java 对象和地图互转及去掉图中为空的元素

Posted 2021-05-08

import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

/**
 * TODO: 请添加描述
 *
 * @author gongdaoshun
 * @date 2017/8/22
 * @since 1.0.0
 */
public class BeanMapUtils {
    public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
        if (map == null)
            return null;

        Object obj = beanClass.newInstance();

        BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
        for (PropertyDescriptor property : propertyDescriptors) {
            Method setter = property.getWriteMethod();
            if (setter != null) {
                setter.invoke(obj, map.get(property.getName()));
            }
        }

        return obj;
    }

    public static Map<String, String> objectToMap(Object obj) throws Exception {
        if(obj == null)
            return null;

        Map<String, String> map = new HashMap<>();

        BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
        for (PropertyDescriptor property : propertyDescriptors) {
            String key = property.getName();
            if (key.compareToIgnoreCase("class") == 0) {
                continue;
            }
            Method getter = property.getReadMethod();
            String value = getter!=null ? getter.invoke(obj)!=null?getter.invoke(obj).toString():"" : "";
            map.put(toLowerCaseFirstOne(key), value);
        }

        return map;
    }

    private static String toLowerCaseFirstOne(String s){
        if(Character.isLowerCase(s.charAt(0)))
            return s;
        else
            return (new StringBuilder()).append(Character.toLowerCase(s.charAt(0))).append(s.substring(1)).toString();
    }
    
    public static Map<String, Object> object2Map(Object obj) {
        Map<String, Object> map = new HashMap<>();
        if (obj == null) {
            return map;
        }
        Class clazz = obj.getClass();
        Field[] fields = clazz.getDeclaredFields();
        try {
            for (Field field : fields) {
                field.setAccessible(true);
                map.put(field.getName(), field.get(obj));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return map;
    }
    
    //移除map中值为null的元素
    public static Map removeMapNull(Map map) {
        Set set = map.keySet();
        for (Iterator iterator = set.iterator(); iterator.hasNext(); ) {
            Object obj = (Object) iterator.next();
            Object value = (Object) map.get(obj);
            remove(value, iterator);
        }
        return map;
    }
    
    private static void remove(Object obj, Iterator iterator) {
        if (obj instanceof String) {
            String str = (String) obj;
            if (StringUtil.isEmpty(str)) {
                iterator.remove();
            }
        } else if (obj instanceof Collection) {
            Collection col = (Collection) obj;
            if (col == null || col.isEmpty()) {
                iterator.remove();
            }

        } else if (obj instanceof Map) {
            Map temp = (Map) obj;
            if (temp == null || temp.isEmpty()) {
                iterator.remove();
            }

        } else if (obj instanceof Object[]) {
            Object[] array = (Object[]) obj;
            if (array == null || array.length <= 0) {
                iterator.remove();
            }
        } else {
            if (obj == null) {
                iterator.remove();
            }
        }
    }
}