user/src/com/google/gwt/core/client/ScriptInjector.java - gwt - Git at Google

 /*
  * Copyright 2011 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  * License for the specific language governing permissions and limitations under
  * the License.
  */

 package com.google.gwt.core.client;

 /*
  * Design note: This class intentionally does not use the GWT DOM wrappers so
  * that this code can pull in as few dependencies as possible and live in the
  * Core module.
  */

 /**
  * Dynamically create a script tag and attach it to the DOM.
  *
  * Usage with script as local string:
  * <p>
  *
  * <pre>
  *   String scriptBody = "var foo = ...";
  *   ScriptInjector.fromString(scriptBody).inject();
  * </pre>
  * <p>
  * Usage with script loaded as URL:
  * <p>
  *
  * <pre>
  *   ScriptInjector.fromUrl("http://example.com/foo.js").setCallback(
  *     new Callback<Void, Exception>() {
  *        public void onFailure(Exception reason) {
  *          Window.alert("Script load failed.");
  *        }
  *        public void onSuccess(Void result) {
  *          Window.alert("Script load success.");
  *        }
  *     }).inject();
  * </pre>
  *
  *
  */
 public class ScriptInjector {

   /**
    * Builder for directly injecting a script body into the DOM.
    */
   public static class FromString {
     private boolean removeTag = true;
     private final String scriptBody;
     private JavaScriptObject window;

     /**
      * @param scriptBody The script text to install into the document.
      */
     public FromString(String scriptBody) {
       this.scriptBody = scriptBody;
     }

     /**
      * Injects a script into the DOM. The JavaScript is evaluated and will be
      * available immediately when this call returns.
      *
      * By default, the script is installed in the same window that the GWT code
      * is installed in.
      *
      * @return the script element created for the injection. Note that it may be
      *         removed from the DOM.
      */
     public JavaScriptObject inject() {
       JavaScriptObject wnd = (window == null) ? nativeDefaultWindow() : window;
       assert wnd != null;
       JavaScriptObject doc = nativeGetDocument(wnd);
       assert doc != null;
       JavaScriptObject scriptElement = nativeMakeScriptElement(doc);
       assert scriptElement != null;
       nativeSetText(scriptElement, scriptBody);
       nativePropagateScriptNonceIfPossible(doc, scriptElement);
       nativeAttachToHead(doc, scriptElement);
       if (removeTag) {
         nativeRemove(scriptElement);
       }
       return scriptElement;
     }

     /**
      * @param removeTag If true, remove the tag immediately after injecting the
      *          source. This shrinks the DOM, possibly at the expense of
      *          readability if you are debugging javaScript.
      *
      *          Default value is {@code true}.
      */
     public FromString setRemoveTag(boolean removeTag) {
       this.removeTag = removeTag;
       return this;
     }

     /**
      * @param window Specify which window to use to install the script. If not
      *          specified, the top current window GWT is loaded in is used.
      */
     public FromString setWindow(JavaScriptObject window) {
       this.window = window;
       return this;
     }
   }

   /**
    * Build an injection call for adding a script by URL.
    */
   public static class FromUrl {
     private Callback<Void, Exception> callback;
     private boolean removeTag = false;
     private final String scriptUrl;
     private JavaScriptObject window;

     private FromUrl(String scriptUrl) {
       this.scriptUrl = scriptUrl;
     }

     /**
      * Injects an external JavaScript reference into the document and optionally
      * calls a callback when it finishes loading.
      *
      * @return the script element created for the injection.
      */
     public JavaScriptObject inject() {
       JavaScriptObject wnd = (window == null) ? nativeDefaultWindow() : window;
       assert wnd != null;
       JavaScriptObject doc = nativeGetDocument(wnd);
       assert doc != null;
       JavaScriptObject scriptElement = nativeMakeScriptElement(doc);
       assert scriptElement != null;
       if (callback != null || removeTag) {
         attachListeners(scriptElement, callback, removeTag);
       }
       nativeSetSrc(scriptElement, scriptUrl);
       nativePropagateScriptNonceIfPossible(doc, scriptElement);
       nativeAttachToHead(doc, scriptElement);
       return scriptElement;
     }

     /**
      * Specify a callback to be invoked when the script is loaded or loading
      * encounters an error.
      * <p>
      * <b>Warning:</b> This class <b>does not</b> control whether or not a URL
      * has already been injected into the document. The client of this class has
      * the responsibility of keeping score of the injected JavaScript files.
      * <p>
      * <b>Known bugs:</b>  This class uses the script tag's <code>onerror()
      * </code> callback to attempt to invoke onFailure() if the
      * browser detects a load failure.  This is not reliable on all browsers
      * (Doesn't work on IE or Safari 3 or less).
      * <p>
      * On Safari version 3 and prior, the onSuccess() callback may be invoked
      * even when the load of a page fails.
      * <p>
      * To support failure notification on IE and older browsers, you should
      * check some side effect of the script (such as a defined function)
      * to see if loading the script worked and include timeout logic.
      *
      * @param callback callback that gets invoked asynchronously.
      */
     public FromUrl setCallback(Callback<Void, Exception> callback) {
       this.callback = callback;
       return this;
     }

     /**
      * @param removeTag If true, remove the tag after the script finishes
      *          loading. This shrinks the DOM, possibly at the expense of
      *          readability if you are debugging javaScript.
      *
      *          Default value is {@code false}, but this may change in a future
      *          release.
      */
     public FromUrl setRemoveTag(boolean removeTag) {
       this.removeTag = removeTag;
       return this;
     }

     /**
      * This call allows you to specify which DOM window object to install the
      * script tag in. To install into the Top level window call
      *
      * <code>
      *   builder.setWindow(ScriptInjector.TOP_WINDOW);
      * </code>
      *
      * @param window Specifies which window to install in.
      */
     public FromUrl setWindow(JavaScriptObject window) {
       this.window = window;
       return this;
     }
   }

   /**
    * Returns the top level window object. Use this to inject a script so that
    * global variable references are available under <code>$wnd</code> in JSNI
    * access.
    * <p>
    * Note that if your GWT app is loaded from a different domain than the top
    * window, you may not be able to add a script element to the top window.
    */
   public static final JavaScriptObject TOP_WINDOW = nativeTopWindow();

   /**
    * Build an injection call for directly setting the script text in the DOM.
    *
    * @param scriptBody the script text to be injected and immediately executed.
    */
   public static FromString fromString(String scriptBody) {
     return new FromString(scriptBody);
   }

   /**
    * Build an injection call for adding a script by URL.
    *
    * @param scriptUrl URL of the JavaScript to be injected.
    */
   public static FromUrl fromUrl(String scriptUrl) {
     return new FromUrl(scriptUrl);
   }

   /**
    * Attaches event handlers to a script DOM element that will run just once a
    * callback when it gets successfully loaded.
    * <p>
    * <b>IE Notes:</b> Internet Explorer calls {@code onreadystatechanged}
    * several times while varying the {@code readyState} property: in theory,
    * {@code "complete"} means the content is loaded, parsed and ready to be
    * used, but in practice, {@code "complete"} happens when the JS file was
    * already cached, and {@code "loaded"} happens when it was transferred over
    * the network. Other browsers just call the {@code onload} event handler. To
    * ensure the callback will be called at most once, we clear out both event
    * handlers when the callback runs for the first time. More info at the <a
    * href="http://www.phpied.com/javascript-include-ready-onload/">phpied.com
    * blog</a>.
    * <p>
    * In IE, do not trust the "order" of {@code readyState} values. For instance,
    * in IE 8 running in Vista, if the JS file is cached, only {@code "complete"}
    * will happen, but if the file has to be downloaded, {@code "loaded"} can
    * fire in parallel with {@code "loading"}.
    *
    *
    * @param scriptElement element to which the event handlers will be attached
    * @param callback callback that runs when the script is loaded and parsed.
    */
   private static native void attachListeners(JavaScriptObject scriptElement,
       Callback<Void, Exception> callback, boolean removeTag) /*-{
     function clearCallbacks() {
       scriptElement.onerror = scriptElement.onreadystatechange = scriptElement.onload = null;
       if (removeTag) {
         @com.google.gwt.core.client.ScriptInjector::nativeRemove(Lcom/google/gwt/core/client/JavaScriptObject;)(scriptElement);
       }
     }
     scriptElement.onload = $entry(function() {
       clearCallbacks();
       if (callback) {
         callback.@com.google.gwt.core.client.Callback::onSuccess(Ljava/lang/Object;)(null);
       }
     });
     // or possibly more portable script_tag.addEventListener('error', function(){...}, true);
     scriptElement.onerror = $entry(function() {
       clearCallbacks();
       if (callback) {
         var ex = @com.google.gwt.core.client.CodeDownloadException::new(Ljava/lang/String;)("onerror() called.");
         callback.@com.google.gwt.core.client.Callback::onFailure(Ljava/lang/Object;)(ex);
       }
     });
     scriptElement.onreadystatechange = $entry(function() {
       if (/loaded|complete/.test(scriptElement.readyState)) {
         scriptElement.onload();
       }
     });
   }-*/;

   private static native void nativeAttachToHead(JavaScriptObject doc, JavaScriptObject scriptElement) /*-{
     // IE8 does not have document.head
     (doc.head || doc.getElementsByTagName("head")[0]).appendChild(scriptElement);
   }-*/;

   private static native JavaScriptObject nativeDefaultWindow() /*-{
     return window;
   }-*/;

   private static native JavaScriptObject nativeGetDocument(JavaScriptObject wnd) /*-{
     return wnd.document;
   }-*/;

   private static native JavaScriptObject nativeMakeScriptElement(JavaScriptObject doc) /*-{
     return doc.createElement("script");
   }-*/;

   private static native void nativeRemove(JavaScriptObject scriptElement) /*-{
     scriptElement.parentNode.removeChild(scriptElement);
   }-*/;

   private static native void nativeSetSrc(JavaScriptObject element, String url) /*-{
     element.src = url;
   }-*/;

   private static native void nativeSetText(JavaScriptObject element, String scriptBody) /*-{
     element.text = scriptBody;
   }-*/;

   private static native void nativePropagateScriptNonceIfPossible(
       JavaScriptObject doc, JavaScriptObject element) /*-{
     if (doc.querySelector && doc.querySelector('script[nonce]')) {
       var firstNoncedScript = doc.querySelector('script[nonce]');
       var nonce = firstNoncedScript['nonce'] || firstNoncedScript.getAttribute('nonce');
       element.setAttribute('nonce', nonce);
     }
   }-*/;

   private static native JavaScriptObject nativeTopWindow() /*-{
     return $wnd;
   }-*/;

   /**
    * Utility class - do not instantiate
    */
   private ScriptInjector() {
   }
 }
	/*
	* Copyright 2011 Google Inc.
	*
	* Licensed under the Apache License, Version 2.0 (the "License"); you may not
	* use this file except in compliance with the License. You may obtain a copy of
	* the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	* License for the specific language governing permissions and limitations under
	* the License.
	*/

	package com.google.gwt.core.client;

	/*
	* Design note: This class intentionally does not use the GWT DOM wrappers so
	* that this code can pull in as few dependencies as possible and live in the
	* Core module.
	*/

	/**
	* Dynamically create a script tag and attach it to the DOM.
	*
	* Usage with script as local string:
	* <p>
	*
	* <pre>
	* String scriptBody = "var foo = ...";
	* ScriptInjector.fromString(scriptBody).inject();
	* </pre>
	* <p>
	* Usage with script loaded as URL:
	* <p>
	*
	* <pre>
	* ScriptInjector.fromUrl("http://example.com/foo.js").setCallback(
	* new Callback<Void, Exception>() {
	* public void onFailure(Exception reason) {
	* Window.alert("Script load failed.");
	* }
	* public void onSuccess(Void result) {
	* Window.alert("Script load success.");
	* }
	* }).inject();
	* </pre>
	*
	*
	*/
	public class ScriptInjector {

	/**
	* Builder for directly injecting a script body into the DOM.
	*/
	public static class FromString {
	private boolean removeTag = true;
	private final String scriptBody;
	private JavaScriptObject window;

	/**
	* @param scriptBody The script text to install into the document.
	*/
	public FromString(String scriptBody) {
	this.scriptBody = scriptBody;
	}

	/**
	* Injects a script into the DOM. The JavaScript is evaluated and will be
	* available immediately when this call returns.
	*
	* By default, the script is installed in the same window that the GWT code
	* is installed in.
	*
	* @return the script element created for the injection. Note that it may be
	* removed from the DOM.
	*/
	public JavaScriptObject inject() {
	JavaScriptObject wnd = (window == null) ? nativeDefaultWindow() : window;
	assert wnd != null;
	JavaScriptObject doc = nativeGetDocument(wnd);
	assert doc != null;
	JavaScriptObject scriptElement = nativeMakeScriptElement(doc);
	assert scriptElement != null;
	nativeSetText(scriptElement, scriptBody);
	nativePropagateScriptNonceIfPossible(doc, scriptElement);
	nativeAttachToHead(doc, scriptElement);
	if (removeTag) {
	nativeRemove(scriptElement);
	}
	return scriptElement;
	}

	/**
	* @param removeTag If true, remove the tag immediately after injecting the
	* source. This shrinks the DOM, possibly at the expense of
	* readability if you are debugging javaScript.
	*
	* Default value is {@code true}.
	*/
	public FromString setRemoveTag(boolean removeTag) {
	this.removeTag = removeTag;
	return this;
	}

	/**
	* @param window Specify which window to use to install the script. If not
	* specified, the top current window GWT is loaded in is used.
	*/
	public FromString setWindow(JavaScriptObject window) {
	this.window = window;
	return this;
	}
	}

	/**
	* Build an injection call for adding a script by URL.
	*/
	public static class FromUrl {
	private Callback<Void, Exception> callback;
	private boolean removeTag = false;
	private final String scriptUrl;
	private JavaScriptObject window;

	private FromUrl(String scriptUrl) {
	this.scriptUrl = scriptUrl;
	}

	/**
	* Injects an external JavaScript reference into the document and optionally
	* calls a callback when it finishes loading.
	*
	* @return the script element created for the injection.
	*/
	public JavaScriptObject inject() {
	JavaScriptObject wnd = (window == null) ? nativeDefaultWindow() : window;
	assert wnd != null;
	JavaScriptObject doc = nativeGetDocument(wnd);
	assert doc != null;
	JavaScriptObject scriptElement = nativeMakeScriptElement(doc);
	assert scriptElement != null;
	if (callback != null \|\| removeTag) {
	attachListeners(scriptElement, callback, removeTag);
	}
	nativeSetSrc(scriptElement, scriptUrl);
	nativePropagateScriptNonceIfPossible(doc, scriptElement);
	nativeAttachToHead(doc, scriptElement);
	return scriptElement;
	}

	/**
	* Specify a callback to be invoked when the script is loaded or loading
	* encounters an error.
	* <p>
	* <b>Warning:</b> This class <b>does not</b> control whether or not a URL
	* has already been injected into the document. The client of this class has
	* the responsibility of keeping score of the injected JavaScript files.
	* <p>
	* <b>Known bugs:</b> This class uses the script tag's <code>onerror()
	* </code> callback to attempt to invoke onFailure() if the
	* browser detects a load failure. This is not reliable on all browsers
	* (Doesn't work on IE or Safari 3 or less).
	* <p>
	* On Safari version 3 and prior, the onSuccess() callback may be invoked
	* even when the load of a page fails.
	* <p>
	* To support failure notification on IE and older browsers, you should
	* check some side effect of the script (such as a defined function)
	* to see if loading the script worked and include timeout logic.
	*
	* @param callback callback that gets invoked asynchronously.
	*/
	public FromUrl setCallback(Callback<Void, Exception> callback) {
	this.callback = callback;
	return this;
	}

	/**
	* @param removeTag If true, remove the tag after the script finishes
	* loading. This shrinks the DOM, possibly at the expense of
	* readability if you are debugging javaScript.
	*
	* Default value is {@code false}, but this may change in a future
	* release.
	*/
	public FromUrl setRemoveTag(boolean removeTag) {
	this.removeTag = removeTag;
	return this;
	}

	/**
	* This call allows you to specify which DOM window object to install the
	* script tag in. To install into the Top level window call
	*
	* <code>
	* builder.setWindow(ScriptInjector.TOP_WINDOW);
	* </code>
	*
	* @param window Specifies which window to install in.
	*/
	public FromUrl setWindow(JavaScriptObject window) {
	this.window = window;
	return this;
	}
	}

	/**
	* Returns the top level window object. Use this to inject a script so that
	* global variable references are available under <code>$wnd</code> in JSNI
	* access.
	* <p>
	* Note that if your GWT app is loaded from a different domain than the top
	* window, you may not be able to add a script element to the top window.
	*/
	public static final JavaScriptObject TOP_WINDOW = nativeTopWindow();

	/**
	* Build an injection call for directly setting the script text in the DOM.
	*
	* @param scriptBody the script text to be injected and immediately executed.
	*/
	public static FromString fromString(String scriptBody) {
	return new FromString(scriptBody);
	}

	/**
	* Build an injection call for adding a script by URL.
	*
	* @param scriptUrl URL of the JavaScript to be injected.
	*/
	public static FromUrl fromUrl(String scriptUrl) {
	return new FromUrl(scriptUrl);
	}

	/**
	* Attaches event handlers to a script DOM element that will run just once a
	* callback when it gets successfully loaded.
	* <p>
	* <b>IE Notes:</b> Internet Explorer calls {@code onreadystatechanged}
	* several times while varying the {@code readyState} property: in theory,
	* {@code "complete"} means the content is loaded, parsed and ready to be
	* used, but in practice, {@code "complete"} happens when the JS file was
	* already cached, and {@code "loaded"} happens when it was transferred over
	* the network. Other browsers just call the {@code onload} event handler. To
	* ensure the callback will be called at most once, we clear out both event
	* handlers when the callback runs for the first time. More info at the <a
	* href="http://www.phpied.com/javascript-include-ready-onload/">phpied.com
	* blog</a>.
	* <p>
	* In IE, do not trust the "order" of {@code readyState} values. For instance,
	* in IE 8 running in Vista, if the JS file is cached, only {@code "complete"}
	* will happen, but if the file has to be downloaded, {@code "loaded"} can
	* fire in parallel with {@code "loading"}.
	*
	*
	* @param scriptElement element to which the event handlers will be attached
	* @param callback callback that runs when the script is loaded and parsed.
	*/
	private static native void attachListeners(JavaScriptObject scriptElement,
	Callback<Void, Exception> callback, boolean removeTag) /*-{
	function clearCallbacks() {
	scriptElement.onerror = scriptElement.onreadystatechange = scriptElement.onload = null;
	if (removeTag) {
	@com.google.gwt.core.client.ScriptInjector::nativeRemove(Lcom/google/gwt/core/client/JavaScriptObject;)(scriptElement);
	}
	}
	scriptElement.onload = $entry(function() {
	clearCallbacks();
	if (callback) {
	callback.@com.google.gwt.core.client.Callback::onSuccess(Ljava/lang/Object;)(null);
	}
	});
	// or possibly more portable script_tag.addEventListener('error', function(){...}, true);
	scriptElement.onerror = $entry(function() {
	clearCallbacks();
	if (callback) {
	var ex = @com.google.gwt.core.client.CodeDownloadException::new(Ljava/lang/String;)("onerror() called.");
	callback.@com.google.gwt.core.client.Callback::onFailure(Ljava/lang/Object;)(ex);
	}
	});
	scriptElement.onreadystatechange = $entry(function() {
	if (/loaded\|complete/.test(scriptElement.readyState)) {
	scriptElement.onload();
	}
	});
	}-*/;

	private static native void nativeAttachToHead(JavaScriptObject doc, JavaScriptObject scriptElement) /*-{
	// IE8 does not have document.head
	(doc.head \|\| doc.getElementsByTagName("head")[0]).appendChild(scriptElement);
	}-*/;

	private static native JavaScriptObject nativeDefaultWindow() /*-{
	return window;
	}-*/;

	private static native JavaScriptObject nativeGetDocument(JavaScriptObject wnd) /*-{
	return wnd.document;
	}-*/;

	private static native JavaScriptObject nativeMakeScriptElement(JavaScriptObject doc) /*-{
	return doc.createElement("script");
	}-*/;

	private static native void nativeRemove(JavaScriptObject scriptElement) /*-{
	scriptElement.parentNode.removeChild(scriptElement);
	}-*/;

	private static native void nativeSetSrc(JavaScriptObject element, String url) /*-{
	element.src = url;
	}-*/;

	private static native void nativeSetText(JavaScriptObject element, String scriptBody) /*-{
	element.text = scriptBody;
	}-*/;

	private static native void nativePropagateScriptNonceIfPossible(
	JavaScriptObject doc, JavaScriptObject element) /*-{
	if (doc.querySelector && doc.querySelector('script[nonce]')) {
	var firstNoncedScript = doc.querySelector('script[nonce]');
	var nonce = firstNoncedScript['nonce'] \|\| firstNoncedScript.getAttribute('nonce');
	element.setAttribute('nonce', nonce);
	}
	}-*/;

	private static native JavaScriptObject nativeTopWindow() /*-{
	return $wnd;
	}-*/;

	/**
	* Utility class - do not instantiate
	*/
	private ScriptInjector() {
	}
	}