反射的常用操作及一些使用特征-蒲公英云

反射的常用操作及一些使用特征

- 日理万妓 2022-04-06 13:52 232阅读 0赞

反射：

反射获取类的实体：

class Factory{

public static fruit getInstance(String ClassName)\{  
    fruit f=null;  
    try\{  
        f=(fruit)Class.forName(ClassName).newInstance();  
    \}catch (Exception e) \{  
        e.printStackTrace();  
    \}  
    return f;  
\}

}

class hello{

public static void main(String\[\] a)\{  
    fruit f=Factory.getInstance("Reflect.Apple");  
    if(f!=null)\{  
        f.eat();  
    \}  
\}

反射调用属性的操作方法：

public class Person implements Serializable {

private String name;
private int age;

// get/set方法

}

public static void main(String[] args) {

Person person = new Person("luoxn28", 23);
Class clazz = person.getClass();
Field\[\] fields = clazz.getDeclaredFields();
for (Field field : fields) \{
    String key = field.getName();
    PropertyDescriptor descriptor = new PropertyDescriptor(key, clazz);
    Method method = descriptor.getReadMethod();
    Object value = method.invoke(person);
    System.out.println(key + ":" + value);
\}

}

反射获取具体实体的某一个字段值的快速方法（包括list）：

field.get(object)；

/**

 \* 检查bean中含有List的必要参数
 \*
 \* @param object
 \* @return
 \* @throws Exception
 \*/
public static String checkBeans(Object object) throws Exception \{
    Class cls = object.getClass();
    StringBuilder stringBuilder = new StringBuilder();
    for (; cls != Object.class; cls = cls.getSuperclass()) \{ //从本类一直遍历到父类
        Field\[\] fieldes = cls.getDeclaredFields();
        for (Field field : fieldes) \{
            field.setAccessible(true);
            NotEmpty annotation = field.getAnnotation(NotEmpty.class);
            IsJsonArray isJsonArray = field.getAnnotation(IsJsonArray.class);
            Valid valid = field.getAnnotation(Valid.class);
            if (annotation != null
                    && StringUtils.isBlank((String) field.get(object))) \{
                stringBuilder.append(field.getName());
                stringBuilder.append(";");
            \}
            if (isJsonArray != null
                    && !JsonUtils.isJsonArrayString((String) field.get(object))) \{
                stringBuilder.append(field.getName());
                stringBuilder.append(";");
            \}
            if (valid != null
                    && !ArrayIsNotNull.isNull( (List<Object>)field.get(object))) \{
                List<Object> os=(List<Object>) field.get(object);
               for(Object o :  os)\{
                   checkBean(stringBuilder,o);
               \}
            \}else if(valid != null && ArrayIsNotNull.isNull( (List<Object>)field.get(object)))\{
                stringBuilder.append(field.getName());
                stringBuilder.append(";");
            \}
        \}
    \}
    return stringBuilder.toString();
\}