(Android) ContentProvider 实例

最新推荐文章于 2024-08-03 14:33:35 发布

palmerma

最新推荐文章于 2024-08-03 14:33:35 发布

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分类专栏： Android

本文链接：https://blog.youkuaiyun.com/palmerma/article/details/9928659

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本文介绍了一个具体的Android ContentProvider实现案例，演示了如何通过ContentProvider在两个应用间进行数据的插入、更新、删除和查询操作。示例中详细展示了ContentProvider的创建过程，包括UriMatcher的使用、不同类型数据的处理方式等。

ContentProvider 用于应用程序(Android Application)之间传递数据，包括Insert, update, delete, query。

下面的例子是在两个应用之间传递数据。

应用一（创建ContentProviderTestA)

TestContentProvider.java

public class TestContentProvider extends ContentProvider {

private final static UriMatcher URI_MATCHER;
private final static int ALL_MESSAGES = 1;
private final static int SPECIFIC_MESSAGE = 2;

static {
  URI_MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
  URI_MATCHER.addURI("com.example.contentprovidertesta", "item", ALL_MESSAGES);
  URI_MATCHER.addURI("com.example.contentprovidertesta", "specialitem", SPECIFIC_MESSAGE);
}

public static final Uri CONTENT_URI = Uri
.parse("content://com.example.contentprovidertesta");

private final static String DEBUG = "ContentProvider";

@Override
public String getType(Uri uri) {
  switch (URI_MATCHER.match(uri)) {
  case SPECIFIC_MESSAGE:
   Log.d(DEBUG, "specialitem");
   return "specialitem";
  case ALL_MESSAGES:
   Log.d(DEBUG, "item");
   return "item/normal";
  }
  return "item";
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
  Log.d(DEBUG, uri.toString());
  if (getType(uri).equals("specialitem")) {
   Log.d(DEBUG, "-----------delete sepcial items-------------");
  } else {
   Log.d(DEBUG, "-----------delete-------------");
  }
  return 0;
}

@Override
public Uri insert(Uri uri, ContentValues values) {
return null;
}

@Override
public boolean onCreate() {
return false;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
return null;
}

@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
return 0;
}
}

AndroidManifest.xml

</application>

应用二 ContentProviderTest

public class MainActivity extends Activity {

private final Uri testallmessage = Uri
.parse("content://com.example.contentprovidertesta/item");
private final Uri testspecialmessage = Uri
.parse("content://com.example.contentprovidertesta/specialitem");

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

@Override
protected void onResume() {
super.onResume();
testContentProvider();
}

private void testContentProvider() {
getContentResolver().delete(testallmessage, null, null);
getContentResolver().delete(testspecialmessage, null, null);
}

}

当安装两个应用后，再运行应用二出现的log，

content://com.example.contentprovidertesta/item
item
-----------delete-------------
content://com.example.contentprovidertesta/specialitem
specialitem
-----------delete sepcial items-------------