工作中遇到一个需求，根据对方返回Json来更新Java对象。查阅资料，写了个工具类，同时学到了反射获取集合泛型类型。代码里json类库为fastjson
public class JsonUtil {
/**
* JavaBean的属性比Json多时，根据Json更新JavaBean同名字段的值
*
* @param bean
* @param json
* @param <T>
*/
public static <T> void patchUpdate(T bean, JSONObject json) throws Exception {
Set<String> keys = json.keySet();
Field[] fields = bean.getClass().getDeclaredFields();
for (String key : keys) {
for (Field field : fields) {
if (field.getName().equals(key)) {
String value = json.getString(key);
String type = field.getType().toString();
field.setAccessible(true);
if (type.endsWith("String")) {
field.set(bean, value);
} else if (type.endsWith("int")) {
field.set(bean, Integer.parseInt(value));
} else if (type.endsWith("double")) {
field.set(bean, Double.parseDouble(value));
} else if (type.endsWith("Date")) {
DateFormat fmtDateTime = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = fmtDateTime.parse(value);
field.set(bean, date);
} else if (type.endsWith("List")) {
//先获取List的类型：java.util.List<E>
ParameterizedType pt = (ParameterizedType)field.getGenericType();
//获取泛型：E
Class e = (Class)pt.getActualTypeArguments()[0];
List list = JSONArray.parseArray(value, e);
field.set(bean, list);
}
}
}
}
}
}