spring boot+mybatis搭建一个后端restfull服务的实例详解

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>
 
 <groupId>com.best</groupId>
 <artifactId>spring-boot-mybatis</artifactId>
 <version>1.0-SNAPSHOT</version>
 
 <properties>
  <java.version>1.8</java.version>
  <fastjson.version>1.2.74</fastjson.version>
  <spring.version>5.3.5.RELEASE</spring.version>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
 </properties>
 <parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>2.3.5.RELEASE</version>
 </parent>
 <dependencies>
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-test</artifactId>
   <scope>test</scope>
  </dependency>
  <dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-jdbc</artifactId>
   <exclusions>
    <!-- 排除 tomcat-jdbc 以使用 HikariCP -->
    <exclusion>
     <groupId>org.apache.tomcat</groupId>
     <artifactId>tomcat-jdbc</artifactId>
    </exclusion>
   </exclusions>
  </dependency>
  <!--  <dependency>-->
  <!--   <groupId>org.springframework.boot</groupId>-->
  <!--   <artifactId>spring-boot-starter-security</artifactId>-->
  <!--  </dependency>-->
  <dependency>
   <groupId>org.mybatis.spring.boot</groupId>
   <artifactId>mybatis-spring-boot-starter</artifactId>
   <version>2.1.3</version>
  </dependency>
  <dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>8.0.22</version>
  </dependency>
  <dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>druid</artifactId>
   <version>1.2.1</version>
  </dependency>
  <dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>fastjson</artifactId>
   <version>${fastjson.version}</version>
  </dependency>
  <dependency>
   <groupId>org.projectlombok</groupId>
   <artifactId>lombok</artifactId>
   <version>1.18.10</version>
  </dependency>
  <dependency>
   <groupId>org.mybatis.spring.boot</groupId>
   <artifactId>mybatis-spring-boot-starter</artifactId>
   <version>2.1.3</version>
  </dependency>
 </dependencies>
 <build>
  <plugins>
   <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.0</version>
    <configuration>
     <source>1.8</source>
     <target>1.8</target>
    </configuration>
   </plugin>
  </plugins>
 </build>
</project>

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(255) COLLATE utf8_bin DEFAULT NULL,
 `create_date` datetime DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
 
-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', 'user1', '2020-11-10 21:01:54');
INSERT INTO `user` VALUES ('2', 'user2', '2020-11-01 21:02:12');

spring:
 datasource:
 type: com.alibaba.druid.pool.DruidDataSource
 driver-class-name: com.mysql.cj.jdbc.Driver
 platform: mysql
 url: jdbc:mysql://localhost:3306/springboottest?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=CTT
 username: root
 password:
server:
 port: 8080

package com.best.db;
 
import com.alibaba.druid.pool.DruidDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
 
import javax.sql.DataSource;
 
/**
 * @author:sunxj
 * @date:2020-11-10 21:08:53
 * @description: 数据连接池
 */
@Configuration
public class DruidDBConfig {
 @Value("${spring.datasource.url}")
 private String url;
 @Value("${spring.datasource.username}")
 private String username;
 @Value("${spring.datasource.password}")
 private String password;
 @Value("${spring.datasource.driver-class-name}")
 private String driverClassName;
 @Bean//DataSource 对象为 Spring 容器所管理;
 @Primary//表示这里定义的DataSource将覆盖其他来源的DataSource。
 public DataSource dataSource(){
  DruidDataSource datasource = new DruidDataSource();
  datasource.setUrl(this.url);
  datasource.setUsername(username);
  datasource.setPassword(password);
  datasource.setDriverClassName(driverClassName);
  return datasource;
 }
 //配置数据库事务
 @Bean(name = "transactionManager")
 public DataSourceTransactionManager dbOneTransactionManager(
   @Qualifier("dataSource") DataSource dataSource) {
  return new DataSourceTransactionManager(dataSource);
 }
 //配置数据库工厂
 @Bean(name = "sqlSessionFactory")
 @ConditionalOnMissingBean(name = "sqlSessionFactory")
 public SqlSessionFactory dbOneSqlSessionFactory(@Qualifier("dataSource") DataSource dataSource) throws Exception {
  final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
  sessionFactory.setDataSource(dataSource);
  return sessionFactory.getObject();
 }
}

package com.best.entity;
 
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.util.Date;
 
/**
 * @author:sunxj
 * @date:2020-11-10 21:12:58
 * @description:用户实体类
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
 private Integer id;
 private String name;
 private Date createDate;
}

package com.best.dao;
 
import com.best.entity.User;
import org.springframework.stereotype.Repository;
 
import java.util.List;
/**
 * @author:sunxj
 * @date:2020-11-10 21:17:27
 * @description:用户表的映射接口文件
 */
@Repository
public interface UserMapper {
 List<User> selectAll();
 User selectById(Integer id);
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.best.dao.UserMapper">
 <resultMap type="com.best.entity.User" id="UserMap">
  <result property="id" column="id" jdbcType="INTEGER"></result>
  <result property="name" column="name" jdbcType="VARCHAR"></result>
  <result property="createDate" column="create_date" jdbcType="TIMESTAMP"></result>
 </resultMap>
 <select id="selectAll" resultMap="UserMap">
  SELECT * FROM user
 </select>
 <select id="selectById" resultMap="UserMap">
  SELECT * FROM user WHERE id=#{id}
 </select>
</mapper>

spring:
 datasource:
 type: com.alibaba.druid.pool.DruidDataSource
 driver-class-name: com.mysql.cj.jdbc.Driver
 platform: mysql
 url: jdbc:mysql://localhost:3306/springboottest?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=CTT
 username: root
 password:
mybatis:
 #如果有多个目录则可以写多个，比如com/best/dao/*.xml，com/best/*/dao/*.xml,com/best/*/sss/*/dao/*.xml
 mapper-locations: classpath:com/best/dao/*.xml
 #配置包，这里同样可以配置多个，
 type-aliases-package: com.best.dao
server:
 port: 8080

package com.best.service;
 
import com.best.entity.User;
import java.util.List;
/**
 * @author:sunxj
 * @date:2020-11-10 21:33:23
 * @description:用户接口表
 */
public interface IUserService {
 List<User> selectAll();
 User selectById(Integer id);
}

package com.best.service.impl;
 
import com.best.dao.UserMapper;
import com.best.entity.User;
import com.best.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import java.util.List;
 
/**
 * @author:sunxj
 * @date:2020-11-10 21:34:34
 * @description:用户接口实现类
 */
@Service("userService")
public class UserServiceImpl implements IUserService {
 @Autowired
 private UserMapper userMapper;
 @Override
 public List<User> selectAll() {
  return userMapper.selectAll();
 }
 
 @Override
 public User selectById(Integer id) {
  return userMapper.selectById(id);
 }
}

package com.best.controller;
 
import com.alibaba.fastjson.JSONObject;
import com.best.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
/**
 * @author:sunxj
 * @date:2020-11-10 21:38:09
 * @description:
 */
@RestController//使用此注解，那么该类下的所有返回都是以json方式返回
@RequestMapping(value="best")//加上value后，在url访问时必须加上/best才行
public class UserController {
 @Autowired
 private IUserService userService;
 @RequestMapping("/getUser")
 public JSONObject getUser(HttpServletRequest request, HttpServletResponse response) {
  JSONObject obj = new JSONObject();
  obj.put("user","1111");
  return obj;
 }
}

package com.best;
 
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
 
/**
 * @author:sunxj
 * @date:2020-11-10 21:46:43
 * @description:
 */
@SpringBootApplication
public class Application {
 public static void main(String[] args) {
  SpringApplication.run(Application.class,args);
 }
}

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-11-10 21:48:21.635 ERROR 10320 --- [   main] o.s.b.d.LoggingFailureAnalysisReporter : 
 
***************************
APPLICATION FAILED TO START
***************************
 
Description:
 
Field userMapper in com.best.service.impl.UserServiceImpl required a bean of type 'com.best.dao.UserMapper' that could not be found.
 
The injection point has the following annotations:
	- @org.springframework.beans.factory.annotation.Autowired(required=true)
 
 
Action:
 
Consider defining a bean of type 'com.best.dao.UserMapper' in your configuration.

package com.best;
 
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
 
/**
 * @author:sunxj
 * @date:2020-11-10 21:46:43
 * @description:
 */
@SpringBootApplication
@MapperScan({"com.best.dao"})//如果有多个可以使用{"com.best.dao","com.best.sss.dao"}
public class Application {
 public static void main(String[] args) {
  SpringApplication.run(Application.class,args);
 }
}

package com.best.common.enums;
 
/**
 * @author:sunxj
 * @date:2020-11-10 22:08:11
 * @description:返回码定义
 */
public enum ResultCode {
 //成功
 SUCCESS(200,"成功"),
 //默认失败
 COMMON_FAIL(404,"失败"),
 ;
 private Integer code;
 private String message;
 
 ResultCode(Integer code, String message) {
  this.code = code;
  this.message = message;
 }
 
 public Integer getCode() {
  return code;
 }
 
 public void setCode(Integer code) {
  this.code = code;
 }
 
 public String getMessage() {
  return message;
 }
 
 public void setMessage(String message) {
  this.message = message;
 }
 
 public static String getMessageByCode(Integer code) {
  for (ResultCode ele : values()) { //values会默认取出enum中的值对象列表，每个值都是一个ResultCode对象
   if (ele.getCode().equals(code)) {
    return ele.getMessage();
   }
  }
  return null;
 }
}

package com.best.common.entity;
 
import com.best.common.enums.ResultCode;
 
import java.io.Serializable;
 
/**
 * @author:sunxj
 * @date:2020-11-10 22:06:50
 * @description:统一返回的实体类
 */
public class JsonResult<T> implements Serializable {
 private Boolean success;
 private Integer errorCode;
 private String errorMsg;
 private T data;
 
 public JsonResult() {
 }
 
 public JsonResult(Boolean success) {
  this.success = success;
  this.errorCode = success ? ResultCode.SUCCESS.getCode():ResultCode.COMMON_FAIL.getCode();
  this.errorMsg = success ? ResultCode.SUCCESS.getMessage():ResultCode.COMMON_FAIL.getMessage();
 }
 public JsonResult(Boolean success,ResultCode resultCode) {
  this.success = success;
  this.errorCode = success ? ResultCode.SUCCESS.getCode():(resultCode == null ? ResultCode.COMMON_FAIL.getCode():resultCode.getCode());
  this.errorMsg = success ? ResultCode.SUCCESS.getMessage():(resultCode == null ? ResultCode.COMMON_FAIL.getMessage():resultCode.getMessage());
 }
 public JsonResult(Boolean success,T data) {
  this.success = success;
  this.errorCode = success ? ResultCode.SUCCESS.getCode():ResultCode.COMMON_FAIL.getCode();
  this.errorMsg = success ? ResultCode.SUCCESS.getMessage() : ResultCode.COMMON_FAIL.getMessage();
  this.data = data;
 }
 public JsonResult(Boolean success,ResultCode resultCode,T data) {
  this.success = success;
  this.errorCode = success ? ResultCode.SUCCESS.getCode():(resultCode == null ? ResultCode.COMMON_FAIL.getCode():resultCode.getCode());
  this.errorMsg = success ? ResultCode.SUCCESS.getMessage():(resultCode == null ? ResultCode.COMMON_FAIL.getMessage():resultCode.getMessage());
  this.data = data;
 }
 
 public Boolean getSuccess() {
  return success;
 }
 
 public void setSuccess(Boolean success) {
  this.success = success;
 }
 
 public Integer getErrorCode() {
  return errorCode;
 }
 
 public void setErrorCode(Integer errorCode) {
  this.errorCode = errorCode;
 }
 
 public String getErrorMsg() {
  return errorMsg;
 }
 
 public void setErrorMsg(String errorMsg) {
  this.errorMsg = errorMsg;
 }
 
 public T getData() {
  return data;
 }
 
 public void setData(T data) {
  this.data = data;
 }
}

package com.best.common.utils;
 
import com.best.common.entity.JsonResult;
import com.best.common.enums.ResultCode;
 
/**
 * @author:sunxj
 * @date:2020-11-10 22:11:03
 * @description:json返回构造工具
 */
public class ResultTool {
 public static JsonResult success() {
  return new JsonResult(true);
 }
 public static <T> JsonResult<T> success(T data) {
  return new JsonResult<>(true,data);
 }
 public static JsonResult fail() {
  return new JsonResult(false);
 }
 public static JsonResult fail(ResultCode resultCode) {
  return new JsonResult(false,resultCode);
 }
}

package com.best.controller;
 
import com.best.common.entity.JsonResult;
import com.best.common.utils.ResultTool;
import com.best.entity.User;
import com.best.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.List;
 
/**
 * @author:sunxj
 * @date:2020-11-10 21:38:09
 * @description:
 */
@RestController//使用此注解，那么该类下的所有返回都是以json方式返回
@RequestMapping(value="best")//加上value后，在url访问时必须加上/best才行
public class UserController {
 @Autowired
 private IUserService userService;
 @RequestMapping("/getUser")
 public JsonResult getUser(HttpServletRequest request, HttpServletResponse response) {
  List<User> users = userService.selectAll();
  return ResultTool.success(users);
 }
}

package com.best.controller;
 
import com.best.common.entity.JsonResult;
import com.best.common.utils.ResultTool;
import com.best.entity.User;
import com.best.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.List;
 
/**
 * @author:sunxj
 * @date:2020-11-10 21:38:09
 * @description:
 */
@RestController//使用此注解，那么该类下的所有返回都是以json方式返回
@RequestMapping(value="best")//加上value后，在url访问时必须加上/best才行
public class UserController {
 @Autowired
 private IUserService userService;
 @RequestMapping("/getUser")
 public JsonResult getUser(HttpServletRequest request, HttpServletResponse response) {
  List<User> users = userService.selectAll();
  return ResultTool.success(users);
 }
}