contentProvider 内容提供者

http://blog.csdn.net/woshixuye/article/details/8280879

实例代码
当数据需要在应用程序间共享时，我们就可以利用ContentProvider为数据定义一个URI。之后其他应用程序对数据进行查询或者修改时，只需要从当前上下文对象获得一个ContentResolver(内容解析器)传入相应的URI就可以了。
contentProvider和Activity一样是Android的组件，故使用前需要在AndroidManifest.xml中注册，必须放在主应用所在包或其子包下。

 <application android:icon="@drawable/icon" android:label="@string/app_name">  
     <activity android:name=".MainActivity"  
               android:label="@string/app_name">  
         <intent-filter>  
             <action android:name="android.intent.action.MAIN" />  
             <category android:name="android.intent.category.LAUNCHER" />  
         </intent-filter>  
         <intent-filter>  
             <data android:mimeType="vnd.android.cursor.dir/person" />  
         </intent-filter>  
         <intent-filter>  
             <data android:mimeType="vnd.android.cursor.item/person" />  
         </intent-filter>  
     </activity>  
     <!-- 配置内容提供者,android:authorities为该内容提供者取名作为在本应用中的唯一标识 -->  
     <provider android:name=".providers.PersonProvider"   
android:authorities="cn.xyCompany.providers.personProvider"/>  
 </application>  
 
内容提供者和测试代码
 

package cn.xy.cotentProvider.app.providers;  
import android.content.ContentProvider;  
import android.content.ContentUris;  
import android.content.ContentValues;  
import android.content.UriMatcher;  
import android.database.Cursor;  
import android.database.sqlite.SQLiteDatabase;  
import android.net.Uri;  
import android.util.Log;  
import cn.xy.cotentProvider.service.DBOpeningHelper;  
  
/** 
 * contentProvider作为一种组件必须放在应用所在包或其子包下，主要作用是对外共享数据 
 * 测试步骤1：将本项目先部署 
 * 测试步骤2：调用测试方法 
 * @author xy 
 *  
 */  
public class PersonProvider extends ContentProvider  
{  
    private DBOpeningHelper dbHelper;  
  
    // 若不匹配采用UriMatcher.NO_MATCH(-1)返回  
    private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH);  
  
    // 匹配码  
    private static final int CODE_NOPARAM = 1;  
    private static final int CODE_PARAM = 2;  
  
    static  
    {  
        // 对等待匹配的URI进行匹配操作，必须符合cn.xyCompany.providers.personProvider/person格式  
        // 匹配返回CODE_NOPARAM，不匹配返回-1  
        MATCHER.addURI("cn.xyCompany.providers.personProvider", "person", CODE_NOPARAM);  
  
        // #表示数字 cn.xyCompany.providers.personProvider/person/10  
        // 匹配返回CODE_PARAM，不匹配返回-1  
        MATCHER.addURI("cn.xyCompany.providers.personProvider", "person/#", CODE_PARAM);  
    }  
  
    @Override  
    public boolean onCreate()  
    {  
        dbHelper = new DBOpeningHelper(this.getContext());  
        return true;  
    }  
  
    /** 
     * 外部应用向本应用插入数据 
     */  
    @Override  
    public Uri insert(Uri uri, ContentValues values)  
    {  
        SQLiteDatabase db = dbHelper.getWritableDatabase();  
        switch (MATCHER.match(uri))  
        {  
            case CODE_NOPARAM:  
                // 若主键值是自增长的id值则返回值为主键值，否则为行号，但行号并不是RecNo列  
                long id = db.insert("person", "name", values);   
                Uri insertUri = ContentUris.withAppendedId(uri, id);   
                return insertUri;  
            default:  
                throw new IllegalArgumentException("this is unkown uri:" + uri);  
        }  
    }  
  
    /** 
     * 外部应用向本应用删除数据 
     */  
    @Override  
    public int delete(Uri uri, String selection, String[] selectionArgs)  
    {  
        SQLiteDatabase db = dbHelper.getWritableDatabase();  
        switch (MATCHER.match(uri))  
        {  
            case CODE_NOPARAM:  
                return db.delete("person", selection, selectionArgs); // 删除所有记录  
            case CODE_PARAM:  
                long id = ContentUris.parseId(uri); // 取得跟在URI后面的数字  
                Log.i("provider", String.valueOf(id));  
                String where = "id = " + id;  
                if (null != selection && !"".equals(selection.trim()))  
                {  
                    where += " and " + selection;  
                }  
                return db.delete("person", where, selectionArgs);  
            default:  
                throw new IllegalArgumentException("this is unkown uri:" + uri);  
        }  
    }  
  
    /** 
     * 外部应用向本应用更新数据 
     */  
    @Override  
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs)  
    {  
        SQLiteDatabase db = dbHelper.getWritableDatabase();  
        switch (MATCHER.match(uri))  
        {  
            case CODE_NOPARAM:  
                return db.update("person",values,selection, selectionArgs); // 更新所有记录  
            case CODE_PARAM:  
                long id = ContentUris.parseId(uri); // 取得跟在URI后面的数字  
                String where = "id = " + id;  
                if (null != selection && !"".equals(selection.trim()))  
                {  
                    where += " and " + selection;  
                }  
                return db.update("person",values,where,selectionArgs);  
            default:  
                throw new IllegalArgumentException("this is unkown uri:" + uri);  
        }  
    }  
      
    /** 
     * 返回对应的内容类型 
     * 如果返回集合的内容类型，必须以vnd.android.cursor.dir开头 
     * 如果是单个元素，必须以vnd.android.cursor.item开头 
     */  
    @Override  
    public String getType(Uri uri)  
    {  
        switch(MATCHER.match(uri))  
        {  
            case CODE_NOPARAM:  
                return "vnd.android.cursor.dir/person";  
            case CODE_PARAM:  
                return "vnd.android.cursor.item/person";  
            default:  
                throw new IllegalArgumentException("this is unkown uri:" + uri);  
        }  
    }  
  
    @Override  
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)  
    {  
        SQLiteDatabase db = dbHelper.getReadableDatabase();  
        switch (MATCHER.match(uri))  
        {  
            case CODE_NOPARAM:  
                return db.query("person", projection, selection, selectionArgs, null, null, sortOrder);  
            case CODE_PARAM:  
                long id = ContentUris.parseId(uri); // 取得跟在URI后面的数字  
                String where = "id = " + id;  
                if (null != selection && !"".equals(selection.trim()))  
                {  
                    where += " and " + selection;  
                }  
                return db.query("person", projection, where, selectionArgs, null, null, sortOrder);  
            default:  
                throw new IllegalArgumentException("this is unkown uri:" + uri);  
        }  
    }  
  
}  
  
  
  
测试代码  
package cn.xy.test.test;  
import android.content.ContentResolver;  
import android.content.ContentValues;  
import android.database.Cursor;  
import android.net.Uri;  
import android.test.AndroidTestCase;  
import android.util.Log;  
  
/** 
 * 测试代码 
 * @author xy 
 * 
 */  
public class TestProviders extends AndroidTestCase  
{  
    // 在执行该测试方法时需要先将还有内容提供者的项目部署到Android中，否则无法找到内容提供者  
    public void testInsert()  
    {  
        Uri uri = Uri.parse("content://cn.xyCompany.providers.personProvider/person");  
        ContentResolver resolver = this.getContext().getContentResolver();  
        ContentValues values = new ContentValues();  
        values.put("name", "xy");  
        values.put("phone", "111");  
        resolver.insert(uri, values); // 内部调用内容提供者的insert方法  
    }  
  
    // 不带id参数的删除  
    public void testDelete1()  
    {  
        Uri uri = Uri.parse("content://cn.xyCompany.providers.personProvider/person");  
        ContentResolver resolver = this.getContext().getContentResolver();  
        int rowAffect = resolver.delete(uri, null, null);  
        Log.i("rowAffect", String.valueOf(rowAffect));  
    }  
  
    // 带参数的删除，通过URI传递了id至contentProvider并可追加其他条件  
    public void testDelete2()  
    {  
        Uri uri = Uri.parse("content://cn.xyCompany.providers.personProvider/person/18");  
        ContentResolver resolver = this.getContext().getContentResolver();  
        int rowAffect = resolver.delete(uri, "name = ?", new String[] { "XY2" }); // 在provider中手动进行了拼装  
        Log.i("rowAffect", String.valueOf(rowAffect));  
    }  
      
    public void testUpdate()  
    {  
        Uri uri = Uri.parse("content://cn.xyCompany.providers.personProvider/person/19");  
        ContentResolver resolver = this.getContext().getContentResolver();  
        ContentValues values = new ContentValues();  
        values.put("name", "newxy");  
        values.put("phone", "new111");  
        int rowAffect = resolver.update(uri, values, null, null);  
        Log.i("rowAffect", String.valueOf(rowAffect));  
    }  
      
    public void testQuery()  
    {  
        Uri uri = Uri.parse("content://cn.xyCompany.providers.personProvider/person/19");  
        ContentResolver resolver = this.getContext().getContentResolver();  
        Cursor cursor = resolver.query(uri, new String[]{"id","name","phone"}, null, null, "id asc");  
        if(cursor.moveToFirst())  
        {  
            Log.i("query", cursor.getString(cursor.getColumnIndex("name")));  
        }  
        cursor.close();  
    }  
}