実例はJava基礎の反射を説明します。

前期の準備
本物のphoneを作成して、listインターフェースを実現します。

public class Phone implements List {
  public double price;
  public String name;
  public Phone() {
  }
  public Phone(double price, String name) {
    this.price = price;
    this.name = name;
  }
  public double getPrice() {
    return price;
  }
  public void gege(String h){
    System.out.println("gege "+h);
  }
  public void setPrice(double price) {
    this.price = price;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  @Override
  public String toString() {
    return "Phone{" +
        "price=" + price +
        ", name='" + name + '\'' +
        '}';
  }
  @Override
  public int size() {
    return 0;
  }
  @Override
  public boolean isEmpty() {
    return false;
  }
  @Override
  public boolean contains(Object o) {
    return false;
  }
  @Override
  public Iterator iterator() {
    return null;
  }
  @Override
  public Object[] toArray() {
    return new Object[0];
  }
  @Override
  public boolean add(Object o) {
    return false;
  }
  @Override
  public boolean remove(Object o) {
    return false;
  }
  @Override
  public boolean addAll(Collection c) {
    return false;
  }
  @Override
  public boolean addAll(int index, Collection c) {
    return false;
  }
  @Override
  public void clear() {
  }
  @Override
  public Object get(int index) {
    return null;
  }
  @Override
  public Object set(int index, Object element) {
    return null;
  }
  @Override
  public void add(int index, Object element) {
  }
  @Override
  public Object remove(int index) {
    return null;
  }
  @Override
  public int indexOf(Object o) {
    return 0;
  }
  @Override
  public int lastIndexOf(Object o) {
    return 0;
  }
  @Override
  public ListIterator listIterator() {
    return null;
  }
  @Override
  public ListIterator listIterator(int index) {
    return null;
  }
  @Override
  public List subList(int fromIndex, int toIndex) {
    return null;
  }
  @Override
  public boolean retainAll(Collection c) {
    return false;
  }
  @Override
  public boolean removeAll(Collection c) {
    return false;
  }
  @Override
  public boolean containsAll(Collection c) {
    return false;
  }
  @Override
  public Object[] toArray(Object[] a) {
    return new Object[0];
  }
}

1.反射の4種類のnewオブジェクト

public class Test2 {
  public static void main(String[] args) throws IllegalAccessException, InstantiationException, ClassNotFoundException {
    //   
    Phone p = new Phone(2999,"  ");
    System.out.println(p);//Phone{price=2999.0, name='  '}
    //            
    Class<Phone> phoneClass = Phone.class;
    Phone phone = phoneClass.newInstance();
    phone.setName("  ");
    phone.setPrice(3499);
    System.out.println(phone);//Phone{price=3499.0, name='  '}
    //   
    Class<?> aclass = Class.forName("com.demo.bean.Phone");
    Phone p2 = (Phone) aclass.newInstance();
    p2.setPrice(2999);
    p2.setName("  ");
    System.out.println(p2);//Phone{price=2999.0, name='  '}
    //   ,        phone.properties
    String name = ResourceBundle.getBundle("phone").getString("myphone");
    Class<?> bClass = Class.forName(name);
    Phone p3 = (Phone) bClass.newInstance();
    p3.setPrice(3299);
    p3.setName("  ");
    System.out.println(p3);//Phone{price=3299.0, name='  '}
  }
}

プロファイルphone.properties
myphone=comp.demo.bean.Phone
2.反射の取得類、親類、実現インターフェース

public class Test3 {
  public static void main(String[] args) throws ClassNotFoundException {
    String string = ResourceBundle.getBundle("phone").getString("myphone");
    Class<?> aClass = Class.forName(string);
    //        
    System.out.println(aClass.getName());//com.demo.bean.Phone
    //        
    System.out.println(aClass.getSimpleName());//Phone
    //      
    Class<?> superclass = aClass.getSuperclass();
    System.out.println(superclass.getName());//java.lang.Object
    System.out.println(superclass.getSimpleName());//Object
    //      
    Class<?>[] interfaces = aClass.getInterfaces();
    for (Class<?> in:interfaces
       ) {
      System.out.println(in.getSimpleName());
    }
  }
}

3.反射の取得空参、有参構造

public class Test4 {
  public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, InstantiationException, NoSuchMethodException {
    String string = ResourceBundle.getBundle("phone").getString("myphone");
    Class<?> aClass = Class.forName(string);
    //           
    Phone p1 = (Phone) aClass.newInstance();
    p1.setName("  ");
    p1.setPrice(2999);//Phone{price=2999.0, name='  '}
    System.out.println(p1);
    //         
    Constructor<?> constructor = aClass.getConstructor();
    System.out.println(constructor);//public com.demo.bean.Phone()
    //         
    Constructor<?>[] constructors = aClass.getConstructors();
    for (Constructor<?> c:constructors
       ) {
      System.out.println(c);
    }
  }
}

4.反射の取得方法

public class Test5 {
  public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException,InstantiationException,IllegalAccessException,InvocationTargetException{
    String string = ResourceBundle.getBundle("phone").getString("myphone");
    Class<?> aClass = Class.forName(string);
    //        
    Method[] methods = aClass.getMethods();
    for (Method m:methods
       ) {
      System.out.println(m);
    }
    //      ，       
    Method[] declaredMethods = aClass.getDeclaredMethods();
    for (Method m:declaredMethods
       ) {
      System.out.println(m);
    }
    Method gege = aClass.getMethod("gege",String.class);
    //  gege        
    System.out.println(Modifier.toString(gege.getModifiers()));
    //  gege        
    System.out.println(gege.getReturnType());
    //  gege    
    Object o = aClass.newInstance();
    gege.invoke(o,"aa");
  }
}

5.反射の取得フィールド

public class Test6 {
  public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException, InstantiationException {
    String string = ResourceBundle.getBundle("phone").getString("myphone");
    Class<?> aClass = Class.forName(string);
    //    public   ,          
    Field[] fields = aClass.getFields();
    for (Field f:fields
       ) {
      System.out.println(f.getName());
    }
    //    public   ，          
    Field[] declaredFields = aClass.getDeclaredFields();
    for (Field f:declaredFields
       ) {
      System.out.println(f.getName());
    }
    //           
    Field name = aClass.getField("name");
    String simpleName = name.getType().getSimpleName();
    System.out.println(simpleName);
    name.setAccessible(true);
    Object o = aClass.newInstance();
    name.set(o,"  ");
    System.out.println(name.get(o));
  }
}

締め括りをつける
以上はこの文章の全部の内容です。本文の内容は皆さんの学習や仕事に対して一定の参考学習価値を持ってほしいです。ありがとうございます。もっと知りたいなら、下のリンクを見てください。