java GWT RequestBuilder - 跨站点请求
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GWT RequestBuilder - Cross Site Requests
提问by Manikandaraj Srinivasan
I'm trying to make Cross Site Request using GWT Request builder, which i couldn't get it to work yet. As you can see, this is much of a Sample GWT Project and i have gone through https://developers.google.com/web-toolkit/doc/latest/tutorial/Xsite. But still i'm missing something.
我正在尝试使用 GWT 请求构建器进行跨站点请求，但我无法使其正常工作。如您所见，这是一个示例 GWT 项目，我已经浏览了https://developers.google.com/web-toolkit/doc/latest/tutorial/Xsite。但我仍然缺少一些东西。
I'm Posting the code here. What am i missing ..?
我在这里发布代码。我错过了什么..？
package com.gwt.reqbuilder.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestBuilder;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.RequestException;
import com.google.gwt.http.client.Response;
import com.google.gwt.http.client.URL;
import com.google.gwt.user.client.Window;
public class GWTRequestBuilder implements EntryPoint
{
private static final String JSON_URL = "http://localhost:8000/?q=ABC&callback=callback125";
public void onModuleLoad()
{
GWTPOSTHTTP();
}
public void GWTPOSTHTTP()
{
String postUrl="http://localhost:8000";
String requestData="q=ABC&callback=callback125";
RequestBuilder builder = new RequestBuilder(RequestBuilder.POST, postUrl);
try {
builder.sendRequest(requestData.toString(), new RequestCallback()
{
public void onError(Request request, Throwable e)
{
Window.alert(e.getMessage());
}
public void onResponseReceived(Request request, Response response)
{
if (200 == response.getStatusCode())
{
Window.alert(response.getText());
} else {
Window.alert("Received HTTP status code other than 200 : "+ response.getStatusText());
}
}
});
} catch (RequestException e) {
// Couldn't connect to server
Window.alert(e.getMessage());
}
}
}
采纳答案by Manikandaraj Srinivasan
Actually we can make Cross Site Requests from GWT RequestBuilder if we can set in Servlet Response Header
实际上，如果我们可以在 Servlet Response Header 中设置，我们可以从 GWT RequestBuilder 发出跨站点请求
Response.setHeader("Access-Control-Allow-Origin","http://myhttpserver");
It's working Cool , if anyone need the GWT Project and Python Servlet, please do let me know, i can upload the files.
它的工作很酷，如果有人需要 GWT 项目和 Python Servlet，请告诉我，我可以上传文件。
GWT Client Code : https://github.com/manikandaraj/MLabs/tree/master/GWT/GWTClient
回答by jonasr
You've missed to finish reading the tutorial.
您错过了阅读本教程的机会。
Direct quote from the tutorial:
直接引用教程：
The RequestBuilder code is replaced by a call to the getJson method. So you no longer need the following codein the refreshWatchList method:
RequestBuilder 代码替换为对 getJson 方法的调用。因此您不再需要refreshWatchList 方法中的以下代码：
RequestBuilder builder = new RequestBuilder(RequestBuilder.GET, url);
try {
Request request = builder.sendRequest(null, new RequestCallback() {
public void onError(Request request, Throwable exception) {
displayError("Couldn't retrieve JSON");
}
public void onResponseReceived(Request request, Response response) {
if (200 == response.getStatusCode()) {
updateTable(asArrayOfStockData(response.getText()));
} else {
displayError("Couldn't retrieve JSON (" + response.getStatusText()
+ ")");
}
}
});
} catch (RequestException e) {
displayError("Couldn't retrieve JSON");
}
Which is broadly what you've got, and should be replaced by a JSNI function given in the tutorial a few lines below :
这大致上是你所拥有的，应该由教程中给出的 JSNI 函数替换以下几行：
/**
* Make call to remote server.
*/
public native static void getJson(int requestId, String url,
StockWatcher handler) /*-{
var callback = "callback" + requestId;
// [1] Create a script element.
var script = document.createElement("script");
script.setAttribute("src", url+callback);
script.setAttribute("type", "text/javascript");
// [2] Define the callback function on the window object.
window[callback] = function(jsonObj) {
// [3]
[email protected]::handleJsonResponse(Lcom/google/gwt/core/client/JavaScriptObject;)(jsonObj);
window[callback + "done"] = true;
}
...
