【实例8】调用其他类中的方法
[
java]
package org.zhang.test;
import
java.lang.reflect.Constructor;
import
java.lang.reflect.InvocationTargetException;
import
java.lang.reflect.Method;
import
java.lang.reflect.Modifier;
interface Chiness{
void say();
}
class Person implements Chiness{
public Person(){
}
@Override
public void say() {
System.out.println("我是中国人");
}
public void sayHello(String str,int x){
System.out.println("Hello, String is: " + str + ", int is: " + x);
}
}
public class ReflectTest {
public static void main(String[] args){
Class<?> personClass = null;
try {
personClass = Class.forName("org.zhang.test.Person");
Method method = personClass.getMethod("say");
method.invoke(personClass.newInstance());
Method sayHello = personClass.getMethod("sayHello",String.class,int.class);
sayHello.invoke(personClass.newInstance(),"你好",25);
} catch (ClassNotFoundException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (NoSuchMethodException e){
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (InvocationTargetException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (InstantiationException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
}
}
【结果：】
[html]
我是中国人
Hello, String is: 你好, int is: 25
【实例9】调用其他类的getter、setter方法
[
java]
package org.zhang.test;
import
java.lang.reflect.InvocationTargetException;
import
java.lang.reflect.Method;
class Person {
private String name;
private String sex;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
}
public class ReflectTest {
public static void main(String[] args) {
Class<?> personClass = null;
try {
personClass = Class.forName("org.zhang.test.Person");
Person person = (Person) personClass.newInstance();
setter(person,"name","xiaozhang");
setter(person,"sex","男");
getter(person,"name");
getter(person,"sex");
} catch (InstantiationException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (IllegalAccessException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (ClassNotFoundException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
}
public static void getter(Object obj, String attr) {
try {
Class<?> objClass = obj.getClass();
String methodName = "get" + attr.substring(0, 1).toUpperCase() + attr.substring(1);
Method getMethod = objClass.getMethod(methodName);
System.out.println(getMethod.invoke(obj));
} catch (NoSuchMethodException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (IllegalAccessException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (InvocationTargetException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
}
public static void setter(Object obj, String attr, Object value) {
try {
Class<?> objClass = obj.getClass();
String methodName = "set" + attr.substring(0, 1).toUpperCase() + attr.substring(1);
Method setMethod = objClass.getMethod(methodName, value.getClass());
setMethod.invoke(obj,value);
} catch (NoSuchMethodException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (IllegalAccessException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (InvocationTargetException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
}
}
【结果：】
[html]
xiaozhang
男
【实例10】通过反射操作类的属性
[
java]
public class ReflectTest {
public static void main(String[] args) {
Class<?> personClass = null;
try {
personClass = Class.forName("org.zhang.test.Person");
Person person = (Person) personClass.newInstance();
person.setName("old name");
person.setSex("male");
System.out.println(person.getName());
Field nameField = personClass.getDeclaredField("name");
nameField.setAccessible(true);
nameField.set(person,"new name");
System.out.println(nameField.get(person));
} catch (InstantiationException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (IllegalAccessException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (ClassNotFoundException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (NoSuchFieldException e){
e.printStackTrace();
}
}
}
【结果：】
[html]
old name
new name
【实例11】通过反射，操作数组
[
java]
public class ReflectTest {
public static void main(String[] args) {
int [] temp = {1,2,3,4,5};
Class<?> tempClass = temp.getClass().getComponentType();
System.out.println("数组类型：" + tempClass.getName());
System.out.println("数组长度：" + Array.getLength(temp));
System.out.println("数组的第一个元素：" + Array.get(temp,0));
Array.set(temp,0,100);
System.out.println("修改后的第一个元素是：" + Array.get(temp,0));
}
}
【结果：】
[html]
数组类型：int
数组长度：5
数组的第一个元素：1
修改后的第一个元素是：100
【实例12】获取类加载器
[
java]
public class ReflectTest {
public static void main(String[] args) {
Person p = new Person();
System.out.println(p.getClass().getClassLoader().getClass().getName());
}
}
【结果：】
[html]
sun.misc.Launcher$AppClassLoader
【注：】
java 中有3种类加载器
1、引导类加载器（bootstrap class loader）：它用来加载
java 的核心库，是用原生代码来实现的，并不继承自
java.lang.ClassLoader
2、扩展类加载器（extensions class loader）：一般在 jre\lib\ext 目录下
3、AppClassLoader：常用，
java中默认加载器
