反射有关的定义

package com.hu;

public class Person {
public String name;
private int age;
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;
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + "]";
}

public Person() {
super();
}

public Person(String name) {
super();
this.name = name;
}

public Person(int age) {
super();
this.age = age;
}
public Person(String name, int age) {
super();
this.name = name;
this.age = age;
}
public void show(){
System.out.println("我是一个人");
}
public void nation(String nation){
System.out.println("我的国际是"+nation);
}

}

*************************************************

package com.hu;

import static org.junit.Assert.*;

import java.beans.FeatureDescriptor;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.FieldPosition;
import java.util.Properties;

import org.junit.Test;

public class TestReflection {

@Test
public void test() {
//反射之前的调用
Person person=new Person();
person.setAge(11);
person.setName("Muyongyuan");
person.show();
person.nation("HK");
System.out.println(person);
}
//有了反射可以通过反射创建一个类的对象 ，并调用其中的方法
@Test
public void test2() throws Exception{
//创建clazz运行时类对应的Person类对象
//如果知道类型就是用泛型，如果不知道需要强转
//Class clazz=Person.class;
//Person p=(Person)clazz.newInstance();
Class<Person> clazz=Person.class;
Person person=clazz.newInstance();
Field f1=clazz.getField("name");
f1.set(person, "Liyunlong");
System.out.println(person);
//下面一段代码是用反射调用私有属性的方案
Field f2=clazz.getDeclaredField("age");
f2.setAccessible(true);
f2.set(person, 23);
System.out.println(person);

//通过calzz 调用运行时类的方法
Method method=clazz.getMethod("show");
method.invoke(person);
//含有参数的调用
Method m2=clazz.getMethod("nation", String.class);
m2.invoke(person, "Erop");

}
@Test
public void test34(){
//java.lang.Calss是反射的源头
Person p=new Person();
Class clazz=p.getClass();
System.out.println(clazz);//通过运行时类的对象，调用getclass()返回运行时类
}


//如何获取Class事例（3种方法）
@Test
public void test5() throws ClassNotFoundException{
//1，直接对用运行时类本身的.class方法
Class<Person> clazz=Person.class;
System.out.println(clazz.getName());
//2，通过运行时类的对象来创建
Person p =new Person();
Class clazzClass=p.getClass();
System.out.println(clazzClass.getName());
//3通过Class的静态方法
String classSt="com.hu.Person";
Class clazz4=Class.forName(classSt);
System.out.println(clazz4);
//4，了解通过类的加载器
ClassLoader classLoader=this.getClass().getClassLoader();
classLoader.loadClass(classSt);
System.out.println(classLoader.loadClass(classSt));
}
//类的加载器
@Test
public void test323() throws IOException{
ClassLoader classLoader=ClassLoader.getSystemClassLoader();
System.out.println(classLoader);

ClassLoader classLoader2=classLoader.getParent();
System.out.println(classLoader2);

ClassLoader classLoader3=classLoader2.getParent();
System.out.println(classLoader3);

//掌握一下的用法
ClassLoader clazzload=this.getClass().getClassLoader();
System.out.println(clazzload.getClass());
InputStream inputStream= clazzload.getResourceAsStream("com/hu/jdbc.properties");
Properties properties=new Properties();
properties.load(inputStream);
String usString=properties.getProperty("user");
System.out.println(usString);
}
@Test
public void test233() throws IOException{
//如果创建的在当前的工程下的时候调用
FileInputStream fileInputStream=new FileInputStream(new File("jdbc.properties"));
Properties properties=new Properties();
properties.load(fileInputStream);
String password=properties.getProperty("password");
System.out.println(password);
}
@Test
public void test555() throws Exception, InvocationTargetException{
Class claz=Person.class;
Constructor method=claz.getDeclaredConstructor(String.class,int.class);
method.setAccessible(true);
Person person=(Person) method.newInstance("Wang",10);
System.out.println(person);
}

}