SimpleCursorTreeAdapter

最新推荐文章于 2023-02-22 12:46:17 发布

iteye_13411

最新推荐文章于 2023-02-22 12:46:17 发布

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文章标签：移动开发数据库 java

本文介绍了如何利用SimpleCursorTreeAdapter将cursor数据与XML布局文件中的TextView和ImageView进行高效绑定，实现数据展示。通过定义哪些列对应哪些视图以及XML布局文件来定制显示样式，支持子项和分组的分离XML文件，绑定过程分为两阶段，确保数据与UI的无缝对接。

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publicabstractclass
SimpleCursorTreeAdapter
extendsResourceCursorTreeAdapter
java.lang.Object
android.widget.BaseExpandableListAdapter
android.widget.CursorTreeAdapter
android.widget.ResourceCursorTreeAdapter
android.widget.SimpleCursorTreeAdapter
ClassOverview
AneasyadaptertomapcolumnsfromacursortoTextViewsorImageViewsdefinedinanXMLfile.
Youcanspecifywhichcolumnsyouwant,
whichviewsyouwanttodisplaythecolumns,
andtheXMLfilethatdefinestheappearanceoftheseviews.
SeparateXMLfilesforchildandgroupsarepossible.Bindingoccursintwophases.
First,ifaSimpleCursorTreeAdapter.ViewBinderisavailable,setViewValue(android.view.View,
android.database.Cursor,int)isinvoked.
Ifthereturnedvalueistrue,bindinghasoccurred.
IfthereturnedvalueisfalseandtheviewtobindisaTextView,setViewText(TextView,String)isinvoked.
IfthereturnedvalueisfalseandtheviewtobindisanImageView,setViewImage(ImageView,String)isinvoked.
Ifnoappropriatebindingcanbefound,anIllegalStateExceptionisthrown.

SimpleCursorTreeAdapter继承于ResourceCursorTreeAdapter。 它为cursor和ExpandableListView提供了连接的桥梁。 它提供把cursor的数据绑定到Group和child的布局文件中的控件的功能。绑定的控件只能是TextView和ImageView SimpleCursorTreeAdapter的子类： 无 他实现了来自于ResourceCursorTreeAdapter的两个方法： bindChildView，bindGroupView 但使用CursorTreeAdapter还需要实现下面一个方法： ProtectedMethods abstractCursorgetChildrenCursor(CursorgroupCursor) GetstheCursorforthechildrenatthegivengroup. 注：关于cursor的数据到Group和child的布局文件中控件的绑定机制和SimpleCursorAdapter差不多。 具体可参考《<a title="阅读全文" target="_blank" href="http://hubingforever.blog.163.com/blog/static/1710405792010431621954/" style="color:rgb(207,121,28); line-height:25px; text-decoration:none">SimpleCursorAdapter</a>》
importandroid.app.ExpandableListActivity;
importandroid.content.ContentUris;
importandroid.content.Context;
importandroid.database.Cursor;
importandroid.net.Uri;
importandroid.os.Bundle;
importandroid.provider.ContactsContract.CommonDataKinds.Phone;
importandroid.widget.ExpandableListAdapter;
importandroid.widget.SimpleCursorTreeAdapter;
publicclassExpandableListSample2XmlextendsExpandableListActivity{
privateintmGroupIdColumnIndex;
privateStringmPhoneNumberProjection[]=newString[]{
Phone._ID,Phone.NUMBER
};
privateExpandableListAdaptermAdapter;
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
//Queryforpeople
CursorgroupCursor=managedQuery(Phone.CONTENT_URI,
newString[]{Phone._ID,Phone.DISPLAY_NAME},null,null,null);
//CachetheIDcolumnindex
mGroupIdColumnIndex=groupCursor.getColumnIndexOrThrow(Phone._ID);
//Setupouradapter
mAdapter=newMyExpandableListAdapter(groupCursor,
this,
android.R.layout.simple_expandable_list_item_1,//这个是系统的
android.R.layout.simple_expandable_list_item_1,//这个是系统的
newString[]{Phone.DISPLAY_NAME},//Nameforgrouplayouts
newint[]{android.R.id.text1},//用于显示的标签,也是系统的
newString[]{Phone.NUMBER},//Numberforchildlayouts
newint[]{android.R.id.text1});//用于显示的标签，也是系统的
setListAdapter(mAdapter);
}
publicclassMyExpandableListAdapterextendsSimpleCursorTreeAdapter{
publicMyExpandableListAdapter(Cursorcursor,Contextcontext,intgroupLayout,
intchildLayout,String[]groupFrom,int[]groupTo,String[]childrenFrom,
int[]childrenTo){
super(context,cursor,groupLayout,groupFrom,groupTo,childLayout,childrenFrom,
childrenTo);
}
//注意二级项数据在这里取得
@Override
protectedCursorgetChildrenCursor(CursorgroupCursor){
//Giventhegroup,wereturnacursorforallthechildrenwithinthatgroup
//Returnacursorthatpointstothiscontact'sphonenumbers
Uri.Builderbuilder=Phone.CONTENT_URI.buildUpon();
ContentUris.appendId(builder,groupCursor.getLong(mGroupIdColumnIndex));
UriphoneNumbersUri=builder.build();
//ThereturnedCursorMUSTbemanagedbyus,soweuseActivity'shelper
//functionalitytomanageitforus.
returnmanagedQuery(phoneNumbersUri,mPhoneNumberProjection,null,null,null);
}
}
}