对于SQLiteHelper的应用
package com.example.helloworld;import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;import data.User;public class UserSQLHelper extends SQLiteOpenHelper {private static final String name="uer.db";private static final int version=1;private static UserSQLHelper mHelper=null;private SQLiteDatabase mRDB=null;private SQLiteDatabase mWDB=null;private UserSQLHelper(Context context){super(context,name,null,version);}public static UserSQLHelper getInstance(Context context){if(mHelper==null){mHelper=new UserSQLHelper(context);}return mHelper;}//数据库读连接public SQLiteDatabase openReadLink(){if(mRDB==null||!mRDB.isOpen()){mRDB=mHelper.getReadableDatabase();}return mRDB;}//数据库写连接private SQLiteDatabase openWriteLink(){if(mWDB==null||!mWDB.isOpen()){mWDB=mHelper.getWritableDatabase();}return mWDB;}//关闭连接private void closeLink(){if(mRDB!=null&&mRDB.isOpen()){mRDB.close();mRDB=null;}if(mWDB!=null&&mWDB.isOpen()){mWDB.close();mWDB=null;}}@Overridepublic void onCreate(SQLiteDatabase db) {String sql="create table if not exists users(" +"id varchar," +"password varchar);";db.execSQL(sql);}//版本升级@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {}//插入public void insert(User user){ContentValues values=new ContentValues();values.put("id",user.getId());values.put("password",user.getPassword());mWDB.insert(name,null,values);}
}
