ie8中支持onhashchange事件，在ie6中不支持，ie6使用一个iframe的open，将token记录在iframe中实现的。
以下是js版本：
<iframe src="javascript:''" id='__gwt_historyFrame' style='position: absolute; width: 0; height: 0; border: 0'></iframe>
<a href="javascript:myhistory.newItem('a')">a</a>
<a href="javascript:myhistory.newItem('b')">b</a>
<script>
var myhistory={
historyFrame:null,
callback:[],
addCallback:function(callback){
myhistory.callback[myhistory.callback.length] = callback;
},
init:function (){
myhistory.historyFrame = document.getElementById('__gwt_historyFrame');
var token = '';
// Get the initial token from the url's hash component.
var href = window.location.href;
var hashLoc = href.lastIndexOf("#");
var token= (hashLoc > 0) ? href.substring(hashLoc+1) : "";
myhistory.setToken(token);
var tokenElement;
if (myhistory.historyFrame.contentWindow) {
var doc = myhistory.historyFrame.contentWindow.document;
tokenElement = doc.getElementById('__gwt_historyToken');
}
if(tokenElement){
myhistory.setToken(tokenElement.innerText);
}else{
myhistory.navigateFrame(token);
}
},
__gwt_onHistoryLoad : function(token) {
if(token){
var hash = myhistory.encodeFragment(token);
window.location.hash=hash;
myhistory.newItemOnEvent(token);
}
},
newItemOnEvent:function(token){
for(var i = 0 ; i<myhistory.callback.length;i++){
var call = myhistory.callback[i];
call(token);
}
},
decodeFragment:function(fragment){
// decodeURI() does *not* decode the '#' character.
return decodeURI(fragment.replace("%23", "#"));
},
encodeFragment:function(fragment){
// encodeURI() does *not* encode the '#' character.
return encodeURI(fragment).replace("#", "%23");
},
setToken:function(token){
window.__gwt_historyToken = token;
},
getToken:function(){
return window.__gwt_historyToken;
},
newItem:function(historyToken){
var historyToken = (historyToken == null) ? "" : historyToken;
if (historyToken!=(myhistory.getToken())) {
myhistory.setToken(historyToken);
myhistory.nativeUpdate(historyToken);
//if (issueEvent) {
// fireHistoryChangedImpl(historyToken);
//}
}
},
navigateFrame:function(token){
var div = document.createElement('div');
div.innerText=token;
var escaped = div.innerHTML;
var doc = myhistory.historyFrame.contentWindow.document;
doc.open();
doc.write('<html><body onload="if(parent.myhistory.__gwt_onHistoryLoad)parent.myhistory.__gwt_onHistoryLoad(__gwt_historyToken.innerText)"><div id="__gwt_historyToken">' + escaped + '</div></body></html>');
doc.close();
},
nativeUpdate:function(token){
var hash = myhistory.encodeFragment(token);
window.location.hash=hash;
myhistory.navigateFrame(token);
}
}
myhistory.addCallback(function mycall(token){ alert("hahah="+token);});
myhistory.init();
</script>
gwt实现history前进后退的代码：
http://code.google.com/p/google-web-toolkit/source/browse/trunk/user/src/com/google/gwt/user/client/impl/HistoryImpl.java?r=5606
/*
* Copyright 2008 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.user.client.impl;
import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.GWT.UncaughtExceptionHandler;
import com.google.gwt.event.logical.shared.HasValueChangeHandlers;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.GwtEvent;
import com.google.gwt.event.shared.HandlerManager;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.event.shared.HasHandlers;
/**
* Native implementation associated with
* {@link com.google.gwt.user.client.History}.
* User classes should not use this class directly.
*
* <p>
* This base version uses the HTML5 standard window.onhashchange event to
* determine when the URL hash identifier changes.
* </p>
*/
public class HistoryImpl implements HasValueChangeHandlers<String>,
HasHandlers {
static boolean updateHashOnIE6 = true;
/**
* Sets whether the IE6 history implementation will update the URL hash when
* creating a new item. This should be used only for applications with large
* DOM structures that are suffering from performance problems when creating
* a new history item on IE6 and 7.
*/
public static void setUpdateHashOnIE6(boolean updateHash) {
HistoryImpl.updateHashOnIE6 = updateHash;
}
public static native String getToken() /*-{
return $wnd.__gwt_historyToken || "";
}-*/;
protected static native void setToken(String token) /*-{
$wnd.__gwt_historyToken = token;
}-*/;
private HandlerManager handlers = new HandlerManager(null);
/**
* Adds a {@link ValueChangeEvent} handler to be informed of changes to the
* browser's history stack.
*
* @param handler the handler
*/
public HandlerRegistration addValueChangeHandler(
ValueChangeHandler<String> handler) {
return handlers.addHandler(ValueChangeEvent.getType(), handler);
}
public void fireEvent(GwtEvent<?> event) {
handlers.fireEvent(event);
}
/**
* Fires the {@link ValueChangeEvent} to all handlers with the given tokens.
*/
public void fireHistoryChangedImpl(String newToken) {
ValueChangeEvent.fire(this, newToken);
}
public HandlerManager getHandlers() {
return handlers;
}
public native boolean init() /*-{
var token = '';
// Get the initial token from the url's hash component.
var hash = $wnd.location.hash;
if (hash.length > 0) {
token = [email protected]::decodeFragment(Ljava/lang/String;)(hash.substring(1));
}
@com.google.gwt.user.client.impl.HistoryImpl::setToken(Ljava/lang/String;)(token);
var historyImpl = this;
$wnd.onhashchange = function() {
var token = '', hash = $wnd.location.hash;
if (hash.length > 0) {
token = [email protected]::decodeFragment(Ljava/lang/String;)(hash.substring(1));
}
[email protected]::newItemOnEvent(Ljava/lang/String;)(token);
};
return true;
}-*/;
public final void newItem(String historyToken, boolean issueEvent) {
historyToken = (historyToken == null) ? "" : historyToken;
if (!historyToken.equals(getToken())) {
setToken(historyToken);
nativeUpdate(historyToken);
if (issueEvent) {
fireHistoryChangedImpl(historyToken);
}
}
}
public final void newItemOnEvent(String historyToken) {
historyToken = (historyToken == null) ? "" : historyToken;
if (!historyToken.equals(getToken())) {
setToken(historyToken);
nativeUpdateOnEvent(historyToken);
fireHistoryChanged(historyToken);
}
}
protected native String decodeFragment(String encodedFragment) /*-{
// decodeURI() does *not* decode the '#' character.
return decodeURI(encodedFragment.replace("%23", "#"));
}-*/;
protected native String encodeFragment(String fragment) /*-{
// encodeURI() does *not* encode the '#' character.
return encodeURI(fragment).replace("#", "%23");
}-*/;
/**
* The standard updateHash implementation assigns to location.hash() with an
* encoded history token.
*/
protected native void nativeUpdate(String historyToken) /*-{
$wnd.location.hash = [email protected]::encodeFragment(Ljava/lang/String;)(historyToken);
}-*/;
protected void nativeUpdateOnEvent(String historyToken) {
// Do nothing, the hash is already updated.
}
private void fireHistoryChanged(String newToken) {
UncaughtExceptionHandler handler = GWT.getUncaughtExceptionHandler();
if (handler != null) {
fireHistoryChangedAndCatch(newToken, handler);
} else {
fireHistoryChangedImpl(newToken);
}
}
private void fireHistoryChangedAndCatch(String newToken,
UncaughtExceptionHandler handler) {
try {
fireHistoryChangedImpl(newToken);
} catch (Throwable e) {
handler.onUncaughtException(e);
}
}
}