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1 package sample.evolve;
2
3 import javassist.*;
4 import java.io.IOException  ;
5
6
26 public class Evolution implements Translator {
27 public final static String handlerMethod = "_makeInstance";
28 public final static String latestVersionField
29 = VersionManager.latestVersionField;
30 public final static String versionManagerMethod = "initialVersion";
31
32 private static CtMethod trapMethod;
33 private static final int initialVersion = 0;
34 private ClassPool pool;
35 private String updatableClassName = null;
36 private CtClass updatableClass = null;
37
38 public void start(ClassPool _pool) throws NotFoundException {
39 pool = _pool;
40
41 trapMethod = _pool.getMethod("sample.evolve.Sample", "make");
44 }
45
46 public void onLoad(ClassPool _pool, String classname)
47 throws NotFoundException, CannotCompileException
48 {
49 onLoadUpdatable(classname);
50
51
55 CtClass clazz = _pool.get(classname);
56 CtClass absClass = updatableClass;
57 CodeConverter converter = new CodeConverter();
58 converter.replaceNew(absClass, absClass, handlerMethod);
59 clazz.instrument(converter);
60 }
61
62 private void onLoadUpdatable(String classname)
63 throws NotFoundException, CannotCompileException
64 {
65
68 int i = classname.lastIndexOf('$');
69 if (i <= 0)
70 return;
71
72 String orgname = classname.substring(0, i);
73 if (!orgname.equals(updatableClassName))
74 return;
75
76 int version;
77 try {
78 version = Integer.parseInt(classname.substring(i + 1));
79 }
80 catch (NumberFormatException e) {
81 throw new NotFoundException(classname, e);
82 }
83
84 CtClass clazz = pool.getAndRename(orgname, classname);
85 makeConcreteClass(clazz, updatableClass, version);
86 }
87
88
90 public void makeUpdatable(String classname)
91 throws NotFoundException, CannotCompileException
92 {
93 if (pool == null)
94 throw new RuntimeException (
95 "Evolution has not been linked to ClassPool.");
96
97 CtClass c = pool.get(classname);
98 updatableClassName = classname;
99 updatableClass = makeAbstractClass(c);
100 }
101
102
105 protected CtClass makeAbstractClass(CtClass clazz)
106 throws CannotCompileException, NotFoundException
107 {
108 int i;
109
110 CtClass absClass = pool.makeClass(clazz.getName());
111 absClass.setModifiers(Modifier.PUBLIC | Modifier.ABSTRACT);
112 absClass.setSuperclass(clazz.getSuperclass());
113 absClass.setInterfaces(clazz.getInterfaces());
114
115
117 CtField fld = new CtField(pool.get("java.lang.Class"),
118 latestVersionField, absClass);
119 fld.setModifiers(Modifier.PUBLIC | Modifier.STATIC);
120
121 CtField.Initializer finit
122 = CtField.Initializer.byCall(
123 pool.get("sample.evolve.VersionManager"),
124 versionManagerMethod,
125 new String [] { clazz.getName() });
126 absClass.addField(fld, finit);
127
128 CtField[] fs = clazz.getDeclaredFields();
129 for (i = 0; i < fs.length; ++i) {
130 CtField f = fs[i];
131 if (Modifier.isPublic(f.getModifiers()))
132 absClass.addField(new CtField(f.getType(), f.getName(),
133 absClass));
134 }
135
136 CtConstructor[] cs = clazz.getDeclaredConstructors();
137 for (i = 0; i < cs.length; ++i) {
138 CtConstructor c = cs[i];
139 int mod = c.getModifiers();
140 if (Modifier.isPublic(mod)) {
141 CtMethod wm
142 = CtNewMethod.wrapped(absClass, handlerMethod,
143 c.getParameterTypes(),
144 c.getExceptionTypes(),
145 trapMethod, null, absClass);
146 wm.setModifiers(Modifier.PUBLIC | Modifier.STATIC);
147 absClass.addMethod(wm);
148 }
149 }
150
151 CtMethod[] ms = clazz.getDeclaredMethods();
152 for (i = 0; i < ms.length; ++i) {
153 CtMethod m = ms[i];
154 int mod = m.getModifiers();
155 if (Modifier.isPublic(mod))
156 if (Modifier.isStatic(mod))
157 throw new CannotCompileException(
158 "static methods are not supported.");
159 else {
160 CtMethod m2
161 = CtNewMethod.abstractMethod(m.getReturnType(),
162 m.getName(),
163 m.getParameterTypes(),
164 m.getExceptionTypes(),
165 absClass);
166 absClass.addMethod(m2);
167 }
168 }
169
170 return absClass;
171 }
172
173
180 protected void makeConcreteClass(CtClass clazz,
181 CtClass abstractClass, int version)
182 throws CannotCompileException, NotFoundException
183 {
184 int i;
185 clazz.setSuperclass(abstractClass);
186 CodeConverter converter = new CodeConverter();
187 CtField[] fs = clazz.getDeclaredFields();
188 for (i = 0; i < fs.length; ++i) {
189 CtField f = fs[i];
190 if (Modifier.isPublic(f.getModifiers()))
191 converter.redirectFieldAccess(f, abstractClass, f.getName());
192 }
193
194 CtConstructor[] cs = clazz.getDeclaredConstructors();
195 for (i = 0; i < cs.length; ++i)
196 cs[i].instrument(converter);
197
198 CtMethod[] ms = clazz.getDeclaredMethods();
199 for (i = 0; i < ms.length; ++i)
200 ms[i].instrument(converter);
201 }
202 }
203 |
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