ctbehavior.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

/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999-2006 Shigeru Chiba. All Rights Reserved.
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 */

package javassist;

import javassist.bytecode.*;
import javassist.compiler.Javac;
import javassist.compiler.CompileError;
import javassist.expr.ExprEditor;

/**
 * <code>CtBehavior</code> represents a method, a constructor,
 * or a static constructor (class initializer). 
 * It is the abstract super class of
 * <code>CtMethod</code> and <code>CtConstructor</code>.
 */
public abstract class CtBehavior extends CtMember {
    protected MethodInfo methodInfo;

    protected CtBehavior(CtClass clazz, MethodInfo minfo) {
        super(clazz);
        methodInfo = minfo;
    }

    /**
     * @param isCons        true if this is a constructor.
     */
    void copy(CtBehavior src, boolean isCons, ClassMap map)
        throws CannotCompileException
    {
        CtClass declaring = declaringClass;
        MethodInfo srcInfo = src.methodInfo;
        CtClass srcClass = src.getDeclaringClass();
        ConstPool cp = declaring.getClassFile2().getConstPool();

        map = new ClassMap(map);
        map.put(srcClass.getName(), declaring.getName());
        try {
            boolean patch = false;
            CtClass srcSuper = srcClass.getSuperclass();
            CtClass destSuper = declaring.getSuperclass();
            String destSuperName = null;
            if (srcSuper != null && destSuper != null) {
                String srcSuperName = srcSuper.getName();
                destSuperName = destSuper.getName();
                if (!srcSuperName.equals(destSuperName))
                    if (srcSuperName.equals(CtClass.javaLangObject))
                        patch = true;
                    else
                        map.put(srcSuperName, destSuperName);
            }

            methodInfo = new MethodInfo(cp, srcInfo.getName(), srcInfo, map);
            if (isCons && patch)
                methodInfo.setSuperclass(destSuperName);
        }
        catch (NotFoundException e) {
            throw new CannotCompileException(e);
        }
        catch (BadBytecode e) {
            throw new CannotCompileException(e);
        }
    }

    protected void extendToString(StringBuffer buffer) {
        buffer.append(' ');
        buffer.append(getName());
        buffer.append(' ');
        buffer.append(methodInfo.getDescriptor());
    }

    /**
     * Returns the MethodInfo representing this method/constructor in the
     * class file.
     */
    public MethodInfo getMethodInfo() {
        declaringClass.checkModify();
        return methodInfo;
    }

    /**
     * Returns the MethodInfo representing the method/constructor in the
     * class file (read only).
     * Normal applications do not need calling this method.  Use
     * <code>getMethodInfo()</code>.
     *
     * <p>The <code>MethodInfo</code> object obtained by this method
     * is read only.  Changes to this object might not be reflected
     * on a class file generated by <code>toBytecode()</code>,
     * <code>toClass()</code>, etc in <code>CtClass</code>.
     *
     * <p>This method is available even if the <code>CtClass</code>
     * containing this method is frozen.  However, if the class is
     * frozen, the <code>MethodInfo</code> might be also pruned.
     *
     * @see #getMethodInfo()
     * @see CtClass#isFrozen()
     * @see CtClass#prune()
     */
    public MethodInfo getMethodInfo2() { return methodInfo; }

    /**
     * Obtains the modifiers of the method/constructor.
     *
     * @return          modifiers encoded with
     *                  <code>javassist.Modifier</code>.
     * @see Modifier
     */
    public int getModifiers() {
        return AccessFlag.toModifier(methodInfo.getAccessFlags());
    }

    /**
     * Sets the encoded modifiers of the method/constructor.
     *
     * <p>Changing the modifiers may cause a problem.
     * For example, if a non-static method is changed to static,
     * the method will be rejected by the bytecode verifier.
     *
     * @see Modifier
     */
    public void setModifiers(int mod) {
        declaringClass.checkModify();
        methodInfo.setAccessFlags(AccessFlag.of(mod));
    }

    /**
     * Returns the annotations associated with this method or constructor.
     *
     * @return an array of annotation-type objects.
     * @see #getAvailableAnnotations()
     * @since 3.1
     */
    public Object[] getAnnotations() throws ClassNotFoundException {
       return getAnnotations(false);
   }

    /**
     * Returns the annotations associated with this method or constructor.
     * If any annotations are not on the classpath, they are not included
     * in the returned array.
     * 
     * @return an array of annotation-type objects.
     * @see #getAnnotations()
     * @since 3.3
     */
    public Object[] getAvailableAnnotations(){
       try{
           return getAnnotations(true);
       }
       catch (ClassNotFoundException e){
           throw new RuntimeException("Unexpected exception", e);
       }
    }

    private Object[] getAnnotations(boolean ignoreNotFound)
       throws ClassNotFoundException
    {
       MethodInfo mi = getMethodInfo2();
       AnnotationsAttribute ainfo = (AnnotationsAttribute)
                   mi.getAttribute(AnnotationsAttribute.invisibleTag);  
       AnnotationsAttribute ainfo2 = (AnnotationsAttribute)
                   mi.getAttribute(AnnotationsAttribute.visibleTag);  
       return CtClassType.toAnnotationType(ignoreNotFound,
                                           getDeclaringClass().getClassPool(),
                                           ainfo, ainfo2);
    }

    /**
     * Returns the parameter annotations associated with this method or constructor.
     *
     * @return an array of annotation-type objects.  The length of the returned array is
     * equal to the number of the formal parameters.  If each parameter has no
     * annotation, the elements of the returned array are empty arrays.
     *
     * @see #getAvailableParameterAnnotations()
     * @see #getAnnotations()
     * @since 3.1
     */
    public Object[][] getParameterAnnotations() throws ClassNotFoundException {
        return getParameterAnnotations(false);
    }

    /**
     * Returns the parameter annotations associated with this method or constructor.
     * If any annotations are not on the classpath, they are not included in the
     * returned array.
     * 
     * @return an array of annotation-type objects.  The length of the returned array is
     * equal to the number of the formal parameters.  If each parameter has no
     * annotation, the elements of the returned array are empty arrays.
     *
     * @see #getParameterAnnotations()
     * @see #getAvailableAnnotations()
     * @since 3.3
     */
    public Object[][] getAvailableParameterAnnotations(){
        try {
            return getParameterAnnotations(true);
        }
        catch(ClassNotFoundException e) {
            throw new RuntimeException("Unexpected exception", e);
        }
    }

    Object[][] getParameterAnnotations(boolean ignoreNotFound)
        throws ClassNotFoundException
    {
        MethodInfo mi = getMethodInfo2();
        ParameterAnnotationsAttribute ainfo = (ParameterAnnotationsAttribute)
                    mi.getAttribute(ParameterAnnotationsAttribute.invisibleTag);  
        ParameterAnnotationsAttribute ainfo2 = (ParameterAnnotationsAttribute)
                    mi.getAttribute(ParameterAnnotationsAttribute.visibleTag);  
        return CtClassType.toAnnotationType(ignoreNotFound,
                                            getDeclaringClass().getClassPool(),
                                            ainfo, ainfo2, mi);
    }

    /**
     * Obtains parameter types of this method/constructor.
     */
    public CtClass[] getParameterTypes() throws NotFoundException {
        return Descriptor.getParameterTypes(methodInfo.getDescriptor(),
                                            declaringClass.getClassPool());
    }

    /**
     * Obtains the type of the returned value.
     */
    CtClass getReturnType0() throws NotFoundException {
        return Descriptor.getReturnType(methodInfo.getDescriptor(),
                                        declaringClass.getClassPool());
    }

    /**
     * Returns the method signature (the parameter types
     * and the return type).
     * The method signature is represented by a character string
     * called method descriptor, which is defined in the JVM specification.
     * If two methods/constructors have
     * the same parameter types
     * and the return type, <code>getSignature()</code> returns the
     * same string (the return type of constructors is <code>void</code>).
     *
     * @see javassist.bytecode.Descriptor
     */
    public String getSignature() {
        return methodInfo.getDescriptor();
    }

    /**
     * Obtains exceptions that this method/constructor may throw.
     *
     * @return a zero-length array if there is no throws clause.
     */
    public CtClass[] getExceptionTypes() throws NotFoundException {
        String[] exceptions;
        ExceptionsAttribute ea = methodInfo.getExceptionsAttribute();
        if (ea == null)
            exceptions = null;
        else
            exceptions = ea.getExceptions();

        return declaringClass.getClassPool().get(exceptions);
    }

    /**
     * Sets exceptions that this method/constructor may throw.
     */
    public void setExceptionTypes(CtClass[] types) throws NotFoundException {
        declaringClass.checkModify();
        if (types == null || types.length == 0) {
            methodInfo.removeExceptionsAttribute();
            return;
        }

        String[] names = new String[types.length];
        for (int i = 0; i < types.length; ++i)
            names[i] = types[i].getName();

        ExceptionsAttribute ea = methodInfo.getExceptionsAttribute();
        if (ea == null) {
            ea = new ExceptionsAttribute(methodInfo.getConstPool());
            methodInfo.setExceptionsAttribute(ea);
        }

        ea.setExceptions(names);
    }

    /**
     * Returns true if the body is empty.
     */
    public abstract boolean isEmpty();

    /**
     * Sets a method/constructor body.
     *
     * @param src       the source code representing the body.
     *                  It must be a single statement or block.
     *                  If it is <code>null</code>, the substituted
     *                  body does nothing except returning zero or null.
     */
    public void setBody(String src) throws CannotCompileException {
        setBody(src, null, null);
    }

    /**
     * Sets a method/constructor body.
     *
     * @param src       the source code representing the body.
     *                  It must be a single statement or block.
     *                  If it is <code>null</code>, the substituted
     *                  body does nothing except returning zero or null.
     * @param delegateObj       the source text specifying the object
     *                          that is called on by <code>$proceed()</code>.
     * @param delegateMethod    the name of the method
     *                          that is called by <code>$proceed()</code>.
     */
    public void setBody(String src,
                        String delegateObj, String delegateMethod)