Examples of java.util.jar.Pack200.Packer

java.util.jar.Pack200.Unpacker

sun.com/docs/books/vmspec/html/ClassFile.doc.html">http://java.sun.com/docs/books/vmspec/html/ClassFile.doc.html.

By default, the packer does not change the order of JAR elements. Also, the modification time and deflation hint of each JAR element is passed unchanged. (Any other ZIP-archive information, such as extra attributes giving Unix file permissions, are lost.)

Note that packing and unpacking a JAR will in general alter the bytewise contents of classfiles in the JAR. This means that packing and unpacking will in general invalidate any digital signatures which rely on bytewise images of JAR elements. In order both to sign and to pack a JAR, you must first pack and unpack the JAR to "normalize" it, then compute signatures on the unpacked JAR elements, and finally repack the signed JAR. Both packing steps should use precisely the same options, and the segment limit may also need to be set to "-1", to prevent accidental variation of segment boundaries as class file sizes change slightly.

(Here's why this works: Any reordering the packer does of any classfile structures is idempotent, so the second packing does not change the orderings produced by the first packing. Also, the unpacker is guaranteed by the JSR 200 specification to produce a specific bytewise image for any given transmission ordering of archive elements.)

In order to maintain backward compatibility, if the input JAR-files are solely comprised of 1.5 (or lesser) classfiles, a 1.5 compatible pack file is produced. Otherwise a 1.6 compatible pack200 file is produced.

@since 1.5

    private byte[] pack200(byte[] data) throws Exception
    {
        JarInputStream in = new JarInputStream(new ByteArrayInputStream(data));
        ByteArrayOutputStream out = new ByteArrayOutputStream();


        Packer packer = Pack200.newPacker();


        SortedMap<String, String> props = packer.properties();
        props.put(Packer.EFFORT, "9");
        props.put(Packer.KEEP_FILE_ORDER, Packer.TRUE);
        props.put(Packer.UNKNOWN_ATTRIBUTE, Packer.PASS);


        final PrintStream err = new PrintStream(System.err);
        System.setErr(new PrintStream(Constants.getNullStream()));
        packer.pack(in, out);
        System.setErr(err);


        in.close();
        out.close();

        Packer packer = Pack200.newPacker();
        assertEquals("org.apache.harmony.pack200.Pack200PackerAdapter", packer.getClass().getName());
    }


    public void testUnpacker() {
        Unpacker unpacker = Pack200.newUnpacker();
        assertEquals("org.apache.harmony.unpack200.Pack200UnpackerAdapter", unpacker.getClass().getName());
    }

Examples of java.util.jar.Pack200.Packer

Related Classes of java.util.jar.Pack200.Packer