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 张汉国
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。