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

逃离我推掉我的手 2023-02-18 14:02 67阅读 0赞

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）**][step1_LitePal]

**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。  
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--------------------

## ①UI界面 ##

**布局如下：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzY2MDQ5Nw_size_16_color_FFFFFF_t_70 1]  
**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());
                    }
                }
            });
    
    
        }
    
    
    }

[step1_LitePal]: https://blog.csdn.net/weixin_43660497/article/details/106821709
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