Android开发中使用sqlite实现新闻收藏和取消收藏的功能

//创建数据库，建表
privatestaticfinal String DBNAME="news.db";
privatestaticfinalint VERSION=3; //设置版本号
privatestaticfinal String TBL_DETAILNEWS="news"; //创建表名为news的表
privatestaticfinal String TBL_DETAILNEWS_COLUMN_TITLE="_title"; 
privatestaticfinal String TBL_DETAILNEWS_COLUMN_URL="_url";
privatestaticfinal String TBL_DETAILNEWS_COLUMN_DOCID="_docid";
privatestaticfinal String TBL_DETAILNEWS_COLUMN_STATE="_state"; 
public NewsDBHelper(Context context){
super(context,DBNAME,null,VERSION);
}
@Override
publicvoid onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub16 StringBuffer sb=new StringBuffer();
sb.append("create table if not exists ");
sb.append(TBL_DETAILNEWS+"(");
sb.append(TBL_DETAILNEWS_COLUMN_DOCID +" varchar(100) primary key ,"); //设置主键
sb.append(TBL_DETAILNEWS_COLUMN_TITLE+ " varchar(100) ,");
sb.append(TBL_DETAILNEWS_COLUMN_URL+" varchar(100) ,");
sb.append(TBL_DETAILNEWS_COLUMN_STATE+" integer ");
sb.append(")");
db.execSQL(sb.toString()); 
}
@Override
publicvoid onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
String sql2="drop table if exists "+TBL_DETAILNEWS;
db.execSQL(sql2); //创建
onCreate(db);
}

publicclass DetailNewsDao {
private NewsDBHelper helper;
public DetailNewsDao(Context context){ 
helper=new NewsDBHelper(context); //与数据库建立连接 }
//插入数据
publicvoid insertDetsilNews(News news){
SQLiteDatabase db=helper.getWritableDatabase(); 
db.execSQL("insert into news(_title,_url,_docid)" + //将要收藏新闻的标题title，标识docid，详细地址url传入数据库，便可以依此打开新闻详显 "values(&＃63;,&＃63;,&＃63;)",new String[]{news.getTitle(),news.getDetailUrl(),news.getDocid()});
db.close();
}
//删除数据
publicvoid del(String docid){ //根据传入参数docid删除数据 SQLiteDatabase db=helper.getReadableDatabase();
db.execSQL("delete from news where _docid = &＃63;",new Object[]{docid});
db.close();
}
//查询数据
public List findSelected(){
SQLiteDatabase db=helper.getReadableDatabase();
Cursor c=db.rawQuery("select * from news", null); //只有对数据进行查询时，才用rawQuery()，增、删、改和建表，都用execSQl() List list=new ArrayList();
while(c.moveToNext()){
News news=new News();
news.setTitle(c.getString(c.getColumnIndex("_title")));
news.setDetailUrl(c.getString(c.getColumnIndex("_url")));
news.setDocid(c.getString(c.getColumnIndex("_docid")));
list.add(news);
}
c.close();
db.close();
return list;
}
}

if(item.getTitle().equals("收藏")){　　　　
Toast.makeText(this,"收藏成功", Toast.LENGTH_LONG).show();
detailNewsDao.insertDetsilNews(news);
item.setTitle("取消收藏");
}else{
detailNewsDao.del(news.getDocid());
Toast.makeText(this,"取消收藏", Toast.LENGTH_LONG).show();
item.setTitle("收藏");
}