Overview of Application Examples reflective reflector _

Reflection (reflection) is regarded as the key dynamic languages,
reflection by means of the Reflection API allows a program in the execution of any type of internal information acquired,
and the internal property and a method of operation of any object can be directly

package com.aff.reflection;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import org.junit.Test;

/*
      Reflection (reflection) is regarded as the key to dynamic languages,
      Reflection Reflection API allows a program to make any type of internal information by means of the implementation period,
      And can directly operate any internal object properties and methods
      
Java reflection mechanism provides functionality:
              ① any one object belongs to the class determined at runtime
              ② a configuration of objects of any class at runtime
              ③ determining any class has member variables and methods at runtime
              ④ to call any member variables and methods of an object at runtime
              ⑤ generate dynamic proxy 
Reflecting mainly related API:
              ① java.lang.Class: on behalf of a class
              ②java.lang.reflect.Method: method represents a class of
              Field representing the class: ③java.lang.reflect.Field
              ④java.lang.reflect.Constructor: Representative class constructor
                 。。。
 */
public class TestReflection {

    // With reflective, can be created by a reflecting object class and invoke a configuration 
    @Test
     public  void test2 () throws Exception {
        Class . <Person> = clazz Person class ;
         // 1. Create clazz Person class corresponding runtime class 
        Person P = clazz.newInstance ();
        System.out.println(p);// Person [name=null, age=0]

        // specified attribute when invoked by reflection 2. Run class
         // attributes 2.1public of 
        Field, F1 = clazz.getField ( "name" );
        f1.set (P, "Bai" );
        System.out.println(p);// Person [name=李白, age=0]

        // 2.2private 的属性 使用getDeclaredField ，setAccessible(true)
        Field f2 = clazz.getDeclaredField("age");
        f2.setAccessible(true);
        f2.set(p, 33);
        System.out.println(p);// Person [name=李白, age=33]

        // specified 3. Run class when invoked by reflection 
        Method, M1 = clazz.getMethod ( "Show" );
        m1.invoke (the p-); // can be followed, then remove with no parameters, namely singing was lost, ie Hugh 
        Method, M2 = clazz.getMethod ( "Run the display", String. class ); // <?> Class ... parameterTypes ,   
                                                             // class should write the type of 
        m2.invoke (p, "Luo Yin"); // a worry also hate the lengthy \ n Luo Yin 
    }

    
    
    // In the previous reflection mechanism, how to create a class of objects and invoke methods, properties 
    @Test
     public  void test1 () {
        Person p = new Person();
        p.setAge(35);
        p.setName("罗隐");
        System.out.println(p);
        p.show();
        p.display ( "Late Tang" );
    }
}