软件工程日报——第八天

关于Android studio自带数据库SQlite的链接

1.首先创建一个User类用来返回对象

package com.example.myapplication;

public class User {
    private  int id;
    private  String name;
    private  String password;
    public User(String name,String password){
        super();
        this.name = name;
        this.password = password;
    }
    public  int getId() {return  id;}
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "User{id ="+ id + ", name = "+ name +",password ="+password +"}";
    }
}

 

 2.创建一个SQlite类用来连接数据库

package com.example.myapplication;

import android.annotation.SuppressLint;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import com.example.myapplication.User;

import java.util.ArrayList;

public class SQlite extends SQLiteOpenHelper {
    private SQLiteDatabase db;
    public SQlite(Context context){
        super(context,"db_test",null,1);
        db = getReadableDatabase();
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE IF NOT EXISTS user(" +
                "_id INTEGER PRIMARY KEY AUTOINCREMENT," +
                "name TEXT," +
                "password TEXT)");
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS user");
        onCreate(db);
    }
    public void add(String name,String password ){
        db.execSQL("INSERT INTO user(name,password)VALUES(?,?)",new Object[]{name,password});
    }
    public ArrayList<User> getAllDATA(){
        ArrayList<User> list = new ArrayList<User>();
        Cursor cursor = db.query("user",null,null,null,null,null,"name DESC");
        while(cursor.moveToNext()){
           String name = cursor.getString(cursor.getColumnIndex("name"));
          String password = cursor.getString(cursor.getColumnIndex("password"));
            list.add(new User(name,password));
        }
        return list;
    }
}

 

 super中的“db_test”是创建的数据库的名称，“1”是数据库的版本号  

db.execSQL是用来创建user表名和字段名称。