ctclasstype.java

Javassist是一个开源的分析、编辑和创建Java字节码的类库。是由东京技术学院的数学和计算机科学系的 Shigeru Chiba 所创建的。它已加入了开放源代码JBoss 应用服务器项目,通过使

            throw new CannotCompileException("cannot add");

        getConstructorsCache();
        constructorsCache = (CtConstructor)CtMember.append(constructorsCache, c);
        getClassFile2().addMethod(c.getMethodInfo2());
    }

    public void removeConstructor(CtConstructor m) throws NotFoundException {
        checkModify();
        MethodInfo mi = m.getMethodInfo2();
        ClassFile cf = getClassFile2();
        if (cf.getMethods().remove(mi)) {
            constructorsCache = CtMember.remove(constructorsCache, m);
            memberRemoved = true;
        }
        else
            throw new NotFoundException(m.toString());
    }

    public void addMethod(CtMethod m) throws CannotCompileException {
        checkModify();
        if (m.getDeclaringClass() != this)
            throw new CannotCompileException("cannot add");

        getMethodsCache();
        methodsCache = CtMember.append(methodsCache, m);
        getClassFile2().addMethod(m.getMethodInfo2());
        if ((m.getModifiers() & Modifier.ABSTRACT) != 0)
            setModifiers(getModifiers() | Modifier.ABSTRACT);
    }

    public void removeMethod(CtMethod m) throws NotFoundException {
        checkModify();
        MethodInfo mi = m.getMethodInfo2();
        ClassFile cf = getClassFile2();
        if (cf.getMethods().remove(mi)) {
            methodsCache = CtMember.remove(methodsCache, m);
            memberRemoved = true;
        }
        else
            throw new NotFoundException(m.toString());
    }

    public byte[] getAttribute(String name) {
        AttributeInfo ai = getClassFile2().getAttribute(name);
        if (ai == null)
            return null;
        else
            return ai.get();
    }

    public void setAttribute(String name, byte[] data) {
        checkModify();
        ClassFile cf = getClassFile2();
        cf.addAttribute(new AttributeInfo(cf.getConstPool(), name, data));
    }

    public void instrument(CodeConverter converter)
        throws CannotCompileException
    {
        checkModify();
        ClassFile cf = getClassFile2();
        ConstPool cp = cf.getConstPool();
        List list = cf.getMethods();
        int n = list.size();
        for (int i = 0; i < n; ++i) {
            MethodInfo minfo = (MethodInfo)list.get(i);
            converter.doit(this, minfo, cp);
        }
    }

    public void instrument(ExprEditor editor)
        throws CannotCompileException
    {
        checkModify();
        ClassFile cf = getClassFile2();
        List list = cf.getMethods();
        int n = list.size();
        for (int i = 0; i < n; ++i) {
            MethodInfo minfo = (MethodInfo)list.get(i);
            editor.doit(this, minfo);
        }
    }

    /**
     * @see javassist.CtClass#prune()
     * @see javassist.CtClass#stopPruning(boolean)
     */
    public void prune() {
        if (wasPruned)
            return;

        wasPruned = wasFrozen = true;
        getClassFile2().prune();
    }

    public void toBytecode(DataOutputStream out)
        throws CannotCompileException, IOException
    {
        try {
            if (isModified()) {
                checkPruned("toBytecode");
                ClassFile cf = getClassFile2();
                if (memberRemoved) {
                    cf.compact();
                    memberRemoved = false;
                }

                modifyClassConstructor(cf);
                modifyConstructors(cf);
                cf.write(out);
                out.flush();
                fieldInitializers = null;
                if (doPruning) {
                    // to save memory
                    cf.prune();
                    wasPruned = true;
                }
            }
            else {
                classPool.writeClassfile(getName(), out);
                // to save memory
                eraseCache();
                classfile = null;
            }

            wasFrozen = true;
        }
        catch (NotFoundException e) {
            throw new CannotCompileException(e);
        }
        catch (IOException e) {
            throw new CannotCompileException(e);
        }
    }

    /* See also checkModified()
     */
    private void checkPruned(String method) {
        if (wasPruned)
            throw new RuntimeException(method + "(): " + getName()
                                       + " was pruned.");
    }

    public boolean stopPruning(boolean stop) {
        boolean prev = !doPruning;
        doPruning = !stop;
        return prev;
    }

    private void modifyClassConstructor(ClassFile cf)
        throws CannotCompileException, NotFoundException
    {
        if (fieldInitializers == null)
            return;

        Bytecode code = new Bytecode(cf.getConstPool(), 0, 0);
        Javac jv = new Javac(code, this);
        int stacksize = 0;
        boolean doInit = false;
        for (FieldInitLink fi = fieldInitializers; fi != null; fi = fi.next) {
            CtField f = fi.field;
            if (Modifier.isStatic(f.getModifiers())) {
                doInit = true;
                int s = fi.init.compileIfStatic(f.getType(), f.getName(),
                                                code, jv);
                if (stacksize < s)
                    stacksize = s;
            }
        }

        if (doInit)    // need an initializer for static fileds.
            modifyClassConstructor(cf, code, stacksize, 0);
    }

    private void modifyClassConstructor(ClassFile cf, Bytecode code,
                                        int stacksize, int localsize)
        throws CannotCompileException
    {
        MethodInfo m = cf.getStaticInitializer();
        if (m == null) {
            code.add(Bytecode.RETURN);
            code.setMaxStack(stacksize);
            code.setMaxLocals(localsize);
            m = new MethodInfo(cf.getConstPool(), "<clinit>", "()V");
            m.setAccessFlags(AccessFlag.STATIC);
            m.setCodeAttribute(code.toCodeAttribute());
            cf.addMethod(m);
        }
        else {
            CodeAttribute codeAttr = m.getCodeAttribute();
            if (codeAttr == null)
                throw new CannotCompileException("empty <clinit>");

            try {
                CodeIterator it = codeAttr.iterator();
                int pos = it.insertEx(code.get());
                it.insert(code.getExceptionTable(), pos);
                int maxstack = codeAttr.getMaxStack();
                if (maxstack < stacksize)
                    codeAttr.setMaxStack(stacksize);

                int maxlocals = codeAttr.getMaxLocals();
                if (maxlocals < localsize)
                    codeAttr.setMaxLocals(localsize);
            }
            catch (BadBytecode e) {
                throw new CannotCompileException(e);
            }
        }
    }

    private void modifyConstructors(ClassFile cf)
        throws CannotCompileException, NotFoundException
    {
        if (fieldInitializers == null)
            return;

        ConstPool cp = cf.getConstPool();
        List list = cf.getMethods();
        int n = list.size();
        for (int i = 0; i < n; ++i) {
            MethodInfo minfo = (MethodInfo)list.get(i);
            if (minfo.isConstructor()) {
                CodeAttribute codeAttr = minfo.getCodeAttribute();
                if (codeAttr != null)
                    try {
                        Bytecode init = new Bytecode(cp, 0,
                                                codeAttr.getMaxLocals());
                        CtClass[] params
                            = Descriptor.getParameterTypes(
                                                minfo.getDescriptor(),
                                                classPool);
                        int stacksize = makeFieldInitializer(init, params);
                        insertAuxInitializer(codeAttr, init, stacksize);
                    }
                    catch (BadBytecode e) {
                        throw new CannotCompileException(e);
                    }
            }
        }
    }

    private static void insertAuxInitializer(CodeAttribute codeAttr,
                                             Bytecode initializer,
                                             int stacksize)
        throws BadBytecode
    {
        CodeIterator it = codeAttr.iterator();
        int index = it.skipSuperConstructor();
        if (index < 0) {
            index = it.skipThisConstructor();
            if (index >= 0)
                return;         // this() is called.

            // Neither this() or super() is called.
        }

        int pos = it.insertEx(initializer.get());
        it.insert(initializer.getExceptionTable(), pos);
        int maxstack = codeAttr.getMaxStack();
        if (maxstack < stacksize)
            codeAttr.setMaxStack(stacksize);
    }

    private int makeFieldInitializer(Bytecode code, CtClass[] parameters)
        throws CannotCompileException, NotFoundException
    {
        int stacksize = 0;
        Javac jv = new Javac(code, this);
        try {
            jv.recordParams(parameters, false);
        }
        catch (CompileError e) {
            throw new CannotCompileException(e);
        }

        for (FieldInitLink fi = fieldInitializers; fi != null; fi = fi.next) {
            CtField f = fi.field;
            if (!Modifier.isStatic(f.getModifiers())) {
                int s = fi.init.compile(f.getType(), f.getName(), code,
                                        parameters, jv);
                if (stacksize < s)
                    stacksize = s;
            }
        }

        return stacksize;
    }

    // Methods used by CtNewWrappedMethod

    Hashtable getHiddenMethods() {
        if (hiddenMethods == null)
            hiddenMethods = new Hashtable();

        return hiddenMethods;
    }

    int getUniqueNumber() { return uniqueNumberSeed++; }

    public String makeUniqueName(String prefix) {
        HashMap table = new HashMap();
        makeMemberList(table);
        Set keys = table.keySet();
        String[] methods = new String[keys.size()];
        keys.toArray(methods);

        if (notFindInArray(prefix, methods))
            return prefix;

        int i = 100;
        String name;
        do {
            if (i > 999)
                throw new RuntimeException("too many unique name");

            name = prefix + i++;
        } while (!notFindInArray(name, methods));
        return name;
    }

    private static boolean notFindInArray(String prefix, String[] values) {
        int len = values.length;
        for (int i = 0; i < len; i++)
            if (values[i].startsWith(prefix))
                return false;

        return true;
    }

    private void makeMemberList(HashMap table) {
        int mod = getModifiers();
        if (Modifier.isAbstract(mod) || Modifier.isInterface(mod))
            try {
                CtClass[] ifs = getInterfaces();
                int size = ifs.length;
                for (int i = 0; i < size; i++) {
                    CtClass ic =ifs[i];
                    if (ic != null && ic instanceof CtClassType)
                        ((CtClassType)ic).makeMemberList(table);
                }
            }
            catch (NotFoundException e) {}

        try {
            CtClass s = getSuperclass();
            if (s != null && s instanceof CtClassType)
                ((CtClassType)s).makeMemberList(table);
        }
        catch (NotFoundException e) {}

        List list = getClassFile2().getMethods();
        int n = list.size();
        for (int i = 0; i < n; i++) {
            MethodInfo minfo = (MethodInfo)list.get(i);
            table.put(minfo.getName(), this);
        }

        list = getClassFile2().getFields();
        n = list.size();
        for (int i = 0; i < n; i++) {
            FieldInfo finfo = (FieldInfo)list.get(i);
            table.put(finfo.getName(), this);
        }
    }
}

class FieldInitLink {
    FieldInitLink next;
    CtField field;
    CtField.Initializer init;

    FieldInitLink(CtField f, CtField.Initializer i) {
        next = null;
        field = f;
        init = i;
    }
}