SQLiteOpenHelper的使用

package com.zzxy.chenyb;

1 创建数据库辅助类，继承于SQLiteOpenHelper

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DataBaseUtil extends SQLiteOpenHelper {
private static final String DATABASENAME="llh.db";
private static final int DATABASEVERSION=1;//版本号修改时，会执行onUpgrade方法
private static final String USER="user";
public DataBaseUtil(Context context){
super(context,DATABASENAME,null,DATABASEVERSION);
}
public DataBaseUtil(Context context,String name,CursorFactory factory,
int version) {
super(context,factory,DATABASEVERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
String sql="create table "+USER+" (" +
"ID INTEGER PRIMARY KEY" +
",NAME VARCHAR(50) NOT NULL" +
",PASSWORD VARCHAR(15) NOT NULL)";
db.execSQL(sql);
System.out.println("create user successfully...");
}

@Override
public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion) {
String sql="DROP TABLE IF EXISTS "+USER;
db.execSQL(sql);
this.onCreate(db);
System.out.println("drop user successfully...");
}

}

2 编写测试类，验证创建的数据库

SQLiteOpenHelper sqlite=new DataBaseUtil(LoginView.this);
sqlite.getWritableDatabase();

验证执行完成程序后，到指定的文件夹内寻找生成的llh.db文件。

默认的目录在data/data/项目包名/databases/..

（编辑：李大同）

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