
=head1 名前

guestfs-java - Java から libguestfs を使用する方法

=head1 書式

 import com.redhat.et.libguestfs.*;
 
 GuestFS g = new GuestFS ();
 g.add_drive ("disk.img",
              new HashMap<String,Object>() {
                {
                    put ("readonly", Boolean.TRUE);
                    put ("format", "raw");
                }
              });
 g.launch ();

=head1 説明

This manual page documents how to call libguestfs from the Java programming language.  This page just documents the differences from the C API and gives some examples.  If you are not familiar with using libguestfs, you also need to read L<guestfs(3)>.

=head2 ハンドルの閉じ方

The handle is closed when it is reaped by the garbage collector.  Because libguestfs handles include a lot of state, it is also possible to close (and hence free) them explicitly by calling the C<close> method.

=head2 例外

Errors from libguestfs functions are mapped into the C<LibGuestFSException> exception.  This has a single parameter which is the error message (a C<String>).

Calling any method on a closed handle raises the same exception.

If L<malloc(3)> or some other allocation fails inside the bindings, the C<LibGuestFSOutOfMemory> exception is thrown.

=head2 イベント

The L<libguestfs event API|guestfs(3)/EVENTS> is fully supported from Java. Create a class which implements the C<EventCallback> interface, create an instance of this class, and then call the C<GuestFS#set_event_callback> method to register this instance.  The C<event> method of the class is called when libguestfs generates an event.

For example, this will print all trace events:

 GuestFS g = new GuestFS ();
 g.set_trace (true);
 g.set_event_callback (
   new EventCallback () {
     public void event (long event, int eh,
                        String buffer, long[] array) {
       System.out.println (GuestFS.eventToString (event) +
                           ": " + buffer);
     }
   },
   GuestFS.EVENT_TRACE);
 g.add_drive_ro ("disk.img");
 // etc.

The output looks similar to this:

 EVENT_TRACE: add_drive_ro "disk.img"
 EVENT_TRACE: add_drive_ro = 0
 // etc.

=head2 オプション引数

Some methods take an optional map of optional parameters.  An example of this is C<g.add_drive> which can be called in one of two ways:

 g.add_drive ("disk.img");

or with optional arguments:

 Map<String, Object> optargs =
   new HashMap<String, Object>() {
   {
     put ("readonly", Boolean.TRUE);
     put ("format", "raw");
   }
 };
 g.add_drive ("disk.img", optargs);

For more information on this topic, see L<guestfs(3)/CALLS WITH OPTIONAL ARGUMENTS>.

=head3 Optional handle parameters

When creating the handle you can also pass a map of optional parameters:

 Map<String, Object> optargs =
   new HashMap<String, Object>() {
   {
     put ("close_on_exit", Boolean.FALSE);
     put ("environment", Boolean.TRUE);
   }
 };
 GuestFS g = new GuestFS (optargs);

For more information, see L<guestfs(3)/guestfs_create_flags>.

=head1 COMPILING AND RUNNING

Libguestfs for Java is a Java Native Interface (JNI) extension, supplied in three parts:

=over 4

=item F<libguestfs.jar>

=item F<libguestfs-I<VERSION>.jar>

The pure Java JAR file which contains several classes, the primary one being C<com.redhat.et.libguestfs.GuestFS>.  Upstream, the JAR file contains a version number in the filename, but some Linux distros may rename it without the version number.

=item F<libguestfs_jni.so>

The JNI code (written in C).  This contains private native functions that interface between Java code and the regular libguestfs C library.  You should B<not> call these directly.

=item F<libguestfs.so>

The regular libguestfs C library.

=back

To compile your Java program, you need to locate the JAR file and add it to the class path.  For example:

 export CLASSPATH=/usr/share/java/libguestfs.jar
 javac MyProgram.java

To run your Java program, you also need to ensure that the JAR file is on the class path, as well as the path of your program.  For example:

 export CLASSPATH=.:/usr/share/java/libguestfs.jar
 java MyProgram

=head1 例 1: ディスクイメージの作成

@EXAMPLE1@

=head1 例 2: 仮想マシンのディスクイメージの検査

@EXAMPLE2@

=head1 関連項目

L<guestfs(3)>, L<guestfs-examples(3)>, L<guestfs-erlang(3)>, L<guestfs-gobject(3)>, L<guestfs-golang(3)>, L<guestfs-lua(3)>, L<guestfs-ocaml(3)>, L<guestfs-perl(3)>, L<guestfs-python(3)>, L<guestfs-recipes(1)>, L<guestfs-ruby(3)>, L<http://libguestfs.org/>, L<http://caml.inria.fr/>.

=head1 著者

Richard W.M. Jones (C<rjones at redhat dot com>)

=head1 COPYRIGHT

Copyright (C) 2011-2025 Red Hat Inc.

