map和object互相转换

/**
 * 使用org.apache.commons.beanutils进行转换
 */
class A {  

    public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
        if (map == null)
            return null;  

        Object obj = beanClass.newInstance();  

        org.apache.commons.beanutils.BeanUtils.populate(obj, map);  

        return obj;
    }    

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

        return new org.apache.commons.beanutils.BeanMap(obj);
    }    

}  

/**
 * 使用Introspector进行转换
 */
class B {  

    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, Object> objectToMap(Object obj) throws Exception {
        if(obj == null)
            return null;      

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

        BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
        for (PropertyDescriptor property : propertyDescriptors) {
            String key = property.getName();  
            //默认PropertyDescriptor会有一个class对象，剔除之

if (key.compareToIgnoreCase("class") == 0) {
                continue;
            }
            Method getter = property.getReadMethod();
            Object value = getter!=null ? getter.invoke(obj) : null;
            map.put(key, value);
        }    

        return map;
    }    

}  

/**
 * 使用reflect进行转换
 */
class C {  

    public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
        if (map == null)
            return null;    

        Object obj = beanClass.newInstance();  

        Field[] fields = obj.getClass().getDeclaredFields();
        for (Field field : fields) {
            int mod = field.getModifiers();
            if(Modifier.isStatic(mod) || Modifier.isFinal(mod)){
                continue;
            }    

            field.setAccessible(true);
            field.set(obj, map.get(field.getName()));
        }   

        return obj;
    }    

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

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

        Field[] declaredFields = obj.getClass().getDeclaredFields();
        for (Field field : declaredFields) {
            field.setAccessible(true);
            map.put(field.getName(), field.get(obj));
        }    

        return map;
    }
}

推荐使用方法二，方法一的内部实现也是方法二，区别是方法一不会剔除“class”这个key，obj转成map后，会多一个key为class，value为类路径的Entry