接口

调用接口时要返回状态码，返回的信息，返回的data，新建一个ServerResponse

    private int status;
    private String msg;
    private T data;
    //省略get方法

把构造器变成私有的再提供共有的调用方法

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;
    }

声明一个枚举类型放响应码便于以后扩展，新建一个ResponseCode

public enum ResponseCode {

    SUCCESS(0,"SUCCESS"),
    ERROR(1,"ERROR"),
    NEED_LOGIN(10,"NEED_LOGIN"),
    ILLEGAL_ARGUMENT(2,"ILLEGAL_ARGUMENT");

    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;
    }
}

写一个判断响应是否成功的方法isSuccess()，等于success说明响应成功，JsonIgnore注解让这个方法不会被序列化显示在json中

@JsonIgnore
    //不在序列号结果中
    public boolean isSuccess(){
        return this.status == ResponseCode.SUCCESS.getCode();
    }

开放静态的共有方法

    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);
    }

在类名上加上注解JsonSerialize，返回时不需要的属性就不会显示出来

@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)//序列化json的时候不会有值为空的key
public class ServerResponse<T> implements Serializable{
  ···
}