我对 gjs 非常陌生,我想连接 dbus。我想创建一个服务并监听它。
一个小例子或指南会很有用。谢谢
答案1
我读到 Gnome 正在将 Java Script (GJS) 路线应用于其大部分桌面,并减少 C++ 和 Python 的数量。所以今天我发现这个问题特别有趣。
这是一个Java 脚本示例我将亲自尝试。在此示例中,您将学习如何创建 D-Bus 客户端以连接到服务,您将学习如何调用方法、连接到信号以及从服务获取属性。该示例使用管理键盘背光的 D-Bus 服务:
const Gio = imports.gi.Gio;
const GLib = imports.gi.GLib;
// This the D-Bus interface as XML
const KbdBacklightInterface = '<node>\
<interface name="org.freedesktop.UPower.KbdBacklight"> \
<method name="SetBrightness"> \
<arg name="value" type="i" direction="in"/> \
</method> \
<method name="GetBrightness"> \
<arg name="value" type="i" direction="out"/> \
</method> \
<method name="GetMaxBrightness"> \
<arg name="value" type="i" direction="out"/> \
</method> \
<signal name="BrightnessChanged"> \
<arg type="i"/> \
</signal> \
</interface> \
</node>';
// Declare the proxy class based on the interface
const KbdBacklightProxy = Gio.DBusProxy.makeProxyWrapper(KbdBacklightInterface);
// Get the /org/freedesktop/UPower/KbdBacklight instance from the bus
let kbdProxy = new KbdBacklightProxy(
Gio.DBus.system,
"org.freedesktop.UPower",
"/org/freedesktop/UPower/KbdBacklight"
);
// You can use proxy.<method>Sync syntax to
// call the D-Bus method in a Sync way
print("The max brightness of your keyboard is " + kbdProxy.GetMaxBrightnessSync());
// Or you can use the syntax proxy.<method>Remote
// to call the method in an Async way
kbdProxy.GetBrightnessRemote(function(currentBrightness) {
print("The current keyboard brightness is " + currentBrightness);
});
// Connecting to a D-Bus signal
kbdProxy.connectSignal("BrightnessChanged", function(proxy) {
let newBrightness = proxy.GetBrightnessSync();
print("The keyboard brightness has been changed, new brightness is " + newBrightness);
});
// Also you can get properties value using this syntax
// let property = proxy.PropertyName;
// Or you can set a property value
// proxy.PropertyName = "new value";
let loop = new GLib.MainLoop(null, false);
loop.run();
如果尚未完成,请安装 gjs:
sudo apt update && sudo apt install gjs
为您的 Java 脚本创建一个目录:
mkdir ~/javascript
使用gedit
上面创建示例脚本并保存:
gedit ~/javascript/dbusclient.js
现在运行它:
cd ~/javascript
gjs dbusclient.js
报告了 WIP 错误(我将修复它并返回此问答页面并提供结果):
(gjs:10134): Gjs-WARNING **: JS ERROR: Gio.DBusError: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface 'org.freedesktop.UPower.KbdBacklight' on object at path /org/freedesktop/UPower/KbdBacklight
_proxyInvoker@resource:///org/gnome/gjs/modules/overrides/Gio.js:98
_makeProxyMethod/<@resource:///org/gnome/gjs/modules/overrides/Gio.js:124
@dbusclient.js:36
JS_EvaluateScript() failed
没有键盘灯
虽然笔记本电脑有键盘灯,并且无线键盘有 3 种灯光设置,但 Gnome 的 UPOWER 无法将它们视为以下 shell 命令:
$ dbus-send --print-reply \
--system \
--dest=org.freedesktop.UPower \
/org/freedesktop/UPower \
org.freedesktop.UPower.EnumerateDevices
返回此:
method return time=1564075040.686545 sender=:1.49 -> destination=:1.145 serial=4392 reply_serial=2
array [
object path "/org/freedesktop/UPower/devices/line_power_ACAD"
object path "/org/freedesktop/UPower/devices/battery_BAT1"
object path "/org/freedesktop/UPower/devices/ups_hiddev2"
object path "/org/freedesktop/UPower/devices/mouse_0003o046Do101Ax0017"
object path "/org/freedesktop/UPower/devices/keyboard_0003o046Do2010x0018"
]
不过,这可能是一个方便的脚本,可以修改以监控笔记本电脑电池的充电百分比。
(待续...)