注解

注解类：

@Retention(RetentionPolicy.RUNTIME)
public @interface ExcelValidate
{
    public boolean ignoreBlank() default false;
    
    public int max() default Integer.MAX_VALUE;
    
    public int min() default 0;
    
    public boolean notNull() default false;
    
    public String format() default "";
}

被注解类：

public class ExcelAssetsBusinessVO {

    @ExcelValidate(notNull=true,max=100)
    private String name;

    @ExcelValidate(notNull=true)
    private String ip;

    private String port;
}

注解解析工具：

public class ExcelValidateUtil {
    public static <E> List<String> check(List<E> list, int index) throws Exception {
        List<String> strList = new ArrayList<>();
        Iterator<E> it = list.iterator();
        int i = 0;
        while(it.hasNext()) {
            int offset = i + index;
            E e = it.next();
            Field[] fields = e.getClass().getDeclaredFields();

            //对excel中的空行进行校验
            int count = 0, step = 0;
            ExcelValidate excelValidateClass = e.getClass().getAnnotation(ExcelValidate.class);
            if (excelValidateClass.ignoreBlank()) {
                for (Field field : fields) {
                    count++;
                    field.setAccessible(true);
                    if (field.get(e) == null || StringUtils.isBlank(field.get(e).toString())) {
                        step++;
                    }
                }
            }
            if (count == step) {
                it.remove();
                continue;
            }

            for (Field field : fields) {
                field.setAccessible(true);
                if (field.isAnnotationPresent(ExcelValidate.class)) {
                    ExcelValidate excelValidate = field.getAnnotation(ExcelValidate.class);
                    ExcelField excelField = field.getAnnotation(ExcelField.class);
                    if (excelValidate.notNull()) {
                        if (field.get(e) == null || field.get(e).toString().trim().length() == 0) {
                            String str = "第" + offset + "行，" + excelField.title().substring(0, excelField.title().length()-1) + "不能为空！";
                            strList.add(str);
                            continue;
                        }
                    }
                    if (excelValidate.max() != Integer.MAX_VALUE) {
                        if (field.get(e)!=null && field.get(e).toString().length() > excelValidate.max()) {
                            String str = "";
                            if(excelField.title().endsWith("*")) {
                                str = "第" + offset + "行，" + excelField.title().substring(0, excelField.title().length()-1) + "不能超过" + excelValidate.max() + "字符！";
                            }else {
                                str = "第" + offset + "行，" + excelField.title() + "不能超过" + excelValidate.max() + "字符！";
                            }
                            strList.add(str);
                            continue;
                        }
                    }
                    if (excelValidate.min() != 0) {
                        if (field.get(e)!=null && field.get(e).toString().length() < excelValidate.min()) {
                            String str = "";
                            if(excelField.title().endsWith("*")) {
                                str = "第" + offset + "行，" + excelField.title().substring(0, excelField.title().length()-1) + "不能少于" + excelValidate.max() + "字符！";
                            }else {
                                str = "第" + offset + "行，" + excelField.title() + "不能少于" + excelValidate.max() + "字符！";
                            }
                            strList.add(str);
                            continue;
                        }
                    }
                    if (field.get(e)!=null && !"".equals(excelValidate.format())) {
                        boolean valid = Pattern.matches(excelValidate.format(), field.get(e).toString());

                        if (!valid) {
                            String str = "";
                            if(excelField.title().endsWith("*")) {
                                str = "第" + offset + "行，" + excelField.title().substring(0, excelField.title().length()-1) + "格式不正确！";
                            } else {
                                str = "第" + offset + "行，" + excelField.title() + "格式不正确！";
                            }
                            strList.add(str);
                            continue;
                        }
                    }
                }
            }
            i++;
        }
        return strList;
    }
}