如何使用dbus glib-binding传递一个图片文件

  

 

这里主要目的：用dbus 消息来传递一个大概10K的图片文件。

 

使用Garray是比较合适的，它可以包含任何类型的数据。实际调试过程中发现：实际的消息大小是图片文件大小的4倍！这是怎么回事？难道是dbus把Garray映射成DBUS_TYPE_ARRAY，而DBUS_TYPE_ARRAY是uint32的数组。其实问题的原因就在这里：你不要在XML文件中定义uint32数组(au)，而定义byte 数组(ay), 这样，你的消息体的数据与实际的图片文件大小相符。

 

 

代码如下：

 

//客户端程序

int main (int argc, char **argv)

{

    DBusGConnection *connection;

    GError *error;

    DBusGProxy *proxy;

    GArray *array;

    guint length;

    FILE *fp = NULL;

    int len;

    g_type_init ();

    error = NULL;

    connection = dbus_g_bus_get (DBUS_BUS_SESSION,

                               &error);

    if (connection == NULL)

    {

      g_printerr ("Failed to open connection to bus: %s/n",

                  error->message);

      g_error_free (error);

      exit (1);

    }

    proxy = dbus_g_proxy_new_for_name (connection,

                                     "com.example.SomeObject",

                                     "/com/example/SomeObject",

                                     "com.example.SomeObject");

    error = NULL;

//从消息中读取数据文件，并且把读取的数据写到copy-client文件中    if(!com_example_SomeObject_method1(proxy,10,&array,&length,&error))

    {

        printf("Error --- %s/n",error->message);

        return 1;

    }

    printf("File details... length = %d/n",length);

    error = NULL;

    fp = fopen("copy-client","wb");

    len = fwrite(array->data,4,array->len,fp);

    fclose(fp);

    return 0;

}

 

 

//server侧的代码：

//some-object.h

#ifndef __SOME_OBJECT_H__

#define __SOME_OBJECT_H__

#include <glib-object.h>

typedef struct _SomeObject SomeObject;

struct _SomeObject

{

    GObject        parent_obj;

    gint         m_a;

    gchar*        m_b;

    gfloat        m_c;

};

typedef struct _SomeObjectClass SomeObjectClass;

struct _SomeObjectClass

{

    GObjectClass    parent_class;

    /* Some useful methods may follow. */

    gboolean    (*method1)    (SomeObject *self, gint x,GArray **y,gint

 *z,GError **error);

    void        (*method2)    (SomeObject *self, gchar*);

};

GType    some_object_get_type ();

gboolean some_object_method1 (SomeObject *self, gint x,GArray **y,gint

 *z,GError **);    /* virtual */

void    some_object_method2 (SomeObject *self, gchar*);    /* virtual

 */

void    some_object_method3 (SomeObject *self, gfloat);    /*

 non-virtual */

/* Handy macros */

#define SOME_OBJECT_TYPE        (some_object_get_type ())

#define SOME_OBJECT(obj)        (G_TYPE_CHECK_INSTANCE_CAST ((obj),

 SOME_OBJECT_TYPE, SomeObject))

#define SOME_OBJECT_CLASS(c)        (G_TYPE_CHECK_CLASS_CAST ((c),

 SOME_OBJECT_TYPE, SomeObjectClass))

#define SOME_IS_OBJECT(obj)        (G_TYPE_CHECK_TYPE ((obj),

 SOME_OBJECT_TYPE))

#define SOME_IS_OBJECT_CLASS(c)        (G_TYPE_CHECK_CLASS_TYPE ((c),

 SOME_OBJECT_TYPE))

#define SOME_OBJECT_GET_CLASS(obj)    (G_TYPE_INSTANCE_GET_CLASS

 ((obj), SOME_OBJECT_TYPE, SomeObjectClass))

#endif

// End some-object.h

 

 

 

/// some-object.c

#include <string.h>

#include <sys/stat.h>

#include <stdio.h>

#include <stdlib.h>

#include "some-object.h"

#include "some-object-glue.h"

#include <dbus/dbus-glib-bindings.h>

#include <errno.h>

static GObjectClass *parent_class = ((void *)0);

static void some_object_init (SomeObject *self);

char *FILENAME = "test.jpeg";

int SIZE = 0;

//把图片文件test.jpeg打包到消息体中

gboolean some_object_method1_impl (SomeObject *self, gint a, GArray

 **y,gint *z,GError **error)

{

    struct stat stat_buf;

    gchar *ptr = NULL;

    FILE *fp = NULL;

    int err;

    unsigned int length = 0;

    self->m_a = a;

    g_print ("Method1: %i/n", self->m_a);

    *y = g_array_new(FALSE,FALSE,1);

    stat(FILENAME,&stat_buf);

    SIZE = stat_buf.st_size;

    ptr = g_malloc(SIZE);

    errno = 0;

    fp = fopen(FILENAME,"rb");

    err = errno;

    if(fp)

    {

        FILE *fp2 = fopen("c://copy-server","wb");

        fread(ptr,1,SIZE,fp);

        if(fp2)

            fwrite(ptr,1,SIZE,fp2);

        g_array_append_vals(*y,ptr,SIZE/4);

        *z = SIZE;    

    }

    fclose(fp);

    free(ptr);

    return TRUE;

}

void some_object_method2_impl (SomeObject *self, gchar* b)

{

    self->m_b = b;

    g_print ("Method2: %s/n", self->m_b);

}

/* Public methods. */

gboolean some_object_method1 (SomeObject *self, gint a,GArray **y,gint

 *z,GError **error)

{

    return SOME_OBJECT_GET_CLASS (self)->method1 (self, a,y,z,error);

}

void    some_object_method2 (SomeObject *self, gchar* b)

{

    SOME_OBJECT_GET_CLASS (self)->method2 (self, b);

}

void    some_object_method3 (SomeObject *self, gfloat c)

{

    self->m_c = c;

    g_print ("Method3: %f/n", self->m_c);

}

void    some_object_dispose (GObject *self)

{

    static gboolean first_run = TRUE;

    if (first_run)

    {

        first_run = FALSE;

        /* Call g_object_unref on any GObjects that we hold, but don't

 break the object */

        parent_class-> dispose (self);

    }

}

void    some_object_finalize (GObject *self)

{

    parent_class-> finalize (self);

}

/* Here is where we override any functions. Since we have no properties

 or even fields, none of the below are needed. */

void    some_object_class_init        (gpointer g_class, gpointer

 class_data)

{

    GObjectClass    *object_class    = G_OBJECT_CLASS (g_class);

    SomeObjectClass    *this_class    = SOME_OBJECT_CLASS (g_class);

    //assign value to parent class

    parent_class = g_type_class_peek_parent (g_class);

    //assing pointer values to the base class members

    object_class-> dispose = &some_object_dispose;

    object_class-> finalize = &some_object_finalize;

    //assign value to derived class members

    this_class->method1 = &some_object_method1_impl;

    this_class->method2 = &some_object_method2_impl;

  dbus_g_object_type_install_info(G_TYPE_FROM_CLASS(this_class),&dbus_glib__object_info);

}

void some_object_init (SomeObject *self)

{

    self->m_a = 1;

    self->m_c = 1.03f;

    self->m_b = "sumit";

}

GType some_object_get_type () 

{

    static GType g_define_type_id = 0; 

    if ((g_define_type_id == 0)) 

    { 

        static const GTypeInfo g_define_type_info = 

        { 

            sizeof (SomeObjectClass), 

            (GBaseInitFunc) ((void *)0), 

            (GBaseFinalizeFunc) ((void *)0), 

            (GClassInitFunc) some_object_class_init, 

            (GClassFinalizeFunc) ((void *)0), 

            ((void *)0), 

            sizeof (SomeObject), 

            0, 

            (GInstanceInitFunc) some_object_init, 

        }; 

        g_define_type_id = g_type_register_static 

        (

            G_TYPE_OBJECT, 

            "SomeObject", 

            &g_define_type_info, 

            (GTypeFlags) 0

        );

    } 

    return g_define_type_id; 

}

int main(int argc,char *argv[])

{

    SomeObject *so = NULL;

    DBusGConnection *bus;

    GMainLoop *mainLoop = NULL;

    unsigned int request_ret;

    GError *error = NULL;

    DBusGProxy *proxy = NULL;

    char *x;

    g_type_init();

    so = g_object_new(SOME_OBJECT_TYPE,NULL);

    bus = dbus_g_bus_get(DBUS_BUS_SESSION,NULL);

    proxy =

 dbus_g_proxy_new_for_name(bus,DBUS_SERVICE_DBUS,DBUS_PATH_DBUS,DBUS_INTERFACE_DBUS);

  dbus_g_connection_register_g_object(bus,"/com/example/SomeObject",G_OBJECT(so));

  if(!org_freedesktop_DBus_request_name(proxy,"com.example.SomeObject",0,&request_ret,&error))

    {

        g_print("Unable to register service/n");

        return 1;

    }

    mainLoop = g_main_loop_new(NULL,FALSE);

   g_main_loop_run(mainLoop);

    return 0;

}