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