Android基础-ContentProvider.PPT

1、1,Android四大组件之ContentProvider,2,一、什么是ContentProvider,ContentProvider用来存储和检索数据 ContentProvider是应用之间互相访问数据的唯一方法 Android自身提供了一些常用的Provider audio、video、image、contacts等 如果你想使你的数据能够共享，要么建立一个你自己的ContentProvider；要么往已存在的ContentProvider中写数据,3,如何访问ContentProvider,借助工具类ContentResolver 获得ContentResolver 由activit

2、y或context的方法：getContentResolver() 使用ContentResolver的方法访问数据库 查找：query 插入：insert 更新：update 删除：delete,4,Content Provider如何存储数据,每一个Content Provider都有一个Uri来标识它本身 vider.Contacts.Phones.CONTENT_URI Content Provider存储数据的形式,5,Content Provider的查找,final Cursor ContentResolver.query(Uri uri, String p

3、rojection, String selection, String selectionArgs, String sortOrder) 使用者自行管理Cursor的生命周期 final Cursor Activity.managedQuery(Uri uri, String projection, String selection, String selectionArgs, String sortOrder) 由所在的Activity来管理Cursor的生命周期,6,Content Provider的查找,String projection = new String People._ID,

4、 People._COUNT, People.NAME, People.NUMBER ; Uri contacts = People.CONTENT_URI; Cursor managedCursor = managedQuery(contacts, projection, / Which columns to return null, / Which rows to return (all rows) null, / Selection arguments (none) / Put the results in ascending order by name People.NAME + AS

5、C,7,Content Provider的查找,private void getColumnData(Cursor cur) if (cur.moveToFirst() String name, phoneNumber; int nameColumn = cur.getColumnIndex(People.NAME); int phoneColumn = cur.getColumnIndex(People.NUMBER); String imagePath; do name = cur.getString(nameColumn); phoneNumber = cur.getString(pho

6、neColumn); while (cur.moveToNext();,8,修改Content Provider的数据,增加一条新记录：insert 给一条已存在的记录增加新信息：insert 更新记录：update 删除记录：delete 借助：ContentValues、ContentResolver,9,增加一条新记录,ContentValues values = new ContentValues(); / Add Abraham Lincoln to contacts and make him a favorite. values.put(People.NAME, Abraham L

7、incoln); / 1 = the new contact is added to favorites / 0 = the new contact is not added to favorites values.put(People.STARRED, 1); Uri uri = getContentResolver().insert(People.CONTENT_URI, values,10,已有记录增加新信息,Uri phoneUri = null; phoneUri = Uri.withAppendedPath(uri, People.Phones.CONTENT_DIRECTORY)

8、; values.clear(); values.put(People.Phones.TYPE, People.Phones.TYPE_MOBILE); values.put(People.Phones.NUMBER, 1233214567); getContentResolver().insert(phoneUri, values,11,更新和删除,更新： ContentResolver.update() 删除： ContentResolver.delete(,12,如何创建Content Provider,通过Sqlite的方式建立ContentProvider 继承ContentProvider类 实现SQLite