SpringBoot（三）thymeleaf+JPA+MySql

接着上一节的

第一步：在pom文件中加入以下代码：

<!--JPA-->
      <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
       </dependency>

<!--   MySql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

第二步：在application.yml文件中加入以下代码

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    #useUnicode=true&characterEncoding=utf-8:这个代表允许用户自己设定数据库编码，而且设置成UTF-8
    #&useSSL=false:
    url: jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8&useSSL=false
    username: root
    password: root

  jpa:
    hibernate:
      ddl-auto: update
#ddl-auto:有五个值可选，create：是每次都是先检查表是否存在，如果存在删除再新建；update：不会新建只是更新；
#         create-drop：新建但是一旦sessionFactory停止就自动销毁；none：什么都不做；validate：验证表结构

     show-sql: true
#show-sql：是否显示sql语句

第三步：在bean包选新建User类

package com.oda.springboot.bean;

import org.springframework.stereotype.Component;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

//@Component
@Entity
//@Entity说明这个class是实体类，并且使用默认的orm规则，即class名即数据库表中表名，class字段名即表中的字段名
//如果想改变这种默认的orm规则，就要使用@Table来改变class名与数据库中表名的映射规则，@Column来改变class中字段名与db中表的字段名的映射规则
public class User {
    @Id
    @GeneratedValue
    private int id;
    private String name;
    private int age;

    public User() {
    }

    public User(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    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 int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

第四步：新建dao包，在其下面新建UserMapper接口

package com.oda.springboot.dao;

import com.oda.springboot.bean.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

public interface UserMapper extends JpaRepository<User,Integer> {
}

第五步：新建service包，在其下面新建Userservice类

package com.oda.springboot.service;

import com.oda.springboot.bean.User;
import com.oda.springboot.dao.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;

@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;

    public List<User> users() {
        return userMapper.findAll();
    }
}

第六步：在controller包下新建UserController

package com.oda.springboot.controller;

import com.oda.springboot.bean.User;
import com.oda.springboot.service.UserService;
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 javax.annotation.Resource;
import java.util.List;

@Controller
public class UserController {

    @Resource
    private UserService userService;

    @RequestMapping("/users")
    public String uses(){
        return "redirect:/select";
    }

    @RequestMapping("/select")
    public String select(Model model){
       List<User> users = userService.users();
       model.addAttribute("users",users);
        return "users/index";
    }
}

第七步：在templates包下，新建users包，在其下新建index.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org"><!--这里引入thymeleaf命名空间-->
<head>
    <meta charset="UTF-8">
    <title>thymeleaf模板的应用</title>
</head>
<body>
    <table>
        <tr>
            <td>序号</td>
            <td>名字</td>
            <td>年龄</td>
        </tr>
        <tr th:each="user,count:${users}">
            <td th:text="${count.count}"></td>
            <td th:text="${user.name}"></td>
            <td th:text="${user.age}"></td>
        </tr>
    </table>

</body>
</html>

然后启动，访问http://localhost:8080/zm/users

项目结构：

注意：application.yml文件中的

    url: jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8&useSSL=false