定义通过错误接口类：CommonError

public interface CommonError {

    // 获取错误码
    int getErrorCode();

    // 获取错误消息
    String getErrorMsg();

    // 设置错误消息，用于覆盖Enumeration中设置的默认错误消息
    CommonError setErrorMsg(String errorMsg);
}

定义错误枚举类：EnumError

/**
 * 继承至CommonError
 */
public enum EnumError implements CommonError {

    // 10000开头为通用错误类型
    UNKNOWN_ERROR(10001, "未知错误"),
    PARAMETER_VALIDATION_ERROR(10002, "参数不合法"),

    // 20000开头为用户信息相关错误码定义
    USER_NOT_EXIST(20001, "用户不存在"),
    USER_LOGIN_FAIL(20003, "用户名或密码错误"),
    USER_NOT_LOGIN(20004, "用户未登录"),

    // 30000开头为商品相关错误码定义
    STOCK_NOT_ENOUGH(30001, "库存不足"),
    ;

    // 定义错误码和错误消息字段
    private int errorCode;
    private String errorMsg;

    EnumError(int errorCode, String errorMsg) {
        this.errorCode = errorCode;
        this.errorMsg = errorMsg;
    }

    @Override
    public int getErrorCode() {
        return errorCode;
    }

    @Override
    public String getErrorMsg() {
        return errorMsg;
    }

    // 主要的作用：可以修改错误码对应的errorMessage
    @Override
    public CommonError setErrorMsg(String errorMsg) {
        this.errorMsg = errorMsg;
        return this;
    }
}

定义业务异常类：BusinessException

/**
 * 包装器业务异常类实现模式
 */
public class BusinessException extends Exception implements CommonError {

    private CommonError commonError;

    // 通用构造器
    public BusinessException(CommonError commonError){
        super();
        this.commonError = commonError;
    }

    // 覆盖ErrorMessage的构造器
    public BusinessException(CommonError commonError, String errorMsg){
        super();
        this.commonError = commonError;
        this.commonError.setErrorMsg(errorMsg);
    }

    @Override
    public int getErrorCode() {
        return this.commonError.getErrorCode();
    }

    @Override
    public String getErrorMsg() {
        return this.commonError.getErrorMsg();
    }

    // 覆盖默认的errorMessage
    @Override
    public CommonError setErrorMsg(String errorMsg) {
        this.commonError.setErrorMsg(errorMsg);
        return this;
    }
}