传统型程序员必备技能2——枚举

java中对常量数据的配置可以使用枚举类型实现，它也有对象、属性、方法等，枚举类型将它的对象（实例）设置为常量方便读取和使用。

public enum MyFamilyMember {
    SONGWENLONG("虫子哥","老公"),
    QIFAN("臭亓帆","臭老婆");

    private String name;
    private String description;

    MyFamilyMember(){}

    MyFamilyMember(String name, String description) {
        this.name = name;
        this.description = description;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public static void main(String[] args) {
        System.out.println(MyFamilyMember.QIFAN.name+"：我是"+MyFamilyMember.QIFAN.description);
    }
}

举一个项目使用的返回值包装类；首先 枚举类ResultCode 实现接口IResultCode ；返回值包装类中引用枚举类ResultCode

接口：

public interface IResultCode extends Serializable {
    String getMessage();

    int getCode();
}

enum类：

public enum ResultCode implements IResultCode {
    SUCCESS(200, "操作成功"),
    FAILURE(500, "业务异常"),
    UN_AUTHORIZED(401, "请求未授权"),
    CLIENT_UN_AUTHORIZED(401, "客户端请求未授权"),
    NOT_FOUND(404, "404 没找到请求"),
    MSG_NOT_READABLE(500, "消息不能读取"),
    METHOD_NOT_SUPPORTED(405, "不支持当前请求方法"),
    MEDIA_TYPE_NOT_SUPPORTED(415, "不支持当前媒体类型"),
    REQ_REJECT(403, "请求被拒绝"),
    INTERNAL_SERVER_ERROR(500, "服务器异常"),
    PARAM_MISS(500, "缺少必要的请求参数"),
    PARAM_TYPE_ERROR(500, "请求参数类型错误"),
    PARAM_BIND_ERROR(500, "请求参数绑定错误"),
    PARAM_VALID_ERROR(500, "参数校验失败");

    final int code;
    final String message;

    public int getCode() {
        return this.code;
    }

    public String getMessage() {
        return this.message;
    }

    private ResultCode(int code, String message) {
        this.code = code;
        this.message = message;
    }
}

R类：

public class R implements Serializable {
    private static final long serialVersionUID = 1L;
    
    //"状态码"
    private int code;
  
    //"是否成功",
    private boolean success;
    
    //"承载数据"
    private T data;
    
    //"返回消息"
    private String msg;

    private R(IResultCode resultCode) {
        this(resultCode, (Object)null, resultCode.getMessage());
    }

    private R(IResultCode resultCode, String msg) {
        this(resultCode, (Object)null, msg);
    }

    private R(IResultCode resultCode, T data) {
        this(resultCode, data, resultCode.getMessage());
    }

    private R(IResultCode resultCode, T data, String msg) {
        this(resultCode.getCode(), data, msg);
    }

    private R(int code, T data, String msg) {
        this.code = code;
        this.data = data;
        this.msg = msg;
        this.success = ResultCode.SUCCESS.code == code;
    }

    public static boolean isSuccess(@Nullable R result) {
        return (Boolean)Optional.ofNullable(result).map((x) -> {
            return ObjectUtil.nullSafeEquals(ResultCode.SUCCESS.code, x.code);
        }).orElse(Boolean.FALSE);
    }

    public static boolean isNotSuccess(@Nullable R result) {
        return !isSuccess(result);
    }

    public static  R data(T data) {
        return data(data, "操作成功");
    }

    public static  R data(T data, String msg) {
        return data(200, data, msg);
    }

    public static  R data(int code, T data, String msg) {
        return new R(code, data, data == null ? "暂无承载数据" : msg);
    }

    public static  R success(String msg) {
        return new R(ResultCode.SUCCESS, msg);
    }

    public static  R success(IResultCode resultCode) {
        return new R(resultCode);
    }

    public static  R success(IResultCode resultCode, String msg) {
        return new R(resultCode, msg);
    }

    public static  R fail(String msg) {
        return new R(ResultCode.FAILURE, msg);
    }

    public static  R fail(int code, String msg) {
        return new R(code, (Object)null, msg);
    }

    public static  R fail(IResultCode resultCode) {
        return new R(resultCode);
    }

    public static  R fail(IResultCode resultCode, String msg) {
        return new R(resultCode, msg);
    }

    public static  R status(boolean flag) {
        return flag ? success("操作成功") : fail("操作失败");
    }

    public int getCode() {
        return this.code;
    }

    public boolean isSuccess() {
        return this.success;
    }

    public T getData() {
        return this.data;
    }

    public String getMsg() {
        return this.msg;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public void setSuccess(boolean success) {
        this.success = success;
    }

    public void setData(T data) {
        this.data = data;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public String toString() {
        return "R(code=" + this.getCode() + ", success=" + this.isSuccess() + ", data=" + this.getData() + ", msg=" + this.getMsg() + ")";
    }

    public R() {
    }
}

枚举都是常量，所以用==比较即可；