How can i handle form data in a java httpserver server

How can i handle form data in a java httpserver server - java

I'm hosting a http webserver in java(just localhost) to show an offline website(plain html). To send data back to java, a save button does a call with post/ form data using ajax.
I'm using com.sun.net.httpserver.HttpServer;
and would like to just being able to obtain the xml string in the handler.
I've tried several mapping functions, and examples found online. none which helped. They all found empty results so far.
My goal is to just select the xml variable, other variables do not matter. ( no iterative search / parser is required)
thanks in advance!
Erik
Javascript code:
<script type ="text/javascript">
function saveFile() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
alert(this.responseText);
}
};
xhttp.open("POST", "/", true);
//xhttp.setRequestHeader("Accept", "text");
xhttp.setRequestHeader("content-type", "multipart/form-data");
formData.append('xml', '<xml>some xml thing here</xml>');
xhttp.send(formData);
}
</script>
java handler code:
private static void handleRequest(HttpExchange exchange) throws IOException {
String root = "TestPlanDesigner";
URI uri = exchange.getRequestURI();
//System.out.println(uri);
//printRequestInfo(exchange);
//if its the root, this means its posting the data
if(uri.getPath().equals("/"))
{
if(exchange.getRequestMethod().equals("POST"))
{
//handle the post request.
String response = "File saved successfully";
exchange.sendResponseHeaders(200, response.getBytes().length);
OutputStream os = exchange.getResponseBody();
os.write(response.getBytes());
os.close();
}
}
Single line to select the xml form data in java, inside the handler.

Found it, it was in the body not the header.
in the handler:
String payloadrequest = getStringFromInputStream(exchange.getRequestBody());
private static String getStringFromInputStream(java.io.InputStream inputStream) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String line;
try {
br = new BufferedReader(new InputStreamReader(inputStream));
while ((line = br.readLine()) != null) {
sb.append(line);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return sb.toString();
}

Related

Read a resource from URL and return directly those bytes as response of REST request, with no memory storing with Java 7 and spring MVC 3.2

I have a REST endpoint that has to be accessed to retrieve a resource (image, document, ...).
#RequestMapping(value = "/attachement", method = RequestMethod.GET)
#ResponseBody
public Object getTrademarkAttachement(HttpServletResponse response, HttpServletRequest request) {
//TODO : Retrieve bytes from microservice url
//TODO : Send bytes to frontend page
}
For retrieving this document, I want to do it via streaming . I don't want to store in memory the info . I want to , as I get the info, send the bytes as a response . My version of spring MVC is Spring MVC 3.2 and my version of java is java 7 . Is it possible to achieve this ? could you give any clue to start investigating ? . I know I'm giving little details about implementation but I'm starting with this point and I would want to get some ideas from you .
EDIT 1 :
I have achieved half of the problem . Retrieving different blocks of the url . I have used the following code
#Override
public byte[] getTrademarkAttachement() {
String urlSample = "http://testUrl.com";
HttpURLConnection httpConn = null;
String line = null;
try {
httpConn = (HttpURLConnection) new URL(urlSample).openConnection();
InputStream ins = httpConn.getInputStream();
BufferedReader is = new BufferedReader(new InputStreamReader(ins));
while ((line = is.readLine()) != null) {
System.out.println(line);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
httpConn.disconnect();
}
return null;
}
Being able to have access to the inputstream , the part that is left is returning each of this lines that I'm reading , so I can stream the response . I have to look for a method in spring MVC that gives a partial response .

Since you can get the InputStream, you should be able to return an OutputStream as a response to the request. Take a look at this (https://stackoverflow.com/a/27742486/):
#RequestMapping(value = "/attachement", method = RequestMethod.GET)
#ResponseBody
public void getAttachment(OutputStream out) {
InputStream in = ; // Set this to the InputStream from HTTP as your provided example
byte[] buffer = new byte[1024]; // You will need a small buffer mem though
int len;
while ((len = in.read(buffer)) != -1) {
out.write(buffer, 0, len);
}
in.close();
out.flush();
}

Ok , I have solved my problem . I attach the solution . Maybe it's useful to anybody.
Controller
#RequestMapping(value="/eutm/{trademarkId}/snapshots/{historyId}/attachements/{attachementId}", method = RequestMethod.GET)
#ResponseBody
public void getTrademarkAttachement(HttpServletResponse response, #PathVariable String trademarkId, #PathVariable String historyId, #PathVariable String attachementId) {
try {
registerService.getTrademarkAttachement(trademarkId, historyId, attachementId, LanguageController.getLocale(), response.getOutputStream());
} catch (IOException e) {
e.printStackTrace();
}
}
Service
#Override
public void getTrademarkAttachement(String trademarkId, String historyId, String attachementId, Locale locale, ServletOutputStream outputStream) {
URI uri = loadHistoryUri(generateUri(REGISTER_BASE_MS_URL, REGISTER_HISTORY_ENTRY_TM_ATTACHEMENT_WS_URL, trademarkId, historyId, attachementId), locale.getLanguage());
HttpURLConnection httpConn = null;
String line = null;
InputStream ins = null;
try {
httpConn = (HttpURLConnection) new URL(uri.toString()).openConnection();
ins = httpConn.getInputStream();
BufferedReader is = new BufferedReader(new InputStreamReader(ins));
while ((line = is.readLine()) != null) {
outputStream.write(line.getBytes());
}
outputStream.flush();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
httpConn.disconnect();
if(ins != null){
try {
ins.close();
} catch (IOException e) {
logger.error("Bad close of inputStream ins");
}
}
}
}
This way, as it reads lines from inputStream ( url to retrieve via GET connection ), it writes it directly to the response via outputStream . It doesn't send bit to bit as in reactive mode , so the user is not getting the info directly, but I think that with Spring MVC 3.2 and Java 7 is the most approximate way to avoid elements in memory .

Java read from URL stream working selectively

Summary: Sample Java code that reads over a URLConnection reads only certain URLs, not others.
Details: I have this sample Java code that I am using to read over a URLConnection. When the URL is "http://www.example.com", the code reads the page content without any issues. However, if the URL is "http://www.cnn.com", the page content is not read
public class StackOverflow {
public static void main(String[] args) throws Exception {
BufferedReader inputStream = null;
try {
String urlStr = "http://www.cnn.com"; // Does not work
// urlStr = "http://www.example.com"; // **Works if this line is uncommented**
URL url = new URL(urlStr);
inputStream = new BufferedReader(new InputStreamReader(url.openStream()));
String textLine = null;
while((textLine = inputStream.readLine()) != null) {
System.out.println(textLine);
}
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if(inputStream != null) inputStream.close();
}
}
}

CNN redirects from http to https but your call doesn't follow redirects. You are getting a 307 with an empty body so the readline results in a null and your loop is skipped. Try with https for CNN.

How to extract XML data to a string via URL

I wanna convert xml data from URL to json using this library , but it doesn't handle xml from URLs..! only if it was a string or file, so I wanna convert the data inside the url into a string!
is it possible?

This fragment can help you
new Thread() {
public void run() {
URL url = null;
BufferedReader in = null;
try {
url = new URL("your url");
in = new BufferedReader(
new InputStreamReader(
url.openStream(),"UTF-8"));//in most cases there is utf 8
String inputLine;
StringBuilder builder = new StringBuilder();
while ((inputLine = in.readLine()) != null)
builder.append(inputLine);
String urlContent = builder.toString();
// process your received data somehow
} catch (IOException e) {
e.printStackTrace();
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}.start();

How to make http call from standalone java application

I'm making a small dictionary kind of app using java swings. I'm using oxford dictionary api for that. Is there any way to make a simple ajax request in java without using servelets and all advanced java concepts. As in android we use http url connection to do this job.I googled a lot for finding this but I could't find a solution as every page is showing results using servelets. But I know core java alone.If it is possible to make ajax call without servelts please help me...Thanks in advance...

Use HttpURLConnection class to make http call.
If you need more help for that then go for offical documentation site of java Here
Example
public class JavaHttpUrlConnectionReader {
public static void main(String[] args) throws IOException{
String results = doHttpUrlConnectionAction("https://your.url.com/", "GET");
System.out.println(results);
}
public static String doHttpUrlConnectionAction(String desiredUrl, String requestType) throws IOException {
BufferedReader reader = null;
StringBuilder stringBuilder;
try {
HttpURLConnection connection = (HttpURLConnection) new URL(desiredUrl).openConnection();
connection.setRequestMethod(requestType);// Can be "GET","POST","DELETE",etc
connection.setReadTimeout(3 * 1000);
connection.connect();// Make call
reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));// Reading Responce
stringBuilder = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
stringBuilder.append(line).append("\n");
}
return stringBuilder.toString();
} catch (IOException e) {
throw new IOException("Problam in connection : ", e);
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException ioe) {
throw new IOException("Problam in closing reader : ", ioe);
}
}
}
}
}
It will make a call and give response as return string. If you want to make POST call the need to do some extra for that :
try{
DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
wr.write(postParam.getBytes());
} catch(IOException e){
}
Note : Here postParam is String type with value somthing like "someId=156422&someAnotherId=32651"
And put this porson befor connection.connect() statement.

How do you Programmatically Download a Webpage in Java

I would like to be able to fetch a web page's html and save it to a String, so I can do some processing on it. Also, how could I handle various types of compression.
How would I go about doing that using Java?

I'd use a decent HTML parser like Jsoup. It's then as easy as:
String html = Jsoup.connect("http://stackoverflow.com").get().html();
It handles GZIP and chunked responses and character encoding fully transparently. It offers more advantages as well, like HTML traversing and manipulation by CSS selectors like as jQuery can do. You only have to grab it as Document, not as a String.
Document document = Jsoup.connect("http://google.com").get();
You really don't want to run basic String methods or even regex on HTML to process it.
See also:
What are the pros and cons of leading HTML parsers in Java?

Here's some tested code using Java's URL class. I'd recommend do a better job than I do here of handling the exceptions or passing them up the call stack, though.
public static void main(String[] args) {
URL url;
InputStream is = null;
BufferedReader br;
String line;
try {
url = new URL("http://stackoverflow.com/");
is = url.openStream(); // throws an IOException
br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (MalformedURLException mue) {
mue.printStackTrace();
} catch (IOException ioe) {
ioe.printStackTrace();
} finally {
try {
if (is != null) is.close();
} catch (IOException ioe) {
// nothing to see here
}
}
}

Bill's answer is very good, but you may want to do some things with the request like compression or user-agents. The following code shows how you can various types of compression to your requests.
URL url = new URL(urlStr);
HttpURLConnection conn = (HttpURLConnection) url.openConnection(); // Cast shouldn't fail
HttpURLConnection.setFollowRedirects(true);
// allow both GZip and Deflate (ZLib) encodings
conn.setRequestProperty("Accept-Encoding", "gzip, deflate");
String encoding = conn.getContentEncoding();
InputStream inStr = null;
// create the appropriate stream wrapper based on
// the encoding type
if (encoding != null && encoding.equalsIgnoreCase("gzip")) {
inStr = new GZIPInputStream(conn.getInputStream());
} else if (encoding != null && encoding.equalsIgnoreCase("deflate")) {
inStr = new InflaterInputStream(conn.getInputStream(),
new Inflater(true));
} else {
inStr = conn.getInputStream();
}
To also set the user-agent add the following code:
conn.setRequestProperty ( "User-agent", "my agent name");

Well, you could go with the built-in libraries such as URL and URLConnection, but they don't give very much control.
Personally I'd go with the Apache HTTPClient library.
Edit: HTTPClient has been set to end of life by Apache. The replacement is: HTTP Components

All the above mentioned approaches do not download the web page text as it looks in the browser. these days a lot of data is loaded into browsers through scripts in html pages. none of above mentioned techniques supports scripts, they just downloads the html text only. HTMLUNIT supports the javascripts. so if you are looking to download the web page text as it looks in the browser then you should use HTMLUNIT.

You'd most likely need to extract code from a secure web page (https protocol). In the following example, the html file is being saved into c:\temp\filename.html Enjoy!
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import javax.net.ssl.HttpsURLConnection;
/**
* <b>Get the Html source from the secure url </b>
*/
public class HttpsClientUtil {
public static void main(String[] args) throws Exception {
String httpsURL = "https://stackoverflow.com";
String FILENAME = "c:\\temp\\filename.html";
BufferedWriter bw = new BufferedWriter(new FileWriter(FILENAME));
URL myurl = new URL(httpsURL);
HttpsURLConnection con = (HttpsURLConnection) myurl.openConnection();
con.setRequestProperty ( "User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0" );
InputStream ins = con.getInputStream();
InputStreamReader isr = new InputStreamReader(ins, "Windows-1252");
BufferedReader in = new BufferedReader(isr);
String inputLine;
// Write each line into the file
while ((inputLine = in.readLine()) != null) {
System.out.println(inputLine);
bw.write(inputLine);
}
in.close();
bw.close();
}
}

To do so using NIO.2 powerful Files.copy(InputStream in, Path target):
URL url = new URL( "http://download.me/" );
Files.copy( url.openStream(), Paths.get("downloaded.html" ) );

On a Unix/Linux box you could just run 'wget' but this is not really an option if you're writing a cross-platform client. Of course this assumes that you don't really want to do much with the data you download between the point of downloading it and it hitting the disk.

Get help from this class it get code and filter some information.
public class MainActivity extends AppCompatActivity {
EditText url;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate( savedInstanceState );
setContentView( R.layout.activity_main );
url = ((EditText)findViewById( R.id.editText));
DownloadCode obj = new DownloadCode();
try {
String des=" ";
String tag1= "<div class=\"description\">";
String l = obj.execute( "http://www.nu.edu.pk/Campus/Chiniot-Faisalabad/Faculty" ).get();
url.setText( l );
url.setText( " " );
String[] t1 = l.split(tag1);
String[] t2 = t1[0].split( "</div>" );
url.setText( t2[0] );
}
catch (Exception e)
{
Toast.makeText( this,e.toString(),Toast.LENGTH_SHORT ).show();
}
}
// input, extrafunctionrunparallel, output
class DownloadCode extends AsyncTask<String,Void,String>
{
#Override
protected String doInBackground(String... WebAddress) // string of webAddress separate by ','
{
String htmlcontent = " ";
try {
URL url = new URL( WebAddress[0] );
HttpURLConnection c = (HttpURLConnection) url.openConnection();
c.connect();
InputStream input = c.getInputStream();
int data;
InputStreamReader reader = new InputStreamReader( input );
data = reader.read();
while (data != -1)
{
char content = (char) data;
htmlcontent+=content;
data = reader.read();
}
}
catch (Exception e)
{
Log.i("Status : ",e.toString());
}
return htmlcontent;
}
}
}

Jetty has an HTTP client which can be use to download a web page.
package com.zetcode;
import org.eclipse.jetty.client.HttpClient;
import org.eclipse.jetty.client.api.ContentResponse;
public class ReadWebPageEx5 {
public static void main(String[] args) throws Exception {
HttpClient client = null;
try {
client = new HttpClient();
client.start();
String url = "http://example.com";
ContentResponse res = client.GET(url);
System.out.println(res.getContentAsString());
} finally {
if (client != null) {
client.stop();
}
}
}
}
The example prints the contents of a simple web page.
In a Reading a web page in Java tutorial I have written six examples of dowloading a web page programmaticaly in Java using URL, JSoup, HtmlCleaner, Apache HttpClient, Jetty HttpClient, and HtmlUnit.

I used the actual answer to this post (url) and writing the output into a
file.
package test;
import java.net.*;
import java.io.*;
public class PDFTest {
public static void main(String[] args) throws Exception {
try {
URL oracle = new URL("http://www.fetagracollege.org");
BufferedReader in = new BufferedReader(new InputStreamReader(oracle.openStream()));
String fileName = "D:\\a_01\\output.txt";
PrintWriter writer = new PrintWriter(fileName, "UTF-8");
OutputStream outputStream = new FileOutputStream(fileName);
String inputLine;
while ((inputLine = in.readLine()) != null) {
System.out.println(inputLine);
writer.println(inputLine);
}
in.close();
} catch(Exception e) {
}
}
}

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

How can i handle form data in a java httpserver server - java

Related

Read a resource from URL and return directly those bytes as response of REST request, with no memory storing with Java 7 and spring MVC 3.2

Java read from URL stream working selectively

How to extract XML data to a string via URL

How to make http call from standalone java application

How do you Programmatically Download a Webpage in Java

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