Spring Boot学习01--使用mybatis查询

本文使用IDEA创建一个Spring Boot的项目，连接MySQL数据库，使用MyBatis实现数据库查询操作。

1建立Spring Boot项目

使用IDEA创建Spring Initializr项目，勾选常用的组件，通过Maven添加到项目中。

项目的POM文件如下：

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 3          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 4     <modelVersion>4.0.0</modelVersion>
 5     <parent>
 6         <groupId>org.springframework.boot</groupId>
 7         <artifactId>spring-boot-starter-parent</artifactId>
 8         <version>2.2.1.RELEASE</version>
 9         <relativePath/> <!-- lookup parent from repository -->
10     </parent>
11     <groupId>com.example</groupId>
12     <artifactId>demo</artifactId>
13     <version>0.0.1-SNAPSHOT</version>
14     <name>demo</name>
15     <description>Demo project for Spring Boot</description>
16 
17     <properties>
18         <java.version>1.8</java.version>
19     </properties>
20 
21     <dependencies>
22         <dependency>
23             <groupId>org.springframework.boot</groupId>
24             <artifactId>spring-boot-starter-amqp</artifactId>
25         </dependency>
26         <dependency>
27             <groupId>org.springframework.boot</groupId>
28             <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
29         </dependency>
30         <dependency>
31             <groupId>org.springframework.boot</groupId>
32             <artifactId>spring-boot-starter-data-jdbc</artifactId>
33         </dependency>
34         <dependency>
35             <groupId>org.springframework.boot</groupId>
36             <artifactId>spring-boot-starter-data-mongodb</artifactId>
37         </dependency>
38         <dependency>
39             <groupId>org.springframework.boot</groupId>
40             <artifactId>spring-boot-starter-data-redis</artifactId>
41         </dependency>
42         <dependency>
43             <groupId>org.springframework.boot</groupId>
44             <artifactId>spring-boot-starter-thymeleaf</artifactId>
45         </dependency>
46         <dependency>
47             <groupId>org.springframework.boot</groupId>
48             <artifactId>spring-boot-starter-web</artifactId>
49         </dependency>
50         <dependency>
51             <groupId>org.mybatis.spring.boot</groupId>
52             <artifactId>mybatis-spring-boot-starter</artifactId>
53             <version>2.1.1</version>
54         </dependency>
55 
56         <dependency>
57             <groupId>mysql</groupId>
58             <artifactId>mysql-connector-java</artifactId>
59             <scope>runtime</scope>
60         </dependency>
61         <dependency>
62             <groupId>org.springframework.boot</groupId>
63             <artifactId>spring-boot-starter-test</artifactId>
64             <scope>test</scope>
65             <exclusions>
66                 <exclusion>
67                     <groupId>org.junit.vintage</groupId>
68                     <artifactId>junit-vintage-engine</artifactId>
69                 </exclusion>
70             </exclusions>
71         </dependency>
72         <dependency>
73             <groupId>org.springframework.amqp</groupId>
74             <artifactId>spring-rabbit-test</artifactId>
75             <scope>test</scope>
76         </dependency>
77         <dependency>
78             <groupId>org.webjars</groupId>
79             <artifactId>jquery</artifactId>
80             <version>3.4.1</version>
81         </dependency>
82     </dependencies>
83 
84     <build>
85         <plugins>
86             <plugin>
87                 <groupId>org.springframework.boot</groupId>
88                 <artifactId>spring-boot-maven-plugin</artifactId>
89             </plugin>
90         </plugins>
91     </build>
92 
93 </project>

2添加Modle层文件，com.example.demo.model.Users：

 1 package com.example.demo.model;
 2 
 3 public class Users {
 4     public Integer id;
 5     public String last_name;
 6     public Integer gender;
 7     public String email;
 8 
 9     public Users() {
10     }
11 
12     public Users(Integer id, String last_name, Integer gender, String email) {
13         this.id = id;
14         this.last_name = last_name;
15         this.gender = gender;
16         this.email = email;
17     }
18 
19     public Integer getId() {
20         return id;
21     }
22 
23     public void setId(Integer id) {
24         this.id = id;
25     }
26 
27     public String getLast_name() {
28         return last_name;
29     }
30 
31     public void setLast_name(String last_name) {
32         this.last_name = last_name;
33     }
34 
35     public Integer getgender() {
36         return gender;
37     }
38 
39     public void setgender(Integer gender) {
40         this.gender = gender;
41     }
42 
43     public String getemail() {
44         return email;
45     }
46 
47     public void setemail(String eamil) {
48         this.email = eamil;
49     }
50 
51     @Override
52     public String toString() {
53         return "Users{" +
54                 "Id=" + id +
55                 ", LastName='" + last_name + '\'' +
56                 ", Gender=" + gender +
57                 ", Eamil='" + email + '\'' +
58                 '}';
59     }
60 }

3数据库中创建表，tbl_employee：

 1 SET NAMES utf8;
 2 SET FOREIGN_KEY_CHECKS = 0;
 3 
 4 -- ----------------------------
 5 --  Table structure for `tbl_employee`
 6 -- ----------------------------
 7 DROP TABLE IF EXISTS `tbl_employee`;
 8 CREATE TABLE `tbl_employee` (
 9   `id` int(11) NOT NULL AUTO_INCREMENT,
10   `last_name` varchar(255) DEFAULT NULL,
11   `gender` char(1) DEFAULT NULL,
12   `email` varchar(255) DEFAULT NULL,
13   PRIMARY KEY (`id`)
14 ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=latin1;
15 
16 -- ----------------------------
17 --  Records of `tbl_employee`
18 -- ----------------------------
19 BEGIN;
20 INSERT INTO `tbl_employee` VALUES ('1', 'yang', '1', 'francs1@sina.com');
21 COMMIT;
22 
23 SET FOREIGN_KEY_CHECKS = 1;

3配置MyBatis

3.1配置文件application.properties

1 spring.datasource.driverClassName = com.mysql.cj.jdbc.Driver
2 spring.datasource.url = jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8
3 spring.datasource.username = root
4 spring.datasource.password = root
5 
6 
7 spring.data.mongodb.uri=mongodb://localhost:27017/blog
8 mybatis.config-location=classpath:mybatis-config.xml
9 mybatis.mapper-locations=classpath:UserMapper.xml

3.2Mybatis全局配置文件，mybatis-config.xml：

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
 3 <configuration>
 4 </configuration>

3.3Mybatis映射文件，UserMapper.xml：

1 <?xml version="1.0" encoding="UTF-8"?>
2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
3 <!--        namespace 所对应的是一个接口的全限定名-->
4 <mapper namespace="com.example.demo.mapper.IUserMapper">
5     <select id="getUserById" resultType="com.example.demo.model.Users">
6         SELECT id,last_name,gender,email FROM tbl_employee WHERE id = #{id}
7     </select>
8 </mapper>

3.4Mybatis接口文件，com.example.demo.mapper.IUserMapper：

1 package com.example.demo.mapper;
2 
3 import com.example.demo.model.Users;
4 import org.springframework.stereotype.Component;
5 
6 @Mapper
7 public interface IUserMapper {
8     public Users getUserById(Integer id);
9 }

4添加Service层文件，调用Mybatis实现数据库操作：

 1 @Service
 2 public class Users {
 3 
 4     @Autowired
 5     IUserMapper userMapper;
 6 
 7     public com.example.demo.model.Users getUserById(Integer id) throws IOException {
 8         return userMapper.getUserById(id);
 9     }
10 }

5添加Controller文件：

 1 package com.example.demo.controller;
 2 
 3 import org.springframework.beans.factory.annotation.Autowired;
 4 import org.springframework.web.bind.annotation.PathVariable;
 5 import org.springframework.web.bind.annotation.RequestMapping;
 6 import org.springframework.web.bind.annotation.RestController;
 7 
 8 import java.io.IOException;
 9 
10 @RestController
11 public class UserController {
12 
13     @Autowired
14     com.example.demo.service.Users userService;
15 
16     @RequestMapping("/user/{id}")
17     public String getUserById(@PathVariable Integer id) throws IOException {
18 
19         com.example.demo.model.Users users = userService.getUserById(id);
20         return users.getLastName();
21     }
22 }

6测试：

启动文件

 1 package com.example.demo;
 2 
 3 
 4 import org.springframework.boot.SpringApplication;
 5 import org.springframework.boot.autoconfigure.SpringBootApplication;
 6 
 7 import java.io.IOException;
 8 import java.io.InputStream;
 9 
10 @SpringBootApplication
11 public class DemoApplication {
12 
13     public static <StudentMapper> void main(String[] args){
14 
15         SpringApplication.run(DemoApplication.class, args);
16     }
17 
18 }

Spring Boot运行在本机8080端口，通过地址：[http://localhost:8080/user/1]，完成查询操作。

posted on 2020-09-13 20:45 Sempron2800+ 阅读(261) 评论(0) 编辑收藏举报