SpringBoot构建电商基础秒杀项目总结

Posted 2021-05-26 hequnwang10

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一、定义通用的返回对象——返回正确信息

比如修改UserController.java代码

public UserVO getUser(@RequestParam(name = "id")Integer id){

        //调用service服务获取对应id的用户对象并返回给前端
        UserModel userModel = userService.getUserById(id);

        userModel = null;
        userModel.setEncrptPassword("123");

        //将核心领域模型用户对象转化为可供UI使用的viewobject
        return convertFromModel(userModel);

    }

重新运行，测试结果：
在这里插入图片描述
之前的程序一旦出错，只会返回一个白页，并没有错误信息，需要返回一个有意义的错误信息。

1、新建response包

创建CommonReturnType.java类
在这里插入图片描述

public class CommonReturnType {
    //表明对应请求的返回处理结果“success”或“fail”
    private String status;
    //若status=success，则data内返回前端需要的json数据
    //若status=fail，则data内使用通用的错误码格式
    private Object data;
    //定义一个通用的创建方法
    public static CommonReturnType create(Object result) {
        return CommonReturnType.create(result, "success");
    }
    public static CommonReturnType create(Object result,String status) {
        CommonReturnType type = new CommonReturnType();
        type.setStatus(status);
        type.setData(result);
        return type;
    }
    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public Object getData() {
        return data;
    }

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

2、修改UserController.java

UserController.java

@Controller("user")
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/get")
    @ResponseBody
    public CommonReturnType getUser(@RequestParam(name = "id")Integer id){
        //调用service服务获取对应id的用户对象并返回给前端
        UserModel userModel = userService.getUserById(id);
        UserVO userVO = convertFromModel(userModel);
        //将核心领域模型用户对象转化为可供UI使用的viewobject
        return CommonReturnType.create(userVO);

    }
    private UserVO convertFromModel(UserModel userModel){
        if (userModel==null){
            return null;
        }
        UserVO userVO = new UserVO();
        BeanUtils.copyProperties(userModel,userVO);
        return userVO;
    }
}

3、重新运行

重新运行项目，测试，输入
http://localhost:8090/user/get?id=1
在这里插入图片描述
返回数据正确!

二、定义通用的返回对象——返回错误信息

新建一个error包
在这里插入图片描述

1、创建commonError接口

public interface CommonError {
    public int getErrCode();
    public String getErrMsg();
    public CommonError setErrMsg(String errMs);
}

2、EmBusinessError枚举

public enum EmBusinessError implements CommonError{
    //通用错误类型00001
    PARAMETER_VALIDATION_ERROR(00001, "参数不合法"),
    //10000开头为用户信息相关错误定义
    USER_NOT_EXIST(10001, "用户不存在")
    ;
    private EmBusinessError(int errCode, String errMsg) {
        this.errCode = errCode;
        this.errMsg = errMsg;
    }
    private int errCode;
    private String errMsg;
    @Override
    public int getErrCode() {
        return this.errCode;
    }
    @Override
    public String getErrMsg() {
        return this.errMsg;
    }
    @Override
    public CommonError setErrMsg(String errMs) {
        this.errMsg = errMs;
        return this;
    }
}

3、BusinessException.java包装器模式

//包装器业务异常实现
public class BusinessException extends Exception implements CommonError{
    private CommonError commonError;
    //直接接受EmBusinessError的传参用于构造业务异常
    public BusinessException(CommonError commonError){
        super();//Exception自带一些机制
        this.commonError = commonError;
    }
    //接收自定义errMsg的方式构造业务异常
    public BusinessException(CommonError commonError, String errMsg) {
        super();
        this.commonError = commonError;
        this.commonError.setErrMsg(errMsg);
    }
    @Override
    public int getErrCode() {
        return this.commonError.getErrCode();
    }
    @Override
    public String getErrMsg() {
        return this.commonError.getErrMsg();
    }
    @Override
    public CommonError setErrMsg(String errMs) {
        this.commonError.setErrMsg(errMs);
        return this;
    }
}

4、UserController.java修改

@Controller("user")
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;
    @RequestMapping("/get")
    @ResponseBody
    public CommonReturnType getUser(@RequestParam(name = "id")Integer id) throws BusinessException {

        //调用service服务获取对应id的用户对象并返回给前端
        UserModel userModel = userService.getUserById(id);
        UserVO userVO = convertFromModel(userModel);
        //若获取的对应用户信息不存在
        if (userModel == null) {
            throw new BusinessException(EmBusinessError.USER_NOT_EXIST);
        }
        //将核心领域模型用户对象转化为可供UI使用的viewobject
        return CommonReturnType.create(userVO);

    }
    private UserVO convertFromModel(UserModel userModel){
        if (userModel==null){
            return null;
        }
        UserVO userVO = new UserVO();
        BeanUtils.copyProperties(userModel,userVO);
        return userVO;
    }
}

5、运行测试

http://localhost:8090/user/get?id=2
在这里插入图片描述

三、定义通用的返回对象——异常处理

1、定义exceptionHandler解决未被controller层吸收的exception

//定义exceptionHandler解决未被controller层吸收的exception
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.OK)
    @ResponseBody
    public Object handlerException(HttpServletRequest request,Exception ex){

        Map<String,Object> responseData = new HashMap<>();
        if (ex instanceof BusinessException){
            BusinessException businessException = (BusinessException)ex;

            responseData.put("errCode",businessException.getErrCode());
            responseData.put("errMsg",businessException.getErrMsg());

        }else {
            responseData.put("errCode",EmBusinessError.UNKNOWN_ERROR.getErrCode());
            responseData.put("errMsg",EmBusinessError.UNKNOWN_ERROR.getErrMsg());
        }
        return CommonReturnType.create(responseData,"fail");
        /*
        CommonReturnType commonReturnType = new CommonReturnType();
        commonReturnType.setStatus("fail");
        Map<String,Object> responseData = new HashMap<>();
        responseData.put("errCode",businessException.getErrCode());
        responseData.put("errMsg",businessException.getErrMsg());
        commonReturnType.setData(responseData);
        return commonReturnType;
        */
    }

2、UserController.java完整代码

@Controller("user")
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/get")
    @ResponseBody
    public CommonReturnType getUser(@RequestParam(name = "id")Integer id) throws BusinessException {

        //调用service服务获取对应id的用户对象并返回给前端
        UserModel userModel = userService.getUserById(id);
        UserVO userVO = convertFromModel(userModel);


        //若获取的对应用户信息不存在
        if (userModel == null) {
            userModel.setEncrptPassword("123");
//            throw new BusinessException(EmBusinessError.USER_NOT_EXIST);
        }

        //将核心领域模型用户对象转化为可供UI使用的viewobject
        return CommonReturnType.create(userVO);

    }
    private UserVO convertFromModel(UserModel userModel){
        if (userModel==null){
            return null;
        }
        UserVO userVO = new UserVO();
        BeanUtils.copyProperties(userModel,userVO);
        return userVO;
    }
    //定义exceptionHandler解决未被controller层吸收的exception
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.OK)
    @ResponseBody
    public Object handlerException(HttpServletRequest request,Exception ex){

        Map<String,Object> responseData = new HashMap<>();
        if (ex instanceof BusinessException){
            BusinessException businessException = (BusinessException)ex;

            responseData.put("errCode",businessException.getErrCode());
            responseData.put("errMsg",businessException.getErrMsg());

        }else {
            responseData.put("errCode",EmBusinessError.UNKNOWN_ERROR.getErrCode());
            responseData.put("errMsg",EmBusinessError.UNKNOWN_ERROR.getErrMsg());
        }
        return CommonReturnType.create(responseData,"fail");

        /*
        CommonReturnType commonReturnType = new CommonReturnType();
        commonReturnType.setStatus("fail");
        Map<String,Object> responseData = new HashMap<>();
        responseData.put("errCode",businessException.getErrCode());
        responseData.put("errMsg",businessException.getErrMsg());
        commonReturnType.setData(responseData);
        return commonReturnType;
        */
    }
}

3、运行测试

http://localhost:8090/user/get?id=2
在这里插入图片描述

4、代码优化

定义exceptionHandler解决未被controller层吸收的exception：
将handlerException的方法抽象出来，新建一个BaseController类，
在这里插入图片描述
BaseController.java

public class BaseController {
    //定义exceptionHandler解决未被controller层吸收的exception
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.OK)
    @ResponseBody
    public Object handlerException(HttpServletRequest request, Exception ex){

        Map<String,Object> responseData = new HashMap<>();
        if (ex instanceof BusinessException){
            BusinessException businessException = (BusinessException)ex;

            responseData.put("errCode",businessException.getErrCode());
            responseData.put("errMsg",businessException.getErrMsg());

        }else {
            responseData.put("errCode", EmBusinessError.UNKNOWN_ERROR.getErrCode());
          responseData.put("errMsg",EmBusinessError.UNKNOWN_ERROR.getErrMsg());
        }
        return CommonReturnType.create(responseData,"fail");
        /*
        CommonReturnType commonReturnType = new CommonReturnType();
        commonReturnType.setStatus("fail");
        Map<String,Object> responseData = new HashMap<>();
        responseData.put("errCode",businessException.getErrCode());
        responseData.put("errMsg",businessException.getErrMsg());
        commonReturnType.setData(responseData);
        return commonReturnType;
        */
    }
}

UserController.java修改

@Controller("user")
@RequestMapping("/user")
public class UserController extends BaseController{
    @Autowired
    private UserService userService;
    @RequestMapping("/get")
    @ResponseBody
    public CommonReturnType getUser(@RequestParam(name = "id")Integer id) throws BusinessException {
        //调用service服务获取对应id的用户对象并返回给前端
        UserModel userModel = userService.getUserById(id);
        UserVO userVO = convertFromModel(userModel);
        //若获取的对应用户信息不存在
        if (userModel == null) {
//            userModel.setEncrptPassword("123");

            throw new BusinessException(EmBusinessError.USER_NOT_EXIST);
        }
        //将核心领域模型用户对象转化为可供UI使用的viewobject
        return CommonReturnType.create(userVO);

    }

    private UserVO convertFromModel(UserModel userModel){
        if (userModel==null){
            return null;
        }
        UserVO userVO = new UserVO();
        BeanUtils.copyProperties(userModel,userVO);
        return userVO;
    }
}

运行测试

http://localhost:8090/user/get?id=2
在这里插入图片描述

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