bytecode.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

     * Appends INVOKESPECIAL.
     *
     * @param clazz     the index of <code>CONSTANT_Class_info</code>
     *                  structure.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     * @see Descriptor#ofConstructor(CtClass[])
     */
    public void addInvokespecial(int clazz, String name, String desc) {
        add(INVOKESPECIAL);
        addIndex(constPool.addMethodrefInfo(clazz, name, desc));
        growStack(Descriptor.dataSize(desc) - 1);
    }

    /**
     * Appends INVOKESTATIC.
     *
     * @param clazz     the target class.
     * @param name      the method name
     * @param returnType        the return type.
     * @param paramTypes        the parameter types.
     */
    public void addInvokestatic(CtClass clazz, String name,
                                CtClass returnType, CtClass[] paramTypes) {
        String desc = Descriptor.ofMethod(returnType, paramTypes);
        addInvokestatic(clazz, name, desc);
    }

    /**
     * Appends INVOKESTATIC.
     *
     * @param clazz     the target class.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokestatic(CtClass clazz, String name, String desc) {
        addInvokestatic(constPool.addClassInfo(clazz), name, desc);
    }

    /**
     * Appends INVOKESTATIC.
     *
     * @param classname the fully-qualified class name.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokestatic(String classname, String name, String desc) {
        addInvokestatic(constPool.addClassInfo(classname), name, desc);
    }

    /**
     * Appends INVOKESTATIC.
     *
     * @param clazz     the index of <code>CONSTANT_Class_info</code>
     *                  structure.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokestatic(int clazz, String name, String desc) {
        add(INVOKESTATIC);
        addIndex(constPool.addMethodrefInfo(clazz, name, desc));
        growStack(Descriptor.dataSize(desc));
    }

    /**
     * Appends INVOKEVIRTUAL.
     *
     * <p>The specified method must not be an inherited method.
     * It must be directly declared in the class specified
     * in <code>clazz</code>.
     *
     * @param clazz     the target class.
     * @param name      the method name
     * @param returnType        the return type.
     * @param paramTypes        the parameter types.
     */
    public void addInvokevirtual(CtClass clazz, String name,
                                 CtClass returnType, CtClass[] paramTypes) {
        String desc = Descriptor.ofMethod(returnType, paramTypes);
        addInvokevirtual(clazz, name, desc);
    }

    /**
     * Appends INVOKEVIRTUAL.
     *
     * <p>The specified method must not be an inherited method.
     * It must be directly declared in the class specified
     * in <code>clazz</code>.
     *
     * @param clazz     the target class.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokevirtual(CtClass clazz, String name, String desc) {
        addInvokevirtual(constPool.addClassInfo(clazz), name, desc);
    }

    /**
     * Appends INVOKEVIRTUAL.
     *
     * <p>The specified method must not be an inherited method.
     * It must be directly declared in the class specified
     * in <code>classname</code>.
     *
     * @param classname the fully-qualified class name.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokevirtual(String classname, String name, String desc) {
        addInvokevirtual(constPool.addClassInfo(classname), name, desc);
    }

    /**
     * Appends INVOKEVIRTUAL.
     *
     * <p>The specified method must not be an inherited method.
     * It must be directly declared in the class specified
     * by <code>clazz</code>.
     *
     * @param clazz     the index of <code>CONSTANT_Class_info</code>
     *                  structure.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokevirtual(int clazz, String name, String desc) {
        add(INVOKEVIRTUAL);
        addIndex(constPool.addMethodrefInfo(clazz, name, desc));
        growStack(Descriptor.dataSize(desc) - 1);
    }

    /**
     * Appends INVOKEINTERFACE.
     *
     * @param clazz     the target class.
     * @param name      the method name
     * @param returnType        the return type.
     * @param paramTypes        the parameter types.
     * @param count     the count operand of the instruction.
     */
    public void addInvokeinterface(CtClass clazz, String name,
                                   CtClass returnType, CtClass[] paramTypes,
                                   int count) {
        String desc = Descriptor.ofMethod(returnType, paramTypes);
        addInvokeinterface(clazz, name, desc, count);
    }

    /**
     * Appends INVOKEINTERFACE.
     *
     * @param clazz     the target class.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     * @param count     the count operand of the instruction.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokeinterface(CtClass clazz, String name,
                                   String desc, int count) {
        addInvokeinterface(constPool.addClassInfo(clazz), name, desc,
                           count);
    }

    /**
     * Appends INVOKEINTERFACE.
     *
     * @param classname the fully-qualified class name.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     * @param count     the count operand of the instruction.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokeinterface(String classname, String name,
                                   String desc, int count) {
        addInvokeinterface(constPool.addClassInfo(classname), name, desc,
                           count);
    }

    /**
     * Appends INVOKEINTERFACE.
     *
     * @param clazz     the index of <code>CONSTANT_Class_info</code>
     *                  structure.
     * @param name      the method name
     * @param desc      the descriptor of the method signature.
     * @param count     the count operand of the instruction.
     *
     * @see Descriptor#ofMethod(CtClass,CtClass[])
     */
    public void addInvokeinterface(int clazz, String name,
                                   String desc, int count) {
        add(INVOKEINTERFACE);
        addIndex(constPool.addInterfaceMethodrefInfo(clazz, name, desc));
        add(count);
        add(0);
        growStack(Descriptor.dataSize(desc) - 1);
    }

    /**
     * Appends LDC or LDC_W.  The pushed item is a <code>String</code>
     * object.
     *
     * @param s         the character string pushed by LDC or LDC_W.
     */
    public void addLdc(String s) {
        addLdc(constPool.addStringInfo(s));
    }

    /**
     * Appends LDC or LDC_W.
     *
     * @param i         index into the constant pool.
     */
    public void addLdc(int i) {
        if (i > 0xFF) {
            addOpcode(LDC_W);
            addIndex(i);
        }
        else {
            addOpcode(LDC);
            add(i);
        }
    }

    /**
     * Appends LDC2_W.  The pushed item is a long value.
     */
    public void addLdc2w(long l) {
        addOpcode(LDC2_W);
        addIndex(constPool.addLongInfo(l));
    }

    /**
     * Appends LDC2_W.  The pushed item is a double value.
     */
    public void addLdc2w(double d) {
        addOpcode(LDC2_W);
        addIndex(constPool.addDoubleInfo(d));
    }

    /**
     * Appends NEW.
     *
     * @param clazz     the class of the created instance.
     */
    public void addNew(CtClass clazz) {
        addOpcode(NEW);
        addIndex(constPool.addClassInfo(clazz));
    }

    /**
     * Appends NEW.
     *
     * @param classname         the fully-qualified class name.
     */
    public void addNew(String classname) {
        addOpcode(NEW);
        addIndex(constPool.addClassInfo(classname));
    }

    /**
     * Appends ANEWARRAY.
     *
     * @param classname         the qualified class name of the element type.
     */
    public void addAnewarray(String classname) {
        addOpcode(ANEWARRAY);
        addIndex(constPool.addClassInfo(classname));
    }

    /**
     * Appends ICONST and ANEWARRAY.
     *
     * @param clazz     the elememnt type.
     * @param length    the array length.
     */
    public void addAnewarray(CtClass clazz, int length) {
        addIconst(length);
        addOpcode(ANEWARRAY);
        addIndex(constPool.addClassInfo(clazz));
    }

    /**
     * Appends NEWARRAY for primitive types.
     *
     * @param atype     <code>T_BOOLEAN</code>, <code>T_CHAR</code>, ...
     * @see Opcode
     */
    public void addNewarray(int atype, int length) {
        addIconst(length);
        addOpcode(NEWARRAY);
        add(atype);
    }

    /**
     * Appends MULTINEWARRAY.
     *
     * @param clazz             the array type.
     * @param dimensions        the sizes of all dimensions.
     * @return          the length of <code>dimensions</code>.
     */
    public int addMultiNewarray(CtClass clazz, int[] dimensions) {
        int len = dimensions.length;
        for (int i = 0; i < len; ++i)
            addIconst(dimensions[i]);

        growStack(len);
        return addMultiNewarray(clazz, len);
    }

    /**
     * Appends MULTINEWARRAY.  The size of every dimension must have been
     * already pushed on the stack.
     *
     * @param clazz             the array type.
     * @param dim               the number of the dimensions.
     * @return                  the value of <code>dim</code>.
     */
    public int addMultiNewarray(CtClass clazz, int dim) {
        add(MULTIANEWARRAY);
        addIndex(constPool.addClassInfo(clazz));
        add(dim);
        growStack(1 - dim);
        return dim;
    }

    /**
     * Appends MULTINEWARRAY.
     *
     * @param desc      the type descriptor of the created array.
     * @param dim       dimensions.
     * @return          the value of <code>dim</code>.
     */
    public int addMultiNewarray(String desc, int dim) {
        add(MULTIANEWARRAY);
        addIndex(constPool.addClassInfo(desc));
        add(dim);
        growStack(1 - dim);
        return dim;
    }

    /**
     * Appends PUTFIELD.
     *
     * @param c         the target class.
     * @param name      the field name.
     * @param desc      the descriptor of the field type.
     */
    public void addPutfield(CtClass c, String name, String desc) {
        addPutfield0(c, null, name, desc);
    }

    /**
     * Appends PUTFIELD.
     *
     * @param classname         the fully-qualified name of the target class.
     * @param name      the field name.
     * @param desc      the descriptor of the field type.
     */
    public void addPutfield(String classname, String name, String desc) {
        // if classnaem is null, the target class is THIS.
        addPutfield0(null, classname, name, desc);
    }

    private void addPutfield0(CtClass target, String classname,
                              String name, String desc) {
        add(PUTFIELD);
        // target is null if it represents THIS.
        int ci = classname == null ? constPool.addClassInfo(target)
                                   : constPool.addClassInfo(classname);
        addIndex(constPool.addFieldrefInfo(ci, name, desc));
        growStack(-1 - Descriptor.dataSize(desc));
    }

    /**
     * Appends PUTSTATIC.
     *
     * @param c         the target class.
     * @param name      the field name.
     * @param desc      the descriptor of the field type.
     */
    public void addPutstatic(CtClass c, String name, String desc) {
        addPutstatic0(c, null, name, desc);
    }

    /**
     * Appends PUTSTATIC.
     *
     * @param classname         the fully-qualified name of the target class.
     * @param fieldName         the field name.
     * @param desc              the descriptor of the field type.
     */
    public void addPutstatic(String classname, String fieldName, String desc) {
        // if classname is null, the target class is THIS.
        addPutstatic0(null, classname, fieldName, desc);
    }

    private void addPutstatic0(CtClass target, String classname,
                               String fieldName, String desc) {
        add(PUTSTATIC);
        // target is null if it represents THIS.
        int ci = classname == null ? constPool.addClassInfo(target)
                                : constPool.addClassInfo(classname);
        addIndex(constPool.addFieldrefInfo(ci, fieldName, desc));
        growStack(-Descriptor.dataSize(desc));
    }

    /**
     * Appends ARETURN, IRETURN, .., or RETURN.
     *
     * @param type      the return type.
     */
    public void addReturn(CtClass type) {
        if (type == null)
            addOpcode(RETURN);
        else if (type.isPrimitive()) {
            CtPrimitiveType ptype = (CtPrimitiveType)type;
            addOpcode(ptype.getReturnOp());
        }
        else
            addOpcode(ARETURN);
    }

    /**
     * Appends RET.
     *
     * @param var       local variable
     */
    public void addRet(int var) {
        if (var < 0x100) {
            addOpcode(RET);
            add(var);
        }
        else {
            addOpcode(WIDE);
            addOpcode(RET);
            addIndex(var);
        }
    }

    /**
     * Appends instructions for executing
     * <code>java.lang.System.println(<i>message</i>)</code>.
     *
     * @param message           printed message.
     */
    public void addPrintln(String message) {
        addGetstatic("java.lang.System", "err", "Ljava/io/PrintStream;");
        addLdc(message);
        addInvokevirtual("java.io.PrintStream",
                         "println", "(Ljava/lang/String;)V");
    }
}