javascript - nsI 协议(protocol)示例不清楚

Question

我在 MDN 上比较了这个例子: https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIProtocolHandler#Implementation

关于如何创建自定义协议(protocol)的此附加组件: https://addons.mozilla.org/en-US/firefox/files/browse/141969/file/components/AboutFosdem.js#top

有人可以详细说明它到底想做什么吗？ SMTP 的东西让我很失望。

我无法理解 MDN 上的示例在做什么，无论它在没有 chrome.manifst 的情况下做什么。我知道该插件正在创建“fosdem://blah”，其中 blah 是根据 WhereToGo 中的定义我想要的任何内容，但它使用 chrome.manifest。

我认为 mdn 示例正在做与插件相同的事情，我会在复制粘贴该 mdn 代码后执行类似的操作来设置我的自定义协议(protocol):

function myCustomBlah() {}

myCustomBlah.prototype =
  makeProtocolHandler("mycustomblah",
                      -1,
                      "b14c2b67-8680-4c11-8d63-9403c7d4f757"); //i can generate any id

var components = [myCustomBlah];
const NSGetFactory = XPCOMUtils.generateNSGetFactory(components);

Answer 1

好吧，让我们给出一个更合理的自定义协议(protocol)处理程序示例。

我决定实现一个 ddg: 协议(protocol)处理程序，注册后可用于在地址栏中输入 ddg:some search terms(除其他外)，它将加载“一些搜索词”的 DuckDuckGo 搜索页面。

组件

需要实现nsIProtocolHandler界面。

这个示例组件的作用是“重定向”到 DuckDuckGo(好吧，不是真正的重定向，但它返回了 duckduckgo.com 的 channel )。请参阅内嵌评论。

var {classes: Cc,
     interfaces: Ci,
     manager: Cm,
     results: Cr,
     Constructor: CC
    } = Components;
Cm.QueryInterface(Ci.nsIComponentRegistrar);

Components.utils.import("resource://gre/modules/Services.jsm");
Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");

const SCHEME = "ddg";
const DDG_URI = Services.io.newURI("https://duckduckgo.com/?q=%s", null, null);

const nsIURI = CC("@mozilla.org/network/simple-uri;1", "nsIURI");

function DuckDuckGoProtocolHandler() {}
DuckDuckGoProtocolHandler.prototype = Object.freeze({
  classDescription: "DuckDuckGo Protocol Handler",
  contractID: "@mozilla.org/network/protocol;1?name=" + SCHEME,
  classID: Components.ID('{858ea860-129a-11e4-9191-0800200c9a66}'),
  QueryInterface: XPCOMUtils.generateQI([Ci.nsIProtocolHandler]),

  // nsIProtocolHandler
  scheme: SCHEME,
  defaultPort: -1, // No default port.

  // nsIProtocolHandler
  allowPort: function(port, scheme) {
    // This protocol handler does not support ports.
    return false;
  },

  // nsIProtocolHandler
  // Our protocol handler does not support authentication,
  // but it is OK to be loaded from any web-page, not just privileged pages""
  protocolFlags: Ci.nsIProtocolHandler.URI_NOAUTH |
                 Ci.nsIProtocolHandler.URI_LOADABLE_BY_ANYONE,

  // nsIProtocolHandler
  newURI: function(aSpec, aOriginCharset, aBaseURI) {
    // Nothing special here, actually. We were asked to create a new URI.

    // If there is a base-URI, this means that the browser tries to resolve
    // a dependent resource (an image, script) or the user clicked on a relative link.
    // In this case we cannot really return another "ddg" URI, but need to return
    // the proper https URI.
    if (aBaseURI && aBaseURI.scheme == SCHEME) {
      return Services.io.newURI(aSpec, aOriginCharset, DDG_URI);
    }

    // We don't care about the charset, so just ignore that
    // (we support what nsIURI supports).
    let rv = new nsIURI();
    rv.spec = aSpec;
    return rv;
  },

  // nsIProtocolHandler
  newChannel: function(aURI) {
    // We were asked to open a new channel.
    // We could implement an entirely custom channel that supports
    // (most of) nsIChannel. But that is tremendous work and outside
    // of the scope of this basic example (which is about protocol handlers and
    // not channels).
    // Or we can just return any other channel we can create.
    // Since we're going to implement the "ddg:" protocol, lets just open a
    // regular https channel to duckduckgo.com, use the URI as the search term
    // and return that channel.
    let spec = DDG_URI.spec.replace("%s", aURI.path);
    let channel = Services.io.newChannel(spec, aURI.originCharset, null);

    // Setting .originalURI will not only let other code know where this
    // originally came from, but the UI will actually show that .originalURI.
    channel.originalURI = aURI;

    return channel;
  }
});

在 chrome.manifest 中注册组件

如果我们的组件是 JavaScript 组件，我们需要实现 NSGetFactory通过 chrome.manifest 注册。幸运的是，XPCOMUtils.jsm 有一个帮助程序。

var NSGetFactory =
  XPCOMUtils.generateNSGetFactory([DuckDuckGoProtocolHandler]);

在引导加载项(和便签本)中注册

在引导/无需重新启动的附加组件(包括 SDK 附加组件)和 Scratchpad 中，需要手动注册组件，因为 chrome.manifest 注册不可用。

可以注册NSGetFactory(classID)的结果，但这里有一些代码手动创建工厂并注册它。

function Factory(component) {
  this.createInstance = function(outer, iid) {
    if (outer) {
      throw Cr.NS_ERROR_NO_AGGREGATION;
    }
    return new component();
  };
  this.register = function() {
    Cm.registerFactory(component.prototype.classID,
                       component.prototype.classDescription,
                       component.prototype.contractID,
                       this);
  };
  this.unregister = function() {
    Cm.unregisterFactory(component.prototype.classID, this);
  }
    Object.freeze(this);
  this.register();
}
var factory = new Factory(DuckDuckGoProtocolHandler);

请注意，在无需重新启动的附加组件中，您还需要取消注册它再次关闭!

factory.unregister();

在便签本中测试

将组件代码和手动注册代码复制到暂存器中，将Enviroment设置为Browser，然后运行。然后在选项卡中打开 ddg:some search terms ;)