Java 实现 Map 和 Object 互相转换的几种方法

Java 实现 Map 和 Object 互相转换的几种方法

/**
* 使用 com.fasterxml.jackson.databind.ObjectMapper 进行转换
*/
class A {

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

ObjectMapper objectMapper = new ObjectMapper();
Object obj = objectMapper.convertValue(map, beanClass);

return obj;
}

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

ObjectMapper objectMapper = new ObjectMapper();
Map<?, ?> mappedObject = objectMapper.convertValue(obj, Map.class);

return mappedObject;
}
}

/**
* 使用 org.apache.commons.beanutils 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();

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 C {

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();
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 D {

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;
}
}