Android开发——数据存储之ContentProvider(2)

----------------接上文---------------------

2、创建自定义ContentProvider

创建内容供应器，需要继承ContentProvider

 

示例代码三：

1: 

2: /**

3: * 内容提供者

4: * @author LeoYang

5: */

6: public class TodoListProvider extends ContentProvider {

7: 

8: private static final String TAG = TodoListProvider.class.getSimpleName();

9: 

10: //数据库名

11: private static final String DATABASE_NAME = "todolist.db";

12: //版本

13: private static final int DATABASE_VERSION = 1;

14: //表名

15: private static final String TABLE_NAME = "todos";

16: //属性表

17: private static HashMap<String, String> sTodosProjectionMap;

18: 

19: private static final int TODOS = 1;

20: private static final int TODO_ID = 2;

21: 

22: //uri匹配器

23: private static final UriMatcher uriMatcher;

24: 

25: private DataBaseHelper dataBaseHelper;

26: 

27: static {

28: //数据初始化

29: uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

30: uriMatcher.addURI(TodoList.AUTHORITY, "todos", TODOS);

31: uriMatcher.addURI(TodoList.AUTHORITY, "todos/#", TODO_ID);

32: 

33: sTodosProjectionMap = new HashMap<String, String>();

34: sTodosProjectionMap.put(Todo._ID, Todo._ID);

35: sTodosProjectionMap.put(Todo.TITLE, Todo.TITLE);

36: sTodosProjectionMap.put(Todo.CONTENT, Todo.CONTENT);

37: sTodosProjectionMap.put(Todo.CREATED_DATE, Todo.CREATED_DATE);

38: sTodosProjectionMap.put(Todo.MODIFIED_DATE, Todo.MODIFIED_DATE);

39: }

40: 

41: private static class DataBaseHelper extends SQLiteOpenHelper {

42: 

43: public DataBaseHelper(Context context) {

44: super(context, DATABASE_NAME, null, DATABASE_VERSION);

45: }

46: 

47: //创建表

48: @Override

49: public void onCreate(SQLiteDatabase db) {

50: Log.d(TAG, "create table :" + TABLE_NAME);

51: db.execSQL("CREATE TABLE IF NOT EXISTS " + TABLE_NAME + "(" + Todo._ID + " INTEGER PRIMARY KEY," + Todo.TITLE

52: + " TEXT," + Todo.CONTENT + " TEXT," + Todo.CREATED_DATE + " INTEGER," + Todo.MODIFIED_DATE

53: + " INTEGER)");

54: ContentValues values = new ContentValues();

55: values.put(Todo.TITLE, "test");

56: values.put(Todo.CONTENT, "dddddddd");

57: db.insert(TABLE_NAME, "title", values);

58: }

59: 

60: //更新数据库表

61: @Override

62: public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

63: Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion

64: + ", which will destroy all old data");

65: db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);

66: onCreate(db);

67: }

68: 

69: }

70: 

71: //删除数据操作

72: @Override

73: public int delete(Uri uri, String selection, String[] selectionArgs) {

74: SQLiteDatabase db = dataBaseHelper.getWritableDatabase();

75: int count = 0;

76: //判断uri类型

77: switch (uriMatcher.match(uri)) {

78: case TODOS:

79: //如果以"/todo"结尾，则删除整个表数据

80: count = db.delete(TABLE_NAME, selection, selectionArgs);

81: break;

82: case TODO_ID:

83: //如果以“/todo/1”结尾，则删除ID=1的数据

84: String todoId = uri.getPathSegments().get(1);

85: count = db.delete(TABLE_NAME, Todo._ID + "=" + todoId

86: + ((TextUtils.isEmpty(selection)) ? "" : " AND " + selection), selectionArgs);

87: break;

88: default:

89: throw new IllegalArgumentException("Unknown URI :" + uri);

90: }

91: getContext().getContentResolver().notifyChange(uri, null);

92: return count;

93: }

94: ......

95: ......

96: //其他方法省略

至此我们就创建了一个ContentProvider了

3、Provider的配置，在AndroidMainfest.xml配置

示例代码三：

1: <?xml version="1.0" encoding="utf-8"?>

2: <manifest xmlns:android="http://schemas.android.com/apk/res/android"

3: package="com.halzhang.android.provider" android:versionCode="1"

4: android:versionName="1.0">

5: <application android:icon="@drawable/icon" android:label="@string/app_name">

6: <!--

7: name属性为继承ContentProvider的类

8: authorities属性为属性对象路径

9: -->

10: <provider android:name=".TodoListProvider"

11: android:authorities="com.halzhang.android.provider.TodoList"></provider>

12: <activity android:name=".ContentProviderDemo" android:label="@string/app_name">

 

OK，至此我们就创建了一个ContentProvider了