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