Java example source code file (ConstantPoolInfo.java)

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Java - Java tags/keywords

constant_class, constant_double, constant_field, constant_float, constant_long, constant_nameandtype, constant_utf8, constantpoolinfo, datainputstream, exception, howdy, ioexception, java_magic, jdi, string, util

The ConstantPoolInfo.java Java example source code

/*
 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/**
 *  @test
 *  @bug 5024104
 *  @summary Test ReferenceType.majorVersion(), minorVersion, constantPoolCount and ConstantPool apis.
 *
 *  @author Swamy Venkataramanappa
 *
 *  @run build TestScaffold VMConnection
 *  @run compile -g ConstantPoolInfo.java
 *  @run main ConstantPoolInfo
 */
import com.sun.jdi.*;
import com.sun.jdi.event.*;
import com.sun.jdi.request.*;

import java.util.*;
import java.io.*;

    /********** target program **********/

class ConstantPoolTarg {
    public static void main(String[] args){
        System.out.println("Howdy!"); // don't change the string value "Howdy!" it is
                                      // used to test the constant pool entry
    }
}

    /********** test program **********/

public class ConstantPoolInfo extends TestScaffold {
    ReferenceType targetClass;
    ThreadReference mainThread;
    int cpool_count;
    byte[] cpbytes;
    static int expectedMajorVersion;
    static int expectedMinorVersion;
    static int expectedCpoolCount;

    /* Class File Constants */
    public static final int JAVA_MAGIC                   = 0xcafebabe;

    /* Constant table :  copied from sun/javap */
    public static final int CONSTANT_UTF8                = 1;
    public static final int CONSTANT_UNICODE             = 2;
    public static final int CONSTANT_INTEGER             = 3;
    public static final int CONSTANT_FLOAT               = 4;
    public static final int CONSTANT_LONG                = 5;
    public static final int CONSTANT_DOUBLE              = 6;
    public static final int CONSTANT_CLASS               = 7;
    public static final int CONSTANT_STRING              = 8;
    public static final int CONSTANT_FIELD               = 9;
    public static final int CONSTANT_METHOD              = 10;
    public static final int CONSTANT_INTERFACEMETHOD     = 11;
    public static final int CONSTANT_NAMEANDTYPE         = 12;

    ConstantPoolInfo (String args[]) {
        super(args);
    }

    public static void main(String[] args)      throws Exception {
        new ConstantPoolInfo(args).startTests();
    }

    /********** test core **********/

    protected void runTests() throws Exception {
        /*
         * Get to the top of main()
         * to determine targetClass and mainThread
         */
        BreakpointEvent bpe = startToMain("ConstantPoolTarg");
        targetClass = bpe.location().declaringType();
        mainThread = bpe.thread();


        String targPathname = System.getProperty("test.classes") + File.separator + "ConstantPoolTarg.class";

        readClassData(new FileInputStream(targPathname));

        /* Test constant pool apis
         */
        if (vm().canGetClassFileVersion()) {
            if (expectedMajorVersion != targetClass.majorVersion()) {
                failure("unexpected major version: actual value: " + targetClass.majorVersion()
                        + "expected value :" + expectedMajorVersion);

            }
            if (expectedMinorVersion != targetClass.minorVersion()) {
                failure("unexpected minor version: actual value: " + targetClass.minorVersion()
                        + "expected value :" + expectedMinorVersion);

            }
        } else {
            System.out.println("can get class version not supported");
        }


        if (vm().canGetConstantPool()) {

            cpool_count = targetClass.constantPoolCount();

            cpbytes = targetClass.constantPool();

            try {
                printcp();
            } catch (IOException x){
                System.out.println("IOexception reading cpool bytes " + x);
            }

            if (expectedCpoolCount != cpool_count) {
                failure("unexpected constant pool count: actual value: " + cpool_count
                        + "expected value :" + expectedCpoolCount);
            }

        } else {
            System.out.println("can get constant pool version not supported");
        }


        /*
         * resume until end
         */
        listenUntilVMDisconnect();

        /*
         * deal with results of test
         * if anything has called failure("foo") testFailed will be true
         */
        if (!testFailed) {
            println("ConstantPoolInfo: passed");
        } else {
            throw new Exception("ConstantPoolInfo: failed");
        }
    }

    public void printcp() throws IOException {
        boolean found = false;

        ByteArrayInputStream bytesStream = new ByteArrayInputStream(cpbytes);
        DataInputStream in = new DataInputStream(bytesStream);
        for (int i = 1; i < cpool_count; i++) {
            int tag = in.readByte();
            System.out.print("const #" + i + ":   ");
            switch(tag) {
                    case CONSTANT_UTF8:
                    String str=in.readUTF();
                    System.out.println("Asciz " + str);
                    // "Howdy!" is an expected constant pool entry
                    // of test program. It should exist.
                    if (str.compareTo("Howdy!") == 0) {
                        found = true;
                    }
                    break;
                case CONSTANT_INTEGER:
                    System.out.println("int " + in.readInt());
                    break;
                case CONSTANT_FLOAT:
                    System.out.println("Float " + in.readFloat());
                    break;
                case CONSTANT_LONG:
                    System.out.println("Long " + in.readLong());
                    break;
                case CONSTANT_DOUBLE:
                    System.out.println("Double " + in.readDouble());
                    break;
                case CONSTANT_CLASS:
                    System.out.println("Class " + in.readUnsignedShort());
                    break;
                case CONSTANT_STRING:
                    System.out.println("String " + in.readUnsignedShort());
                    break;
                case CONSTANT_FIELD:
                    System.out.println("Field " + in.readUnsignedShort() + " " + in.readUnsignedShort());
                    break;
                case CONSTANT_METHOD:
                    System.out.println("Method " + in.readUnsignedShort() + " " + in.readUnsignedShort());
                    break;
                case CONSTANT_INTERFACEMETHOD:
                    System.out.println("InterfaceMethod " + in.readUnsignedShort() + " " + in.readUnsignedShort());
                    break;
                case CONSTANT_NAMEANDTYPE:
                    System.out.println("NameAndType " + in.readUnsignedShort() + " " + in.readUnsignedShort());
                    break;
                case 0:
                default:
                    System.out.println("class format error");
            }

        }

        if (!found) {
            failure("expected string \"Howdy!\" not found in constant pool");
        }
    }


    /**
     * Read classfile
     */
    void readClassData(InputStream infile){
        try{
            this.read(new DataInputStream(infile));
        }catch (FileNotFoundException ee) {
            failure("cant read file");
        }catch (Error ee) {
            ee.printStackTrace();
            failure("fatal error");
        } catch (Exception ee) {
            ee.printStackTrace();
            failure("fatal exception");
        }
    }

        /**
         * Read major, minor and cp count.
         */
    public void read(DataInputStream in) throws IOException {
        int magic = in.readInt();
        if (magic != JAVA_MAGIC) {
            failure("fatal bad class file format");
        }
        expectedMinorVersion = in.readShort();;
        expectedMajorVersion = in.readShort();
        expectedCpoolCount = in.readUnsignedShort();
        in.close();
    } // end read()
}