guestfs-java - Java から libguestfs
を使用する方法
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 ();
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
guestfs(3).
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 "close" method.
Errors from libguestfs functions are mapped into the
"LibGuestFSException" exception. This has a single parameter which
is the error message (a "String").
Calling any method on a closed handle raises the same exception.
If
malloc(3) or some other allocation fails inside the bindings, the
"LibGuestFSOutOfMemory" exception is thrown.
The libguestfs event API is fully supported from Java. Create a class which
implements the "EventCallback" interface, create an instance of this
class, and then call the "GuestFS#set_event_callback" method to
register this instance. The "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.
Some methods take an optional map of optional parameters. An example of this is
"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 "CALLS WITH OPTIONAL
ARGUMENTS" in
guestfs(3).
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 "guestfs_create_flags" in
guestfs(3).
Libguestfs for Java is a Java Native Interface (JNI) extension, supplied in
three parts:
- libguestfs.jar
-
libguestfs-VERSION.jar
- The pure Java JAR file which contains several classes, the
primary one being "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.
- 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 not call these directly.
- libguestfs.so
- The regular libguestfs C library.
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
@EXAMPLE1@
@EXAMPLE2@
guestfs(3),
guestfs-examples(3),
guestfs-erlang(3),
guestfs-gobject(3),
guestfs-golang(3),
guestfs-lua(3),
guestfs-ocaml(3),
guestfs-perl(3),
guestfs-python(3),
guestfs-recipes(1),
guestfs-ruby(3),
http://libguestfs.org/,
http://caml.inria.fr/.
Richard W.M. Jones ("rjones at redhat dot com")
Copyright (C) 2011-2012 Red Hat Inc.
To get a list of bugs against libguestfs, use this link:
https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
To report a new bug against libguestfs, use this link:
https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
When reporting a bug, please supply:
- •
- The version of libguestfs.
- •
- Where you got libguestfs (eg. which Linux distro, compiled
from source, etc)
- •
- Describe the bug accurately and give a way to reproduce
it.
- •
- Run libguestfs-test-tool(1) and paste the
complete, unedited output into the bug report.