//1.通过权限定类名获得        try {            Class
      studentClazz1 = Class.forName("com.reflact.Student");        } catch (ClassNotFoundException e) {            e.printStackTrace();        }        //2.通过Java类型获得        Class
     
       studentClass1 = Student.class;        //3.通过实例对象获得        Class
       studentClazz = new Student().getClass();
     

try {            Class
      studentClazz = Class.forName("com.reflact.Student");            //可以获得指定形参的构造方法            Constructor
      studentClazzConstructor =                    studentClazz.getDeclaredConstructor(int.class,String.class);        //获得指定的形参构造方法后初始化对象            Student student = (Student)studentClazzConstructor.newInstance(1,"小明");            System.out.println(student);        } catch (ClassNotFoundException e) {            e.printStackTrace();        } catch (NoSuchMethodException e) {            e.printStackTrace();        } catch (IllegalAccessException e) {            e.printStackTrace();        } catch (InstantiationException e) {            e.printStackTrace();        } catch (InvocationTargetException e) {            e.printStackTrace();        }    }

//直接通过类对象创建实例    @Test    public void run2(){        Class
     
       studentClass = Student.class;        try {            Student student = studentClass.newInstance();        } catch (InstantiationException e) {            e.printStackTrace();        } catch (IllegalAccessException e) {            e.printStackTrace();        }    }
     

//强制访问私有方法，创建实例    @Test    public void run3(){        Class
     
       studentClass = Student.class;        try {            Constructor
      
        studentConstructor                    = studentClass.getDeclaredConstructor(int.class);            studentConstructor.setAccessible(true);//开启强制访问            Student student                    = studentConstructor.newInstance(1);            student.setName("小明");            System.out.println(student);        } catch (NoSuchMethodException e) {            e.printStackTrace();        } catch (IllegalAccessException e) {            e.printStackTrace();        } catch (InstantiationException e) {            e.printStackTrace();        } catch (InvocationTargetException e) {            e.printStackTrace();        }    }
      
     

@Test    public void run4(){        //获得类对象        Class
     
       studentClass = Student.class;        try {            //创建实例            Student student = studentClass.newInstance();            //获得方法            Method setIdMethod = studentClass.getMethod("setId", int.class);            //通过实例调用方法            setIdMethod.invoke(student,1);            Method getIdMethod = studentClass.getMethod("getId");            int id = (int)getIdMethod.invoke(student);            System.out.println(id);        } catch (NoSuchMethodException e) {            e.printStackTrace();        } catch (IllegalAccessException e) {            e.printStackTrace();        } catch (InstantiationException e) {            e.printStackTrace();        } catch (InvocationTargetException e) {            e.printStackTrace();        }    }
     

//获得私有字段    @Test    public void run5(){        Class
     
       studentClass = Student.class;        try {            Student student = studentClass.newInstance();            Field idField = studentClass.getDeclaredField("id");            idField.setAccessible(true);            idField.set(student,1);            int id = (int)idField.get(student);            System.out.println(id);        } catch (NoSuchFieldException e) {            e.printStackTrace();        } catch (IllegalAccessException e) {            e.printStackTrace();        } catch (InstantiationException e) {            e.printStackTrace();        }    }