methodareapanel.java

这是有关Java虚拟机的实现代码,是学习和使用Java虚拟机的朋友们不可或缺的代码

/*
* Copyright (c) 1996-1999 Bill Venners. All Rights Reserved.
*
* This Java source file is part of the Interactive Illustrations Web
* Site, which is delivered in the applets directory of the CD-ROM
* that accompanies the book "Inside the Java 2 Virtual Machine" by Bill
* Venners, published by McGraw-Hill, 1999, ISBN: 0-07-135093-4. This
* source file is provided for evaluation purposes only, but you can
* redistribute it under certain conditions, described in the full
* copyright notice below.
*
* Full Copyright Notice:
*
* All the web pages and Java applets delivered in the applets
* directory of the CD-ROM, consisting of ".html," ".gif," ".class,"
* and ".java" files, are copyrighted (c) 1996-1999 by Bill
* Venners, and all rights are reserved.  This material may be copied
* and placed on any commercial or non-commercial web server on any
* network (including the internet) provided that the following
* guidelines are followed:
*
* a. All the web pages and Java Applets (".html," ".gif," ".class,"
* and ".java" files), including the source code, that are delivered
* in the applets directory of the CD-ROM that
* accompanies the book must be published together on the same web
* site.
*
* b. All the web pages and Java Applets (".html," ".gif," ".class,"
* and ".java" files) must be published "as is" and may not be altered
* in any way.
*
* c. All use and access to this web site must be free, and no fees
* can be charged to view these materials, unless express written
* permission is obtained from Bill Venners.
*
* d. The web pages and Java Applets may not be distributed on any
* media, other than a web server on a network, and may not accompany
* any book or publication.
*
* BILL VENNERS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
* SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR PARTICULAR PURPOSE, OR NON-INFRINGEMENT.  BILL VENNERS
* SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY A LICENSEE AS A
* RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES.
*/
package COM.artima.jvmsim;
import java.awt.*;

/**
* This class represents that portion of the user interface
* that displays the bytecodes in the method area.
*
* @author  Bill Venners
*/
class MethodAreaPanel extends Panel {

    private int memoryLocationsVisibleCount;

    private Label[] pointer;
    private Label[] address;
    private Label[] byteValue;
    private Label[] logicalValue;

    private int[] theProgram;
    private String[] theMnemonics;

    private int firstVisibleRow;
    private int currentProgramCounterRow;

    private ColoredLabel pcRegister;

    MethodAreaPanel(int memoryLocationsVisibleCount, int[] theProgram,
        String[] theMnemonics) {

        this.memoryLocationsVisibleCount = memoryLocationsVisibleCount;
        this.theProgram = theProgram;
        this.theMnemonics = theMnemonics;

        pointer = new Label[memoryLocationsVisibleCount];
        address = new Label[memoryLocationsVisibleCount];
        byteValue = new Label[memoryLocationsVisibleCount];
        logicalValue = new Label[memoryLocationsVisibleCount];

        // Initialize the title
        Label title = new Label(StringTable.theMethod, Label.CENTER);
        title.setFont(new Font("Helvetica", Font.BOLD, 11));

        // Initialize the labelled pc register panel
        Panel registerPanel = new Panel();
        registerPanel.setLayout(new GridLayout(1, 2, 5, 5));
        pcRegister = new ColoredLabel("00000000", Label.CENTER, Color.lightGray);
        pcRegister.setFont(new Font("TimesRoman", Font.PLAIN, 11));
        Label pcRegTitle = new Label(StringTable.pc, Label.RIGHT);
        pcRegTitle.setFont(new Font("Helvetica", Font.ITALIC, 11));
        registerPanel.add(pcRegTitle);
        registerPanel.add(pcRegister);

        // Put the title and the pc register panel on the same panel
        Panel titleRegisterPanel = new Panel();
        titleRegisterPanel.setLayout(new BorderLayout());
        titleRegisterPanel.add("West", registerPanel);
        titleRegisterPanel.add("Center", title);

        // Initialize column titles
        Panel columnTitles = new Panel();
        int[] hComponentCellWidths = { 2, 2, 2, 3 };
        columnTitles.setLayout(new GridSnapLayout(1, 9, hComponentCellWidths));
        columnTitles.setFont(new Font("Helvetica", Font.ITALIC, 11));
        columnTitles.add(new Label("", Label.CENTER));
        columnTitles.add(new Label(StringTable.offset, Label.CENTER));
        columnTitles.add(new Label(StringTable.bytecodes, Label.CENTER));
        columnTitles.add(new Label(StringTable.mnemonics, Label.LEFT));

        // Initialize the 4 column view of the method
        Panel methodView = new Panel();
        methodView.setLayout(new GridSnapLayout(memoryLocationsVisibleCount, 9, hComponentCellWidths));
        methodView.setBackground(Color.lightGray);
        Font plainFont = new Font("TimesRoman", Font.PLAIN, 11);
        methodView.setFont(plainFont);
        Font italicFont = new Font("TimesRoman", Font.ITALIC, 11);

        for (int i = 0; i < memoryLocationsVisibleCount; ++i) {

            pointer[i] = new Label("", Label.RIGHT);
            pointer[i].setFont(italicFont);
            methodView.add(pointer[i]);

            address[i] = new Label("", Label.CENTER);
            methodView.add(address[i]);

            byteValue[i] = new Label("", Label.CENTER);
            methodView.add(byteValue[i]);

            logicalValue[i] = new Label("", Label.LEFT);
            methodView.add(logicalValue[i]);
        }

        Panel methodViewWithTitles = new Panel();
        methodViewWithTitles.setLayout(new BorderLayout());
        methodViewWithTitles.add("North", columnTitles);
        methodViewWithTitles.add("Center", methodView);

        setLayout(new BorderLayout());
        add("North", titleRegisterPanel);
        add("Center", methodViewWithTitles);

        // Call updateView() first because updateProgramCounter() only changes
        // the address, byte, and mnemonic columns if the program counter has
        // moved off the page.
        updateView(0);
        updateProgramCounter(0);
    }

    // UpdateView() repaints the rightmost three columns: address, byte, and mnemonic
    // starting with the passed initialaddress of theProgram.
    private void updateView(int initialAddress){

        int filledRowsCount = theProgram.length < memoryLocationsVisibleCount ?
            theProgram.length : memoryLocationsVisibleCount;

        for (int i = 0; i < filledRowsCount; ++i) {

            address[i].setText(Integer.toString(initialAddress + i));

            int theByte = theProgram[initialAddress + i];
            HexString byteValueHexString = new HexString(theByte, 2);
            byteValue[i].setText(byteValueHexString.getString());

            String logicalValueStr = theMnemonics[initialAddress + i];
            logicalValue[i].setText(logicalValueStr);
        }
    }

    // Will change the pc register and pc> pointer. If necessary, will also shift
    // the other three columns--address, byte, and mnemonic--by calling updateView().
    public void updateProgramCounter(int newPCValue) {

        // Erase the old "pc>" pointer
        pointer[currentProgramCounterRow].setText("");

        // Only change the address, byte, and mnemonic columns if the program
        // counter has gone off the edge of the screen.
        if (newPCValue - firstVisibleRow >= memoryLocationsVisibleCount) {
            firstVisibleRow = newPCValue;
            if (firstVisibleRow > theProgram.length - memoryLocationsVisibleCount) {
                firstVisibleRow = theProgram.length - memoryLocationsVisibleCount;
            }
            updateView(firstVisibleRow);
        }
        else if (newPCValue < firstVisibleRow) {
            firstVisibleRow = newPCValue;
            updateView(firstVisibleRow);
        }

        // Place the "pc>" pointer
        pointer[newPCValue - firstVisibleRow].setText(StringTable.pcPointer);
        currentProgramCounterRow = newPCValue - firstVisibleRow;

        // Set the program counter register
        //HexString hexString = new HexString(newPCValue, 8);
        pcRegister.setLabelText("    " + Integer.toString(newPCValue));
    }

    public Insets insets() {
        return new Insets(5, 5, 5, 5);
    }
}