枚举类型 表示不同的 HTTP 状态码和相应的错误消息

java web业务中经常用常量来表示不同的 HTTP 响应状态,比如

public enum AppHttpCodeEnum {

    // 成功段0
    SUCCESS(200,"操作成功"),
    // 登录段1~50
    NEED_LOGIN(1,"需要登录后操作"),
    LOGIN_PASSWORD_ERROR(2,"密码错误"),
    // TOKEN50~100
    TOKEN_INVALID(50,"无效的TOKEN"),
    TOKEN_EXPIRE(51,"TOKEN已过期"),
    TOKEN_REQUIRE(52,"TOKEN是必须的"),
    // SIGN验签 100~120
    SIGN_INVALID(100,"无效的SIGN"),
    SIG_TIMEOUT(101,"SIGN已过期"),
    // 参数错误 500~1000
    PARAM_REQUIRE(500,"缺少参数"),
    PARAM_INVALID(501,"无效参数"),
    PARAM_IMAGE_FORMAT_ERROR(502,"图片格式有误"),
    SERVER_ERROR(503,"服务器内部错误"),
    // 数据错误 1000~2000
    DATA_EXIST(1000,"数据已经存在"),
    AP_USER_DATA_NOT_EXIST(1001,"ApUser数据不存在"),
    DATA_NOT_EXIST(1002,"数据不存在"),
    // 数据错误 3000~3500
    NO_OPERATOR_AUTH(3000,"无权限操作"),
    NEED_ADMIND(3001,"需要管理员权限");




    int code;
    String errorMessage;

    AppHttpCodeEnum(int code, String errorMessage){
        this.code = code;
        this.errorMessage = errorMessage;
    }

    public int getCode() {
        return code;
    }

    public String getErrorMessage() {
        return errorMessage;
    }
}

这种枚举的使用方式允许你在代码中使用这些常量来表示不同的 HTTP 响应状态，而不需要硬编码状态码和错误消息。这提高了代码的可读性和可维护性，并降低了错误的风险，因为你可以使用这些常量而不是手动输入状态码和消息。例如，你可以使用 AppHttpCodeEnum.SUCCESS.getCode() 来获取成功状态码，使用 AppHttpCodeEnum.SUCCESS.getErrorMessage() 来获取成功消息。并且无需要,实列化,直接写常量就会在加载服务的时候实列化，这个枚举类型 AppHttpCodeEnum 中定义的枚举常量是可以直接使用的，不需要创建新的枚举对象，就像使用静态变量一样

一般配合响应类来进行使用

public class ResponseResult implements Serializable {

    private String host;

    private Integer code;

    private String errorMessage;

    private T data;

    public ResponseResult() {
        this.code = 200;
    }

    public ResponseResult(Integer code, T data) {
        this.code = code;
        this.data = data;
    }

    public ResponseResult(Integer code, String msg, T data) {
        this.code = code;
        this.errorMessage = msg;
        this.data = data;
    }

    public ResponseResult(Integer code, String msg) {
        this.code = code;
        this.errorMessage = msg;
    }

    public static ResponseResult errorResult(int code, String msg) {
        ResponseResult result = new ResponseResult();
        return result.error(code, msg);
    }

    public static ResponseResult okResult(int code, String msg) {
        ResponseResult result = new ResponseResult();
        return result.ok(code, null, msg);
    }

    public static ResponseResult okResult(Object data) {
        ResponseResult result = setAppHttpCodeEnum(AppHttpCodeEnum.SUCCESS, AppHttpCodeEnum.SUCCESS.getErrorMessage());
        if(data!=null) {
            result.setData(data);
        }
        return result;
    }

    public static ResponseResult errorResult(AppHttpCodeEnum enums){
        return setAppHttpCodeEnum(enums,enums.getErrorMessage());
    }

    public static ResponseResult errorResult(AppHttpCodeEnum enums, String errorMessage){
        return setAppHttpCodeEnum(enums,errorMessage);
    }

    public static ResponseResult setAppHttpCodeEnum(AppHttpCodeEnum enums){
        return okResult(enums.getCode(),enums.getErrorMessage());
    }

    private static ResponseResult setAppHttpCodeEnum(AppHttpCodeEnum enums, String errorMessage){
        return okResult(enums.getCode(),errorMessage);
    }

    public ResponseResult error(Integer code, String msg) {
        this.code = code;
        this.errorMessage = msg;
        return this;
    }

    public ResponseResult ok(Integer code, T data) {
        this.code = code;
        this.data = data;
        return this;
    }

    public ResponseResult ok(Integer code, T data, String msg) {
        this.code = code;
        this.data = data;
        this.errorMessage = msg;
        return this;
    }

    public ResponseResult ok(T data) {
        this.data = data;
        return this;
    }

    public Integer getCode() {
        return code;
    }

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

    public String getErrorMessage() {
        return errorMessage;
    }

    public void setErrorMessage(String errorMessage) {
        this.errorMessage = errorMessage;
    }

    public T getData() {
        return data;
    }

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

    public String getHost() {
        return host;
    }

    public void setHost(String host) {
        this.host = host;
    }
}