Spring Boot学习——统一异常处理

       本随笔记录使用Spring Boot统一处理异常。

       本文实例是从数据库中根据ID查询学生信息，要求学生的年龄在14——20岁之间。小于14岁，提示“你可能在上初中”；大于20岁，提示“呢可能在上大学”。

       第一步，创建枚举类ResultEnum，用来管理异常信息

package *;//自己定义

public enum ResultEnum {
    UNKONW_ERROR(-1, "未知错误"),
    SUCCESS(0, "成功"),
    PRIMARY_SCHOOL(100, "年龄小于14岁，可能正在上中学"),
    UNIVERSITY(101, "年龄大于20岁，可能正在上大学");
    
    private Integer code;
    private String msg;

    ResultEnum( Integer code, String msg){
        this.code = code;
        this.msg = msg;
    }

    public Integer getCode(){
        return  this.code;
    }

    public String getMsg(){
        return this.msg;
    }
}

       第二步，创建自己的异常类StudentException，代码如下：

package *;//自己定义

import *.ResultEnum; //自己定义路径

public class StudentException extends RuntimeException {
    private Integer code;

    public StudentException(ResultEnum resultEnum){
        super(resultEnum.getMsg());
        this.code = resultEnum.getCode();
    }

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

    public Integer getCode() {
        return code;
    }
}

       第三步，创建返回报文实体类Result.java

package *;//自己定义

import *.Result; //自己定义的路径

/**
 * HTTP请求返回处理工具类
 */
public class ResultUtil {
    public static Result success(){
        return success(null);
    }
    public static Result success(Object object){
        Result result = new Result();
        result.setCode(0);
        result.setMsg("成功");
        result.setDate(object);
        return result;
    }

    public static Result error(Integer code, String msg){
        Result result = new Result();
        result.setCode(code);
        result.setMsg(msg);
        return result;
    }
}

　　第四步，创建请求返回工具类ResultUtil.java

package *;//自己定义

import *.Result;//自己定义的路径

/**
 * HTTP请求返回处理工具类
 */
public class ResultUtil {
    public static Result success(){
        return success(null);
    }
    public static Result success(Object object){
        Result result = new Result();
        result.setCode(0);
        result.setMsg("成功");
        result.setDate(object);
        return result;
    }

    public static Result error(Integer code, String msg){
        Result result = new Result();
        result.setCode(code);
        result.setMsg(msg);
        return result;
    }
}

       第五步，创建统一处理异常的类ExceptionHandle.java，代码如下：

package *; //自己定义

import *.StudentException; //自己定义路径
import *.Result; //自己定义路径
import *.ResultUtil; //自己定义路径
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

@ControllerAdvice
public class ExceptionHandle {
    private final static Logger logger = LoggerFactory.getLogger(ExceptionHandle.class);

    @ExceptionHandler(value = Exception.class)
    @ResponseBody
    public Result handler( Exception e){
        if( e instanceof StudentException){
            StudentException studentException = (StudentException) e;
            return ResultUtil.error( studentException.getCode(), studentException.getMessage());
        }else {
            logger.info("[系统异常] {}",e);
            return ResultUtil.error( -1, "未知错误");
        }
    }
}

       第六步，在service中编写业务逻辑代码：

package *; //自己定义

import *.ResultEnum; //自己定义的路径
import *.StudentException; //自己定义的路径
import *.StudentRepository; //自己定义的路径
import *.Student; //自己定义的路径
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.transaction.Transactional;

@Service
public class StudentService {
    @Autowired
    private StudentRepository studentRepository;

    /**
     * 根据ID查询符合条件的学生
     * @param id
     * @throws Exception
     */
    public Student getStudentById( Integer id) throws Exception{
        Student student = studentRepository.findOne(id);
        Integer age = student.getAge();
        if(age < 14){
            throw new StudentException(ResultEnum.PRIMARY_SCHOOL);
        }else if(age > 20){
            throw new StudentException(ResultEnum.UNIVERSITY);
        }

        //进行下面逻辑操作
        return student;
    }
}

       第七步，在controller中调用service方法，代码如下：

package *; //自己定义路径

import *.Result; //自己定义路径
import *.StudentService; //自己定义路径
import *.ResultUtil; //自己定义路径
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.*;

import javax.validation.Valid;
import java.util.List;

@RestController
public class StudentController {
    @Autowired
    private StudentService studentService;

    /**
     * 根据ID查询学生
     */
    @GetMapping(value = "/student/getage/{id}")
    public Result getStudentById(@PathVariable("id") Integer id) throws Exception{
        return ResultUtil.success(studentService.getStudentById(id));
    }

}

       最后，使用postman访问http://127.0.0.1:8080/student/getage/1 ，查看结果。