注解和反射实例，减少重复封装

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Inherited
public @interface BankAPI {
    String desc() default "";
    String url() default "";
}

@Retention(RetentionPolicy.RUNTIME)\
@Target(ElementType.FIELD)\
@Documented\
@Inherited\
public @interface BankAPIField {\
    int order() default -1;\
    int length() default -1;\
    String type() default "";\
}

使用

@BankAPI(url = "/bank/createUser", desc = "创建用户接口")\
@Data\
public class CreateUserAPI extends AbstractAPI {\
    @BankAPIField(order = 1, type = "S", length = 10)\
    private String name;\
    @BankAPIField(order = 2, type = "S", length = 18)\
    private String identity;\
    @BankAPIField(order = 4, type = "S", length = 11) //注意这里的order需要按照API表格中的顺序\
    private String mobile;\
    @BankAPIField(order = 3, type = "N", length = 5)\
    private int age;\
}

解析注解，利用反射获取数据

private static String remoteCall(AbstractAPI api) throws IOException {\
    //从BankAPI注解获取请求地址\
    BankAPI bankAPI = api.getClass().getAnnotation(BankAPI.class);\
    bankAPI.url();\
    StringBuilder stringBuilder = new StringBuilder();\
    Arrays.stream(api.getClass().getDeclaredFields()) //获得所有字段\
            .filter(field -> field.isAnnotationPresent(BankAPIField.class)) //查找标记了注解的字段\
            .sorted(Comparator.comparingInt(a -> a.getAnnotation(BankAPIField.class).order())) //根据注解中的order对字段排序\
            .peek(field -> field.setAccessible(true)) //设置可以访问私有字段\
            .forEach(field -> {\
                //获得注解\
                BankAPIField bankAPIField = field.getAnnotation(BankAPIField.class);\
                Object value = "";\
                try {\
                    //反射获取字段值\
                    value = field.get(api);\
                } catch (IllegalAccessException e) {\
                    e.printStackTrace();\
                }\
                //根据字段类型以正确的填充方式格式化字符串\
                switch (bankAPIField.type()) {\
                    case "S": {\
                        stringBuilder.append(String.format("%-" + bankAPIField.length() + "s", value.toString()).replace(' ', '_'));\
                        break;\
                    }\
                    case "N": {\
                        stringBuilder.append(String.format("%" + bankAPIField.length() + "s", value.toString()).replace(' ', '0'));\
                        break;\
                    }\
                    case "M": {\
                        if (!(value instanceof BigDecimal))\
                            throw new RuntimeException(String.format("{} 的 {} 必须是BigDecimal", api, field));\
                        stringBuilder.append(String.format("%0" + bankAPIField.length() + "d", ((BigDecimal) value).setScale(2, RoundingMode.DOWN).multiply(new BigDecimal("100")).longValue()));\
                        break;\
                    }\
                    default:\
                        break;\
                }\
            });\
    //签名逻辑\
   stringBuilder.append(DigestUtils.md2Hex(stringBuilder.toString()));\
    String param = stringBuilder.toString();\
    long begin = System.currentTimeMillis();\
    //发请求\
    String result = Request.Post("http://localhost:45678/reflection" + bankAPI.url())\
            .bodyString(param, ContentType.APPLICATION_JSON)\
            .execute().returnContent().asString();\
    log.info("调用银行API {} url:{} 参数:{} 耗时:{}ms", bankAPI.desc(), bankAPI.url(), param, System.currentTimeMillis() - begin);\
    return result;\
}