详解Java 反射和反射的应用场景

Class alunbarClass = TargetObject.class;

Class alunbarClass1 = Class.forName("cn.javaguide.TargetObject");

package cn.javaguide;

public class TargetObject {
  private String value;

  public TargetObject() {
    value = "JavaGuide";
  }

  public void publicMethod(String s) {
    System.out.println("I love " + s);
  }

  private void privateMethod() {
    System.out.println("value is " + value);
  }
}

package cn.javaguide;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {
  public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException, InstantiationException, InvocationTargetException, NoSuchFieldException {
    /**
     * 获取TargetObject类的Class对象并且创建TargetObject类实例
     */
    Class<?> tagetClass = Class.forName("cn.javaguide.TargetObject");
    TargetObject targetObject = (TargetObject) tagetClass.newInstance();
    /**
     * 获取所有类中所有定义的方法
     */
    Method[] methods = tagetClass.getDeclaredMethods();
    for (Method method : methods) {
      System.out.println(method.getName());
    }
    /**
     * 获取指定方法并调用
     */
    Method publicMethod = tagetClass.getDeclaredMethod("publicMethod",
        String.class);

    publicMethod.invoke(targetObject, "JavaGuide");
    /**
     * 获取指定参数并对参数进行修改
     */
    Field field = tagetClass.getDeclaredField("value");
    //为了对类中的参数进行修改我们取消安全检查
    field.setAccessible(true);
    field.set(targetObject, "JavaGuide");
    /**
     * 调用 private 方法
     */
    Method privateMethod = tagetClass.getDeclaredMethod("privateMethod");
    //为了调用private方法我们取消安全检查
    privateMethod.setAccessible(true);
    privateMethod.invoke(targetObject);
  }
}