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"); // Print switch indices in first row (and default) jump_table = new int[high - low + 1]; for(int i=0; i < jump_table.length; i++) { jump_table[i] = offset + bytes.readInt(); buf.append("<TH>" + (low + i) + ""); } buf.append("<TH>default\n"); // Print target and default indices in second row for(int i=0; i < jump_table.length; i++) buf.append("<TD>"); buf.append("<TD>\n

Java example source code file (CodeHTML.java)

This example Java source code file (CodeHTML.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

constantpool, href, ioexception, lookupswitch, string, table, tableswitch, util

The CodeHTML.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
package com.sun.org.apache.bcel.internal.util;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import com.sun.org.apache.bcel.internal.classfile.*;
import java.io.*;
import java.util.BitSet;

/**
 * Convert code into HTML file.
 *
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm
 *
 */
final class CodeHTML implements com.sun.org.apache.bcel.internal.Constants {
  private String        class_name;     // name of current class
  private Method[]      methods;        // Methods to print
  private PrintWriter   file;           // file to write to
  private BitSet        goto_set;
  private ConstantPool  constant_pool;
  private ConstantHTML  constant_html;
  private static boolean wide=false;

  CodeHTML(String dir, String class_name,
           Method[] methods, ConstantPool constant_pool,
           ConstantHTML constant_html) throws IOException
  {
    this.class_name     = class_name;
    this.methods        = methods;
    this.constant_pool  = constant_pool;
    this.constant_html = constant_html;

    file = new PrintWriter(new FileOutputStream(dir + class_name + "_code.html"));
    file.println("<HTML>");

    for(int i=0; i < methods.length; i++)
      writeMethod(methods[i], i);

    file.println("</BODY>");
    file.close();
  }

  /**
   * Disassemble a stream of byte codes and return the
   * string representation.
   *
   * @param  stream data input stream
   * @return String representation of byte code
   */
  private final String codeToHTML(ByteSequence bytes, int method_number)
       throws IOException
  {
    short        opcode = (short)bytes.readUnsignedByte();
    StringBuffer buf;
    String       name, signature;
    int          default_offset=0, low, high;
    int          index, class_index, vindex, constant;
    int[]        jump_table;
    int          no_pad_bytes=0, offset;

    buf = new StringBuffer("<TT>" + OPCODE_NAMES[opcode] + "
"); /* Special case: Skip (0-3) padding bytes, i.e., the * following bytes are 4-byte-aligned */ if((opcode == TABLESWITCH) || (opcode == LOOKUPSWITCH)) { int remainder = bytes.getIndex() % 4; no_pad_bytes = (remainder == 0)? 0 : 4 - remainder; for(int i=0; i < no_pad_bytes; i++) bytes.readByte(); // Both cases have a field default_offset in common default_offset = bytes.readInt(); } switch(opcode) { case TABLESWITCH: low = bytes.readInt(); high = bytes.readInt(); offset = bytes.getIndex() - 12 - no_pad_bytes - 1; default_offset += offset; buf.append("<TABLE BORDER=1>
\n"); break; /* Lookup switch has variable length arguments. */ case LOOKUPSWITCH: int npairs = bytes.readInt(); offset = bytes.getIndex() - 8 - no_pad_bytes - 1; jump_table = new int[npairs]; default_offset += offset; buf.append("<TABLE BORDER=1>"); // Print switch indices in first row (and default) for(int i=0; i < npairs; i++) { int match = bytes.readInt(); jump_table[i] = offset + bytes.readInt(); buf.append("<TH>" + match + ""); } buf.append("<TH>default\n"); // Print target and default indices in second row for(int i=0; i < npairs; i++) buf.append("<TD>"); buf.append("<TD>\n\n"); break; /* Two address bytes + offset from start of byte stream form the * jump target. */ case GOTO: case IFEQ: case IFGE: case IFGT: case IFLE: case IFLT: case IFNE: case IFNONNULL: case IFNULL: case IF_ACMPEQ: case IF_ACMPNE: case IF_ICMPEQ: case IF_ICMPGE: case IF_ICMPGT: case IF_ICMPLE: case IF_ICMPLT: case IF_ICMPNE: case JSR: index = (int)(bytes.getIndex() + bytes.readShort() - 1); buf.append("<A HREF=\"#code" + method_number + "@" + index + "\">" + index + ""); break; /* Same for 32-bit wide jumps */ case GOTO_W: case JSR_W: int windex = bytes.getIndex() + bytes.readInt() - 1; buf.append("<A HREF=\"#code" + method_number + "@" + windex + "\">" + windex + "</A>"); break; /* Index byte references local variable (register) */ case ALOAD: case ASTORE: case DLOAD: case DSTORE: case FLOAD: case FSTORE: case ILOAD: case ISTORE: case LLOAD: case LSTORE: case RET: if(wide) { vindex = bytes.readShort(); wide=false; // Clear flag } else vindex = bytes.readUnsignedByte(); buf.append("%" + vindex); break; /* * Remember wide byte which is used to form a 16-bit address in the * following instruction. Relies on that the method is called again with * the following opcode. */ case WIDE: wide = true; buf.append("(wide)"); break; /* Array of basic type. */ case NEWARRAY: buf.append("<FONT COLOR=\"#00FF00\">" + TYPE_NAMES[bytes.readByte()] + ""); break; /* Access object/class fields. */ case GETFIELD: case GETSTATIC: case PUTFIELD: case PUTSTATIC: index = bytes.readShort(); ConstantFieldref c1 = (ConstantFieldref)constant_pool.getConstant(index, CONSTANT_Fieldref); class_index = c1.getClassIndex(); name = constant_pool.getConstantString(class_index, CONSTANT_Class); name = Utility.compactClassName(name, false); index = c1.getNameAndTypeIndex(); String field_name = constant_pool.constantToString(index, CONSTANT_NameAndType); if(name.equals(class_name)) { // Local field buf.append("<A HREF=\"" + class_name + "_methods.html#field" + field_name + "\" TARGET=Methods>" + field_name + "</A>\n"); } else buf.append(constant_html.referenceConstant(class_index) + "." + field_name); break; /* Operands are references to classes in constant pool */ case CHECKCAST: case INSTANCEOF: case NEW: index = bytes.readShort(); buf.append(constant_html.referenceConstant(index)); break; /* Operands are references to methods in constant pool */ case INVOKESPECIAL: case INVOKESTATIC: case INVOKEVIRTUAL: case INVOKEINTERFACE: int m_index = bytes.readShort(); String str; if(opcode == INVOKEINTERFACE) { // Special treatment needed int nargs = bytes.readUnsignedByte(); // Redundant int reserved = bytes.readUnsignedByte(); // Reserved ConstantInterfaceMethodref c=(ConstantInterfaceMethodref)constant_pool.getConstant(m_index, CONSTANT_InterfaceMethodref); class_index = c.getClassIndex(); str = constant_pool.constantToString(c); index = c.getNameAndTypeIndex(); } else { ConstantMethodref c = (ConstantMethodref)constant_pool.getConstant(m_index, CONSTANT_Methodref); class_index = c.getClassIndex(); str = constant_pool.constantToString(c); index = c.getNameAndTypeIndex(); } name = Class2HTML.referenceClass(class_index); str = Class2HTML.toHTML(constant_pool.constantToString(constant_pool.getConstant(index, CONSTANT_NameAndType))); // Get signature, i.e., types ConstantNameAndType c2 = (ConstantNameAndType)constant_pool. getConstant(index, CONSTANT_NameAndType); signature = constant_pool.constantToString(c2.getSignatureIndex(), CONSTANT_Utf8); String[] args = Utility.methodSignatureArgumentTypes(signature, false); String type = Utility.methodSignatureReturnType(signature, false); buf.append(name + ".<A HREF=\"" + class_name + "_cp.html#cp" + m_index + "\" TARGET=ConstantPool>" + str + "</A>" + "("); // List arguments for(int i=0; i < args.length; i++) { buf.append(Class2HTML.referenceType(args[i])); if(i < args.length - 1) buf.append(", "); } // Attach return type buf.append("):" + Class2HTML.referenceType(type)); break; /* Operands are references to items in constant pool */ case LDC_W: case LDC2_W: index = bytes.readShort(); buf.append("<A HREF=\"" + class_name + "_cp.html#cp" + index + "\" TARGET=\"ConstantPool\">" + Class2HTML.toHTML(constant_pool.constantToString(index, constant_pool. getConstant(index).getTag()))+ "</a>"); break; case LDC: index = bytes.readUnsignedByte(); buf.append("<A HREF=\"" + class_name + "_cp.html#cp" + index + "\" TARGET=\"ConstantPool\">" + Class2HTML.toHTML(constant_pool.constantToString(index, constant_pool. getConstant(index).getTag()))+ "</a>"); break; /* Array of references. */ case ANEWARRAY: index = bytes.readShort(); buf.append(constant_html.referenceConstant(index)); break; /* Multidimensional array of references. */ case MULTIANEWARRAY: index = bytes.readShort(); int dimensions = bytes.readByte(); buf.append(constant_html.referenceConstant(index) + ":" + dimensions + "-dimensional"); break; /* Increment local variable. */ case IINC: if(wide) { vindex = bytes.readShort(); constant = bytes.readShort(); wide = false; } else { vindex = bytes.readUnsignedByte(); constant = bytes.readByte(); } buf.append("%" + vindex + " " + constant); break; default: if(NO_OF_OPERANDS[opcode] > 0) { for(int i=0; i < TYPE_OF_OPERANDS[opcode].length; i++) { switch(TYPE_OF_OPERANDS[opcode][i]) { case T_BYTE: buf.append(bytes.readUnsignedByte()); break; case T_SHORT: // Either branch or index buf.append(bytes.readShort()); break; case T_INT: buf.append(bytes.readInt()); break; default: // Never reached System.err.println("Unreachable default case reached!"); System.exit(-1); } buf.append(" "); } } } buf.append("</TD>"); return buf.toString(); } /** * Find all target addresses in code, so that they can be marked * with <A NAME = ...>. Target addresses are kept in an BitSet object. */ private final void findGotos(ByteSequence bytes, Method method, Code code) throws IOException { int index; goto_set = new BitSet(bytes.available()); int opcode; /* First get Code attribute from method and the exceptions handled * (try .. catch) in this method. We only need the line number here. */ if(code != null) { CodeException[] ce = code.getExceptionTable(); int len = ce.length; for(int i=0; i < len; i++) { goto_set.set(ce[i].getStartPC()); goto_set.set(ce[i].getEndPC()); goto_set.set(ce[i].getHandlerPC()); } // Look for local variables and their range Attribute[] attributes = code.getAttributes(); for(int i=0; i < attributes.length; i++) { if(attributes[i].getTag() == ATTR_LOCAL_VARIABLE_TABLE) { LocalVariable[] vars = ((LocalVariableTable)attributes[i]).getLocalVariableTable(); for(int j=0; j < vars.length; j++) { int start = vars[j].getStartPC(); int end = (int)(start + vars[j].getLength()); goto_set.set(start); goto_set.set(end); } break; } } } // Get target addresses from GOTO, JSR, TABLESWITCH, etc. for(int i=0; bytes.available() > 0; i++) { opcode = bytes.readUnsignedByte(); //System.out.println(OPCODE_NAMES[opcode]); switch(opcode) { case TABLESWITCH: case LOOKUPSWITCH: //bytes.readByte(); // Skip already read byte int remainder = bytes.getIndex() % 4; int no_pad_bytes = (remainder == 0)? 0 : 4 - remainder; int default_offset, offset; for(int j=0; j < no_pad_bytes; j++) bytes.readByte(); // Both cases have a field default_offset in common default_offset = bytes.readInt(); if(opcode == TABLESWITCH) { int low = bytes.readInt(); int high = bytes.readInt(); offset = bytes.getIndex() - 12 - no_pad_bytes - 1; default_offset += offset; goto_set.set(default_offset); for(int j=0; j < (high - low + 1); j++) { index = offset + bytes.readInt(); goto_set.set(index); } } else { // LOOKUPSWITCH int npairs = bytes.readInt(); offset = bytes.getIndex() - 8 - no_pad_bytes - 1; default_offset += offset; goto_set.set(default_offset); for(int j=0; j < npairs; j++) { int match = bytes.readInt(); index = offset + bytes.readInt(); goto_set.set(index); } } break; case GOTO: case IFEQ: case IFGE: case IFGT: case IFLE: case IFLT: case IFNE: case IFNONNULL: case IFNULL: case IF_ACMPEQ: case IF_ACMPNE: case IF_ICMPEQ: case IF_ICMPGE: case IF_ICMPGT: case IF_ICMPLE: case IF_ICMPLT: case IF_ICMPNE: case JSR: //bytes.readByte(); // Skip already read byte index = bytes.getIndex() + bytes.readShort() - 1; goto_set.set(index); break; case GOTO_W: case JSR_W: //bytes.readByte(); // Skip already read byte index = bytes.getIndex() + bytes.readInt() - 1; goto_set.set(index); break; default: bytes.unreadByte(); codeToHTML(bytes, 0); // Ignore output } } } /** * Write a single method with the byte code associated with it. */ private void writeMethod(Method method, int method_number) throws IOException { // Get raw signature String signature = method.getSignature(); // Get array of strings containing the argument types String[] args = Utility.methodSignatureArgumentTypes(signature, false); // Get return type string String type = Utility.methodSignatureReturnType(signature, false); // Get method name String name = method.getName(); String html_name = Class2HTML.toHTML(name); // Get method's access flags String access = Utility.accessToString(method.getAccessFlags()); access = Utility.replace(access, " ", " "); // Get the method's attributes, the Code Attribute in particular Attribute[] attributes= method.getAttributes(); file.print("<P>" + access + " " + "<A NAME=method" + method_number + ">" + Class2HTML.referenceType(type) + "</A> ("); for(int i=0; i < args.length; i++) { file.print(Class2HTML.referenceType(args[i])); if(i < args.length - 1) file.print(", "); } file.println(")</B>

"); Code c=null; byte[] code=null; if(attributes.length > 0) { file.print("<H4>Attributes
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