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();
     }
 }