反射_通过反射获取成员变量、构造方法、成员方法的使用

package cn.itcast_01;

public class Person {
  private String name;
  int age;
  public String address;

  public Person() {

  }

  private Person(String name) {
    this.name = name;
  }

  Person(String name, int age) {
    this.name = name;
    this.age = age;
  }

  public Person(String name, int age, String address) {
    this.name = name;
    this.age = age;
    this.address = address;
  }

  public void show() {
    System.out.println("show");
  }

  public void method(String s) {
    System.out.println("method:" + s);
  }

  public String getString(String name, int age) {
    return name + "----" + age;
  }

  private void function() {
    System.out.println("function");
  }

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

package cn.itcast_04;

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

/*
 * 需求:通过反射对Person进行操作使用
 * 
 * private String name;
 * int age;
 * public String address;
 *   
 * public Person()
 * private Person(String name)
 * Person(String name, int age) 
 * public Person(String name, int age, String address) 
 * 
 * public void show()
 * public void method(String s) 
 * public String getString(String name, int age)
 * private void function() 
 */
public class ReflectDemo2 {
  public static void main(String[] args) throws Exception {
    // 获取字节码文件对象
    Class c = Class.forName("cn.itcast_01.Person");

    // 获取无参构造方法对象
    Constructor con = c.getConstructor();
    // 通过无参构造方法对象创建对象
    Object obj = con.newInstance();
    System.out.println(obj);

    // 通过反射给所有成员变量赋值
    System.out.println("****通过反射给所有成员变量赋值****");
    // private String name;
    Field nameField = c.getDeclaredField("name");
    nameField.setAccessible(true);
    nameField.set(obj, "风清杨");
    System.out.println(obj);
    // int age;
    Field ageField = c.getDeclaredField("age");
    ageField.setAccessible(true);
    ageField.set(obj, 27);
    System.out.println(obj);
    // public String address;
    Field addressField = c.getField("address");
    addressField.set(obj, "上海");
    System.out.println(obj);

    // 通过反射给所有构造方法赋值
    System.out.println("****通过反射给所有构造方法赋值****");
    // public Person()
    // private Person(String name)
    Constructor con2 = c.getDeclaredConstructor(String.class);
    con2.setAccessible(true);
    Object obj2 = con2.newInstance("王小明");
    System.out.println(obj2);
    // Person(String name, int age)
    Constructor con3 = c.getDeclaredConstructor(String.class, int.class);
    con3.setAccessible(true);
    Object obj3 = con3.newInstance("林子聪", 35);
    System.out.println(obj3);
    // public Person(String name, int age, String address)
    Constructor con4 = c.getConstructor(String.class, int.class,
        String.class);
    Object obj4 = con4.newInstance("江小斐", 56, "山东");
    System.out.println(obj4);

    // 通过反射调用所有成员方法
    System.out.println("****通过反射调用所有成员方法****");
    // public void show()
    Method m1 = c.getMethod("show");
    m1.invoke(obj);
    // public void method(String s)
    Method m2 = c.getMethod("method", String.class);
    m2.invoke(obj, "hello");
    // public String getString(String name, int age)
    Method m3 = c.getMethod("getString", String.class, int.class);
    Object objString = m3.invoke(obj, "world", 100);
    System.out.println(objString);
    // private void function()
    Method m4 = c.getDeclaredMethod("function");
    m4.setAccessible(true);
    m4.invoke(obj);
  }
}