我要你扮演一个软件工程师。现在我需要你仔细思考，以下代码存在一些问题，headClazz里面获取到的是空值，我想要headClazz能动态获取到entity包中的user、admin表的字段名，我需要你指出代码错误，以及改正方法。代码如下：public class CommonReadListener<T> extends AnalysisEventListener<T> implements ReadListener<T> {private Class<T> headClazz;public CommonReadListener(Class<T> headClazz) { this.headClazz = headClazz; }@Override public void invokeHead(Map<Integer, ReadCellData<?>> headMap, AnalysisContext context) { ExcelPropertyCheck clazzHeadAnno = this.headClazz.getAnnotation(ExcelPropertyCheck.class); Field[] declaredFields = headClazz.getDeclaredFields(); if (clazzHeadAnno != null && clazzHeadAnno.required()) { for (Field declaredField : declaredFields) { nullAbleFieldMap.put(declaredField.getName(), true); } } for (Field declaredField : declaredFields) { ExcelPropertyCheck annotation = declaredField.getAnnotation(ExcelPropertyCheck.class); if (annotation != null) { if (annotation.checkFormat()) { checkFormatFieldMap.put(declaredField.getName(), annotation.type() + ""); } if (annotation.required()) { nullAbleFieldMap.put(declaredField.getName(), true); } else { nullAbleFieldMap.remove(declaredField.getName()); } if (annotation.required() && annotation.length() != -1) { checkLengthFieldMap.put(declaredField.getName(), annotation.length()); } } } }

在这段代码中，headClazz获取到的是空值，可能是因为你没有将entity包中的user、admin表作为参数传入到CommonReadListener构造函数中。

修改代码，需要将entity包中的user、admin表作为参数传入到CommonReadListener构造函数中，然后在invokeHead方法中获取它们的字段名。代码修改如下：

public class CommonReadListener<T> extends AnalysisEventListener<T> implements ReadListener<T> {
    private Class<T> headClazz;
    private Class<?>[] entityClasses;

    public CommonReadListener(Class<T> headClazz, Class<?>... entityClasses) {
        this.headClazz = headClazz;
        this.entityClasses = entityClasses;
    }

    @Override
    public void invokeHead(Map<Integer, ReadCellData<?>> headMap, AnalysisContext context) {
        ExcelPropertyCheck clazzHeadAnno = this.headClazz.getAnnotation(ExcelPropertyCheck.class);
        Map<String, String[]> fieldNamesMap = new HashMap<>();
        for (Class<?> entityClass : entityClasses) {
            String className = entityClass.getSimpleName();
            Field[] declaredFields = entityClass.getDeclaredFields();
            String[] fieldNames = new String[declaredFields.length];
            for (int i = 0; i < declaredFields.length; i++) {
                fieldNames[i] = declaredFields[i].getName();
            }
            fieldNamesMap.put(className.toLowerCase(), fieldNames);
        }

        if (clazzHeadAnno != null && clazzHeadAnno.required()) {
            for (Field declaredField : headClazz.getDeclaredFields()) {
                nullAbleFieldMap.put(declaredField.getName(), true);
            }
        }

        for (Field declaredField : headClazz.getDeclaredFields()) {
            ExcelPropertyCheck annotation = declaredField.getAnnotation(ExcelPropertyCheck.class);
            if (annotation != null) {
                if (annotation.checkFormat()) {
                    checkFormatFieldMap.put(declaredField.getName(), annotation.type() + "");
                }

                if (annotation.required()) {
                    nullAbleFieldMap.put(declaredField.getName(), true);
                } else {
                    nullAbleFieldMap.remove(declaredField.getName());
                }

                if (annotation.required() && annotation.length() != -1) {
                    checkLengthFieldMap.put(declaredField.getName(), annotation.length());
                }

                String entityClassName = annotation.entityClass().getSimpleName().toLowerCase();
                String[] fieldNames = fieldNamesMap.get(entityClassName);
                if (fieldNames != null) {
                    boolean existField = false;
                    for (String fieldName : fieldNames) {
                        if (fieldName.equals(annotation.fieldName())) {
                            existField = true;
                            break;
                        }
                    }
                    if (!existField) {
                        throw new IllegalArgumentException("The field " + annotation.fieldName() + " not exists in entity class " + annotation.entityClass().getSimpleName());
                    }
                } else {
                    throw new IllegalArgumentException("Entity class " + annotation.entityClass().getSimpleName() + " not found");
                }
            }
        }
    }
}

在修改后的代码中，我们将entityClasses作为参数传入到CommonReadListener构造函数中，并在invokeHead方法中获取它们的字段名，然后根据ExcelPropertyCheck注解中的entityClass和fieldName来判断字段是否存在。这样就可以动态获取到entity包中user、admin表的字段名了。