Content Provider 总结
1、实现provider接口，提供给其他程序调用
第一步： 在manifest.xml中配置 provider 组件
<provider android:name="MyProvider" android:authorities="com.ruixin.login" />
其中：name表示 自定义继承于ContentProvider的类名（或者加上包名）
authorities表示主机名，类似域名
第二步： 创建数据库，表用来保存数据
public class DBlite extends SQLiteOpenHelper { public DBlite(Context context) { super(context, RuiXin.DBNAME, null, RuiXin.VERSION); // TODO Auto-generated constructor stub } @Override public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub db.execSQL("create table " + RuiXin.TNAME + "(" + RuiXin.TID + " integer primary key autoincrement not null," + RuiXin.EMAIL + " text not null," + RuiXin.USERNAME + " text not null," + RuiXin.DATE + " interger not null," + RuiXin.SEX + " text not null);"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub } public void add(String email, String username, String date, String sex) { SQLiteDatabase db = getWritableDatabase(); ContentValues values = new ContentValues(); values.put(RuiXin.EMAIL, email); values.put(RuiXin.USERNAME, username); values.put(RuiXin.DATE, date); values.put(RuiXin.SEX, sex); db.insert(RuiXin.TNAME, "", values); } }
第三步： 继承ContentProvider类，提供从数据库中获取数据的接口。 也可以是从文件系统等其他的地方获取
public class MyProvider extends ContentProvider { DBlite dBlite; SQLiteDatabase db; private static final UriMatcher sMatcher; static { /**注册Uri，用来适配传入的 Uri，进行判断，区分处理方式*/ sMatcher = new UriMatcher(UriMatcher.NO_MATCH); sMatcher.addURI(RuiXin.AUTOHORITY, RuiXin.TNAME, RuiXin.ITEM); sMatcher.addURI(RuiXin.AUTOHORITY, RuiXin.TNAME + "/#", RuiXin.ITEM_ID); } public int delete(Uri uri, String selection, String[] selectionArgs) { db = dBlite.getWritableDatabase(); int count = 0; switch (sMatcher.match(uri)) { case RuiXin.ITEM: count = db.delete(RuiXin.TNAME, selection, selectionArgs); break; case RuiXin.ITEM_ID: String id = uri.getPathSegments().get(1); count = db.delete(RuiXin.TID, RuiXin.TID + "=" + id + (!TextUtils.isEmpty(RuiXin.TID = "?") ? "AND(" + selection + ')' : ""), selectionArgs); break; default: throw new IllegalArgumentException("Unknown URI" + uri); } getContext().getContentResolver().notifyChange(uri, null); return count; } public String getType(Uri uri) { switch (sMatcher.match(uri)) { case RuiXin.ITEM: return RuiXin.CONTENT_TYPE; case RuiXin.ITEM_ID: return RuiXin.CONTENT_ITEM_TYPE; default: throw new IllegalArgumentException("Unknown URI" + uri); } } public Uri insert(Uri uri, ContentValues values) { db = dBlite.getWritableDatabase(); long rowId; if (sMatcher.match(uri) != RuiXin.ITEM) { throw new IllegalArgumentException("Unknown URI" + uri); } rowId = db.insert(RuiXin.TNAME, RuiXin.TID, values); if (rowId > 0) { Uri noteUri = ContentUris.withAppendedId(RuiXin.CONTENT_URI, rowId); getContext().getContentResolver().notifyChange(noteUri, null); return noteUri; } throw new IllegalArgumentException("Unknown URI" + uri); } public boolean onCreate() { this.dBlite = new DBlite(this.getContext()); return true; } public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { db = dBlite.getWritableDatabase(); Cursor c; Log.d("-------", String.valueOf(sMatcher.match(uri))); switch (sMatcher.match(uri)) { case RuiXin.ITEM: c = db.query(RuiXin.TNAME, projection, selection, selectionArgs, null, null, null); break; case RuiXin.ITEM_ID: String id = uri.getPathSegments().get(1); c = db.query(RuiXin.TNAME, projection, RuiXin.TID + "=" + id + (!TextUtils.isEmpty(selection) ? "AND(" + selection + ')' : ""), selectionArgs, null, null, sortOrder); break; default: Log.d("!!!!!!", "Unknown URI" + uri); throw new IllegalArgumentException("Unknown URI" + uri); } c.setNotificationUri(getContext().getContentResolver(), uri); return c; } public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { return 0; } }
第四步：添加数据到数据库中
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); dBlite1.add("4141414@qq", "jay", "2012", "man"); dBlite1.add("4141414@qq", "jay", "2013", "man"); dBlite1.add("4141414@qq", "jay", "2014", "man"); dBlite1.add("4141414@qq", "jay", "2015", "man"); dBlite1.add("4141414@qq", "jay", "2016", "man"); }
2、从ContentProver 中获取数据
获取数据使用 ContentResolver类，对于使用数据库来保存数据，ContentProvider提供接口来实现数据共享的方法。
如果Uri后面没有加id项，表示操作目录/表，如果有id项，表示操作该项。下面的例子就是获取Uri路径下所有的项，而不是某一项。
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Log.d("cp" , "content provider"); // 通过contentResolver进行查找 contentResolver = ContentProviderClientActivity.this.getContentResolver(); Uri uri = ContentUris.withAppendedId(RuiXin.CONTENT_URI, 3); String type = contentResolver.getType(uri); Log.d("cp" , type); Cursor cursor = contentResolver.query(RuiXin.CONTENT_URI, new String[] { RuiXin.EMAIL, RuiXin.USERNAME, RuiXin.DATE, RuiXin.SEX }, null, null, null); while (cursor.moveToNext()) { String text = cursor.getString(cursor.getColumnIndex(RuiXin.EMAIL)) + " " + cursor.getString(cursor.getColumnIndex(RuiXin.USERNAME)) + " "+ cursor.getString(cursor.getColumnIndex(RuiXin.DATE)) + " " + cursor.getString(cursor.getColumnIndex(RuiXin.SEX)); Toast.makeText(ContentProviderClientActivity.this,text, Toast.LENGTH_SHORT).show(); Log.d("cp" , text); } startManagingCursor(cursor); // 查找后关闭游标 } public class RuiXin { public static final String DBNAME = "ruixinonlinedb"; public static final String TNAME = "ruixinonline"; public static final int VERSION = 3; public static String TID = "tid"; public static final String EMAIL = "email"; public static final String USERNAME = "username"; public static final String DATE = "date"; public static final String SEX = "sex"; public static final String AUTOHORITY = "com.ruixin.login"; public static final int ITEM = 1; public static final int ITEM_ID = 2; public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.ruixin.login"; public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd.ruixin.login"; public static final Uri CONTENT_URI = Uri.parse("content://" + AUTOHORITY + "/ruixinonline"); }
