SpringBoot-JPA

基于“初级搭建”进行：
链接：https://pan.baidu.com/s/1aFUOgdo8zgFEP5V3aO6LuA 
提取码：o3i3

代码

创建数据库+表
CREATE TABLE category_ (
  id int(11) NOT NULL AUTO_INCREMENT,
  name varchar(30),
  PRIMARY KEY (id)
) DEFAULT CHARSET=UTF8;

insert into category_ values(null,'category 1');
insert into category_ values(null,'category 2');
insert into category_ values(null,'category 3');
insert into category_ values(null,'category 4');

1、加入依赖pom.xml

                 <!-- mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.21</version>
        </dependency>
 
        <!-- jpa-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency> 
    </dependencies>


2、更新application.properties

#数据库连接
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/jpa?characterEncoding=UTF-8
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.jpa.properties.hibernate.hbm2ddl.auto=update

3、Category实体

package com.llhc.model;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity//实体
@Table(name = "category_")//对应表名
public class Category {
    @Id//主键
    @GeneratedValue(strategy = GenerationType.IDENTITY)//自动增长
    @Column(name = "id") //字段
    private int id;
    
    @Column(name = "name")//字段
    private String name;

    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;
    }
}

4、CategoryDao

package com.llhc.dao;
import org.springframework.data.jpa.repository.JpaRepository;
import com.llhc.model.Category;
public interface CategoryDao extends JpaRepository<Category, Integer>{
    
}

5、CategoryController

package com.llhc.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import com.llhc.dao.CategoryDao;
import com.llhc.model.Category;

@Controller
public class CategoryController {
    @Autowired
    private CategoryDao cd;
    @RequestMapping("/listCategory")
    public String listCategory(Model m) throws Exception {
        List<Category> cs=cd.findAll();
        m.addAttribute("cs", cs);
        return "listCategory";
    }
}


6、listCategory.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<table align='center' border='1' cellspacing='0'>
    <tr>
        <td>id</td>
        <td>name</td>
    </tr>
    <c:forEach items="${cs}" var="c" varStatus="st">
        <tr>
            <td>${c.id}</td>
            <td>${c.name}</td>
        </tr>
    </c:forEach>
</table>