package com.zimug.java.reflection;
public class Student {
    public String nickName;
    private Integer age;   //這里是private
    public void dinner(){
        System.out.println("吃晚餐！");
    }
    private void sleep(int minutes){   //private修飾符
        System.out.println("睡" + minutes + "分鐘");
    }
}

Student student = new Student();
student.dinner();

//獲取Student類信息
Class cls = Class.forName("com.zimug.java.reflection.Student");
//對象實例化
Object obj = cls.getDeclaredConstructor().newInstance();
//根據方法名獲取并執(zhí)行方法
Method dinnerMethod = cls.getDeclaredMethod("dinner");
dinnerMethod.invoke(obj);  //打?。撼酝聿停?

Class cls = Class.forName("com.zimug.java.reflection.Student");
Class cls2 = new Student().getClass();
System.out.println(cls == cls2); //比較Class對象的地址，輸出結果是true

/**
* Class.forName方法獲取Class對象，這也是反射中最常用的獲取對象的方法，因為字符串傳參增強了配置實現(xiàn)的靈活性
*/
Class cls = Class.forName("com.zimug.java.reflection.Student");

/**
* `類名.class`的方式獲取Class對象
*/
Class clz = User.class;

/**
* `類對象.getClass()`方式獲取Class對象
*/
User user = new User();
Class clazz = user.getClass();

Class cls = Class.forName("com.zimug.java.reflection.Student");
//獲取類的包名+類名
System.out.println(cls.getName());          //com.zimug.java.reflection.Student
//獲取類的父類
Class cls = Class.forName("com.zimug.java.reflection.Student");
//這個類型是不是一個注解？
System.out.println(cls.isAnnotation());     //false
//這個類型是不是一個枚舉？
System.out.println(cls.isEnum());      //false
//這個類型是不是基礎數(shù)據類型？
System.out.println(cls.isPrimitive()); //false

Class cls = Class.forName("com.zimug.java.reflection.Student");
Field[] fields = cls.getFields();
for (Field field : fields) {
System.out.println(field.getName());      //nickName
}
fields = cls.getDeclaredFields();
for (Field field : fields) {
System.out.println(field.getName());      //nickName 換行  age
}

        Class cls = Class.forName("com.zimug.java.reflection.Student");
        Method[] methods = cls.getMethods();
        System.out.println("Student對象的非私有方法");
        for (Method m : methods) {
            System.out.print(m.getName() + ",");
        }
        System.out.println("  end");
        Method[] allMethods = cls.getDeclaredMethods();
        System.out.println("Student對象的所有方法");
        for (Method m : allMethods) {
            System.out.print(m.getName() + ",");
        }
        System.out.println("  end");
        Method dinnerMethod = cls.getMethod("dinner");
        System.out.println("dinner方法的參數(shù)個數(shù)" + dinnerMethod.getParameterCount());
        Method sleepMethod = cls.getDeclaredMethod("sleep",int.class);
        System.out.println("sleep方法的參數(shù)個數(shù)" + sleepMethod.getParameterCount());
        System.out.println("sleep方法的參數(shù)對象數(shù)組" + Arrays.toString(sleepMethod.getParameters()));
        System.out.println("sleep方法的參數(shù)返回值類型" + sleepMethod.getReturnType());

Method dinnerMethod = cls.getDeclaredMethod("dinner");
dinnerMethod.invoke(obj);  //打?。撼酝聿停?

public Object invoke(Object obj, Object... args)

//獲取Student類信息
Class cls = Class.forName("com.zimug.java.reflection.Student");
//對象實例化
Student student = (Student)cls.getDeclaredConstructor().newInstance();
//下面的這種方法是已經Deprecated了，不建議使用。但是在比較舊的JDK版本中仍然是唯一的方式。
//Student student = (Student)cls.newInstance();

public void invokeClassMethod(String className,String methodName) throws ClassNotFoundException, 
            NoSuchMethodException, 
            InvocationTargetException, 
            InstantiationException, 
            IllegalAccessException {
        //獲取類信息
        Class cls = Class.forName(className);
        //對象實例化
        Object obj = cls.getDeclaredConstructor().newInstance();
        //根據方法名獲取并執(zhí)行方法
        Method dinnerMethod = cls.getDeclaredMethod(methodName);
        dinnerMethod.invoke(obj);
}

@TableName("t_student")
public class Student {
    public String nickName;
    private Integer age;
}

@Target(ElementType.TYPE)  //表示TableName可作用于類、接口或enum Class, 或interface
@Retention(RetentionPolicy.RUNTIME) //表示運行時由JVM加載
public @interface TableName {
       String value() ;   //則使用@TableName注解的時候： @TableName(”t_student”);
}

<dependency>
    <groupId>org.reflections</groupId>
    <artifactId>reflections</artifactId>
    <version>0.9.10</version>
</dependency>

// 要掃描的包
String packageName = "com.zimug.java.reflection";
Reflections f = new Reflections(packageName);
// 獲取掃描到的標記注解的集合
Set<Class<?>> set = f.getTypesAnnotatedWith(TableName.class);
for (Class<?> c : set) {
// 循環(huán)獲取標記的注解
TableName annotation = c.getAnnotation(TableName.class);
// 打印注解中的內容
System.out.println(c.getName() + "類，TableName注解value=" + annotation.value());

//按路徑加載jar包
File file = new File("D:/com/zimug/commons-lang3.jar");
URL url = file.toURI().toURL();
//創(chuàng)建類加載器
ClassLoader classLoader = new URLClassLoader(new URL[]{url});
Class cls = classLoader.loadClass("org.apache.commons.lang3.StringUtils");

//java的.class文件所在路徑
File file = new File("D:/com/zimug");
URL url = file.toURI().toURL();
//創(chuàng)建類加載器
ClassLoader classLoader = new URLClassLoader(new URL[]{url});
//加載指定類，package全路徑
Class<?> cls = classLoader.loadClass("com.zimug.java.reflection.Student");