData.duration[i]);listItems.add(listItem);
}
//创建一个SimpleAdapter
SimpleAdaptersimpleAdapter=newSimpleAdapter(this,listItems,
R.layout.list_row,newString[]{"artist","title","thumb","duration"},newint[]{R.id.artist,R.id.title,R.id.imagethumb,R.id.duration});
list=(ListView)findViewById(R.id.mylist_a);
//为ListView设置Adapter
list.setAdapter(simpleAdapter);
//为ListView的列表项单击事件绑定事件监听器
list.setOnItemClickListener(newOnItemClickListener(){//第position项被单击时激发该方法。
@Override
publicvoidonItemClick(AdapterView<?>parent,Viewview,
intposition,longid){Toast.makeText(getApplicationContext(),
TestData.artist[position]+"被单击了",Toast.LENGTH_SHORT)
.show();
}
});
list.setOnItemSelectedListener(newOnItemSelectedListener(){//第position项被选中时激发该方法。
@Override
publicvoidonItemSelected(AdapterView<?>parent,Viewview,
intposition,longid){Toast.makeText(getApplicationContext(),
TestData.artist[position]+"被选中了",Toast.LENGTH_SHORT)
.show();
}
@Override
publicvoidonNothingSelected(AdapterView<?>parent){}
});
/*
*list=(ListView)findViewById(R.id.mylist);adapter=new
*ComplexAdapter(this,TestData.thumb_url);list.setAdapter(adapter);
*/
/*
*Buttonb=(Button)findViewById(R.id.btn_clear_a);
*b.setOnClickListener(newOnClickListener(){*
*@OverridepublicvoidonClick(Viewarg0){*adapter.imageLoader.clearCache();adapter.notifyDataSetChanged();}
*});
*/
}
@Override
publicvoidonDestroy(){list.setAdapter(null);
super.onDestroy();
}
}
注意上面代码段中Adapter。图5的目的是如何利用android.widget.SimpleAdapter在android.widget.ListView显示歌曲列表。
因此，若将图5的android.widget.ListView改为图4的自定义ListView，就能实现想要的功能，而且修改起来相当容易，只改一个地方。如果想实现更强大的功能，还可以继承android.widget.BaseAdapter自定义Adpater，本文只是使用SimpleAdapter。核心代码如下所示：
packagecom.my.android.app.activity;
importjava.util.ArrayList;
importjava.util.Date;
importjava.util.HashMap;
importjava.util.List;
importjava.util.Map;
importcom.my.android.app.R;
importcom.my.android.app.data.TestData;
importcom.my.android.app.view.PushPullList;
importcom.my.android.app.view.PushPullListListener;
importandroid.app.Activity;
importandroid.os.Bundle;
importandroid.os.Handler;
importandroid.os.Message;
importandroid.view.View;
importandroid.widget.AdapterView;
importandroid.widget.ArrayAdapter;
importandroid.widget.RelativeLayout;
importandroid.widget.SimpleAdapter;
importandroid.widget.Toast;
importandroid.widget.AdapterView.OnItemClickListener;
importandroid.widget.AdapterView.OnItemSelectedListener;
publicclassComplexListTestextendsActivityimplementsPushPullListListener{PushPullListlist;
List<Map<String,Object>>listItems=null;
SimpleAdaptersimpleAdapter=null;
//ArrayAdapter<String>adapter;
intlen=TestData.artist.length;
intstep=10;
//刷新控件状态
Handlerhandler=newHandler(){@Override
publicvoidhandleMessage(Messagemsg){if(msg.what==0){//刷新最新simpleAdapter.notifyDataSetChanged();
list.doneRefresh();
Toast.makeText(ComplexListTest.this,"新加载"+msg.arg1+"条数据!",
Toast.LENGTH_LONG).show();
}elseif(msg.what==1){//加载更多simpleAdapter.notifyDataSetChanged();
list.doneMore();
}else{super.handleMessage(msg);
}
}
};
@Override
publicvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);
setContentView(R.layout.activity_complexlist);
//添加自定义控件
list=newPushPullList(this);
RelativeLayoutroot=(RelativeLayout)findViewById(R.id.root_b);
root.addView(list);
//创建一个List集合，List集合的元素是Map
listItems=newArrayList<Map<String,Object>>();
for(inti=0;i<TestData.artist.length;i++){Map<String,Object>listItem=newHashMap<String,Object>();
listItem.put("thumb",TestData.thumb[i]);listItem.put("artist",TestData.artist[i]);listItem.put("title",TestData.title[i]);listItem.put("duration",TestData.duration[i]);listItems.add(listItem);
}
//创建一个SimpleAdapter
simpleAdapter=newSimpleAdapter(this,listItems,R.layout.list_row,
newString[]{"artist","title","thumb","duration"},newint[]{R.id.artist,R.id.title,R.id.imagethumb,R.id.duration});
//为ListView设置Adapter
list.setAdapter(simpleAdapter);
list.setOnItemClickListener(newOnItemClickListener(){@Override
publicvoidonItemClick(AdapterView<?>arg0,Viewarg1,intarg2,
longarg3){Toast.makeText(ComplexListTest.this,
listItems.get(arg2-1).toString(),Toast.LENGTH_LONG)
.show();
//Log.i("",data.get(arg2-1));}
});
list.setDoMoreWhenBottom(false);//滚动到低端的时候不自己加载更多
list.setOnRefreshListener(this);//刷新最新的监听
list.setOnMoreListener(this);//加载更多的监听
}
@Override
publicvoidonDestroy(){list.setAdapter(null);
super.onDestroy();
}
@Override
publicbooleanonRefreshOrMore(PushPullListdynamicListView,
booleanisRefresh){if(isRefresh){newThread(r_refresh).start();
}else{newThread(r_more).start();
}
returnfalse;
}
//刷新最新，插入前边
Runnabler_refresh=newRunnable(){@Override
publicvoidrun(){//下拉，刷新最新
intpos=0;
List<Map<String,Object>>temp=newArrayList<Map<String,Object>>();
for(inti=len+1;i<=len+step;++i){pos=i%TestData.artist.length;
Map<String,Object>item=newHashMap<String,Object>();
item.put("thumb",TestData.thumb[pos]);item.put("artist",TestData.artist[pos]);item.put("title",TestData.title[pos]);item.put("duration",TestData.duration[pos]);temp.add(item);
try{Thread.sleep(1000);
}catch(InterruptedExceptione){e.printStackTrace();
}
}
synchronized(listItems){listItems.addAll(0,temp);
}
len=len+step;
Messagemessage=newMessage();
message.what=0;
message.arg1=temp.size();
handler.sendMessage(message);
}
};
//加载更多，插入末尾
Runnabler_more=newRunnable(){@Override
publicvoidrun(){//上拉，加载更多
intpos=0;
List<Map<String,Object>>temp=newArrayList<Map<String,Object>>();
for(inti=len+1;i<=len+step;++i){pos=i%TestData.artist.length;
Map<String,Object>item=newHashMap<String,Object>();
item.put("thumb",TestData.thumb[pos]);item.put("artist",TestData.artist[pos]);item.put("title",TestData.title[pos]);item.put("duration",TestData.duration[pos]);temp.add(item);
try{Thread.sleep(1000);
}catch(InterruptedExceptione){e.printStackTrace();
}
}
synchronized(listItems){listItems.addAll(0,temp);
}
len=len+step;
handler.sendEmptyMessage(1);
}
};
}
除了改变了Adapter外，其他代码都没有变化。
