package com.reflection.class_;
/**
 * 對(duì)Class類特點(diǎn)的梳理
 */
public class Class01 {
    public static void main(String[] args) throws ClassNotFoundException {
        //看看Class類圖
        //1. Class也是類，因此也繼承Object類
        //Class
        //2. Class類對(duì)象不是new出來的，而是系統(tǒng)創(chuàng)建的
        //(1) 傳統(tǒng)new對(duì)象
        /*  ClassLoader類
            public Class<?> loadClass(String name) throws ClassNotFoundException {
                return loadClass(name, false);
            }
         */
        //Cat cat = new Cat();
        //(2) 反射方式, 沒有debug到 ClassLoader類的 loadClass, 原因是，我沒有注銷Cat cat = new Cat();
        /*
            ClassLoader類, 仍然是通過 ClassLoader類加載Cat類的 Class對(duì)象
            public Class<?> loadClass(String name) throws ClassNotFoundException {
                return loadClass(name, false);
            }
         */
        Class cls1 = Class.forName("com.Cat");
        //3. 對(duì)于某個(gè)類的Class類對(duì)象，在內(nèi)存中只有一份，因?yàn)轭愔患虞d一次
        Class cls2 = Class.forName("com.Cat");
        System.out.println(cls1.hashCode());
        System.out.println(cls2.hashCode());
        Class cls3 = Class.forName("com.Dog");
        System.out.println(cls3.hashCode());
    }
}

package com.reflection.class_;
import com.Car;
import java.lang.reflect.Field;
/**
 * 演示Class類的常用方法
 */
public class Class02 {
    public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, InstantiationException, NoSuchFieldException {
        String classAllPath = "com.Car";
        //1 . 獲取到Car類 對(duì)應(yīng)的 Class對(duì)象
        //<?> 表示不確定的Java類型
        Class<?> cls = Class.forName(classAllPath);
        //2. 輸出cls
        System.out.println(cls); //顯示cls對(duì)象, 是哪個(gè)類的Class對(duì)象 com.Car
        System.out.println(cls.getClass());//輸出cls運(yùn)行類型 java.lang.Class
        //3. 得到包名
        System.out.println(cls.getPackage().getName());//包名
        //4. 得到全類名
        System.out.println(cls.getName());
        //5. 通過cls創(chuàng)建對(duì)象實(shí)例
        Car car = (Car) cls.newInstance();
        System.out.println(car);//car.toString()
        //6. 通過反射獲取屬性 brand
        Field brand = cls.getField("brand");
        System.out.println(brand.get(car));//寶馬
        //7. 通過反射給屬性賦值
        brand.set(car, "奔馳");
        System.out.println(brand.get(car));//奔馳
        //8 我希望大家可以得到所有的屬性(字段)
        System.out.println("=======所有的字段屬性====");
        Field[] fields = cls.getFields();
        for (Field f : fields) {
            System.out.println(f.getName());//名稱
        }
    }
}
 

package com.reflection.class_;
import com.Car;
/**
 * 演示得到Class對(duì)象的各種方式(6)
 */
public class GetClass_ {
    public static void main(String[] args) throws ClassNotFoundException {
        //1. Class.forName
        String classAllPath = "com.Car"; //通過讀取配置文件獲取
        Class<?> cls1 = Class.forName(classAllPath);
        System.out.println(cls1);
        //2. 類名.class , 應(yīng)用場(chǎng)景: 用于參數(shù)傳遞
        Class cls2 = Car.class;
        System.out.println(cls2);
        //3. 對(duì)象.getClass(), 應(yīng)用場(chǎng)景，有對(duì)象實(shí)例
        Car car = new Car();
        Class cls3 = car.getClass();
        System.out.println(cls3);
        //4. 通過類加載器【4種】來獲取到類的Class對(duì)象
        //(1)先得到類加載器 car
        ClassLoader classLoader = car.getClass().getClassLoader();
        //(2)通過類加載器得到Class對(duì)象
        Class cls4 = classLoader.loadClass(classAllPath);
        System.out.println(cls4);
        //cls1 , cls2 , cls3 , cls4 其實(shí)是同一個(gè)對(duì)象
        System.out.println(cls1.hashCode());
        System.out.println(cls2.hashCode());
        System.out.println(cls3.hashCode());
        System.out.println(cls4.hashCode());
        //5. 基本數(shù)據(jù)(int, char,boolean,float,double,byte,long,short) 按如下方式得到Class類對(duì)象
        Class<Integer> integerClass = int.class;
        Class<Character> characterClass = char.class;
        Class<Boolean> booleanClass = boolean.class;
        System.out.println(integerClass);//int
        //6. 基本數(shù)據(jù)類型對(duì)應(yīng)的包裝類，可以通過 .TYPE 得到Class類對(duì)象
        Class<Integer> type1 = Integer.TYPE;
        Class<Character> type2 = Character.TYPE; //其它包裝類BOOLEAN, DOUBLE, LONG,BYTE等待
        System.out.println(type1);
        System.out.println(integerClass.hashCode());//?
        System.out.println(type1.hashCode());//?
    }
}

package com.reflection.class_;
import java.io.Serializable;
/**
 * 演示哪些類型有Class對(duì)象
 */
public class AllTypeClass {
    public static void main(String[] args) {
        Class<String> cls1 = String.class;//外部類
        Class<Serializable> cls2 = Serializable.class;//接口
        Class<Integer[]> cls3 = Integer[].class;//數(shù)組
        Class<float[][]> cls4 = float[][].class;//二維數(shù)組
        Class<Deprecated> cls5 = Deprecated.class;//注解
        //枚舉
        Class<Thread.State> cls6 = Thread.State.class;
        Class<Long> cls7 = long.class;//基本數(shù)據(jù)類型
        Class<Void> cls8 = void.class;//void數(shù)據(jù)類型
        Class<Class> cls9 = Class.class;//
        System.out.println(cls1);
        System.out.println(cls2);
        System.out.println(cls3);
        System.out.println(cls4);
        System.out.println(cls5);
        System.out.println(cls6);
        System.out.println(cls7);
        System.out.println(cls8);
        System.out.println(cls9);
    }
}