ContentProvider是不同应用程序之间进行数据交换的标准API，ContentProvider以某种Uri的形式对外提供数据，允许其他应用访问或修改数据;其他应用程序使用ContentResolver根据Uri去访问操作指定数据。
人人网Android客户端也是使用ContentProvider对需要保存于Android客户端的数据进行管理。
1. renren.db
SQLLiteOpenHelper是Android提供的一个管理数据库的工具类，可用于管理数据库的创建和版本更新。一般的用法是创建SQLiteOpenHelper的子类，并扩展它的onCreate(SQLiteDatabase db)和onUpgrade(SQLiteDatabase db，int oldVersion，int newVersion)方法。
人人网Android客户端使用该方法创建及修改用户手机中的人人网数据库(renren.db)。
下面是RenRenProvider$DatabaseHelper的代码：
public class RenRenProvider$DatabaseHelper extends SQLiteOpenHelper {
public RenRenProvider$DatabaseHelper(Context context) {
super(context, "renren.db", null, 71);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE pic (_id INTEGER PRIMARY KEY,url TEXT UNIQUE ON CONFLICT REPLACE,_data TEXT,size INTEGER);");
db.execSQL("CREATE TABLE account (_id INTEGER PRIMARY KEY,uid INTEGET,account TEXT UNIQUE ON CONFLICT REPLACE,pwd TEXT,proxy INTEGER,sessionkey TEXT,srt_key TEXT,ticket TEXT,name TEXT,headphoto BLOB,isdefault INTEGER,last_login INTEGER,friend_count INTEGER);");
db.execSQL("CREATE TABLE home (_id INTEGER PRIMARY KEY,item_id INTEGER UNIQUE ON CONFLICT REPLACE,data BLOB);");
db.execSQL("CREATE TABLE profile (_id INTEGER PRIMARY KEY,type INTEGER UNIQUE ON CONFLICT REPLACE,data BLOB);");
db.execSQL("CREATE TABLE friends (_id INTEGER PRIMARY KEY,uid INTEGER UNIQUE ON CONFLICT REPLACE,username TEXT,headurl TEXT,doing TEXT,nameindex TEXT,namepinyin TEXT,friendgroup TEXT,network TEXT,gender TEXT,isfriend INTEGER,suggest_text_1 TEXT,suggest_intent_query TEXT);");
db.execSQL("CREATE TABLE messages (_id INTEGER PRIMARY KEY,messageid INTEGER UNIQUE ON CONFLICT REPLACE,message BLOB);");
db.execSQL("CREATE TABLE favorites (_id INTEGER PRIMARY KEY,favoriteid BIGINT UNIQUE ON CONFLICT REPLACE,favoriteowner INTEGER,type INTEGER,favorite BLOB);");
db.execSQL("CREATE TABLE emonticons (_id INTEGER PRIMARY KEY,url TEXT,emotion TEXT UNIQUE ON CONFLICT REPLACE,img BLOB,size INTEGER,_data TEXT);");
db.execSQL("CREATE TABLE favoritefriends (_id INTEGER PRIMARY KEY,owner INTEGER,uid INTEGER,name TEXT);");
db.execSQL("CREATE TABLE chathistory (_id INTEGER PRIMARY KEY,uid INTEGER,tochatid INTEGER,chatmessage TEXT,comefrom INTEGER,chatname TEXT,chattime LONG);");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS pic");
db.execSQL("DROP TABLE IF EXISTS account");
db.execSQL("DROP TABLE IF EXISTS home");
db.execSQL("DROP TABLE IF EXISTS profile");
db.execSQL("DROP TABLE IF EXISTS friends");
db.execSQL("DROP TABLE IF EXISTS messages");
db.execSQL("DROP TABLE IF EXISTS favorites");
db.execSQL("DROP TABLE IF EXISTS emonticons");
db.execSQL("DROP TABLE IF EXISTS favoritefriends");
db.execSQL("DROP TABLE IF EXISTS favoritefriends");
db.execSQL("DROP TABLE IF EXISTS chathistory");
onCreate(db);
}
}
从代码中我们可以看到人人网Android客户端在用户手机上创建了renren.db数据库，数据库中共有10张表，分别为pic、account、home、profile、friends、messages、favorites、emonticons、favoritefriends、chathistory。
2. RenRenProvider
前面我们已经提到过ContentProvider，下面我们来看看人人网Android客户端是如何开发ContentProvider的。开发ContentProvider的两步：1)开发一个ContentProvider的子类，该子类需要实现增、删、改、查等方法。2)在AndroidManifest.xml文件中注册该ContentProvider。
下面是RenRenProvider核心代码：
public class RenRenProvider extends ContentProvider {
public static final String AUTHORITY = "com.renren.mobile.provider";
public static final class Account implements BaseColumns {
public static final Uri ACCOUNT_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/account");
}
public static final class ChatHistory implements BaseColumns {
public static final Uri CHAT_HISTORY_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/chathistory");
}
public static final class Emonticons implements BaseColumns {
public static final Uri EMONTICONS_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/emonticons");
}
public static final class Favorite implements BaseColumns {
public static final Uri FAVORITE_CONTENTURI = Uri
.parse("content://com.renren.mobile.provider/favorites");
}
public static final class FavoriteFriends implements BaseColumns {
public static final Uri FAVORITE_FRIENDS_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/favoritefriends");
}
public static final class Friends implements BaseColumns {
public static final Uri FRIENDS_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/friends");
}
public static final class Home implements BaseColumns {
public static final Uri HOME_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/home");
}
public static final class Messages implements BaseColumns {
public static final Uri MESSAGES_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/messages");
}
public static final class Pic implements BaseColumns {
public static final Uri PIC_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/pic");
}
public static final class Profile implements BaseColumns {
public static final Uri PROFILE_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/profile");
}
private static final UriMatcher URI_MATCHER;
private RenRenProvider.DatabaseHelper renrenDatabaseHelper;
static {
URI_MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
URI_MATCHER.addURI(AUTHORITY, "pic", 3);
URI_MATCHER.addURI(AUTHORITY, "pic/#", 4);
URI_MATCHER.addURI(AUTHORITY, "account", 5);
URI_MATCHER.addURI(AUTHORITY, "account/#", 6);
URI_MATCHER.addURI(AUTHORITY, "home", 7);
URI_MATCHER.addURI(AUTHORITY, "home/#",
; URI_MATCHER.addURI(AUTHORITY, "profile", 9);
URI_MATCHER.addURI(AUTHORITY, "profile/#", 10);
URI_MATCHER.addURI(AUTHORITY, "friends", 11);
URI_MATCHER.addURI(AUTHORITY, "friends/#", 12);
URI_MATCHER.addURI(AUTHORITY, "search_suggest_query/*", 1);
URI_MATCHER.addURI(AUTHORITY, "search_suggest_query", 2);
URI_MATCHER.addURI(AUTHORITY, "messages", 13);
URI_MATCHER.addURI(AUTHORITY, "messages/#", 14);
URI_MATCHER.addURI(AUTHORITY, "favorites", 15);
URI_MATCHER.addURI(AUTHORITY, "favorites/#", 16);
URI_MATCHER.addURI(AUTHORITY, "emonticons", 17);
URI_MATCHER.addURI(AUTHORITY, "emonticons/#", 18);
URI_MATCHER.addURI(AUTHORITY, "favoritefriends", 19);
URI_MATCHER.addURI(AUTHORITY, "favortiefriends/#", 20);
URI_MATCHER.addURI(AUTHORITY, "chathistory", 21);
URI_MATCHER.addURI(AUTHORITY, "chathistory/#", 22);
URI_MATCHER.addURI(AUTHORITY, "chathistory/*/*", 23);
}
public boolean onCreate()
{
renrenDatabaseHelper = new RenRenProvider.DatabaseHelper(this.getContext());
return true;
}
//其它代码省略...
}
下面是人人网android客户端在AndroidMantifest.xml中对该ContentProvider的注册。
<providerandroid:nameproviderandroid:nameproviderandroid:nameproviderandroid:name=".contentprovider.RenRenProvider" android:permission="com.renren.mobile.android.permission.PERMISSION_ADD_ACCOUNT"
android:authorities="com.renren.mobile.provider" />
从上面的分析我们了解到只要得到com.renren.mobile.android.permission.PERMISSION_ADD_ACCOUNT权限我们就可以通过特定Uri访问人人网Android客户端在用户手机上创建的renren.db中特定表了。
3. 开发Android应用访问renren.db中的数据
从上面分析中我们已经知道renren.db中表结构，及访问特定表对应的Uri，如我们可以通过content://com.renren.mobile.provider/account访问renren.db中的account表等等。下面我们写个很简单的例子来访问account表中的account和ticket字段。
main.xml根节点下简单添加2个TextView，如下：
<TextView
android:id="@+id/textView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="TextView" />
<TextView
android:id="@+id/textView2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="TextView" />
将account和ticket信息显示到TextView中，类代码如下
public class RenRenExtActivity extends Activity {
private static final Uri ACCOUNT_CONTENT_URI = Uri
.parse("content://com.renren.mobile.provider/account");
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
TextView textView1 = (TextView) findViewById(R.id.textView1);
textView1.setText("Sorry.");
TextView textView2 = (TextView) findViewById(R.id.textView2);
textView2.setText("Sorry2.");
Cursor cursor = getContentResolver().query(ACCOUNT_CONTENT_URI, null,
null, null, null);
List<Map<String, String>> resultList = converCursorToList(cursor);
if (!resultList.isEmpty()) {
Map<String, String> map = resultList.get(0);
textView1.setText(map.get("account"));
textView2.setText(map.get("ticket"));
}
}
private List<Map<String, String>> converCursorToList(Cursor cursor) {
List<Map<String, String>> result = new ArrayList<Map<String, String>>();
if (cursor == null) {
return Collections.emptyList();
}
// 遍历Cursor结果集
while (cursor.moveToNext()) {
// 将结果集中的数据存入ArrayList中
Map<String, String> map = new HashMap<String, String>();
map.put("account",
cursor.getString(cursor.getColumnIndex("account")));
map.put("ticket", cursor.getString(cursor.getColumnIndex("ticket")));
result.add(map);
}
return result;
}
}
需要指出的是，上面的应用程序需要操作人人网android客户端中的数据库，因此要记得在AndroidMantifest.xml文件中为该应用程序授权。也就是在该文件的根元素中添加如下元素：
<uses-permission android:name="com.renren.mobile.android.permission.PERMISSION_ADD_ACCOUNT" />
如果你android手机中安装有人人网Android客户端且曾经使用过，那么renren.db中应该有数据存在，把上面应用打包为apk文件安装到你android手机中，运行它，应该能看到屏幕中将显示你的人人网账号及一串ticket，该ticket是人人网Andriod客户端部分功能与人人网服务器通信的sid。
同理，也可以使用其它特定Uri访问手机中renre.db中特定的表，如friends表等等，所有Uri详见RenRenProvider代码。
综合帖：http://www.apkway.com/forum.php?mod=viewthread&tid=4840