Spring Boot基础入门之基于注解的Mybatis

前言

今天学习下SpringBoot集成mybatis,集成mybatis一般有两种方式，一个是基于注解的一个是基于xml配置的。今天先了解下基于注解的mybatis集成。下面话不多说了，来一起看看详细的介绍吧

一、引入依赖项

因为是mybatis嘛,肯定是要有mybatis相关的,同时用的是mysql,所以也需要引入mysql相关的。

<!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
 <dependency>
 <groupId>org.mybatis.spring.boot</groupId>
 <artifactId>mybatis-spring-boot-starter</artifactId>
 <version>1.3.2</version>
 </dependency>
 <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
 <dependency>
 <groupId>mysql</groupId>
 <artifactId>mysql-connector-java</artifactId>
 <version>8.0.11</version>
 </dependency>

二、创建model

这里创建了一个User的model,这样方便与数据库的表对照，这里在mysql中创建了一个名为mybatis的数据库,里面创建了一个user的表.同时创建了枚举类UserSexEnum.

CREATE TABLE `user` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(20) DEFAULT NULL,
 `age` int(11) DEFAULT NULL,
 `sex` varchar(20) DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;

package com.example.model;

import java.io.Serializable;

public class User implements Serializable{
 @Override
 public String toString() {
 // TODO Auto-generated method stub
 return "User [id=" + Id + ", name=" + Name + ", age=" + Age + "]";

 }

 public int getId() {
 return Id;
 }
 public void setId(int id) {
 Id = id;
 }
 public String getName() {
 return Name;
 }
 public void setName(String name) {
 Name = name;
 }
 public int getAge() {
 return Age;
 }
 public void setAge(int age) {
 Age = age;
 }
 private int Id;
 private String Name;
 private int Age; 
 
 private UserSexEnum Sex;

 public UserSexEnum getSex() {
 return Sex;
 }
 public void setSex(UserSexEnum sex) {
 Sex = sex;
 }
}

package com.example.model;

public enum UserSexEnum {
 MAN, WOMAN
}

三、创建Mapper

这里需要把model与操作数据库的sql对照起来，用什么对照呢?那就需要创建一个mapper.这里有增删改查。

package com.example.mapper;
import java.util.List;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.example.model.*;;
public interface UserMapper {
 @Select("SELECT * FROM user")
 @Results({
 @Result(property = "Sex", column = "sex", javaType = UserSexEnum.class),
 @Result(property = "Name", column = "name")

 })

 List<User> getAll();
 @Select("SELECT * FROM user WHERE id = #{id}")

 @Results({
 @Result(property = "Sex", column = "sex", javaType = UserSexEnum.class),
 @Result(property = "Name", column = "name")
 })

 User getOne(int id);
 @Insert("INSERT INTO user(name,age,sex) VALUES(#{name}, #{age}, #{sex})")
 void insert(User user);
 @Update("UPDATE user SET name=#{userName},age=#{age} WHERE id =#{id}")
 void update(User user);
 @Delete("DELETE FROM user WHERE id =#{id}")
 void delete(int id);
}

四、配置扫描

上面配置了mapper,那怎么让系统知道mapper放在哪里呢?于是有了@MapperScan注解。

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.example.mapper")
public class DemoApplication {

 public static void main(String[] args) {
 SpringApplication.run(DemoApplication.class, args);
 }
}

五、创建Controller

这里创建了UserController,一个是显示所有用户,一个是新增一个用户之后再显示所有用户。

package com.example.demo;

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 org.springframework.web.bind.annotation.RequestMethod;

import com.example.mapper.UserMapper;
import com.example.model.User;
import com.example.model.UserSexEnum;

@Controller
@RequestMapping("/user")
public class UserController {
 
 @Autowired
 private UserMapper userMapper;
 
 @RequestMapping(value = "/alluser.do",method = RequestMethod.GET)
 public String getallusers(Model model) {
 List<User> users=userMapper.getAll();
 model.addAttribute("users", users);
 return "userlist";
 }
 @RequestMapping(value = "/insert.do",method = RequestMethod.GET)
 public String adduser(Model model) {
 User user=new User();
 user.setName("cuiyw");
 user.setAge(27);
 user.setSex(UserSexEnum.MAN);
  
 userMapper.insert(user);
 List<User> users=userMapper.getAll();
 model.addAttribute("users", users);
 return "userlist";
 }
}

六、数据库配置

上面mapper也设置了,model也设置了,那要与数据库交互，肯定要配置数据库地址这些信息吧。这里在运行的时候还报了一个错误.nested exception is java.sql.SQLException: The server time zone value 'Öйú±ê׼ʱ¼ä' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.在mysql中设置了下时区:set global time_zone='+8:00';

spring.mvc.view.prefix=/view/

spring.mvc.view.suffix=.jsp
mybatis.type-aliases-package=com.example.model

spring.datasource.driverClassName = com.mysql.cj.jdbc.Driver
spring.datasource.url = jdbc:mysql://localhost:3306/mybatis
spring.datasource.username = root
spring.datasource.password = 123456

七、创建页面显示

这里还是按照上一博客用jsp显示数据。

<%@ page language="java" contentType="text/html; charset=utf-8"
 pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
 <table>
 <tr><th>名字</th><th>年龄</th><th>性别</th></tr>
 <c:forEach items="${users}" var="item">
  <tr><td>${item.name}</td><td>${item.age}</td><td>${item.sex}</td></tr>
 </c:forEach>
 </table>
</body>
</html>

八、测试

这里先在浏览器打开http://localhost:8080/user/alluser.do，可以看到用户列表,然后输入http://localhost:8080/user/insert.do，就会看到列表显示多了一行数据。

九、小结

使用基于注解的集成mybatis比较省事方便，但有利有弊，对于多表相连的可能就不太方便，使用基于xml配置的可能就更会好些。

好了，以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作具有一定的参考学习价值，如果有疑问大家可以留言交流，谢谢大家对小牛知识库的支持。