首先用C语言的GTK生成动态链接库，然后利用java的native方法调用该动态链接库就可以了，是不是很简单。
环境：
JDK 8；
OS：CentOS5；
GTK：gtk+-2.0
首先看下我的文件树（编译运行后的）：
. ├── 37_drawingPic3.c ├── config.sh ├── Demo_03_JButton_JPanel.java ├── Demo$1.class ├── Demo$2.class ├── Demo.class ├── Demo.h └── libGTK.so
首先编写含有native方法的java程序：
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
class Demo extends JFrame {
private Toolkit toolkit;
public native void gtk_draw();
Demo() {
setTitle("Demo");
setSize(300, 200);
toolkit = getToolkit();
Dimension size = toolkit.getScreenSize();
System.loadLibrary("GTK");
setLocation((size.width/2 - getWidth())/2, (size.height - getHeight())/2);
setDefaultCloseOperation(EXIT_ON_CLOSE);
JPanel panel = new JPanel();
//getContentPane().add(panel);
add(panel);
//panel.setLayout(new GridLayout(2,2));
panel.setLayout(null);
JButton beep = new JButton("Beep");
beep.setBounds(150, 60, 80, 30);
beep.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
toolkit.beep();
System.out.println("Beep");
gtk_draw();
}
});
JButton close = new JButton("Close");
close.setBounds(50, 60, 80, 30);
close.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
System.exit(0);
}
});
panel.add(beep);
panel.add(close);
}
public static void main(String[] args) {
Demo demo = new Demo();
demo.setVisible(true);
}
}
编译该java程序：
$ javac Demo_03_JButton_JPanel.java
生成Demo.class文件，改文件名是由含有native方法的类名决定。然后用javah -jni编译生成头文件：
$ javah -jni Demo
然后生成Demo.h文件，改文件名也是由含有native方法的类名决定，文件内容如下：
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class Demo */
#ifndef _Included_Demo
#define _Included_Demo
#ifdef __cplusplus
extern "C" {
#endif
#undef Demo_FOCUS_TRAVERSABLE_UNKNOWN
#define Demo_FOCUS_TRAVERSABLE_UNKNOWN 0L
#undef Demo_FOCUS_TRAVERSABLE_DEFAULT
#define Demo_FOCUS_TRAVERSABLE_DEFAULT 1L
#undef Demo_FOCUS_TRAVERSABLE_SET
#define Demo_FOCUS_TRAVERSABLE_SET 2L
#undef Demo_TOP_ALIGNMENT
#define Demo_TOP_ALIGNMENT 0.0f
#undef Demo_CENTER_ALIGNMENT
#define Demo_CENTER_ALIGNMENT 0.5f
#undef Demo_BOTTOM_ALIGNMENT
#define Demo_BOTTOM_ALIGNMENT 1.0f
#undef Demo_LEFT_ALIGNMENT
#define Demo_LEFT_ALIGNMENT 0.0f
#undef Demo_RIGHT_ALIGNMENT
#define Demo_RIGHT_ALIGNMENT 1.0f
#undef Demo_serialVersionUID
#define Demo_serialVersionUID -7644114512714619750LL
#undef Demo_serialVersionUID
#define Demo_serialVersionUID 4613797578919906343LL
#undef Demo_INCLUDE_SELF
#define Demo_INCLUDE_SELF 1L
#undef Demo_SEARCH_HEAVYWEIGHTS
#define Demo_SEARCH_HEAVYWEIGHTS 1L
#undef Demo_OPENED
#define Demo_OPENED 1L
#undef Demo_serialVersionUID
#define Demo_serialVersionUID 4497834738069338734LL
#undef Demo_DEFAULT_CURSOR
#define Demo_DEFAULT_CURSOR 0L
#undef Demo_CROSSHAIR_CURSOR
#define Demo_CROSSHAIR_CURSOR 1L
#undef Demo_TEXT_CURSOR
#define Demo_TEXT_CURSOR 2L
#undef Demo_WAIT_CURSOR
#define Demo_WAIT_CURSOR 3L
#undef Demo_SW_RESIZE_CURSOR
#define Demo_SW_RESIZE_CURSOR 4L
#undef Demo_SE_RESIZE_CURSOR
#define Demo_SE_RESIZE_CURSOR 5L
#undef Demo_NW_RESIZE_CURSOR
#define Demo_NW_RESIZE_CURSOR 6L
#undef Demo_NE_RESIZE_CURSOR
#define Demo_NE_RESIZE_CURSOR 7L
#undef Demo_N_RESIZE_CURSOR
#define Demo_N_RESIZE_CURSOR 8L
#undef Demo_S_RESIZE_CURSOR
#define Demo_S_RESIZE_CURSOR 9L
#undef Demo_W_RESIZE_CURSOR
#define Demo_W_RESIZE_CURSOR 10L
#undef Demo_E_RESIZE_CURSOR
#define Demo_E_RESIZE_CURSOR 11L
#undef Demo_HAND_CURSOR
#define Demo_HAND_CURSOR 12L
#undef Demo_MOVE_CURSOR
#define Demo_MOVE_CURSOR 13L
#undef Demo_NORMAL
#define Demo_NORMAL 0L
#undef Demo_ICONIFIED
#define Demo_ICONIFIED 1L
#undef Demo_MAXIMIZED_HORIZ
#define Demo_MAXIMIZED_HORIZ 2L
#undef Demo_MAXIMIZED_VERT
#define Demo_MAXIMIZED_VERT 4L
#undef Demo_MAXIMIZED_BOTH
#define Demo_MAXIMIZED_BOTH 6L
#undef Demo_serialVersionUID
#define Demo_serialVersionUID 2673458971256075116LL
#undef Demo_EXIT_ON_CLOSE
#define Demo_EXIT_ON_CLOSE 3L
/*
* Class: Demo
* Method: gtk_draw
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_Demo_gtk_1draw
(JNIEnv *, jobject);
#ifdef __cplusplus
}
#endif
#endif
然后按照该头文件中的函数名编写C语言代码，并包含该头文件：
/* GTK - The GIMP Toolkit
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
* Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GTK+ Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GTK+ at ftp://ftp.gtk.org/pub/gtk/.
*/
//#include <config.h>
#include <stdio.h>
#include "gtk/gtk.h"
#include "Demo.h"
/* Backing pixmap for drawing area */
static GdkPixmap *pixmap = NULL;
/* Information about cursor */
static gint cursor_proximity = TRUE;
static gdouble cursor_x;
static gdouble cursor_y;
/* Unique ID of current device */
static GdkDevice *current_device;
/* Erase the old cursor, and/or draw a new one, if necessary */
static void
update_cursor (GtkWidget *widget, gdouble x, gdouble y)
{
static gint cursor_present = 0;
gint state = !current_device->has_cursor && cursor_proximity;
if (pixmap != NULL)
{
if (cursor_present && (cursor_present != state ||
x != cursor_x || y != cursor_y))
{
gdk_draw_drawable (widget->window,
widget->style->fg_gc[GTK_WIDGET_STATE (widget)],
pixmap,
cursor_x - 5, cursor_y - 5,
cursor_x - 5, cursor_y - 5,
10, 10);
}
cursor_present = state;
cursor_x = x;
cursor_y = y;
if (cursor_present)
{
gdk_draw_rectangle (widget->window,
widget->style->black_gc,
TRUE,
cursor_x - 5, cursor_y -5,
10, 10);
}
}
}
/* Create a new backing pixmap of the appropriate size */
static gint
configure_event (GtkWidget *widget, GdkEventConfigure *event)
{
if (pixmap)
g_object_unref (pixmap);
pixmap = gdk_pixmap_new(widget->window,
widget->allocation.width,
widget->allocation.height,
-1);
gdk_draw_rectangle (pixmap,
widget->style->white_gc,
TRUE,
0, 0,
widget->allocation.width,
widget->allocation.height);
return TRUE;
}
/* Refill the screen from the backing pixmap */
static gint
expose_event (GtkWidget *widget, GdkEventExpose *event)
{
gdk_draw_drawable (widget->window,
widget->style->fg_gc[GTK_WIDGET_STATE (widget)],
pixmap,
event->area.x, event->area.y,
event->area.x, event->area.y,
event->area.width, event->area.height);
return FALSE;
}
/* Draw a rectangle on the screen, size depending on pressure,
and color on the type of device */
static void
draw_brush (GtkWidget *widget, GdkInputSource source,
gdouble x, gdouble y, gdouble pressure)
{
GdkGC *gc;
GdkRectangle update_rect;
switch (source)
{
case GDK_SOURCE_MOUSE:
gc = widget->style->dark_gc[GTK_WIDGET_STATE (widget)];
break;
case GDK_SOURCE_PEN:
gc = widget->style->black_gc;
break;
case GDK_SOURCE_ERASER:
gc = widget->style->white_gc;
break;
default:
gc = widget->style->light_gc[GTK_WIDGET_STATE (widget)];
}
update_rect.x = x - 10 * pressure;
update_rect.y = y - 10 * pressure;
update_rect.width = 20 * pressure;
update_rect.height = 20 * pressure;
gdk_draw_rectangle (pixmap, gc, TRUE,
update_rect.x, update_rect.y,
update_rect.width, update_rect.height);
gtk_widget_queue_draw_area (widget,
update_rect.x, update_rect.y,
update_rect.width, update_rect.height);
gdk_window_process_updates (widget->window, TRUE);
}
static guint32 motion_time;
static void
print_axes (GdkDevice *device, gdouble *axes)
{
int i;
if (axes)
{
g_print ("%s ", device->name);
for (i=0; i<device->num_axes; i++)
g_print ("%g ", axes[i]);
g_print ("\n");
}
}
static gint
button_press_event (GtkWidget *widget, GdkEventButton *event)
{
current_device = event->device;
cursor_proximity = TRUE;
if (event->button == 1 && pixmap != NULL)
{
gdouble pressure = 0.5;
print_axes (event->device, event->axes);
gdk_event_get_axis ((GdkEvent *)event, GDK_AXIS_PRESSURE, &pressure);
draw_brush (widget, event->device->source, event->x, event->y, pressure);
motion_time = event->time;
}
update_cursor (widget, event->x, event->y);
return TRUE;
}
static gint
key_press_event (GtkWidget *widget, GdkEventKey *event)
{
if ((event->keyval >= 0x20) && (event->keyval <= 0xFF))
printf("I got a %c\n", event->keyval);
else
printf("I got some other key\n");
return TRUE;
}
static gint
motion_notify_event (GtkWidget *widget, GdkEventMotion *event)
{
GdkTimeCoord **events;
int n_events;
int i;
current_device = event->device;
cursor_proximity = TRUE;
if (event->state & GDK_BUTTON1_MASK && pixmap != NULL)
{
if (gdk_device_get_history (event->device, event->window,
motion_time, event->time,
&events, &n_events))
{
for (i=0; i<n_events; i++)
{
double x = 0, y = 0, pressure = 0.5;
gdk_device_get_axis (event->device, events[i]->axes, GDK_AXIS_X, &x);
gdk_device_get_axis (event->device, events[i]->axes, GDK_AXIS_Y, &y);
gdk_device_get_axis (event->device, events[i]->axes, GDK_AXIS_PRESSURE, &pressure);
draw_brush (widget, event->device->source, x, y, pressure);
print_axes (event->device, events[i]->axes);
}
gdk_device_free_history (events, n_events);
}
else
{
double pressure = 0.5;
gdk_event_get_axis ((GdkEvent *)event, GDK_AXIS_PRESSURE, &pressure);
draw_brush (widget, event->device->source, event->x, event->y, pressure);
}
motion_time = event->time;
}
if (event->is_hint)
gdk_device_get_state (event->device, event->window, NULL, NULL);
print_axes (event->device, event->axes);
update_cursor (widget, event->x, event->y);
return TRUE;
}
/* We track the next two events to know when we need to draw a
cursor */
static gint
proximity_out_event (GtkWidget *widget, GdkEventProximity *event)
{
cursor_proximity = FALSE;
update_cursor (widget, cursor_x, cursor_y);
return TRUE;
}
static gint
leave_notify_event (GtkWidget *widget, GdkEventCrossing *event)
{
cursor_proximity = FALSE;
update_cursor (widget, cursor_x, cursor_y);
return TRUE;
}
void
input_dialog_destroy (GtkWidget *w, gpointer data)
{
*((GtkWidget **)data) = NULL;
}
void
create_input_dialog (void)
{
static GtkWidget *inputd = NULL;
if (!inputd)
{
inputd = gtk_input_dialog_new ();
g_signal_connect (inputd, "destroy",
G_CALLBACK (input_dialog_destroy), &inputd);
g_signal_connect_swapped (GTK_INPUT_DIALOG (inputd)->close_button,
"clicked",
G_CALLBACK (gtk_widget_hide),
inputd);
gtk_widget_hide (GTK_INPUT_DIALOG (inputd)->save_button);
gtk_widget_show (inputd);
}
else
{
if (!GTK_WIDGET_MAPPED(inputd))
gtk_widget_show(inputd);
else
gdk_window_raise(inputd->window);
}
}
void
quit (void)
{
gtk_main_quit ();
}
JNIEXPORT void JNICALL Java_Demo_gtk_1draw
(JNIEnv *env, jobject obj)
{
int argc;
char **argv;
GtkWidget *window;
GtkWidget *drawing_area;
GtkWidget *vbox;
GtkWidget *button;
gtk_init (&argc, &argv);
current_device = gdk_device_get_core_pointer ();
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_widget_set_name (window, "Test Input");
gtk_widget_set_size_request(window , 300 , 200);
gtk_container_set_border_width(GTK_CONTAINER(window) , 2);
gtk_window_set_resizable(GTK_WINDOW(window) , FALSE);
vbox = gtk_vbox_new (FALSE, 0);
gtk_container_add (GTK_CONTAINER (window), vbox);
gtk_widget_show (vbox);
g_signal_connect (window, "destroy",
G_CALLBACK (quit), NULL);
/* Create the drawing area */
drawing_area = gtk_drawing_area_new ();
gtk_widget_set_size_request (drawing_area, 200, 200);
gtk_box_pack_start (GTK_BOX (vbox), drawing_area, TRUE, TRUE, 0);
gtk_widget_show (drawing_area);
/* Signals used to handle backing pixmap */
g_signal_connect (drawing_area, "expose_event",
G_CALLBACK (expose_event), NULL);
g_signal_connect (drawing_area, "configure_event",
G_CALLBACK (configure_event), NULL);
/* Event signals */
g_signal_connect (drawing_area, "motion_notify_event",
G_CALLBACK (motion_notify_event), NULL);
g_signal_connect (drawing_area, "button_press_event",
G_CALLBACK (button_press_event), NULL);
g_signal_connect (drawing_area, "key_press_event",
G_CALLBACK (key_press_event), NULL);
g_signal_connect (drawing_area, "leave_notify_event",
G_CALLBACK (leave_notify_event), NULL);
g_signal_connect (drawing_area, "proximity_out_event",
G_CALLBACK (proximity_out_event), NULL);
gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK
| GDK_LEAVE_NOTIFY_MASK
| GDK_BUTTON_PRESS_MASK
| GDK_KEY_PRESS_MASK
| GDK_POINTER_MOTION_MASK
| GDK_POINTER_MOTION_HINT_MASK
| GDK_PROXIMITY_OUT_MASK);
/* The following call enables tracking and processing of extension
events for the drawing area */
gtk_widget_set_extension_events (drawing_area, GDK_EXTENSION_EVENTS_ALL);
GTK_WIDGET_SET_FLAGS (drawing_area, GTK_CAN_FOCUS);
gtk_widget_grab_focus (drawing_area);
/* .. And create some buttons */
button = gtk_button_new_with_label ("Input Dialog");
gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
g_signal_connect (button, "clicked",
G_CALLBACK (create_input_dialog), NULL);
gtk_widget_show (button);
button = gtk_button_new_with_label ("Quit");
gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
g_signal_connect_swapped (button, "clicked",
G_CALLBACK (gtk_widget_destroy),
window);
gtk_widget_show (button);
gtk_widget_show (window);
gtk_main ();
}
然后用gcc编译生成动态链接库：
$ gcc -shared -fpic -o libGTK.so -I$JAVA_HOME/include -I$JAVA_HOME/include/linux 37_drawingPic3.c `pkg-config --cflags --libs gtk+-2.0`
最后用java连同动态链接库运行java的包含native方法的类的main函数：
$ java -Djava.library.path=. Demo
大功告成。
整体的编译过程是：
#!/bin/sh javac Demo_03_JButton_JPanel.java javah -jni Demo gcc -shared -fpic -o libGTK.so -I$JAVA_HOME/include -I$JAVA_HOME/include/linux 37_drawingPic3.c `pkg-config --cflags --libs gtk+-2.0` java -Djava.library.path=. Demo