java获取类注解内容和类字段注解内容

墨蓝 2022-12-27 11:19 196阅读 0赞

package com.dev.demo.util;
    
    import com.baomidou.mybatisplus.annotation.TableField;
    import com.dev.demo.model.TbUser;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import javax.persistence.Column;
    import javax.persistence.Table;
    import java.lang.reflect.Field;
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Proxy;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    
    public class BeanUtil {
        static Logger log = LoggerFactory.getLogger(BeanUtil.class);
    
        /**
         * 获取table中的columns和类中的字段集合
         *
         * @param clazz
         * @return
         */
        public static List<DbFiled> getFieldName(Class clazz) {
            List<DbFiled> list = new ArrayList<>();
            Field[] fields = clazz.getDeclaredFields();
            for (int j = 0; j < fields.length; j++) {
                Field field = fields[j];
                if (field.isAnnotationPresent(Column.class)) {
                    if (field.isAnnotationPresent(TableField.class)) {
                        try {
                            //获取SignalsRuleExportDTO字段上的ExcelProperty注解实例
                            TableField column = field.getAnnotation(TableField.class);
                            //获取 ExcelProperty 这个代理实例所持有的 InvocationHandler
                            InvocationHandler ch = Proxy.getInvocationHandler(column);
                            // 获取 AnnotationInvocationHandler 的 memberValues 字段
                            Field fv = ch.getClass().getDeclaredField("memberValues");
                            // 因为这个字段事 private final 修饰，所以要打开权限
                            fv.setAccessible(true);
                            // 获取 memberValues
                            Map kvs = (Map) fv.get(ch);
                            // 修改 value 属性值
                            Object columnName = kvs.get("value");
    
                            list.add(new DbFiled(columnName.toString(), field.getName()));
                        } catch (Exception e) {
                            log.error("getFieldName", e);
                        }
                    } else {
                        list.add(new DbFiled(field.getName(), field.getName()));
                    }
                }
            }
            return list;
        }
    
        /**
         * 获取table中的columns和类中的字段集合(包括表名前提model配置@Table注解且注解包含name属性)
         *
         * @param clazz
         * @return
         */
        public static TableClassBean getTableClassBean(Class clazz) {
            List<DbFiled> list = new ArrayList<>();
            Field[] fields = clazz.getDeclaredFields();
            for (int j = 0; j < fields.length; j++) {
                Field field = fields[j];
                if (field.isAnnotationPresent(Column.class)) {
                    if (field.isAnnotationPresent(TableField.class)) {
                        try {
                            //获取SignalsRuleExportDTO字段上的ExcelProperty注解实例
                            TableField column = field.getAnnotation(TableField.class);
                            //获取 ExcelProperty 这个代理实例所持有的 InvocationHandler
                            InvocationHandler ch = Proxy.getInvocationHandler(column);
                            // 获取 AnnotationInvocationHandler 的 memberValues 字段
                            Field fv = ch.getClass().getDeclaredField("memberValues");
                            // 因为这个字段事 private final 修饰，所以要打开权限
                            fv.setAccessible(true);
                            // 获取 memberValues
                            Map kvs = (Map) fv.get(ch);
                            // 修改 value 属性值
                            Object columnName = kvs.get("value");
    
                            list.add(new DbFiled(columnName.toString(), field.getName()));
                        } catch (Exception e) {
                            log.error("getFieldName", e);
                        }
                    } else {
                        list.add(new DbFiled(field.getName(), field.getName()));
                    }
                }
            }
            Table[] annotationsByType = TbUser.class.getAnnotationsByType(Table.class);
            if (annotationsByType != null && annotationsByType.length >= 1) {
                Table table = annotationsByType[0];
                if (table.name() != null && !"".equals(table.name().trim())) {
                    return new TableClassBean(table.name(), list);
                }
            }
            log.info("no annotation or javax.persistence.Table");
            return new TableClassBean(TbUser.class.getSimpleName(), list);
        }
    
        public static void main(String[] args) {
            System.out.println(getFieldName(TbUser.class));
            System.out.println(getTableClassBean(TbUser.class));
        }
    }

详细参看：[https://blog.csdn.net/CTLLIN/article/details/110958293][https_blog.csdn.net_CTLLIN_article_details_110958293]

[https_blog.csdn.net_CTLLIN_article_details_110958293]: https://blog.csdn.net/CTLLIN/article/details/110958293