How to gzip an ajax response with Struts2? I tried to create a filter but it didn't work. At client-side I'm using jQuery and the ajax response I'm expecting is in json.
This is the code I used on server:
ByteArrayOutputStream out = new ByteArrayOutputStream();
GZIPOutputStream gz = new GZIPOutputStream(out);
gz.write(json.getBytes());
gz.close();
I'm redirecting the response to dummy jsp page defined at struts.xml.
The reason why I want to gzip the data back is because there's a situation where I must send a relatively big sized json back to the client.
Any reference provided will be appreciated.
Thanks.
You shouldn't randomly gzip responses. You can only gzip the response when the client has notified the server that it accepts (understands) gzipped responses. You can do that by determining if the Accept-Encoding request header contains gzip. If it is there, then you can safely wrap the OutputStream of the response in a GZIPOutputStream. You only need to add the Content-Encoding header beforehand with a value of gzip to inform the client what encoding the content is been sent in, so that the client knows that it needs to ungzip it.
In a nutshell:
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
OutputStream output = response.getOutputStream();
String acceptEncoding = request.getHeader("Accept-Encoding");
if (acceptEncoding != null && acceptEncoding.contains("gzip")) {
response.setHeader("Content-Encoding", "gzip");
output = new GZIPOutputStream(output);
}
output.write(json.getBytes("UTF-8"));
(note that you would like to set the content type and character encoding as well, this is taken into account in the example)
You could also configure this at appserver level. Since it's unclear which one you're using, here's just a Tomcat-targeted example: check the compression and compressableMimeType attributes of the <Connector> element in /conf/server.xml: HTTP connector reference. This way you can just write to the response without worrying about gzipping it.
If your response is JSON I would recommend using the struts2-json plugin http://struts.apache.org/2.1.8/docs/json-plugin.html and setting the
enableGZIP param to true.
Related
I want to redirect to a page after writing the excel file. The servlet code is given below:
ByteArrayOutputStream outByteStream = new ByteArrayOutputStream();
workbook.write(outByteStream);
byte [] outArray = outByteStream.toByteArray();
response.setContentType("application/ms-excel");
response.setContentLength(outArray.length);
response.setHeader("Content-Disposition", "attachment; filename=name_"+date+".xlsx");
response.setIntHeader("Refresh", 1);
OutputStream outStream = response.getOutputStream();
outStream.write(outArray);
response.sendRedirect("url/reports.jsp");
This code downloads an Excel file which i have created.
when i call the above servlet, the excel file is being downloaded but it is throwing following exception in the last line :
Servlet Error: ::java.lang.IllegalStateException: Cannot call sendRedirect() after the response has been committed
Hence i am unable to redirect to a new page. what can i do to access the response object after i write the output in "outStream"
The basic problem is that this ...
I want to redirect to a page after writing the excel file.
... describes two separate responses. The server cannot chain them together by itself because the client will expect only one response to each request. Because two requests are required to elicit two responses, automation of this sequence will require client-side scripting.
Personally, I would probably put the script on the front end: a handler on the appropriate button or link that first downloads the file and then (on success) issues a request for the new page. It would also be possible to do as suggested in comments, however: put script in the new page that downloads the file.
You cannot have a body with a redirect because the browser, when receiving a redirect, will issue a second request to the URL it has found (in header Location), and it's the response of that second request that is displayed, unless it is also a redirect, in which case, it will issue a third request, and so on...
I have a custom java console app I am writing to upload non-binary files to a java app server I own. It is performing an HTTPS multipart/form-data POST with the file to a REST api. While it works great for small files, I would like to apply GZIP content-encoding to the post request, so it more efficiently handles large files.
Is there a JAVA library I can use to gzip the post, including the file content and then un-zip it on the other side? I would like to avoid having to zip the file first and would rather rely on HTTP encoding to handle it.
To be pedantic, you wouldn't gzip the entire POST. You would just Gzip the content data, and then in your POST set the Content-Encoding as gzip.
You haven't posted your code (get it???), so some assumptions need to be made to give an example:
import java.util.zip.GZIPOutputStream;
import java.io.ByteArrayOutputStream;
...
final String yourData = "butts";
final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
final GZipOutputStream gzipOutputStream;
try {
gzipOutputStream = new GZipOutputStream(byteArrayOutputStream);
gzipOutputStream.write(yourData.getBytes("utf-8"));
} finally {
gzipOutputStream.close();
}
final byte[] gzippedButts = byteArrayOutputStream.toByteArray();
/*
* Now use the gzipped data as the data in your POST, and also
* make sure to set the Content-Encoding of your HTTP POST to "gzip".
*/
Edit: Reading the question again, it sounds like OP wants a library that will abstract away all of the handling and just Gzip a request body under the hood. Unfortunately, I am not aware of any such library.
I have a Java Servlet that responds to the Twilio API. It appears that Twilio does not support the chunked transfer that my responses are using. How can I avoid using Transfer-Encoding: chunked?
Here is my code:
// response is HttpServletResponse
// xml is a String with XML in it
response.getWriter().write(xml);
response.getWriter().flush();
I am using Jetty as the Servlet container.
I believe that Jetty will use chunked responses when it doesn't know the response content length and/or it is using persistent connections. To avoid chunking you either need to set the response content length or to avoid persistent connections by setting "Connection":"close" header on the response.
Try setting the Content-length before writing to the stream. Don't forget to calculate the amount of bytes according to the correct encoding, e.g.:
final byte[] content = xml.getBytes("UTF-8");
response.setContentLength(content.length);
response.setContentType("text/xml"); // or "text/xml; charset=UTF-8"
response.setCharacterEncoding("UTF-8");
final OutputStream out = response.getOutputStream();
out.write(content);
The container will decide itself to use Content-Length or Transfer-Encoding basing on the size of data to be written by using Writer or outputStream. If the size of the data is larger than the HttpServletResponse.getBufferSize(), then the response will be trunked. If not, Content-Length will be used.
In your case, just remove the 2nd flushing code will solve your problem.
I am trying to do a http request in scala using httpclient from org.apache.httpcomponents version 4.23. In particular I want to do a put using an InputStreamEntity to build the request in order to avoid copying over a large (~100Mb) byte array in memory. Here is the snippet:
val req = new HttpPut(url)
req setEntity new InputStreamEntity(contentStream, -1/*contentlength*/)
val client = new DefaultHttpClient(connManager, httpParams)
val resp = client execute req
In the code url, connManager, httpParams are defined elsewhere. The result of the code is the creation of a file on the desired location with NO content. I am testing with a contentStream which has 3 bytes. Creating the InputStreamEntity with content length as argument set explicitly to 3 will result in the code to create the file the right way. For good reasons in production I won't know the length of the stream hence I want to use negative numbers to make sure the entire stream is sent until, as advertized by the api of InputStreamEntity, the end of the stream is reached.
What am I doing wrong? Why am I getting an empty file when not explicitely setting the content length?
Not setting the content-length, will result in HTTP Client switching to chunked transfer-encoding
For this to work, the http server you are posting to must be HTTP 1.1 compliant. Is it ?
I am calling a restful service that returns JSON using the Apache HttpClient.
The problem is I am getting different results in the encoding of the response when I run the code on different platforms.
Here is my code:
GetMethod get = new GetMethod("http://urltomyrestservice");
get.addRequestHeader("Content-Type", "text/html; charset=UTF-8");
...
HttpResponse response = httpexecutor.execute(request, conn, context);
response.setParams(params);
httpexecutor.postProcess(response, httpproc, context);
StringWriter writer = new StringWriter();
IOUtils.copy(response.getEntity().getContent(), writer);
When I run this on OSX, asian characters etc return fine e.g. 張惠妹 in the response. But when I run this on a linux server the same code displays the characters as ???
The linux server is an Amazon EC2 instance running Java 1.6.0_26-b03
My local OSX is running 1.6.0_29-b11
Any ideas really appreciated!!!!!
If you look at the javadoc of org.apache.commons.io.IOUtils.copy(InputStream, Writer):
Copy bytes from an InputStream to chars on a Writer using the default
character encoding of the platform.
So that will give different answers depending on the client (which is what you're seeing)
Also, Content-Type is usually a response header (unless you're using POST or PUT). The server is likely to ignore it (though you might have more luck with the Accept-Charset request header).
You need to parse the content type's charset-encoding parameter of the response header, and use that to convert the response into a String (if it's a String you're actually after). I expect Commons HTTP has code that will do that automatically for you. If it doesn't, Spring's RESTTemplate definitely does.
I believe that the problem is not in the HTTP encoding but elsewhere (e.g. while reading or forming the answer). Where do you get the content from and how? Is this stored in a DB or file?