#¤j¼Ð=Java¤Ï®g¾÷¨î
#°Æ¼Ð= Java Reflection 
#§@ªÌ=¤å¡þ«J±¶

#
==<box>===========
µ{¦¡1 	Class class¤ù¬q¡Cª`·N¥¦ªºprivate empty ctor¡A·N«ü¤£¤¹³\¥ô¦ó¤H¸g¥Ñ½sµ{¤è¦¡²£¥ÍClass object¡C¬Oªº¡A¨äobject¥u¯à¥ÑJVM²£¥Í¡C

#001 public final
#002     class Class<T> implements java.io.Serializable, 
#003 			        java.lang.reflect.GenericDeclaration, 
#004 			        java.lang.reflect.Type,
#005                        java.lang.reflect.AnnotatedElement {
#006     private Class() {}
#007     public String toString() {
#008         return ( isInterface() ? "interface " : 
#009                 (isPrimitive() ? "" : "class "))
#010                + getName();
#011     }
...
==<end>==============
#¤¤¼Ð="Class" objectªº¨ú±o³~®|
Java¤¹³\§Ú­Ì±q¦hºØºÞ¹D¬°¤@­Óclass¥Í¦¨¹ïÀ³ªºClass object¡Cªí1¬O¤@¥÷¾ã²z¡C
==<list>===============
ªí1	 Java¤¹³\¦hºØºÞ¹D¥Í¦¨Class object¡C



Class object½Ï¥ÍºÞ¹D
¥Ü¨Ò
¹B¥ÎgetClass()
µù¡G¨C­Óclass³£¦³¦¹¨ç¦¡
String str = "abc";
Class c1 = str.getClass();
¹B¥Î
Class.getSuperclass()¡]µù2¡^
Button b = new Button();
Class c1 = b.getClass();
Class c2 = c1.getSuperclass();
¹B¥Îstatic method Class.forName()
¡]³Ì±`³Q¨Ï¥Î¡^
Class c1 = Class.forName ("java.lang.String");
Class c2 = Class.forName ("java.awt.Button");
Class c3 = Class.forName ("java.util.LinkedList$Entry");
Class c4 = Class.forName ("I");
Class c5 = Class.forName ("[I");
¹B¥Î 
.class»yªk
Class c1 = String.class;
Class c2 = java.awt.Button.class;
Class c3 = Main.InnerClass.class;
Class c4 = int.class;
Class c5 = int[].class;
¹B¥Î
primitive wrapper classes
ªºTYPE»yªk
Class c1 = Boolean.TYPE;
Class c2 = Byte.TYPE;
Class c3 = Character.TYPE;
Class c4 = Short.TYPE;
Class c5 = Integer.TYPE;
Class c6 = Long.TYPE;
Class c7 = Float.TYPE;
Class c8 = Double.TYPE;
Class c9 = Void.TYPE;
==<end>==============
#¤¤¼Ð=Java classes²Õ¦¨¤ÀªR
­º¥ý®e§Ú¥Hµ{¦¡2ªºjava.util.LinkedList¬°¨Ò¡A±NJava classªº©w¸q¤j¨ø¤K¶ô¡A¨C¤@¶ô¤À§O¹ïÀ³ªí2©Ò¥ÜªºReflection API¡Cµ{¦¡3«h¬O¡uÀò±oclass¦U°Ï¶ô¸ê°T¡vªºµ{¦¡¥Ü¨Ò¤Î°õ¦æµ²ªG¡A¥¦­Ì³£¨ú¦Û¥»¤å¥Ü¨Òµ{¦¡ªº¹ïÀ³¤ù¬q¡C
==<box>===========
µ{¦¡2	±N¤@­ÓJava class¤j¨ø¤K¶ô¡A¨C¶ô¬ÛÀ³©ó¤@­Ó©Î¤@²ÕReflection APIs¡]ªí2¡^¡C
package java.util;	//(1)
import java.lang.*;	//(2)

public class LinkedList<E>						//(3)(4)(5)
    extends AbstractSequentialList<E>			//(6)
    implements List<E>, Queue<E>, 
                 Cloneable, java.io.Serializable	  	//(7)
{
    private static class Entry<E> { ¡K }			//(8)

    public LinkedList() { ¡K }					//(9)
    public LinkedList(Collection<? extends E> c) { ¡K }

    public E getFirst() { ¡K }					//(10)
    public E getLast() { ¡K }

    private transient Entry<E> header = ¡K;		//(11)
    private transient int size = 0;
}

==<end>==============	
#¤¤¼Ð=Java classes¦U¦¨¥÷©Ò¹ïÀ³ªºReflection APIs
µ{¦¡2ªº¦U­ÓJava class¦¨¥÷¡A¤À§O¹ïÀ³©óªí2ªºReflection API¡A¨ä¤¤¥X²{ªºPackage, Method, Constructor, Fieldµ¥µ¥classes¡A³£©w¸q©ójava.lang.reflect¡C
==<list>===============
ªí2	Java class¤j¨ø¤K¶ô«á¡]¦pµ{¦¡2¡^¡A¨C¤@¶ô©Ò¹ïÀ³ªºReflection API¡C¥»ªí¨Ã«DReflection APIsªº¥þ³¡¡C

Java class¤º³¡¼Ò¶ô¡]°Ñ¨£µ{¦¡2¡^
Java class¤º³¡¼Ò¶ô»¡©ú
¬ÛÀ³¤§Reflection API.
¦h¥b¬°Class methods.
¶Ç¦^­È«¬§O
(return type)
(1) package
classÁõÄÝ­þ­Ópackage
getPackage()
Package
(2) import
class¶×¤J­þ¨Çclasses
µLª½±µ¹ïÀ³¤§API¡C
¸Ñ¨M¿ìªk¨£µ{¦¡3-2¡C

(3) modifier
class¡]©Îmethods, fields¡^ªºÄÝ©Ê
int getModifiers()
Modifier.toString(int)
Modifier.isInterface(int)
int
String
bool
(4) class name
or interface name
class/interface¦WºÙ
getName()
String
(5) type parameters
°Ñ¼Æ¤Æ«¬§Oªº¦WºÙ
getTypeParameters()
TypeVariable
<Class>[]
(6) base class
base class¡]¥u¥i¯à¤@­Ó¡^
getSuperClass()
Class
(7) implemented interfaces
¹ê§@¦³­þ¨Çinterfaces
getInterfaces()
Class[]
(8) inner classes
¤ºÁô¦¡classes 
getDeclaredClasses()
Class[]
(8') outer class
¦pªG§Ú­ÌÆ[¹îªºclass¥»¨­¬Oinner classes¡A¨º»ò¬Û¹ï¥¦´N·|¦³­Óouter class¡C 
getDeclaringClass()
Class
(9) constructors
«Øºc¦¡
getDeclaredConstructors()
¤£½×?public©Îprivate©Î¨ä¥Laccess level¡A¬Ò¥iÀò±o¡C
¥t¦³¥\¯àªñ¦ü¤§¨ú±o¨ç¦¡¡C
Constructor[]
(10) methods
¾Þ§@¨ç¦¡
getDeclaredMethods()
¤£½×?public©Îprivate©Î¨ä¥Laccess level¡A¬Ò¥iÀò±o¡C
¥t¦³¥\¯àªñ¦ü¤§¨ú±o¨ç¦¡¡C
Method[]
(11) fields
Äæ¦ì¡]¦¨­ûÅܼơ^
getDeclaredFields()
¤£½×?public©Îprivate©Î¨ä¥Laccess level¡A¬Ò¥iÀò±o¡C
¥t¦³¥\¯àªñ¦ü¤§¨ú±o¨ç¦¡¡C
Field[]
==<end>==============
#¤¤¼Ð=Java Reflection API¹B¥Î¥Ü¨Ò
µ{¦¡3¥Ü½dªí2´£¹Lªº¨C¤@­ÓReflection API¡A¤Î¨ä°õ¦æµ²ªG¡Cµ{¦¡¤¤¥X²{ªºtName()¬O­Ó»²§U¨ç¦¡¡A¥i±N¨ä²Ä¤@¤Þ¼Æ©Ò¥Nªíªº¡uJava class§¹¾ã¸ô®|¦r¦ê¡v­é°£¸ô®|³¡¤À¡A¯d¤Uclass¦WºÙ¡AÀx¦s¨ì²Ä¤G¤Þ¼Æ©Ò¥Nªíªº¤@­Óhashtable¥h¨Ã¶Ç¦^¡]¦pªG²Ä¤G¤Þ¼Æ¬°null¡A´N¤£Àx¦s¦Ó¥u¬O¶Ç¦^¡^¡C
==<box>===========
µ{¦¡3-1	§ä¥XclassÁõÄݪºpackage¡C¨ä¤¤ªºc±NÄ~Äòªu¥Î©ó¥H¤U¦Uµ{¦¡¤ù¬q¡C
#001 Class c = null;
#002 c = Class.forName(args[0]);
#003 
#004 Package p;
#005 p = c.getPackage();
#006 
#007 if (p != null)
#008    System.out.println("package "+p.getName()+";");

°õ¦æµ²ªG¡]¨Ò¡^¡G
package java.util;
==<end>==============
==<box>===========
µ{¦¡3-2	§ä¥X¶×¤Jªºclasses¡A°Ê§@²Ó¸`¸Ô¨£¤º¤å»¡©ú¡C
#001 ff = c.getDeclaredFields();
#002 for (int i = 0; i < ff.length; i++) 
#003     x = tName(ff[i].getType().getName(), classRef);
#004 
#005 cn = c.getDeclaredConstructors();
#006 for (int i = 0; i < cn.length; i++) {
#007     Class cx[] = cn[i].getParameterTypes();
#008     for (int j = 0; j < cx.length; j++) 
#009          x = tName(cx[j].getName(), classRef);
#010 }
#011 
#012 mm = c.getDeclaredMethods();
#013 for (int i = 0; i < mm.length; i++) {
#014     x = tName(mm[i].getReturnType().getName(), classRef);
#015     Class cx[] = mm[i].getParameterTypes();
#016     for (int j = 0; j < cx.length; j++) 
#017         x = tName(cx[j].getName(), classRef);
#018 }
#019 classRef.remove(c.getName()); //¤£¥²°O¿ý¦Û¤v¡]¤£»Ýimport¦Û¤v¡^

°õ¦æµ²ªG¡]¨Ò¡^¡G
import java.util.ListIterator;
import java.lang.Object;
import java.util.LinkedList$Entry;
import java.util.Collection;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
==<end>==============
==<box>===========
µ{¦¡3-3 	§ä¥Xclass©Îinterfaceªº¦WºÙ¡A¤Î¨äÄÝ©Ê¡]modifiers¡^¡C

#001 int mod = c.getModifiers();
#002 System.out.print(Modifier.toString(mod));   //¾ã­Ómodifier
#003 
#004 if (Modifier.isInterface(mod)) 
#005     System.out.print(" ");  	//ÃöÁä¦r "interface" ¤w§t©ómodifier
#006 else 
#007     System.out.print(" class ");  //ÃöÁä¦r "class"
#008 System.out.print(tName(c.getName(), null)); //class¦WºÙ

°õ¦æµ²ªG¡]¨Ò¡^¡G
public class LinkedList
==<end>==============
==<box>===========
µ{¦¡3-4	§ä¥Xparameterized typesªº¦WºÙ¡C

#001 TypeVariable<Class>[] tv;
#002 tv = c.getTypeParameters(); //warning: unchecked conversion
#003 for (int i = 0; i < tv.length; i++) {
#004     x = tName(tv[i].getName(), null);  //¨Ò¦p E,K,V...
#005     if (i == 0) 	//²Ä¤@­Ó
#006         System.out.print("<" + x);       
#007     else 		//«D²Ä¤@­Ó     
#008         System.out.print("," + x);    
#009     if (i == tv.length-1) //³Ì«á¤@­Ó 
#010         System.out.println(">");                                
#011 } 

°õ¦æµ²ªG¡]¨Ò¡^¡G
   public abstract interface Map<K,V>  
©Î public class LinkedList<E>
==<end>==============
==<box>==============
µ{¦¡3-5	§ä¥Xbase class¡C°õ¦æµ²ªG¦h¥X¤@­Ó¤£¸Ó¦³ªº³r¸¹©ó§ÀºÝ¡C¦¹«D¥»³B­«ÂI¡A¬°Â²¤Æ­p¡A¤£¦h°µ³B²z¡C

#001 Class supClass;
#002 supClass = c.getSuperclass();
#003 if (supClass != null) 		//¦pªG¦³super class
#004     System.out.print("  extends" +  
#005                      tName(supClass.getName(),classRef));

°õ¦æµ²ªG¡]¨Ò¡^¡G
public class LinkedList<E>
  extends AbstractSequentialList, 
==<end>==============
==<box>===========
µ{¦¡3-6 	§ä¥Ximplemented interfaces¡C°õ¦æµ²ªG¦h¥X¤@­Ó¤£¸Ó¦³ªº³r¸¹©ó§ÀºÝ¡C¦¹«D¥»³B­«ÂI¡A¬°Â²¤Æ­p¡A¤£¦h°µ³B²z¡C

#001 Class cc[];
#002 Class ctmp;        
#003 //§ä¥X©Ò¦³³Q¹ê§@ªºinterfaces
#004 cc = c.getInterfaces();  
#005 if (cc.length != 0)
#006     System.out.print(", \r\n" + "  implements ");	//ÃöÁä¦r
#007 for (Class cite : cc)	  //JDK1.5·s¦¡°j°é¼gªk
#008     System.out.print(tName(cite.getName(), null)+", ");

°õ¦æµ²ªG¡]¨Ò¡^¡G
public class LinkedList<E>
  extends AbstractSequentialList, 
    implements List, Queue, Cloneable, Serializable, 
==<end>==============
==<box>===========
µ{¦¡3-7 / §ä¥Xinner classes©Mouter class¡C
#001 cc = c.getDeclaredClasses();  //§ä¥Xinner classes
#002 for (Class cite : cc)
#003      System.out.println(tName(cite.getName(), null));                 
#004 
#005 ctmp = c.getDeclaringClass(); //§ä¥Xouter classes
#006 if (ctmp != null)
#007     System.out.println(ctmp.getName());

°õ¦æµ²ªG¡]¨Ò¡^¡G
LinkedList$Entry
LinkedList$ListItr
==<end>==============
==<box>===========
µ{¦¡3-8a 	§ä¥X©Ò¦³constructors¡C

#001 Constructor cn[];
#002 cn = c.getDeclaredConstructors();
#003 for (int i = 0; i < cn.length; i++) {
#004      int md = cn[i].getModifiers();
#005      System.out.print("  " + Modifier.toString(md) + " " + 
#006                           cn[i].getName());
#007      Class cx[] = cn[i].getParameterTypes();
#008      System.out.print("(");
#009      for (int j = 0; j < cx.length; j++) {
#010           System.out.print(tName(cx[j].getName(), null));
#011           if (j < (cx.length - 1)) System.out.print(", ");
#012      }
#013      System.out.print(")");
#014 }

°õ¦æµ²ªG¡]¨Ò¡^¡G
    public java.util.LinkedList(Collection) 
    public java.util.LinkedList() 
==<end>==============
==<box>===========
µ{¦¡3-8b 	 §ä¥X©Ò¦³constructors¡C¥»¨Ò¦bfor°j°é¤º¨Ï¥ÎtoGenericString()¡A¬Ù¨Æ¡C
#004      System.out.println(cn[i].toGenericString());

°õ¦æµ²ªG¡]¨Ò¡^¡G
    public java.util.LinkedList(java.util.Collection<? extends E>)
    public java.util.LinkedList()
==<end>==============
==<box>===========
µ{¦¡3-9a 	§ä¥X©Ò¦³methods¡C
#001 Method mm[];
#002 mm = c.getDeclaredMethods();
#003 for (int i = 0; i < mm.length; i++) {
#004      int md = mm[i].getModifiers();
#005      System.out.print("    "+Modifier.toString(md)+" "+
#006           tName(mm[i].getReturnType().getName(), null)+" "+
#007           mm[i].getName());
#008      Class cx[] = mm[i].getParameterTypes();
#009      System.out.print("(");
#010      for (int j = 0; j < cx.length; j++) {
#011           System.out.print(tName(cx[j].getName(), null));
#012           if (j < (cx.length - 1)) System.out.print(", ");
#013      }
#014      System.out.print(")");
#015 }

°õ¦æµ²ªG¡]¨Ò¡^¡G
    public Object get(int) 
    public int size() 
==<end>==============
==<box>==============
µ{¦¡3-9b	§ä¥X©Ò¦³methods¡C¥»¨Ò¦bfor°j°é¤º¨Ï¥ÎtoGenericString()¡A¬Ù¨Æ¡C
#004      System.out.println(mm[i].toGenericString());

    public E java.util.LinkedList.get(int)
    public int java.util.LinkedList.size()
==<end>==============
==<box>===========
µ{¦¡3-10a	§ä¥X©Ò¦³fields¡C

#001 Field ff[];
#002 ff = c.getDeclaredFields();
#003 for (int i = 0; i < ff.length; i++) {
#004    int md = ff[i].getModifiers();
#005    System.out.println("    "+Modifier.toString(md)+" "+
#006         tName(ff[i].getType().getName(), null) +" "+
#007         ff[i].getName()+";");
#008 }

°õ¦æµ²ªG¡]¨Ò¡^¡G
    private transient LinkedList$Entry header;
    private transient int size;
==<end>==============
==<box>===========
µ{¦¡3-10b / §ä¥X©Ò¦³fields¡C¥»¨Ò¦bfor°j°é¤º¨Ï¥ÎtoGenericString()¡A¬Ù¨Æ¡C
#004    System.out.println("G: " + ff[i].toGenericString());        

private transient java.util.LinkedList.java.util.LinkedList$Entry<E> „t
java.util.LinkedList.header
private transient int java.util.LinkedList.size
==<end>==============

==<box>===========
µ{¦¡4	°ÊºA¥Í¦¨¡uClass object©Ò¹ïÀ³¤§class¡vªºª«¥ó¹êÅé¡FµL¤Þ¼Æ¡C

#001 Class c = Class.forName("DynTest");
#002 Object obj = null;
#003 obj = c.newInstance();  //¤£±a¤Þ¼Æ
#004 System.out.println(obj);
==<end>==============
==<box>===========
µ{¦¡5	°ÊºA¥Í¦¨¡uClass object¹ïÀ³¤§class¡vªºª«¥ó¹êÅé¡F¤Þ¼Æ¥HObject[]ªí¥Ü¡C

#001 Class c = Class.forName("DynTest");
#002 Class[] pTypes = new Class[] { double.class, int.class };
#003 Constructor ctor = c.getConstructor(pTypes);
#004   //«ü©wparameter list¡A«K¥iÀò±o¯S©w¤§ctor
#005             
#006 Object obj = null;
#007 Object[] arg = new Object[] {3.14159, 125}; //¤Þ¼Æ
#008 obj = ctor.newInstance(arg);
#009 System.out.println(obj);
==<end>==============

==<box>===========
µ{¦¡6	°ÊºA³ê°_method¡C
#001 public String func(String s, Hashtable ht)
#002 {
#003  ¡KSystem.out.println("func invoked"); return s; 
#004 }
#005 public static void main(String args[])
#006 {
#007   Class c = Class.forName("Test");
#008   Class ptypes[] = new Class[2];
#009   ptypes[0] = Class.forName("java.lang.String");
#010   ptypes[1] = Class.forName("java.util.Hashtable");
#011   Method m = c.getMethod("func",ptypes);
#012   Test obj = new Test();
#013   Object args[] = new Object[2];
#014   arg[0] = new String("Hello,world");
#015   arg[1] = null;
#016   Object r = m.invoke(obj, arg);
#017   Integer rval = (String)r;
#018   System.out.println(rval);
#019 }
==<end>==============

==<box>===========
µ{¦¡7	°ÊºAÅܧófield¤º®e¡C
#001 public class Test {
#002   public double d;
#003         
#004   public static void main(String args[])
#005   {
#006      Class c = Class.forName("Test");
#007      Field f = c.getField("d");	//«ü©wfield¦WºÙ
#008      Test obj = new Test();
#009      System.out.println("d= " + (Double)f.get(obj));
#010      f.set(obj, 12.34);
#011      System.out.println("d= " + obj.d);
#012   }
#013 }
==<end>==============



==<box>===========
µ{¦¡8	¤@­Ó¥i¦bDOS Box¤¤¨Ï¥Îªº§å¦¸ÀÉ¡]batch file¡^¡A¥Î¥H¦Û°Ê¤Æjava.lang.Classªº­×§ï°Ê§@¡CPkzipc(.exe)¬O­Ó©R¥O¦CÀ£ÁY¤u¨ã¡Aadd©Mpath³£¬O¨ä©R¥O¡C

del e:\java\lang\*.class					//²M²z°®²b
del c:\jdk150\jre\lib\endorsed\foo.jar		//²M²z°®²b
c:
cd c:\jdk150\src\java\lang
javac -Xlint:unchecked Class.java			//½sĶ·½½X
javac -Xlint:unchecked ClassLoader.java		//½sĶ¥t¤@­Ó·½½X¡]¦p¦³¥²­n¡^
move *.class e:\java\lang					//·h²¾¦Ü¨è·N»s³yªº¥Ø¿ý¤¤
e:
cd e:\java\lang							//¥H¤UÀ£ÁY¦Ü¾A·í¥Ø¿ý
pkzipc -add -path=root c:\jdk150\jre\lib\endorsed\foo.jar *.class
cd e:\test								//¶i¤J´ú¸Õ¥Ø¿ý
javac -Xlint:unchecked Test.java			//½sĶ´ú¸Õµ{¦¡
java Test								//°õ¦æ´ú¸Õµ{¦¡
==<end>==============


==<box>===========
¬ÛÃö¸ê·½
¥H¤U¬Oµø³¥©Ò¤Î»P¥»¤å¥DÃD¬ÛÃöªº§ó¦h°Q½×¡C³o¨Ç¸ê°T¥i¥HÀ±¸É¦]¤å³¹½g´T­­¨î¦Ó±a¨Óªº¤£¨¬¡A©Î±aµ¹§A§ó¦hµø³¥¡C
* "Take an in-depth look at the Java Reflection API -- Learn about the new Java 1.1 tools for finding out information about classes", by Chuck McManis¡C¦¹½g¤å³¹©Òªþµ{¦¡½X¬O¥»¤å¥Ü¨Òµ{¦¡ªº¥D­n¨Ì¾Ú¡]¥»¤å¥Ü¨Òµ{¦¡¥Ü½d¤F§ó¦hReflection APIs¡A¨Ã±Ä¥ÎJDK1.5·s¦¡ªºfor-loop¼gªk¡^¡C
* "Take a look inside Java classes -- Learn to deduce properties of a Java class from inside a Java program", by Chuck McManis¡C
* "The basics of Java class loaders -- The fundamentals of this key component of the Java architecture", by Chuck McManis¡C
* ¡mThe Java Tutorial Continued¡n, Sun microsystems. Lesson58-61, "Reflection".
==<end>==============