泛型作为返回值

2017-11-18 10:57:56 501 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

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如何理解下面代码中

<T>ServerResponse<T>

;两个泛型的使用,为什么需要第一个<T>,表示什么意思?

package com.mmall.common;



import org.codehaus.jackson.annotate.JsonIgnore;

import org.codehaus.jackson.map.annotate.JsonSerialize;



import java.io.Serializable;

import java.util.List;



/**

 * Created by CJ on 2017/11/16.

 */

@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)

public class ServerResponse<T> implements Serializable{

    private int status;

    private String msg;

    private T data;



    public ServerResponse(int status) {

        this.status = status;

    }



    public ServerResponse(int status, String msg) {

        this.status = status;

        this.msg = msg;

    }



    public ServerResponse(int status, T data) {

        this.status = status;

        this.data = data;

    }



    public ServerResponse(int status, String msg, T data) {

        this.status = status;

        this.msg = msg;

        this.data = data;

    }



    @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> createByErrorCodeMessage(int ErrorCode,String ErrorMessage){

        return new ServerResponse<T>(ErrorCode,ErrorMessage);

    }

}