java反射 java反射机制示例详解

public class ReflectDemo { 
public static void main(String args[]) throws Exception 
{  //1. 
 Class clazz = Class.forName("dsa.Person") ; 

//2. 
Class clazz1 = new Person().getClass() ; 

//3. 
Classclazz2=Person.class;
}
}

/**
*构造方法
*/
publicPerson(){
System.out.println("null");
}

publicPerson(Stringname){
System.out.println(name);
}

publicPerson(Stringname,intpwd){
System.out.println(name+"+"+pwd);
}

privatePerson(Listlist){
System.out.println("List");
}

//反射publicPerson()
@Test
publicvoidtest1()throwsException{
Classclazz=Class.forName("RflectorDemo.Person");
Constructorcr=clazz.getConstructor(null);//获取构造器对象
Personp=(Person)cr.newInstance(null);//通过构造器实例化对象
//System.out.println(p.name);
}

//反射publicPerson(Stringname)
@Test
publicvoidtest2()throwsException{
Classclazz=Class.forName("RflectorDemo.Person");
Constructorcr=clazz.getConstructor(String.class);
Personp=(Person)cr.newInstance("haha");
System.out.println(p.name);
}

//反射publicPerson(Stringname,intpwd)
@Test
publicvoidtest3()throwsException{
Classclazz=Class.forName("RflectorDemo.Person");
Constructorcr=clazz.getConstructor(String.class,int.class);
Personp=(Person)cr.newInstance("haha",1);
//System.out.println(p.name);
}

//反射publicPerson(Listlist)
@Test
publicvoidtest4()throwsException{
Classclazz=Class.forName("RflectorDemo.Person");
Constructorcr=clazz.getDeclaredConstructor(List.class);
cr.setAccessible(true);//暴力破解
Personp=(Person)cr.newInstance(newArrayList());
System.out.println(p.name);
}
//另一种创建对象的途径,只适用于无参的构造方法
@Test
publicvoidtest5()throwsException{
Classclazz=Class.forName("RflectorDemo.Person");

Personp=(Person)clazz.newInstance();
System.out.println(p.name);
}

/**
*方法
*/
publicvoidjf()
{

}
publicvoidjf(Stringname,intpwd)
{

}
publicClass[]jf(Stringname,int[]pwd)
{
returnnewClass[]{String.class,int.class};
}
privatevoidjf(InputStreamin)
{
System.out.println(in);
}
publicstaticvoidjf(intnum)
{
System.out.println(num);
}
publicstaticvoidmain(Stringargs[])
{
System.out.println("main!!!");
}

/**
*反射类的方法
*
*@authortanlvxu
*
*/
publicclassDemo2{

//反射类的方法:publicvoidjf()
@Test
publicvoidtest1()throwsException{
Personp=newPerson();
Classclazz=Class.forName("RflectorDemo.Person");
Methodmethod=clazz.getMethod("jf",null);
method.invoke(p,null);
}

//反射类的方法:publicvoidjf(Stringname,intpwd)
@Test
publicvoidtest2()throwsException{
Personp=newPerson();
Classclazz=Class.forName("RflectorDemo.Person");
Methodmethod=clazz.getMethod("jf",String.class,int.class);
method.invoke(p,"dsa",30);
}

//反射类的方法:publicClass[]jf(Stringname,int[]pwd)
@Test
publicvoidtest3()throwsException{
Personp=newPerson();
Classclazz=Class.forName("RflectorDemo.Person");
Methodmethod=clazz.getMethod("jf",String.class,int[].class);
Classcs[]=(Class[])method.invoke(p,"aads",newint[]{1,2,3});
System.out.println(cs[0]);
}

//反射类的方法:privatevoidjf(InputStreamin)
@Test
publicvoidtest4()throwsException{
Personp=newPerson();
Classclazz=Class.forName("RflectorDemo.Person");
Methodmethod=clazz.getDeclaredMethod("jf",InputStream.class);
method.setAccessible(true);
method.invoke(p,newFileInputStream("d:\\qqClient.txt"));
}

//反射类的方法:publicstaticvoidjf(intnum)
@Test
publicvoidtest5()throwsException{
Classclazz=Class.forName("RflectorDemo.Person");
Methodmethod=clazz.getMethod("jf",int.class);
method.invoke(null,30);
}

//反射类的方法:publicstaticvoidm(intnum)
@Test
publicvoidtest6()throwsException{
Classclazz=Class.forName("RflectorDemo.Person");
Methodmethod=clazz.getMethod("main",String[].class);
//method.invoke(null,(Object)newString[]{"ds","das"});
method.invoke(null,newObject[]{newString[]{"ds","das"}});
}

/**
*字段
*/
publicStringname="swr";
privateintpassword=45;
privatestaticintage=35;
测试类中：

Java代码
/**
*反射类的字段
*@authortanlvxu
*
*/
publicclassDemo3{
/**
*反射字段publicStringname="swr";
*@throwsException
*/
@Test
publicvoidtest1()throwsException
{
Personp=newPerson();
Classclazz=Class.forName("RflectorDemo.Person");
Fieldf=clazz.getField("name");
//获取字段的值
Objectvalue=f.get(p);
//获取字段的类型
Classtype=f.getType();
if(type.equals(String.class)){
Stringname=(String)f.get(p);
System.out.println(name);
}

//设置字段的值
f.set(p,"dfafa");
System.out.println(p.name);

}

/**
*反射字段privateintpassword;
*@throwsException
*/
@Test
publicvoidtest2()throwsException
{
Personp=newPerson();
Classclazz=Class.forName("RflectorDemo.Person");
Fieldf=clazz.getDeclaredField("password");
f.setAccessible(true);
f.set(p,36);
System.out.println(f.get(p));

}

/**
*反射字段privatestaticintage=35;
*@throwsException
*/
@Test
publicvoidtest3()throwsException
{
Classclazz=Class.forName("RflectorDemo.Person");
Fieldf=clazz.getDeclaredField("age");
f.setAccessible(true);
f.set(null,24);
System.out.println(f.get(null));

}