Android 数据存储之 ContentProvider

核心提示：import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.net.Uri;public class ContactContentProvider extends ContentProvider

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.net.Uri;

public class ContactContentProvider extends ContentProvider {

// 通过UriMatcher匹配外部请求

private static UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

// 通过openHelper进行数据库读写

private MyOpenHelper openHelper;

// 匹配状态常量

private static final int CONTACT_LIST = 1;

private static final int CONTACT = 2;

// 表名

private static final String tableName = "contacts";

// 添加Uri

static {

uriMatcher.addURI("com.changcheng.sqlite.provider", "contact",

CONTACT_LIST);

uriMatcher.addURI("com.changcheng.sqlite.provider", "contact/#",

CONTACT);

}

@Override

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

SQLiteDatabase db = this.openHelper.getWritableDatabase();

int result;

switch (uriMatcher.match(uri)) {

case CONTACT_LIST:

result = db.delete(tableName, selection, selectionArgs);

break;

case CONTACT:

long id = ContentUris.parseId(uri);

String where = "_id=" + id;

if (selection != null && !"".equals(selection)) {

where = where + " and " + selection;

}

result = db.delete(tableName, where, selectionArgs);

break;

default:

throw new IllegalArgumentException("Uri IllegalArgument:" + uri);

}

return result;

}

@Override

public String getType(Uri uri) {

switch (uriMatcher.match(uri)) {

case CONTACT_LIST:// 集合类型必须在前面加上vnd.android.cursor.dir/

return "vnd.android.cursor.dir/contactlist";