1 package sample; 2 3 import javassist.*; 4 5 /* 6 A very simple sample program 7 8 This program overwrites sample/Test.class (the class file of this 9 class itself) for adding a method g(). If the method g() is not 10 defined in class Test, then this program adds a copy of 11 f() to the class Test with name g(). Otherwise, this program does 12 not modify sample/Test.class at all. 13 14 To see the modified class definition, execute: 15 16 % javap sample.Test 17 18 after running this program. 19 */ 20 public class Test { 21 public int f(int i) { 22 return i + 1; 23 } 24 25 public static void main(String[] args) throws Exception { 26 ClassPool pool = ClassPool.getDefault(); 27 28 CtClass cc = pool.get("sample.Test"); 29 try { 30 cc.getDeclaredMethod("g"); 31 System.out.println("g() is already defined in sample.Test."); 32 } 33 catch (NotFoundException e) { 34 /* getDeclaredMethod() throws an exception if g() 35 * is not defined in sample.Test. 36 */ 37 CtMethod fMethod = cc.getDeclaredMethod("f"); 38 CtMethod gMethod = CtNewMethod.copy(fMethod, "g", cc, null); 39 cc.addMethod(gMethod); 40 cc.writeFile(); // update the class file 41 System.out.println("g() was added."); 42 } 43 } 44 } 45
