将服务器响应封装为一个泛型类

/**
 * 
 * 返回前端数据封装
 */

//当序列化Json对象时，如果是null的对象，key也会消失
@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
public class ServerResponse<T> implements Serializable {
    private int status;
    private String msg;
    private T data;

    private ServerResponse(int status){
        this.status = status;
    }

    private ServerResponse(int status,T data){
        this.status = status;
        this.data = data;
    }

    private ServerResponse(int status,String msg, T data){
        this.status = status;
        this.msg = msg;
        this.data = data;
    }

    private ServerResponse(int status,String msg){
        this.status = status;
        this.msg = msg;
    }

    @JsonIgnore
    public boolean isSuccess(){
        return  this.status == ResponseCode.SUCCESS.getCode();
    }

    public int getStatus() {
        return status;
    }

    public String getMsg() {
        return msg;
    }

    public T getData() {
        return data;
    }

    public static <T> ServerResponse<T> createBySuccess(){
        return new ServerResponse<T>(ResponseCode.SUCCESS.getCode());
    }

    public static <T> ServerResponse<T> createBySuccessMessage(String msg){
        return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(),msg);
    }

    public static <T> ServerResponse<T> createBySuccess(T data){
        return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(),data);
    }

    public static <T> ServerResponse<T> createBySuccess(String msg,T data){
        return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(),msg,data);
    }


    public static <T> ServerResponse<T> createByError(){
        return new ServerResponse<T>(ResponseCode.ERROR.getCode(),ResponseCode.ERROR.getDesc());
    }


    public static <T> ServerResponse<T> createByErrorMessage(String errorMessage){
        return new ServerResponse<T>(ResponseCode.ERROR.getCode(),errorMessage);
    }

    public static <T> ServerResponse<T> createByIllegalArgument(String errorMessage){
        return new ServerResponse<T>(ResponseCode.ILLEGAL_ARGUMENT.getCode(),errorMessage);
    }

    public static <T> ServerResponse<T> createByException(String errorMessage){
        return new ServerResponse<T>(ResponseCode.Exception.getCode(),errorMessage);
    }

    //需要登录的构造器
    public static <T> ServerResponse<T> createByNeedLogin(){
        return new ServerResponse<T>(ResponseCode.NEED_LOGIN.getCode(),ResponseCode.NEED_LOGIN.getDesc());
    }

    //需要登录的构造器SELLER_NEED_LOGIN
    public static <T> ServerResponse<T> createBySellerNeedLogin(){
        return new ServerResponse<T>(ResponseCode.SELLER_NEED_LOGIN.getCode(),ResponseCode.NEED_LOGIN.getDesc());
    }

    public static <T> ServerResponse<T> createByErrorCodeMessage(int errorCode,String errorMessage){
        return new ServerResponse<T>(errorCode,errorMessage);
    }

}

/**
 * 
 * 返回状态的枚举
 */
public enum ResponseCode {

    SUCCESS(0,"SUCCESS"),
    ERROR(1,"ERROR"),
    NEED_LOGIN(10,"NEED_LOGIN"),
    SELLER_NEED_LOGIN(11,"NEED_LOGIN"),
    ILLEGAL_ARGUMENT(2,"ILLEGAL_ARGUMENT"),
    Exception(-1,"Exception");

    private final int code;
    private final String desc;


    ResponseCode(int code,String desc){
        this.code = code;
        this.desc = desc;
    }

    public int getCode(){
        return code;
    }
    public String getDesc(){
        return desc;
    }

}

如上，将服务器响应封装为一个泛型类，类型安全性和通用性大大增加。