constpool.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.bytecode;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import javassist.CtClass;

/**
 * Constant pool table.
 */
public final class ConstPool {
    LongVector items;
    int       numOfItems;
    HashMap classes;
    HashMap strings;
    int       thisClassInfo;

    /**
     * <code>CONSTANT_Class</code>
     */
    public static final int CONST_Class = ClassInfo.tag;

    /**
     * <code>CONSTANT_Fieldref</code>
     */
    public static final int CONST_Fieldref = FieldrefInfo.tag;

    /**
     * <code>CONSTANT_Methodref</code>
     */
    public static final int CONST_Methodref = MethodrefInfo.tag;

    /**
     * <code>CONSTANT_InterfaceMethodref</code>
     */
    public static final int CONST_InterfaceMethodref
                                        = InterfaceMethodrefInfo.tag;

    /**
     * <code>CONSTANT_String</code>
     */
    public static final int CONST_String = StringInfo.tag;

    /**
     * <code>CONSTANT_Integer</code>
     */
    public static final int CONST_Integer = IntegerInfo.tag;

    /**
     * <code>CONSTANT_Float</code>
     */
    public static final int CONST_Float = FloatInfo.tag;

    /**
     * <code>CONSTANT_Long</code>
     */
    public static final int CONST_Long = LongInfo.tag;

    /**
     * <code>CONSTANT_Double</code>
     */
    public static final int CONST_Double = DoubleInfo.tag;

    /**
     * <code>CONSTANT_NameAndType</code>
     */
    public static final int CONST_NameAndType = NameAndTypeInfo.tag;

    /**
     * <code>CONSTANT_Utf8</code>
     */
    public static final int CONST_Utf8 = Utf8Info.tag;

    /**
     * Represents the class using this constant pool table.
     */
    public static final CtClass THIS = null;

    /**
     * Constructs a constant pool table.
     *
     * @param thisclass         the name of the class using this constant
     *                          pool table
     */
    public ConstPool(String thisclass) {
        items = new LongVector();
        numOfItems = 0;
        addItem(null);          // index 0 is reserved by the JVM.
        classes = new HashMap();
        strings = new HashMap();
        thisClassInfo = addClassInfo(thisclass);
    }

    /**
     * Constructs a constant pool table from the given byte stream.
     *
     * @param in        byte stream.
     */
    public ConstPool(DataInputStream in) throws IOException {
        classes = new HashMap();
        strings = new HashMap();
        thisClassInfo = 0;
        /* read() initializes items and numOfItems, and do addItem(null).
         */
        read(in);
    }

    void prune() {
        classes = new HashMap();
        strings = new HashMap();
    }

    /**
     * Returns the number of entries in this table.
     */
    public int getSize() {
        return numOfItems;
    }

    /**
     * Returns the name of the class using this constant pool table.
     */
    public String getClassName() {
        return getClassInfo(thisClassInfo);
    }

    /**
     * Returns the index of <code>CONSTANT_Class_info</code> structure
     * specifying the class using this constant pool table.
     */
    public int getThisClassInfo() {
        return thisClassInfo;
    }

    void setThisClassInfo(int i) {
        thisClassInfo = i;
    }

    ConstInfo getItem(int n) {
        return (ConstInfo)items.elementAt(n);
    }

    /**
     * Returns the <code>tag</code> field of the constant pool table
     * entry at the given index.
     */
    public int getTag(int index) {
        return getItem(index).getTag();
    }

    /**
     * Reads <code>CONSTANT_Class_info</code> structure
     * at the given index.
     *
     * @return  a fully-qualified class or interface name specified
     *          by <code>name_index</code>.
     */
    public String getClassInfo(int index) {
        ClassInfo c = (ClassInfo)getItem(index);
        if (c == null)
            return null;
        else
            return Descriptor.toJavaName(getUtf8Info(c.name));
    }

    /**
     * Reads the <code>name_index</code> field of the
     * <code>CONSTANT_NameAndType_info</code> structure
     * at the given index.
     */
    public int getNameAndTypeName(int index) {
        NameAndTypeInfo ntinfo = (NameAndTypeInfo)getItem(index);
        return ntinfo.memberName;
    }

    /**
     * Reads the <code>descriptor_index</code> field of the
     * <code>CONSTANT_NameAndType_info</code> structure
     * at the given index.
     */
    public int getNameAndTypeDescriptor(int index) {
        NameAndTypeInfo ntinfo = (NameAndTypeInfo)getItem(index);
        return ntinfo.typeDescriptor;
    }

    /**
     * Reads the <code>class_index</code> field of the
     * <code>CONSTANT_Fieldref_info</code> structure
     * at the given index.
     */
    public int getFieldrefClass(int index) {
        FieldrefInfo finfo = (FieldrefInfo)getItem(index);
        return finfo.classIndex;
    }

    /**
     * Reads the <code>class_index</code> field of the
     * <code>CONSTANT_Fieldref_info</code> structure
     * at the given index.
     *
     * @return the name of the class at that <code>class_index</code>.
     */
    public String getFieldrefClassName(int index) {
        FieldrefInfo f = (FieldrefInfo)getItem(index);
        if (f == null)
            return null;
        else
            return getClassInfo(f.classIndex);
    }

    /**
     * Reads the <code>name_and_type_index</code> field of the
     * <code>CONSTANT_Fieldref_info</code> structure
     * at the given index.
     */
    public int getFieldrefNameAndType(int index) {
        FieldrefInfo finfo = (FieldrefInfo)getItem(index);
        return finfo.nameAndTypeIndex;
    }

    /**
     * Reads the <code>name_index</code> field of the
     * <code>CONSTANT_NameAndType_info</code> structure
     * indirectly specified by the given index.
     *
     * @param index     an index to a <code>CONSTANT_Fieldref_info</code>.
     * @return  the name of the field.
     */
    public String getFieldrefName(int index) {
        FieldrefInfo f = (FieldrefInfo)getItem(index);
        if (f == null)
            return null;
        else {
            NameAndTypeInfo n = (NameAndTypeInfo)getItem(f.nameAndTypeIndex);
            if(n == null)
                return null;
            else
                return getUtf8Info(n.memberName);
        }
    }

    /**
     * Reads the <code>descriptor_index</code> field of the
     * <code>CONSTANT_NameAndType_info</code> structure
     * indirectly specified by the given index.
     *
     * @param index     an index to a <code>CONSTANT_Fieldref_info</code>.
     * @return  the type descriptor of the field.
     */
    public String getFieldrefType(int index) {
        FieldrefInfo f = (FieldrefInfo)getItem(index);
        if (f == null)
            return null;
        else {
            NameAndTypeInfo n = (NameAndTypeInfo) getItem(f.nameAndTypeIndex);
            if(n == null)
                return null;
            else
                return getUtf8Info(n.typeDescriptor);
        }
    }

    /**
     * Reads the <code>class_index</code> field of the
     * <code>CONSTANT_Methodref_info</code> structure
     * at the given index.
     */
    public int getMethodrefClass(int index) {
        MethodrefInfo minfo = (MethodrefInfo)getItem(index);
        return minfo.classIndex;
    }

    /**
     * Reads the <code>class_index</code> field of the
     * <code>CONSTANT_Methodref_info</code> structure
     * at the given index.
     *
     * @return the name of the class at that <code>class_index</code>.
     */
    public String getMethodrefClassName(int index) {
        MethodrefInfo minfo = (MethodrefInfo)getItem(index);
        if (minfo == null)
            return null;
        else
            return getClassInfo(minfo.classIndex);
    }

    /**
     * Reads the <code>name_and_type_index</code> field of the
     * <code>CONSTANT_Methodref_info</code> structure
     * at the given index.
     */
    public int getMethodrefNameAndType(int index) {
        MethodrefInfo minfo = (MethodrefInfo)getItem(index);
        return minfo.nameAndTypeIndex;
    }

    /**
     * Reads the <code>name_index</code> field of the
     * <code>CONSTANT_NameAndType_info</code> structure
     * indirectly specified by the given index.
     *
     * @param index     an index to a <code>CONSTANT_Methodref_info</code>.
     * @return  the name of the method.
     */
    public String getMethodrefName(int index) {
        MethodrefInfo minfo = (MethodrefInfo)getItem(index);
        if (minfo == null)
            return null;
        else {
            NameAndTypeInfo n
                = (NameAndTypeInfo)getItem(minfo.nameAndTypeIndex);
            if(n == null)
                return null;
            else
                return getUtf8Info(n.memberName);
        }
    }

    /**
     * Reads the <code>descriptor_index</code> field of the
     * <code>CONSTANT_NameAndType_info</code> structure
     * indirectly specified by the given index.
     *
     * @param index     an index to a <code>CONSTANT_Methodref_info</code>.
     * @return  the descriptor of the method.
     */
    public String getMethodrefType(int index) {
        MethodrefInfo minfo = (MethodrefInfo)getItem(index);
        if (minfo == null)
            return null;
        else {
            NameAndTypeInfo n
                = (NameAndTypeInfo)getItem(minfo.nameAndTypeIndex);
            if(n == null)
                return null;
            else
                return getUtf8Info(n.typeDescriptor);
        }
    }

    /**
     * Reads the <code>class_index</code> field of the
     * <code>CONSTANT_InterfaceMethodref_info</code> structure
     * at the given index.
     */
    public int getInterfaceMethodrefClass(int index) {
        InterfaceMethodrefInfo minfo
            = (InterfaceMethodrefInfo)getItem(index);
        return minfo.classIndex;
    }

    /**
     * Reads the <code>class_index</code> field of the
     * <code>CONSTANT_InterfaceMethodref_info</code> structure
     * at the given index.
     *
     * @return the name of the class at that <code>class_index</code>.
     */
    public String getInterfaceMethodrefClassName(int index) {
        InterfaceMethodrefInfo minfo
            = (InterfaceMethodrefInfo)getItem(index);
        return getClassInfo(minfo.classIndex);
    }

    /**
     * Reads the <code>name_and_type_index</code> field of the
     * <code>CONSTANT_InterfaceMethodref_info</code> structure
     * at the given index.
     */
    public int getInterfaceMethodrefNameAndType(int index) {
        InterfaceMethodrefInfo minfo
            = (InterfaceMethodrefInfo)getItem(index);
        return minfo.nameAndTypeIndex;
    }

    /**
     * Reads the <code>name_index</code> field of the
     * <code>CONSTANT_NameAndType_info</code> structure
     * indirectly specified by the given index.
     *
     * @param index     an index to
     *                  a <code>CONSTANT_InterfaceMethodref_info</code>.
     * @return  the name of the method.
     */
    public String getInterfaceMethodrefName(int index) {
        InterfaceMethodrefInfo minfo
            = (InterfaceMethodrefInfo)getItem(index);
        if (minfo == null)
            return null;
        else {
            NameAndTypeInfo n
                = (NameAndTypeInfo)getItem(minfo.nameAndTypeIndex);
            if(n == null)
                return null;
            else
                return getUtf8Info(n.memberName);
        }
    }

    /**
     * Reads the <code>descriptor_index</code> field of the
     * <code>CONSTANT_NameAndType_info</code> structure
     * indirectly specified by the given index.
     *
     * @param index     an index to
     *                  a <code>CONSTANT_InterfaceMethodref_info</code>.
     * @return  the descriptor of the method.
     */
    public String getInterfaceMethodrefType(int index) {
        InterfaceMethodrefInfo minfo
            = (InterfaceMethodrefInfo)getItem(index);
        if (minfo == null)
            return null;
        else {
            NameAndTypeInfo n
                = (NameAndTypeInfo)getItem(minfo.nameAndTypeIndex);
            if(n == null)
                return null;
            else
                return getUtf8Info(n.typeDescriptor);
        }
    }
    /**
     * Reads <code>CONSTANT_Integer_info</code>, <code>_Float_info</code>,
     * <code>_Long_info</code>, <code>_Double_info</code>, or
     * <code>_String_info</code> structure.
     * These are used with the LDC instruction.
     *
     * @return a <code>String</code> value or a wrapped primitive-type
     * value.
     */
    public Object getLdcValue(int index) {
        ConstInfo constInfo = this.getItem(index);
        Object value = null;
        if (constInfo instanceof StringInfo)
            value = this.getStringInfo(index);
        else if (constInfo instanceof FloatInfo)
            value = new Float(getFloatInfo(index));
        else if (constInfo instanceof IntegerInfo)
            value = new Integer(getIntegerInfo(index));
        else if (constInfo instanceof LongInfo)
            value = new Long(getLongInfo(index));
        else if (constInfo instanceof DoubleInfo)
            value = new Double(getDoubleInfo(index));
        else
            value = null;

        return value;
    }

    /**
     * Reads <code>CONSTANT_Integer_info</code> structure
     * at the given index.
     *
     * @return the value specified by this entry.
     */
    public int getIntegerInfo(int index) {
        IntegerInfo i = (IntegerInfo)getItem(index);
        return i.value;