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SpringMVC的项目架构思想

SpringMVC的项目架构思想

一、DO和Model的区别

DO是对数据库表的映射。Model是处理业务逻辑的模型（领域模型）。例如：用户信息表和用户密码表分别是两个DO，但是对于实体用户来说，密码表的字段也属于用户，所以需要在Service层使用Model来处理业务逻辑，Model包含了两张表的字段的并集。在Mapper层使用DO，在Service层使用Model。

public class UserDO {
    private Integer id;
    private String name;
    private Boolean gender;
    private Integer age;
    private String telphone;
    private String registerType;
    private String thirdPartyId;
    //getter、setter
public class UserPasswordDO {
    private Integer id;
    private String encrptPassword;
    private Integer userId;
    //getter、setter

二、VO和Model的区别

VO（View Object视图对象）,用于前端展示。Model中包含了用户的密码数据，不应该通过Controller层返回给前端，这是不安全的操作。在Controller层通过VO返回部分可以展示到前端的数据即可。

public class UserModel {
    private Integer id;
    private String name;
    private Boolean gender;
    private Integer age;
    private String telphone;
    private String registerMode;
    private String thirdPartyId;
    private String encrptPassword;
    //getter、setter
public class UserVO {
    private Integer id;
    private String name;
    private Boolean gender;
    private Integer age;
    private String telphone;
    //getter、setter

三、层次结构

  1. dao层：定义XXXMapper接口、对应的XXXMapper.xml在resource目录下的mapper文件夹里，使用数据模型DO（Data Object）

  2. service层：定义XXXService接口、实现类XXXServiceImpl、领域模型Model

    @Service
public class UserServiceImpl implements UserService {
​
    @Autowired
    private UserDOMapper userDOMapper;
    @Autowired
    private UserPasswordDOMapper userPasswordDOMapper;
​
    @Override
    public UserModel getUserById(Integer id) {
        UserDO userDO = userDOMapper.selectByPrimaryKey(id);
        if (userDO == null) {
            return null;
        }
        UserPasswordDO userPasswordDO = userPasswordDOMapper.selectByUid(userDO.getId());
        return covertFromDataObject(userDO, userPasswordDO);
    }
​
    private UserModel covertFromDataObject(UserDO userDO, UserPasswordDO userPasswordDO) {
        if (userDO == null) {
            return null;
        }
        UserModel userModel = new UserModel();
        BeanUtils.copyProperties(userDO, userModel);
        if (userPasswordDO != null) {
            userModel.setEncrptPassword(userPasswordDO.getEncrptPassword());
        }
        return userModel;
    }
}

  3. controller层：定义XXXController类、视图模型VO（View Object）

    @RestController("user")
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;
​
    @RequestMapping("/get")
    public UserVO getUser(@RequestParam(name = "id") Integer id){
        UserModel userModel = userService.getUserById(id);
        //将核心的领域模型对象转化为可供UI使用的VO
        return convertFromModel(userModel);
    }
​
    private UserVO convertFromModel(UserModel userModel){
        if(userModel == null){
            return null;
        }
        UserVO userVO = new UserVO();
        BeanUtils.copyProperties(userModel, userVO);
        return userVO;
    }
}

四、归一化Controller层的响应信息

  1. 定义一个公共的返回值类型

    public class CommonReturnType {
    //处理结果 success/fail
    //fail 返回通用的错误码格式
    //success 返回数据
    private String status;
    private Object data;
​
    public static CommonReturnType create(Object result, String status) {
        CommonReturnType returnType = new CommonReturnType();
        returnType.setStatus(status);
        returnType.setData(result);
        return returnType;
    }
​
    public static CommonReturnType create(Object result) {
        return CommonReturnType.create(result, "success");
    }
​
    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. 在Controller层返回CommonResultType

    @RequestMapping("/get")
public CommonReturnType getUser(@RequestParam(name = "id") Integer id){
    UserModel userModel = userService.getUserById(id);
    //将核心的领域模型对象转化为可供UI使用的VO
    UserVO userVO =  convertFromModel(userModel);
    //返回通用对象
    return CommonReturnType.create(userVO);
}

  3. 前端得到的返回正确的结果

    {
    "status":"success",
    "data":{
        "id":1,
        "name":"张三",
        "gender":false,
        "age":12,
        "telphone":"123456"
    }
}

  4. 异常结果的处理（见下一Part）

五、 包装器业务异常类的实现

  1. 定义一个公共错误接口/error

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

  2. 定义一个枚举错误类/error

    public enum EmBusinessError implements CommonError {
    //通用错误类型 00001
    PARAMETER_VALIDATION_ERROR(00001,"参数不合法"),
    //用户信息相关 1000X
    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 errMsg) {
        this.errMsg = errMsg;
        return this;
    }
}

  3. 定义异常包装类/exception

    //包装器业务异常类的实现
public class BusinessException extends Exception implements CommonError {
    private CommonError commonError;
​
    //直接接收EmBusinessError的传参用于构造业务异常
    public BusinessException(CommonError commonError){
        super();
        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 errMsg) {
        this.commonError.setErrMsg(errMsg);
        return this;
    }
}

  4. 在Controller层抛出异常

    @RequestMapping("/get")
public CommonReturnType getUser(@RequestParam(name = "id") Integer id) throws BusinessException {
    UserModel userModel = userService.getUserById(id);
    if(userModel == null){
        throw new BusinessException(EmBusinessError.USER_NOT_EXIST);
    }
    //将核心的领域模型对象转化为可供UI使用的VO
    UserVO userVO =  convertFromModel(userModel);
    //返回通用对象
    return CommonReturnType.create(userVO);
}

六、异常的处理

  1. 定义exceptionHandler解决未被Controller层吸收的exception

    @ExceptionHandler(Exception.class)
@ResponseStatus(HttpStatus.OK)
public Object handlerException(HttpServletRequest request, Exception ex){
    BusinessException businessException = (BusinessException) ex;
    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. 前端得到的JSON数据

    {"status":"fail",
 "data":{
     "errCode":10001,
     "errMsg":"用户不存在"
 }
}

  3. 优化异常处理，定义BaseController，其余Controller继承基类。

    @RestController
public class BaseController {
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.OK)
    public Object handlerException(HttpServletRequest request, Exception ex){
        Map<String, Object> responseData = new HashMap<>();
        if(ex instanceof BusinessException){
            BusinessException businessException = (BusinessException) ex;
            CommonReturnType commonReturnType = new CommonReturnType();
            commonReturnType.setStatus("fail");
            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");
    }
}
07-03 17:09
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