step2：使用LitePal操作数据库，基于AndroidStudio。练习

此项目参考郭霖《第一行代码》中使用LitePal操作数据库。

  
step1：建好项目后先配置LitePal！！！（链接）

step2：UI布局、创建和升级数据库、使用LitePal对数据进行增删查改操作

另外：使用adb shell观察数据可和表的情况。

---

①UI界面

布局如下：

布局xml文件如下：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.dn.library_management_zxy.MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="LitePal的BookStore"
        android:textSize="30sp" />

    <Button
        android:text="创建数据库"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="70dp"
        android:id="@+id/button1"
        android:layout_below="@+id/textView"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:textSize="24sp" />

    <Button
        android:text="添加数据"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button2"
        android:layout_below="@+id/button1"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:textSize="24sp"
        android:layout_marginTop="20dp" />

    <Button
        android:text="更新数据"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button2"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:id="@+id/button3"
        android:textSize="24sp"
        android:layout_marginTop="20dp" />

    <Button
        android:text="删除数据"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/button4"
        android:layout_below="@+id/button3"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:textSize="24sp"
        android:layout_marginTop="20dp" />

    <Button
        android:text="查询数据"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button4"
        android:id="@+id/button5"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:textSize="24sp"
        android:layout_marginTop="20dp" />

</RelativeLayout>

②创建和升级数据库

创建Book表和Category表；
将两个类添加到映射关系中，修改litepal.xml中文件；（step1中以修改）
在MainActivity中建库。
Book 类

package com.example.dn.library_management_zxy;

import org.litepal.crud.DataSupport;

/**
 * Created by ZXY on 2020/6/16.
 */

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

    public String getPress() {
        return press;
    }
    public void setPress(String press) {
        this.press = press;
    }

    public int getId(){
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }

    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;
    }

    public int getPages() {
        return pages;
    }
    public void setPages(int pages) {
        this.pages = pages;
    }

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

Category 类

package com.example.dn.library_management_zxy;

/**
 * Created by ZXY on 2020/6/16.
 */

public class Category {

    private  int id;
    private String categoryName;
    private int categoryCode;

    public void setId(int id) {
        this.id = id;
    }

    public void setCategoryName(String categoryName) {
        this.categoryName = categoryName;
    }

    public void setCategoryCode(int categoryCode) {
        this.categoryCode = categoryCode;
    }
}

创建数据库

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //建库 同时建表
        Button createDatabase=(Button) findViewById(R.id.button1);
        createDatabase.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                LitePal.getDatabase();
            }
        });
}

③使用LitePal对数据进行增删查改操作

MainActivity类

package com.example.dn.library_management_zxy;

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;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //建库 同时建表
        Button createDatabase=(Button) findViewById(R.id.button1);
        createDatabase.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                LitePal.getDatabase();
            }
        });



        //添加数据！！！！！！！！！！！！！！！！！！！
        Button addData=(Button) findViewById(R.id.button2);
        addData.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                Book book=new Book();
                book.setName("第一行代码Android");
                book.setAuthor("郭霖");
                book.setPages(570);
                book.setPrice(79.00);
                book.setPress("人民邮电出版社");
                book.save();
            }
        });


        //更新数据！！！！！！！！！！！！！！！！！！！
        Button updateData=(Button) findViewById(R.id.button3);
        updateData.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){

                //更新价格—只能对已存储的数据进行更新
                Book book=new Book();
                book.setName("昆虫记");
                book.setAuthor("达尔文");
                book.setPages(314);
                book.setPrice(28.80);
                book.setPress("内蒙古人民出版社");
                book.save();
                book.setPrice(20.00);
                book.save();

                /*Book book2=new Book();
                book2.setName("Android开发与应用");
                book2.setAuthor("张荣");
                book2.setPages(275);
                book2.setPrice(45.00);
                book2.setPress("未知");
                book2.save();
                //更新价格和出版社
                Book book=new Book();
                book.setPrice(40.00);
                book.setPress("人民邮电出版社");
                book.updateAll("name=? and author=?","Android开发与应用","张荣");  //类似于where*/



            }
        });




        //删除数据！！！！！！！！！！！！！！！！！！！
        Button deleteData=(Button) findViewById(R.id.button4);
        deleteData.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                DataSupport.deleteAll(Book.class,"price < ?","50");
            }
        });


        //查询数据！！！！！！！！！！！！！！！！！！！
        Button queryData=(Button) findViewById(R.id.button5);
        queryData.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){
                List<Book> books= DataSupport.findAll(Book.class);
                //查询所有book，并打印信息
                for(Book book:books){
                    Log.d("MainActivity","book name is"+book.getName());
                    Log.d("MainActivity","book author is"+book.getAuthor());
                    Log.d("MainActivity","book pages is"+book.getPages());
                    Log.d("MainActivity","book price is"+book.getPrice());
                    Log.d("MainActivity","book press is"+book.getPress());
                }
            }
        });


    }


}

本文地址：https://blog.csdn.net/weixin_43660497/article/details/106821569