Android ContentProvider+ContentObserver

说明：文章仅供本人学习记录所用。

1.理解含义：

ContentProvider： 内容提供者，将数据以表的形式进行操作。主要实现应用程序间数据共享，操作系统本地数据（包括短 信、音频、视屏、数据库）。

ContentObserver：内容观察者，监听数据变化。

2.使用方法：

ContentProvider：

1）步骤：新建MyProvider类继承ContentProvider类;注册URI;重写方法（onCreate、query、bulkInsert、insert、 delete、update）;在AndroidManifest.xml中配置provider；

2）代码：

public class MyProvider extends ContentProvider {
private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
private static final int INSERT = 1;
private static final int UPDATE = 2;
private static final int DELETE = 3;
private static final int QUERY = 4;
private static final int INSERTS = 5;
private DBHelper dbOpenHelper;
private String TAG = "Provider";
static {
// 为UriMatcher注册si四个Uri
matcher.addURI(Picture.AUTHORITY, "insert", INSERT);
matcher.addURI(Picture.AUTHORITY, "update", UPDATE);
matcher.addURI(Picture.AUTHORITY, "delete", DELETE);
matcher.addURI(Picture.AUTHORITY, "query", QUERY);
matcher.addURI(Picture.AUTHORITY, "inserts", INSERTS);
//说明Picture.AUTHORITY：表示你要操作的ContentProvider，一般以要操作的实体类的包名命名。
}

@Override
public boolean onCreate() {
//获取数据库辅助类
dbOpenHelper = DBHelper.getInstance(getContext());
DatabaseManager.initializeInstance(dbOpenHelper);
return true;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// TODO Auto-generated method stub
int code = matcher.match(uri);
Cursor c = null;
switch (code) {
case QUERY:
SQLiteDatabase database = dbOpenHelper.getReadableDatabase();
c = database.query("picture", projection, selection, selectionArgs,
null, null, sortOrder);

c.setNotificationUri(getContext().getContentResolver(), uri);
DatabaseManager.getInstance().closeDatabase();
case UriMatcher.NO_MATCH:
Log.i(TAG, "------------未知的URI" + uri);
break;
}
return c;
}

@Override
public String getType(Uri uri) {
// TODO Auto-generated method stub
return null;
}

@Override
public Uri insert(Uri uri, ContentValues values) {
int code = matcher.match(uri);
switch (code) {
case INSERT:
SQLiteDatabase database = DatabaseManager.getInstance()
.openDatabase();// 线程安全并发操作数据库
try {// 获得数据库实例
database.insert("picture", null, values);
getContext().getContentResolver().notifyChange(uri, null);
} catch (Exception ex) {
Log.i(TAG, "insert ex=====" + ex.toString());
} finally {
DatabaseManager.getInstance().closeDatabase();
}
break;
case UriMatcher.NO_MATCH:
Log.i(TAG, "------------未知的URI" + uri);
break;
}

return null;
}
/**
* 批量插入
*/
@Override
public int bulkInsert(Uri uri, ContentValues[] values) {
int code = matcher.match(uri);
switch (code) {
case INSERTS:
SQLiteDatabase database = DatabaseManager.getInstance()
.openDatabase();// 线程安全并发操作数据库
try {// 获得数据库实例
int numValues = 0;
numValues = values.length;
for (int i = 0; i < numValues; i++) {
ContentValues value = values[i];
database.delete("picture", "name = ?",
new String[] { String.valueOf(value.get("name")) });
Log.i(TAG,
"name===== values"
+ String.valueOf(value.get("name")));
database.insert("picture", null, values[i]);
Log.i(TAG, "Value insert====" + i);
}
getContext().getContentResolver().notifyChange(uri, null);
} catch (Exception ex) {
Log.i(TAG, "insert ex=====" + ex.toString());
} finally {
DatabaseManager.getInstance().closeDatabase();
}
break;
case UriMatcher.NO_MATCH:
Log.i(TAG, "------------未知的URI" + uri);
break;
}

return 0;

}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
int code = matcher.match(uri);
switch (code) {
case DELETE:
SQLiteDatabase database = DatabaseManager.getInstance()
.openDatabase();
int i = 0;
try {
i = database.delete("picture", selection, selectionArgs);
if (i > 0) {
getContext().getContentResolver().notifyChange(uri, null);
}
} catch (Exception ex) {
Log.i(TAG, "delete ex====" + ex.toString());
} finally {
// database.close();
DatabaseManager.getInstance().closeDatabase();
}

return i;
case UriMatcher.NO_MATCH:
Log.i(TAG, "------------未知的URI" + uri);
break;
}
return 0;
}

@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// TODO Auto-generated method stub
int code = matcher.match(uri);
switch (code) {
case UPDATE:
// SQLiteDatabase database = dbOpenHelper.getReadableDatabase();
SQLiteDatabase database = DatabaseManager.getInstance()
.openDatabase();
int i = 0;
try {
i = database
.update("picture", values, selection, selectionArgs);
if (i != 0) {
getContext().getContentResolver().notifyChange(uri, null);
}
} catch (Exception ex) {
Log.i(TAG, "update ex===" + ex.toString());
} finally {
// database.close();
DatabaseManager.getInstance().closeDatabase();
}
return i;
case UriMatcher.NO_MATCH:
Log.i(TAG, "------------未知的URI" + uri);
break;
}
return 0;
}

}

//在数据库操作类中添加以下方法。
//单条数据添加
public static void addPicture(Picture picture) {
Uri uri = Uri.parse("content://" + Picture.AUTHORITY + "/insert");
ContentValues values = new ContentValues();//封装数据
values.put("name", picture.name);
...
AppApplication.getInstance().getContentResolver().insert(uri, values);
}
//多条数据添加
public static void addPictures(List<Picture> pictures) {
Uri uri = Uri.parse("content://" + Picture.AUTHORITY + "/inserts");
ContentValues[] values = new ContentValues[pictures.size()];
for (int i = 0; i < pictures.size(); i++) {
Picture picture = pictures.get(i);
ContentValues value = new ContentValues();
value.put("name", picture.name);
...
values[i] = value;
}
Log.i(TAG, "addPictures_values_size=====" + values.length);
AppApplication.getInstance().getContentResolver().bulkInsert(uri, values);
}
//删除操作
public static void deletePictureTag() {
Uri uri = Uri.parse("content://" + Picture.AUTHORITY + "/delete");
int i = AppApplication.getInstance().getContentResolver()
.delete(uri, "whereName = ?", new String[] { "value" });
}

//修改操作
public static void updatePicture(Picture picture) {
Uri uri = Uri.parse("content://" + Picture.AUTHORITY + "/update");
ContentValues values = new ContentValues();
values.put("tagStatus", picture.tagStatus);
int i = AppApplication.getInstance().getContentResolver()
.update(uri, values, "whereName = ?", new String[] { picture.name });
}
//AndroidManifest.xml中配置provider
<provider
android:name="com....provider.MyProvider"//包名
android:authorities="com....provider.myProvide" />

ContentObserver:

1)步骤:注册与注销ContentObserver；添加ContentObserver方法。

2)代码:

//uri与provider中注册的uri对应
Uri uri = Uri.parse("content://" + Picture.AUTHORITY + "/insert");//监听添加
getContentResolver().registerContentObserver(uri, true, cob);
Uri uri_inserts = Uri.parse("content://" + Picture.AUTHORITY+ "/inserts");//监听批量添加
getContentResolver().registerContentObserver(uri_inserts, true, cob);
Uri uri_update = Uri.parse("content://" + Picture.AUTHORITY + "/update");//监听修改
getContentResolver().registerContentObserver(uri_update, true, cob);

getContentResolver().unregisterContentObserver(cob);//在onDestroy销毁

//监听数据改变的方法
private ContentObserver cob = new ContentObserver(new Handler()) {
@Override
public boolean deliverSelfNotifications() {
return super.deliverSelfNotifications();
}

@Override
public void onChange(boolean selfChange) {
super.onChange(selfChange);
//改变数据时做出相应的操作
......
}
}