[Java知识库]java 接口开发【包括响应状态】

工具：idea，maven，mysql5.7

第一步：创建数据库，创建表，添加数据

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `userName` varchar(32) NOT NULL,
  `passWord` varchar(50) NOT NULL,
  `realName` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

第二步：创建SpringBoot项目

一：pom.xml中导入Mybatis，mysql，lombok依赖

        <!--mybatis依赖-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.0</version>
        </dependency>

        <!--msql依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

        <!--lombok依赖-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <!--可能会出现xml配置文件无法生成，建议添加此配置-->
        <build>
            <resources>
                <resource>
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.xml</include>
                    </includes>
                </resource>
            </resources>
        </build>

二：配置application.yml【修改数据库名】

server:
  port: 8080

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springboot?characterEncoding=utf-8&useSSL=true
    username: root
    password: 123456


mybatis:
  mapper-locations: classpath:mapper/*.xml

第三步：编写代码

一：创建实体类

@Data //Set,Get
@AllArgsConstructor //有参构造
@NoArgsConstructor //无参构造
@ToString //toString方法
public class User {

    private int id;
    private String UserName;
    private String passWord;
    private String realName;

}

二：创建mapper接口

@Mapper
public interface UserMapper {

    List<User> queryUserAll(User user); 


}

三：创建service接口

public interface UserService {

    List<User> queryUserAll(User user);

}

四：创建serviceImpl实现类

@Service
public class UserServiceImpl implements UserService {

    @Resource
    UserMapper userMapper;

    @Override
    public List<User> queryUserAll(User user) {
        return userMapper.queryUserAll(user);
    }

}

五：在resources下创建mapper.xml

<?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.example.demohello.dao.UserMapper">

    <select id="queryUserAll" resultType="com.example.demohello.pojo.User"             
     parameterType="com.example.demohello.pojo.User">

        select * from user
        <where>
            <if test="id!=null and id!=''">
                id=#{id}
            </if>
            <if test="UserName!=null and UserName!=''">
                and UserName=#{UserName}
            </if>
        </where>
    </select>

</mapper>

六：创建utils工具类，编写返回状态码

1、

//枚举类
public enum ResultCode {
    SUCCESS(200,"成功"),
    FAILED(201,"无数据返回"),
    VALIDATE_FAILED(202,"参数验证失败"),
    ERROR(500,"未知错误");


    private int code;
    private String msg;

    ResultCode(int code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

2、

public class BaseResponse {

    private Integer code;
    private String msg;

    public BaseResponse() {
    }

    public BaseResponse(ResultCode code) {
        this.code = code.getCode();
        this.msg = code.getMsg();
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

3、

public class ResponseData<T> extends BaseResponse{

    private T data; 

    public ResponseData(ResultCode code) {
        super(code);
    }

    public ResponseData(ResultCode code, T data) {
        super(code);
        this.data = data;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }

    public static <T> ResponseData<T> out(ResultCode code,T data){
        return new ResponseData<>(code,data);
    }

}

七：创建controller类

@Controller
public class UserController {

    @Autowired
    UserServiceImpl userService;

    @ResponseBody
    @GetMapping("/getListUserALL")
    public ResponseData<List<User>> getListUserAll(User user){
        List<User> users = userService.queryUserAll(user);
        for (int i = 0; i < users.size(); i++) {
            if(null != users.get(i)){
                return ResponseData.out(ResultCode.SUCCESS,users);
            }
        }
        return ResponseData.out(ResultCode.FAILED,users);

    }

}

八：启动项目，浏览器访问

http://localhost:8080/getListUserALL

?九：用postman请求

?结束！