反射_Class对象功能_获取Field
Field:成员变量
操作:
设置值
void set(Object ob, Object value)
获取值
get(Object obj)
忽略访问权限修饰符的安全的检查
举例:
public class Person { private String name; private int age; public String a; protected String b; String c; private String d; @Override public String toString() { return "Person{" + "name='" + name + '\'' + ", age=" + age + ", a='" + a + '\'' + ", b='" + b + '\'' + ", c='" + c + '\'' + ", d='" + d + '\'' + '}'; }
Class personClass = Person.class; Field[] fields = personClass.getFields(); for (Field field : fields) { System.out.println(field); } System.out.println("==============="); Field a = personClass.getField("a");
获取成员变量的a的值
Person person = new Person(); Object value = a.get(person); System.out.println(value); //设置a的值 a.set(person,"张三"); System.out.println(person); System.out.println("================");
Field[] getDeclaredFields(); 获取所有的成员变量不考虑修饰符
Field[] declaredFields = personClass.getDeclaredFields(); for (Field declaredField : declaredFields) { System.out.println(declaredField); } Field d = personClass.getDeclaredField("d"); d.setAccessible(true); Object o = d.get(person); System.out.println(o);
反射_Class对象功能_获取Construct
constructor
创建对象
如果使用空参数构造方法创建对象,操作可以简化: class对象的newInstance方法
实现:
//获取Person的Class对象 Class personClass = Person.class; //Constructor<T> getConstructor(类<?>... parameterTypes) Constructor constructor = personClass.getConstructor(String.class, int.class); System.out.println(constructor); //创建对象 Object person = constructor.newInstance("张三", 23); System.out.println(person); System.out.println("------------"); Constructor constructor1 = personClass.getConstructor(); System.out.println(constructor1); Object person1 = constructor1.newInstance(); System.out.println(person1); Object o = personClass.newInstance(); System.out.println(o);