获取类的运行时结构

Class对象的常用方法

/**
 * @Description 获得类的信息
 * @Author Administrator
 * @Date 2020/12/2 10:55
 */
public class Test08 {

    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException, NoSuchMethodException {

        Class c1 = Class.forName("com.hejin.reflection.User");

        // 获得类的名字：包名 + 类名
        System.out.println(c1.getName());
        // 获得类的简单名字：类名
        System.out.println(c1.getSimpleName());

        System.out.println("==============");
        /**
         * 获得类的属性
         * getFields()只能找到public属性
         * getDeclaredFields()能找到全部的属性
         */
        Field[] fields = c1.getDeclaredFields();
        for (Field field : fields) {
            System.out.println(field);
        }

        // 获取指定属性的值
        System.out.println("==============");
        Field field = c1.getDeclaredField("name");
        System.out.println(field);

        // 获得类的方法getMethods：获取本类以及父类的所有public方法
        System.out.println("==============");
        Method[] methods = c1.getMethods();
        for (Method method : methods) {
            System.out.println("正常的：" + method);
        }
        System.out.println("==============");
        // getDeclaredMethods：获取本类的所有方法
        Method[] methods1 = c1.getDeclaredMethods();
        for (Method method : methods1) {
            System.out.println("getDeclaredMethods：" + method);
        }

        Method getName = c1.getMethod("getName", null);
        Method setName = c1.getMethod("setName", String.class);
        System.out.println("==============");
        System.out.println("getName：" + getName);
        System.out.println("setName：" + setName);

        // 获取所有的构造器
        System.out.println("==============");
        Constructor[] constructors = c1.getConstructors();
        for (Constructor constructor : constructors) {
            System.out.println("getConstructors：" + constructor);
        }
        Constructor[] declaredConstructors = c1.getDeclaredConstructors();
        for (Constructor declaredConstructor : declaredConstructors) {
            System.out.println("getDeclaredConstructors：" + declaredConstructor);
        }

        // 获取指定的构造器
        System.out.println("==============");
        System.out.println(c1.getConstructor(null));
        System.out.println(c1.getConstructor(int.class,String.class,int.class));
    }
}

测试结果

com.hejin.reflection.User
User
==============
private int com.hejin.reflection.User.id
private java.lang.String com.hejin.reflection.User.name
private int com.hejin.reflection.User.age
==============
private java.lang.String com.hejin.reflection.User.name
==============
正常的：public java.lang.String com.hejin.reflection.User.toString()
正常的：public java.lang.String com.hejin.reflection.User.getName()
正常的：public int com.hejin.reflection.User.getId()
正常的：public void com.hejin.reflection.User.setName(java.lang.String)
正常的：public void com.hejin.reflection.User.setAge(int)
正常的：public void com.hejin.reflection.User.setId(int)
正常的：public int com.hejin.reflection.User.getAge()
正常的：public final void java.lang.Object.wait() throws java.lang.InterruptedException
正常的：public final void java.lang.Object.wait(long,int) throws java.lang.InterruptedException
正常的：public final native void java.lang.Object.wait(long) throws java.lang.InterruptedException
正常的：public boolean java.lang.Object.equals(java.lang.Object)
正常的：public native int java.lang.Object.hashCode()
正常的：public final native java.lang.Class java.lang.Object.getClass()
正常的：public final native void java.lang.Object.notify()
正常的：public final native void java.lang.Object.notifyAll()
==============
getDeclaredMethods：public java.lang.String com.hejin.reflection.User.toString()
getDeclaredMethods：public java.lang.String com.hejin.reflection.User.getName()
getDeclaredMethods：public int com.hejin.reflection.User.getId()
getDeclaredMethods：public void com.hejin.reflection.User.setName(java.lang.String)
getDeclaredMethods：private void com.hejin.reflection.User.test()
getDeclaredMethods：public void com.hejin.reflection.User.setAge(int)
getDeclaredMethods：public void com.hejin.reflection.User.setId(int)
getDeclaredMethods：public int com.hejin.reflection.User.getAge()
==============
getName：public java.lang.String com.hejin.reflection.User.getName()
setName：public void com.hejin.reflection.User.setName(java.lang.String)
==============
getConstructors：public com.hejin.reflection.User()
getConstructors：public com.hejin.reflection.User(int,java.lang.String,int)
getDeclaredConstructors：public com.hejin.reflection.User()
getDeclaredConstructors：public com.hejin.reflection.User(int,java.lang.String,int)
==============
public com.hejin.reflection.User()
public com.hejin.reflection.User(int,java.lang.String,int)

Process finished with exit code 0