LitePal的简单使用（kotlin实现）

LitePal 是一款开源的Android数据库框架，它采用了对象关系映射(ORM)的模式，并将一些常用的数据库功能进行封装。
https://github.com/LitePalFramework/LitePal

LitePal的配置

在app/build.gradle文件中加入

compile 'org.litepal.android:core:1.6.0'

修改AndroidManifest.xml的代码，在application标签中加入

android:name="org.litepal.LitePalApplication"

---

创建数据库

定义一个实体类

import org.litepal.crud.DataSupport;

/**
 * Created by hya on 2017/10/17.
 */

public class Book extends DataSupport {
    private int id;
    private String name;
    private String author;
    private double price;

    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 getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }
}

在/app/src/main目录下创建一个assets目录，在assets目录下新建文件litepal.xml。将Book类添加到映射模型列表中。

<?xml version="1.0" encoding="utf-8"?>
<litepal>

    <dbname value="BookStore"></dbname>
    <version value="1"></version>

    <list>
        <mapping class="com.hya.text.Book"></mapping>
        <!--在此处添加要映射的类-->
    </list>
</litepal>

---

使用LitePal对数据库进行操作

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.View
import android.widget.Button
import org.litepal.LitePal
import org.litepal.crud.DataSupport

class MainActivity : AppCompatActivity(), View.OnClickListener {


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val add = findViewById<Button>(R.id.btn_add)
        add.setOnClickListener(this)
        val create = findViewById<Button>(R.id.btn_create)
        create.setOnClickListener(this)
        val remove = findViewById<Button>(R.id.btn_remove)
        remove.setOnClickListener(this)
        val update = findViewById<Button>(R.id.btn_update)
        update.setOnClickListener(this)
        val query = findViewById<Button>(R.id.btn_query)
        query.setOnClickListener(this)
    }

    override fun onClick(p0: View?) {
        when (p0?.id) {
            R.id.btn_create -> {
                LitePal.getDatabase()
                Log.d("create","success")
            }
            R.id.btn_add -> {
                val book = Book()
                book.name = "The Da Vinci Code"
                book.author = "Dan Brown"
                book.price = 16.22
                book.save()
                val book1 = Book()
                book1.name = "The Lost Symbol"
                book1.author = "Dan Brown"
                book1.price = 26.52
                book1.save()
                val book2 = Book()
                book2.name = "Thinking in Java"
                book2.author = "Bruce Eckel"
                book2.price = 44.72
                book2.save()
            }
            R.id.btn_update -> {

                val book = Book()
                book.price = 30.1
                book.updateAll("name = ?","The Da Vinci Code")

            }
            R.id.btn_remove -> {
                DataSupport.deleteAll("Book","price < ?","30")
            }
            R.id.btn_query -> {

               val books:List<Book> = DataSupport.findAll(Book::class.java);
                for (book in books){
                    Log.d("MainAvtivity","name = ${book.name} ,author = ${book.author} , price = ${book.price}")
                }
            }
        }
    }
}

运行效果图

点击按钮add添加数据

点击update修改数据

点击remove删除数据