Java反射使用方法

//简单的例子
public class ReflextionMain {
    public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, InstantiationException, InvocationTargetException, NoSuchFieldException, NoSuchMethodException {

        EqualsMain refOne = new EqualsMain();//类全称为: equals.EqualsMain
        System.out.println(refOne.getClass().getName());//equals.EqualsMain
        System.out.println(EqualsMain.class.getName());//equals.EqualsMain
        System.out.println(EqualsMain.class.getPackage().getName());//equals

        /**
         * 对应的类
         */
        Class<?> classOne = Class.forName("equals.EqualsMain");
        System.out.println(classOne.getName());//equals.EqualsMain

        EqualsMain equOne = (EqualsMain) classOne.newInstance();
        equOne.setId("5");
        System.out.println(equOne.getId());//5

        /**
         * 所有的构造函数
         */
        Constructor<?>[] constructors = classOne.getConstructors();
        EqualsMain equTwo = (EqualsMain) constructors[0].newInstance("123");
        EqualsMain equThree = (EqualsMain) constructors[1].newInstance();

        System.out.println(equTwo.getId() + "|||" + equThree.getId());//123|||null

        System.out.println(classOne.getClassLoader().getClass().getName());//sun.misc.Launcher$AppClassLoader

        /**
         * 名称为id的字段
         */
        Field fieldOne = classOne.getDeclaredField("id");
        fieldOne.setAccessible(true);
        fieldOne.set(equOne, "456");
        System.out.println(fieldOne.get(equOne));//456

        /**
         * 父类
         */
        Class<?> superClass = classOne.getSuperclass();
        System.out.println(superClass.getName());//java.lang.Object

        /**
         * 包含的字段
         */
        Field[] fields = classOne.getDeclaredFields();
        for (Field field : fields){
            System.out.println(field);//private java.lang.String equals.EqualsMain.id
        }

        /**
         * 包含的方法
         */
        Method[] methods = classOne.getDeclaredMethods();
        /**
         * 打印内容如下:
         * public static void equals.EqualsMain.main(java.lang.String[])
         * main
         * void
         * 9
         * [java.lang.String[] arg0]
         * public boolean equals.EqualsMain.equals(java.lang.Object)
         * equals
         * boolean
         * 1
         * [java.lang.Object arg0]
         * public int equals.EqualsMain.hashCode()
         * hashCode
         * int
         * 1
         * []
         * public java.lang.String equals.EqualsMain.getId()
         * getId
         * class java.lang.String
         * 1
         * []
         * public void equals.EqualsMain.setId(java.lang.String)
         * setId
         * void
         * 1
         * [java.lang.String arg0]
         */
        for (Method method : methods){
            System.out.println(method);//函数代码写法
            System.out.println(method.getName());//函数名
            System.out.println(method.getReturnType());//函数返回类型
            System.out.println(method.getModifiers());//函数访问修饰符
            System.out.println(Arrays.toString(method.getParameters()));//函数参数
        }

        /**
         * 实现的接口
         */
        Class<?>[] interfaces = classOne.getInterfaces();
        for (Class clazz : interfaces){
            System.out.println(clazz);//interface java.io.Serializable
        }

        /**
         * 打印内容如下:
         * map中的数据
         * ----------------------
         */
        Method methodMain = classOne.getMethod("main", java.lang.String[].class);
        methodMain.invoke(classOne.newInstance(), (Object) new String[]{"999"});
    }
}

public class EqualsMain implements Serializable {
    private String id;

    public EqualsMain(String id){
        this.id = id;
    }

    public EqualsMain(){};

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    @Override
    public int hashCode() {
        return id.hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        if (null == obj) return false;
        if (this.id.equals(((EqualsMain)obj).getId())){
            return true;
        }else {
            return false;
        }
    }

    public static void main(String[] args){
        EqualsMain equalsMain1 = new EqualsMain("10");
        EqualsMain equalsMain2 = new EqualsMain("20");
        EqualsMain equalsMain3 = new EqualsMain("10");

        Map<Object , String> map = new HashMap<>();
        map.put(equalsMain1, "map中的数据");
        System.out.println(map.get(equalsMain3));
        System.out.println("----------------------");
    }
}