java 反射机制详解及实例代码

/** * Project: Day12_for_lxy * Created: Lulu * Date: 2016/8/10 */public class Human<T> {  private String name;  private int age;  private float height;  private static int legs = 2;  private Map<String, String> jobs;  private T t;  public int say() {    System.out.println("I'm" + name);    return 0;  }  private void sleep(Human human) {    System.out.println(name + " sleep with " + human.name);  }  public List<Integer> getList() {    return new ArrayList<>();  }  public Human() {  }  private Human(String name, int age, float height) {    this.name = name;    this.age = age;    this.height = height;  }  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  public int getAge() {    return age;  }  public void setAge(int age) {    if (age > 150 || age < 0) {      throw new RuntimeException("age > 150 || age < 0");    }    this.age = age;  }  public float getHeight() {    return height;  }  public void setHeight(float height) {    this.height = height;  }  @Override  public String toString() {    return "Human{" +        "name='" + name + '/'' +        ", age=" + age +        ", height=" + height +        '}';  }}

/** * Project: Day12_for_lxy * Created: Lulu * Date: 2016/8/10 *//*获取构造方法 */public class TestConstructor {  public static void main(String[] args) {    //得到相应的类结构, 这是用来描述Human这个类的类    Class<Human> humanClass = Human.class;    try {////      这是在知道构造方法结构的前提下//      //获取都明确参数的构造方法, 获取的是公开的(public)//      Constructor<Human> constructor1 = humanClass.getConstructor(String.class, Integer.TYPE, Float.TYPE);////      Human h1 = constructor1.newInstance("小明", 18, 1.85f);//      System.out.println(h1.toString());////      //构造方法, 修饰符类型//      int modifiers = constructor1.getModifiers();//      if (Modifier.isPublic(modifiers)) {//        System.out.println("是public");//      }//      ////获取都明确参数的构造方法, 获取的是声明的//      Constructor<Human> constructor2 = humanClass.getDeclaredConstructor(String.class, Integer.TYPE, Float.TYPE);//      //设置可以全部访问//      constructor2.setAccessible(true);//      //这样是可以获取到所有的构造方法, 包括私有的//      Human human2 = constructor2.newInstance("zll", 18, 1.80f);//      System.out.println(human2.toString());      //不知道构造方法的类结构      Constructor<?>[] constructors = humanClass.getDeclaredConstructors();      for (Constructor<?> c : constructors) {        c.setAccessible(true);        System.out.println(c.getName());        System.out.println("===========================");        //参数列表        Class<?>[] types = c.getParameterTypes();        for (Class<?> type : types) {          System.out.println(type.getTypeName());        }        //修饰符类型        int modifiers = c.getModifiers();        if (Modifier.isPublic(modifiers)) {          System.out.println("是公开的");        }else if (Modifier.isPrivate(modifiers)){          System.out.println("是私有的");        }      }    } catch (Exception e) {      e.printStackTrace();    }  }}

/** * Project: Day12_for_lxy * Created: Lulu * Date: 2016/8/10 *//*获取属性:属性包括:( 属性名 类型 修饰符 泛型 )父类的属性自身的属性 */public class TestField {  public static void main(String[] args) {    Class<Human> humanClass = Human.class;    Field[] fields = humanClass.getDeclaredFields();    for (Field f : fields) {      //属性名      System.out.print(" 名字: " + f.getName() + " ");      System.out.println();      //类型      System.out.print("类型 :" + f.getType() + " ");      System.out.println();      //修饰符      int modifiers = f.getModifiers();      if (Modifier.isPublic(modifiers)) {        System.out.println("公开的");      } else if (Modifier.isPrivate(modifiers)) {        System.out.println("私有的");      }    }    System.out.println("============================泛型==================================");    try {      //通过类结构获取jobs属性      Field jobs = humanClass.getDeclaredField("jobs");      //泛型      ParameterizedType type = (ParameterizedType) jobs.getAnnotatedType().getType();      Type[] types = type.getActualTypeArguments();           for (Type type1 : types) {        System.out.println(type1);      }    } catch (Exception e) {      e.printStackTrace();    }    System.out.println("===================设置值, 得到值============================");    try {      Human<Object> human = new Human<>();      //非静态, 你要知道给谁设置属性的值      Field nameField = humanClass.getDeclaredField("name");      nameField.setAccessible(true);      nameField.set(human, "路新艺");      System.out.println(human.getName());      //静态      Field legs = humanClass.getDeclaredField("legs");      int modifiers = legs.getModifiers();      legs.setAccessible(true);      if (Modifier.isStatic(modifiers)) {        System.out.println("是静态的");      }      legs.set(null, 4);      System.out.println(legs.get(null));    } catch (Exception e) {      e.printStackTrace();    }  }}

/** * Project: Day12_for_lxy * Created: Lulu * Date: 2016/8/10 *//*获取方法:方法名修饰符返回值类型泛型静态和非静态方法的调用 */public class TestMethod {  public static void main(String[] args) {    Class<Human> humanClass = Human.class;    //方法名    Method[] ms = humanClass.getDeclaredMethods();    for (Method m : ms) {      m.setAccessible(true);      System.out.print("方法名: " + m.getName() + "  " );      int modifiers = m.getModifiers();      if (Modifier.isPublic(modifiers)) {        System.out.println("公开的");      } else if (Modifier.isPrivate(modifiers)) {        System.out.println("私有的");      }    }    //在确定方法参数的情况下  方法名不能唯一的确定, 重载    try {      //普通类型      Method sayM = humanClass.getDeclaredMethod("say");      Class<?> returnType = sayM.getReturnType();      System.out.println(returnType.toString());      //泛型      Method getListM = humanClass.getDeclaredMethod("getList");      System.out.println(getListM.getReturnType());      ParameterizedType type = (ParameterizedType) getListM.getAnnotatedReturnType().getType();      System.out.println(type);      Type[] ts = type.getActualTypeArguments();      for (Type t : ts) {        System.out.println(t);      }    } catch (Exception e) {      e.printStackTrace();    }  }}

public static void main(String[] args) {  printClassInfo(Student.class);}public static void printClassInfo(Class c){    //Java中唯一的父类的类时Object    System.out.println(c.getName());    System.out.println(c.getSimpleName());    System.out.println(c.getSuperclass());    Class[] interfaces = c.getInterfaces();    for (Class anInterface : interfaces) {      System.out.println(anInterface);    }    //外部类类只有两种访问权限修饰(public 和 default)    int modifiers = c.getModifiers();  }