使用ContentProContentProvider共享生词本数据

自定义ContentProvider需要在项目清单中注册：

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.provider.UserDictionary.Words;

public class DictProvider extends ContentProvider{
private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
private static final int WORDS = 1;
private static final int WORD = 2;
private MyDatabaseHelper dbOpenHelper;
static{
//为UriMatcher注册两个Uri
matcher.addURI(mediaprovidertest.Words.AUTHORITY, "words", WORDS);
matcher.addURI(mediaprovidertest.Words.AUTHORITY, "word/#", WORD);
}

//第一次调用该DictProvider时，系统先创建DictProvider对象，并回调该方法
@Override
public boolean onCreate() {
dbOpenHelper = new MyDatabaseHelper(this.getContext(),"myDict.db3",null,1);
return true;
}

//查询数据的方法
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
switch (matcher.match(uri)) {
case WORDS:
//执行查询
return db.query("dict", projection,
selection, selectionArgs, null, null, sortOrder);
case WORD:
//解析出想查询的记录ID
long id = ContentUris.parseId(uri);
String where =mediaprovidertest.Words.Word._ID+"="+id;
//如果原来的where子句存在，拼接where子句
if(selection != null && "".equals(selection)){
where = where + " and "+selection;
}
return db.query("dict", projection, where, selectionArgs,
null, null, sortOrder);

default:
throw new IllegalArgumentException("未知Uri:"+uri);
}
}

//返回指定Uri参数对应的数据的MIME类型
@Override
public String getType(Uri uri) {
switch (matcher.match(uri)) {
//如果操作的数据是多项记录
case WORDS:
return "vnd.android.cursor.dir/org.crazyit.dict";
//如果操作的数据时单项记录
case WORD:
return "vnd.android.cursor.item/org.crazyit.dict";
default:
throw new IllegalArgumentException("未知Uri:"+uri);
}
}

//插入数据
@Override
public Uri insert(Uri uri, ContentValues values) {
// 获得数据库实例
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
//插入数据，返回行ID
long rowId = db.insert("dict", mediaprovidertest.Words.Word._ID, values);
//如果插入成功则返回uri
if(rowId>0){
//在已有的Uri的后面追加ID数据
Uri wordUri = ContentUris.withAppendedId(uri, rowId);
//通知数据已经改变
getContext().getContentResolver().notifyChange(wordUri, null);
return wordUri;
}
return null;
}

//删除数据的方法
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
//记录所删除的记录数
int num = 0;
//对Uri进行匹配
switch (matcher.match(uri)) {
case WORDS:
num = db.delete("dict", selection, selectionArgs);
break;
case WORD:
//解析出所需要删除的记录ID
long id = ContentUris.parseId(uri);
String where = mediaprovidertest.Words.Word._ID+"="+id;
//如果原来的where子句存在，拼接where子句
if(selection != null && selection.equals("")){
where = where +" and "+selection;
}
num = db.delete("dict", where, selectionArgs);
break;
default:
try {
throw new IllegalAccessException("未知Uri:"+uri);
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
//通知数据已经改变
return num;
}

//修改数据的方法
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
SQLiteDatabase db = dbOpenHelper.getWriteDatabase();
//记录所修改的记录数
int num = 0;
switch (matcher.match(uri)) {
case WORDS:
num = db.update("dict", values, selection, selectionArgs);
break;
case WORD:
//解析出想修改的记录ID
long id = ContentUris.parseId(uri);
String where = mediaprovidertest.Words.Word._ID+"="+id;
//如果原来的where子句存在，拼接where子句
if(selection != null && selection.equals("")){
where = where +" and "+selection;
}
num = db.update("dict", values, where, selectionArgs);
default:
throw new IllegalArgumentException("未知Uri:"+uri);
}
//通知数据已经改变
getContext().getContentResolver().notifyChange(uri, null);
return 0;
}

}