黎活明8天快速掌握android视频教程--17_创建数据库与完成数据添删改查

Posted 2020-09-13 luzhouxiaoshuai

1、我们首先来看下整个项目

项目也是采用mvc的框架

 

package dB;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;


public class DbOpenHelper extends SQLiteOpenHelper
{

    public DbOpenHelper(Context context) {

        super(context, "wy.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db)
    {
     db.execSQL("CREATE TABLE person(personid integer primary key autoincrement, name varchar(20), phone VARCHAR(12) NULL)");





    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

操作表的接口类：

package service;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

import java.util.ArrayList;
import java.util.List;

import dB.DbOpenHelper;
import domain.Person;


public class PersonService {
private DbOpenHelper dbOpenHelper;

    public PersonService(Context context) {
        this.dbOpenHelper = new DbOpenHelper(context);
    }
    public void save(Person person){
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        db.execSQL("insert into person(name, phone) values(?,?)",
                new Object[]{person.getName(), person.getPhone()});
    }
    /**
     * 删除记录
     * @param name 记录ID
     */
    public void delete(String name,String phone){
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        db.execSQL("delete from person where name=? and phone=?", new Object[]{name,phone});
    }
    /**
     * 更新记录
     * @param person
     */
    public void update(Person person,String name,String phone){
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        db.execSQL("update person set name=?,phone=? where name=? and phone=?",
                new Object[]{person.getName(), person.getPhone(),name,phone});
    }
    /**
     * 查询记录
     * @param name 记录ID
     * @return
     */
    public Person find(String name,String phone){
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from person where name=? and phone = ?", new String[]{name,phone});
        if(cursor.moveToNext()){
            int personid = cursor.getInt(cursor.getColumnIndex("personid"));
            String name1 = cursor.getString(cursor.getColumnIndex("name"));
            String phone1 = cursor.getString(cursor.getColumnIndex("phone"));
            return new Person( name1, phone1);
        }
        cursor.close();
        return null;
    }
    /**
     * 分页获取记录
     * @param offset 跳过前面多少条记录
     * @param maxResult 每页获取多少条记录
     * @return
     */
    public List<Person> getScrollData(int offset, int maxResult){
        List<Person> persons = new ArrayList<Person>();
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from person order by personid asc limit ?,?",
                new String[]{String.valueOf(offset), String.valueOf(maxResult)});
        while(cursor.moveToNext()){
            int personid = cursor.getInt(cursor.getColumnIndex("personid"));

            /*这里也可以写成
            *   String name = cursor.getString(1);
            String phone = cursor.getString(2);
             默认的表自带的id字段为0 ，name为第一个字段所有为1 ，phone为第二个字段为2*/
            String name = cursor.getString(cursor.getColumnIndex("name"));
            String phone = cursor.getString(cursor.getColumnIndex("phone"));
            persons.add(new Person( name, phone));
        }
        cursor.close();
        return persons;
    }

    /**
     * 获取记录总数
     * @return
     */
    public long getCount(){
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select count(*) from person", null);
        cursor.moveToFirst();
        long result = cursor.getLong(0);//统计之后只有一个默认的字段，所以为0
        cursor.close();
        return result;
    }
}

Person类对象是：

/**
 * 文件名：Person.java
 * 版权:版权所有 (C) 中国电科30所三部
 * 描述:
 * 修改人: wei.yuan
 * 修改时间:2015/1/9
 * 修改内容:新增
 */
package domain;

/**
 * 项目名称：SQLLite1
 * 类描述：
 * 创建人：wei.yuan
 * 创建时间：2015/1/9 11:07
 * 修改人：wei.yuan
 * 修改时间：2015/1/9 11:07
 * 修改备注：
 * 版权:版权所有 (C) 中国电科30所三部
 */
public class Person
{

    private String name;
    private String phone;

    @Override
    public String toString() {
        return "Person{" +
                "name=\'" + name + \'\\\'\' +
                ", phone=\'" + phone + \'\\\'\' +
                \'}\';
    }

    public Person(String name, String phone) {
        this.name = name;
        this.phone = phone;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }
}

我们可以编写一个测试工具类来对上面的功能进行测试：

Android的测试类必须继承AndroidTestCase，该类的方法必须以test开头

package testSQLLite;

import android.test.AndroidTestCase;
import android.util.Log;
import android.widget.Toast;

import java.util.List;

import dB.DbOpenHelper;
import domain.Person;
import service.PersonService;


public class TestSQLLite extends AndroidTestCase {
      final  static String  TAG ="weiyuan";
    public  void testCreateDb()
    {
        DbOpenHelper dbOpenHelper = new DbOpenHelper(getContext());
        dbOpenHelper.getWritableDatabase();
        Log.i(TAG,"数据库创建成功");
    }
    public void testSave() throws Exception{
        PersonService service = new PersonService(this.getContext());
        for(int i = 0;i<20;i++)
        {
            service.save(new Person("weiyuan"+i,"12345"+i));
        }
        Log.i(TAG,"数据保存成功");
    }

      /*主要查找的是姓名和电话一起查找，只要满足了姓名和电话，才正确*/
    public void testFind() throws Exception{
        PersonService service = new PersonService(this.getContext());
        Person person = service.find("chendong","456789");
        Log.i(TAG, person.toString());
        Log.i(TAG,"数据查找成功");

    }

    /*删除某个记录*/
    public void testdelete() throws Exception{
        PersonService service = new PersonService(this.getContext());
        service.delete("weiyuan1","123451");
        Log.i(TAG,"数据删除成功");

    }
    /*给新某个记录*/
    public void testupdate() throws Exception{
        PersonService service = new PersonService(this.getContext());
        service.update(new Person("chendong","456789"),"weiyuan2","123452");
        Log.i(TAG, "数据修改成功");

    }
        /*获得分页的数据*/
    public void testScrollData() throws Exception{
        PersonService service = new PersonService(this.getContext());
        List<Person> persons = service.getScrollData(0, 5);
        for(Person person : persons){
            Log.i(TAG, person.toString());
        }

    }

    public void testCount() throws Exception{
        PersonService service = new PersonService(this.getContext());
        long result = service.getCount();
        Log.i(TAG, result+"");
    }


}