java基础之反射相关

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已于 2025-03-06 15:43:24 修改

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文章标签： java基础反射

于 2019-07-10 10:40:52 首次发布

本文链接：https://blog.youkuaiyun.com/u014755700/article/details/95312651

博客展示了Java反射机制的应用。定义了Person类，通过ReflectTest类获取Person类的声明字段、方法和构造器，创建实例并调用方法赋值。还给出了给实例字段赋值的代码，利用反射机制根据字段名设置对应的值。

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1.测试用Person类

package reflect;

/**
* Created by Administrator on 2018/5/10.
*/
public class Person {
private Integer id;
private String name;
private String address;

public Person() {
}

public Person(Integer id, String name, String address) {
this.id = id;
this.name = name;
this.address = address;
}

public Integer getId() {
return id;
}

public void setId(Integer id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getAddress() {
return address;
}

public void setAddress(String address) {
this.address = address;
}

@Override
public String toString() {
return "Person{" +
"id=" + id +
", name='" + name + '\'' +
", address='" + address + '\'' +
'}';
}
}

2，Reflect测试类

import java.lang.reflect.*;
import java.util.Arrays;

/**
* Created by Administrator on 2018/5/10.
*/
public class ReflectTest {
public static void main(String[] args) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException, NoSuchFieldException {
Class<?> clazz=Person.class;//获取Person的Class
Field[] field=clazz.getDeclaredFields();//获取声明字段
Method[] methods=clazz.getDeclaredMethods();//获取声明方法
Constructor constructors=clazz.getConstructor(new Class[]{});//构造器
Object instance = constructors.newInstance(new Object[]{});//实例
System.out.println(instance);

for (Method m:methods){
if (m.getName().startsWith("set")){
System.out.println(m.getName());
String filedName = m.getName().substring(3).toLowerCase();
Field f = clazz.getDeclaredField(filedName);
Class<?> fclass = f.getType();
if(fclass==Integer.class){
m.invoke(instance,new Object[]{1});
}
if (fclass==String.class&&filedName.equals("name")){
m.invoke(instance,new Object[]{"张三"});
}
if (fclass==String.class && filedName.equals("address")){
m.invoke(instance,new Object[]{"上海"});
}
// m.invoke(instance,new Object[]{1});
}
}
System.out.println(instance.toString());
}
}

3、运行结果

4、给实例的字段赋值

Class<?> clazz = reqObj.getClass();//需要检测的类
               Field[] fields=clazz.getDeclaredFields();
               for (int i = 0; i < fields.length; i++) {
               if(fields[i].getName().equals(mapKey.toString()))
           {
                   fields[i].setAccessible(true);
                   fields[i].set(reqObj,map.get(mapKey).toString()); //给实例对象的字段赋值
           }
               }
           }


调用制定的方法

handlerBean.getClass().getMethod("handler", String.class, String.class).invoke(handlerBean, mqErrorLogDO.getMsgId(), mqErrorLogDO.getMessageContent());