spring-boot简单学习

热备份失败有大佬知道怎么弄吗
idea新建项目先这个

这个随意

web spring web

先给 pom.xml文件

    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.2.2.RELEASE
         
    
    com.example
    demo
    0.0.1-SNAPSHOT
    demo
    Demo project for Spring Boot

    
        1.8
    

    
        
            org.springframework.boot
            spring-boot-starter-web
        

        
            org.springframework.boot
            spring-boot-devtools
            true 
        
        
        
            javax.servlet
            javax.servlet-api
            provided
        
        
            javax.servlet
            jstl
        

        
        
            org.apache.tomcat.embed
            tomcat-embed-jasper
            provided
        
        
        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            1.1.1
        
        
        
            mysql
            mysql-connector-java
            5.1.21
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
            
                
                    org.junit.vintage
                    junit-vintage-engine
                
            
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    true 
                
            
        
    

都是在main下的没有的自己加或者改

先上最关键的 yml的配置文件，我热备份失败了 所以你们那边可以不要，主要就是数据库连接要自己改，其他自行百度就行

server:
  port: 8080
debug: true
spring:
  mvc:
    view:
      prefix: /WEB-INF/views/
      suffix: .jsp
  devtools:
    restart:
      enabled: true  #设置开启热部署
  freemarker:
    cache: false    #页面不加载缓存，修改即时生效
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/zjgm?characterEncoding=UTF-8
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
  jpa:
    hibernate:
      ddl-auto: update

ddl-auto:create----每次运行该程序，没有表格会新建表格，表内有数据会清空
ddl-auto:create-drop----每次程序结束的时候会清空表
ddl-auto:update----每次运行程序，没有表格会新建表格，表内有数据不会清空，只会更新
ddl-auto:validate----运行程序会校验数据与数据库的字段类型是否相同，不同会报错

mapper

package com.example.demo.mapper;

import com.example.demo.pojo.Student;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

@Mapper
public interface StudentMapper {

    @Select("SELECT * FROM student")
    List findAll();
}

contorller

package com.example.demo.controller;

import com.example.demo.mapper.StudentMapper;
import com.example.demo.pojo.Student;
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 StudentController {

    @Resource
    StudentMapper studentMapper;

    @RequestMapping("/listStudent")
    public String listStudent(Model model) {
        List students = studentMapper.findAll();
        model.addAttribute("students", students);
        return "listStudent";
    }
}

pojo student

package com.example.demo.pojo;

public class Student {
    private int id;
    private String NAME;
    private String gender;

    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 getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }
}

最后上listStudent.jsp
因为我表字段大写了NAME不规范，你们创表都小写，我随便用的表

<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8"%>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>


        
            <%--//迭代--%>
        

    

        
id
        
name
    
    

            
${s.id}
            
${s.NAME}
${st.index}
    

简单的成功了下 运行在DemoApplication（main下运行）。网站的地址需要自己输的 http://localhost:8080/listStudent