[学习交流] 反射的用法

反射的用法：

1）、需要获得java类的各个组成部分，首先需要获得类的Class对象，获得Class对象的三种方式：

Class.forName(classname) 用于做类加载

obj.getClass() 用于获得对象的类型

类名.class 用于获得指定的类型，传参用

2)、反射类的构造函数：

Constructorcon = clazz.getConstructor(new Class[]{paramClazz1, paramClazz2,...})

con.newInstance(params...)

3)、反射类的成员方法：

Classclazz = Person.class;

Methodmethod = clazz.getMethod(methodName, new Class[]{paramClazz1, paramClazz2});

method.invoke();

4)、反射类的属性：

Fieldfield = clazz.getField(fieldName);

field.setAccessible(true);

field.setObject(value);

import java.lang.reflect.Constructor;
import java.lang.reflect.*;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
public class test1 {
public static void main(String[] args) throws Exception {
mether1();
mether2();
mether3();
mether4();
}
//获取字节码class
public static void mether1() throws Exception{
// 1. 根据给定的类名来获得用于类加载
String classname = "javaenhance.Person";// 一般来自配置文件
Class c1 = Class.forName(classname);// 此对象代表Person.class
// 2. 如果拿到了对象，不知道是什么类型用于获得对象的类型
Object obj = new Person();
Class c2 = obj.getClass();// 获得对象具体的类型
// 3. 如果是明确地获得某个类的Class对象主要用于传参
Class c3 = Person.class;
System.out.println(c1);
System.out.println(c2);
System.out.println(c3);
System.out.println("获取获取字节码class");
System.out.println();
}
//实例化对象
private static void mether2() throws Exception {
Class c = Person.class;
Constructor co = c.getDeclaredConstructor();
Person p = (Person) co.newInstance();
Constructor co1 = c.getDeclaredConstructor(String.class,int.class);
Person p1 = (Person) co1.newInstance("sharry",11);
System.out.println(p.toString());
System.out.println(p1.toString());
System.out.println("实例化对象");
System.out.println();
}
//调用成员方法
private static void mether3() throws Exception{
// TODO 自动生成的方法存根
Class c = Person.class;
Constructor co1 = c.getDeclaredConstructor(String.class,int.class);
Person p1 = (Person) co1.newInstance("sharry",11);
System.out.println(p1.toString());
Method method = c.getMethod("setName", String.class);
method.invoke(p1, "make");
System.out.println(p1.toString());
System.out.println("调用成员方法");
System.out.println();
}
//获取属性
private static void mether4(){
Class<?> demo = null;
try {
demo = Person.class;
} catch (Exception e) {
e.printStackTrace();
}
// 取得本类的全部属性
Field[] field = demo.getDeclaredFields();
for (int i = 0; i < field.length; i++) {
// 权限修饰符
int mo = field[i].getModifiers();
String priv = Modifier.toString(mo);
// 属性类型
Class<?> type = field[i].getType();
System.out.println(priv + " " + type.getName() + " "
+ field[i].getName() + ";");
}
System.out.println("获取属性");
System.out.println();
}
}
class Person {
private String name;
private int age;
public Person() {
}
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String toString(){
return "name:"+name+" age:"+age;
}
public String sayHello(int age,String name){
return "My name is "+name+","+age+"years old ,nice to meet you ";
}
private void myPrivate(){
System.out.println("i am private");
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}

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[学习交流] 反射的用法

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