I try to create the simplest Simplest WebServer and Client using HTTP. (Please, don't tell me to using Apache HTTPClient).
Client: try to PUT some file to Server.
// **PUT**
if(REQUEST.toUpperCase().equals("PUT")) {
File sourceFile = new File(fileName);
if(!sourceFile.canRead()) {
System.out.println("Have not access to this file...");
return;
}
try {
BufferedInputStream is = new BufferedInputStream(new FileInputStream(sourceFile));
URL url = new URL("http://" + HOST+":"+PORT);
System.setProperty("http.keepAlive", "true");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setRequestMethod("PUT");
connection.setRequestProperty("Content-Type", "Application/octet-stream");
connection.setRequestProperty("Content-Length",Long.toString(sourceFile.length()));
connection.addRequestProperty("Content-disposition","attachment; filename="+fileName);
BufferedOutputStream os = new BufferedOutputStream(connection.getOutputStream());
byte[] buf = new byte[sizeArr];
int r = 1;
while((r = is.read(buf)) > 0) {
os.write(buf, 0, r);
}
os.flush();
os.close();
System.out.println("Waiting for the response...");//this is written to console
System.out.println(connection.getResponseCode());//HERE infinite waiting
is.close();
} catch (MalformedURLException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
}
On Server: if Request == PUT, then:
// **PUT**
if (header.toUpperCase().equals("PUT")) {
System.setProperty("http.keepAlive", "true");
String fileName = null;
if((fileName = extract(request.toUpperCase(),"FILENAME=","\n")) == null) {
fileName = "UnknownFile.out";
}
try {
File sourceFile = new File(fileName);
BufferedOutputStream osFile = new BufferedOutputStream
(new FileOutputStream(sourceFile));
byte[] locbuf = new byte[sizeArr];
int locr = 1;
while((locr = is.read(locbuf)) > 0) {
System.out.println("locr= "+locr);//this is written to console
osFile.write(locbuf, 0, locr);
}
System.out.println("Ending to record the data to the file.");
// this is NOT written to console
osFile.flush();
osFile.close();
}
catch(IOException ex) {
os.write(CodeRequest("500 Internal Server Error").getBytes());
os.close();
ex.printStackTrace();
return;
}
System.out.println("Trying to send 200 OK");
os.write(CodeRequest("200 OK").getBytes());
os.flush();
os.close(); // where os = clientSocket.getOutputStream();
}
Why doesn't the Client get a Response from the Server? If I interrupted the Client's infinite loop, then WebServer would correctly record data to file. But Client will never know that his file was normally uploaded to the server. If I comment out this statement on Client:
// System.out.println(connection.getResponseCode());
Then Client correctly exit from loop and ends. But Server doesn't even write to console this:
while((locr = is.read(locbuf)) > 0) {
System.out.println("locr= "+locr);//this is NOT written to console
osFile.write(locbuf, 0, locr);
}
Server ONLY writes this to console this:
localExcString index out of range: -1
without any Error message.
What's wrong?
Your example code for the server doesn't show the declaration and initialisation of 'is'.
However, my guess is that since the session is keep alive the call to is.read() will block until some data arrives. You have set the content length in the client, so I would be expecting to see the read loop complete when that amount of data has been successfully read.
What string is the CodeRequest method returning in the server code? I think that the problem may be that you are not putting a CRLF at the end of the status line and another one at the end of the response header. For details, read the HTTP 1.1 specification.
You need to call URLConnection#getInputStream() after the write to actually send the request (and thus retrieve the response). Only after this point you can request the response status. This is implemented so because it might take longer to build the request body than to actually sending it and also because there's actually no point of having a request if you're not interested in the response.
Edit sorry, I was wrong. The getResponseCode() already implicitly calls getInputStream().
Anyway, I created a small testcase (see SSCCE for more info) and it just works fine. Try it and see if it works in your case as well.
Client:
import java.io.IOException;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class Test {
public static void main(String[] args) throws Exception {
String data = "Hello!";
URL url = new URL("http://localhost:8080/playground/test");
OutputStream output = null;
try {
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("PUT");
output = connection.getOutputStream();
output.write(data.getBytes());
System.out.println("Response code: " + connection.getResponseCode());
} finally {
if (output != null) try { output.close(); } catch (IOException ignore) {}
}
}
}
Server:
package mypackage;
import java.io.IOException;
import java.io.InputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Test extends HttpServlet {
protected void doPut(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
InputStream input = null;
try {
input = request.getInputStream();
int data;
while ((data = input.read()) > -1) {
System.out.write(data);
}
System.out.println();
} finally {
if (input != null) try { input.close(); } catch (IOException ignore) {}
}
}
}
Result should be a Response code: 200 in the client's stdout and a Hello! in the server's stdout.
Hope this helps in pinpointing the cause of your problem.
On Server:
String strFileLen = extract(request.toUpperCase().trim(),"CONTENT-LENGTH:","\n");
long fileLength = 0;
if(strFileLen != null) {
fileLength = Long.parseLong(strFileLen.trim());
System.out.println("fileLength= "+fileLength);
};
byte[] locbuf = new byte[sizeArr];
int locr = 1;long sumLen = 0;
if(fileLength != 0) {
while((sumLen += (locr=is.read(locbuf))) != fileLength) {
System.out.println("sumLen= "+sumLen);
osFile.write(locbuf, 0, locr);
}
}
===================================================
This works well.
Related
I'm trying to download a file from server using FTP, the Java code works if the file is available in remote server but if the specific file is not available in the remote server a new file is getting created with same file name in local. How can I avoid this?
and I'm trying to check the properties such as last modified time, file created time etc.., of the specific file before download, I used MLST but getting type casting issues..!!
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
public class FTPDownloadFileDemo {
public static void main(String[] args) {
String server = "www.myserver.com";
int port = 21;
String user = "user";
String pass = "pass";
FTPClient ftpClient = new FTPClient();
try {
ftpClient.connect(server, port);
ftpClient.login(user, pass);
ftpClient.enterLocalPassiveMode();
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
// APPROACH #1: using retrieveFile(String, OutputStream)
String remoteFile1 = "/test/video.mp4";
File downloadFile1 = new File("D:/Downloads/video.mp4");
OutputStream outputStream1 = new BufferedOutputStream(new FileOutputStream(downloadFile1));
boolean success = ftpClient.retrieveFile(remoteFile1, outputStream1);
outputStream1.close();
if (success) {
System.out.println("File #1 has been downloaded successfully.");
}
outputStream2.close();
inputStream.close();
} catch (IOException ex) {
System.out.println("Error: " + ex.getMessage());
ex.printStackTrace();
} finally {
try {
if (ftpClient.isConnected()) {
ftpClient.logout();
ftpClient.disconnect();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
}
The retrieveFile() method always writes a local file, whether or not the remote file exists. Instead, you can use retrieveFileStream() and check the reply code.
A handy list of FTP reply codes is available from Wikipedia. If 550 is received, it means the file does not exist.
Finally, you need to use completePendingCommand() to complete the transaction and a FileOutputStream to write the file.
InputStream inputStream = ftpClient.retrieveFileStream(remoteFile1);
int returnCode = ftpClient.getReplyCode();
if (inputStream == null || returnCode == 550) {
System.out.println("Remote file does not exist");
} else {
ftpClient.completePendingCommand();
byte[] buffer = new byte[inputStream.available()];
inputStream.read(buffer);
OutputStream outputStream = new FileOutputStream(downloadFile1);
outputStream.write(buffer);
outputStream.close();
}
Your problem is that your Outputstream automatically creates the File, even if the stream is empty.
I would recommend you check first if the file exists on the server and based on that you don't even create the outputStream:
boolean checkFileExists(String filePath) throws IOException {
InputStream inputStream = ftpClient.retrieveFileStream(remoteFile1);
returnCode = ftpClient.getReplyCode();
return inputStream == null || returnCode == 550;
}
In Java, this code throws an exception when the HTTP result is 404 range:
URL url = new URL("http://stackoverflow.com/asdf404notfound");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.getInputStream(); // throws!
In my case, I happen to know that the content is 404, but I'd still like to read the body of the response anyway.
(In my actual case the response code is 403, but the body of the response explains the reason for rejection, and I'd like to display that to the user.)
How can I access the response body?
Here is the bug report (close, will not fix, not a bug).
Their advice there is to code like this:
HttpURLConnection httpConn = (HttpURLConnection)_urlConnection;
InputStream _is;
if (httpConn.getResponseCode() < HttpURLConnection.HTTP_BAD_REQUEST) {
_is = httpConn.getInputStream();
} else {
/* error from server */
_is = httpConn.getErrorStream();
}
It's the same problem I was having:
HttpUrlConnection returns FileNotFoundException if you try to read the getInputStream() from the connection.
You should instead use getErrorStream() when the status code is higher than 400.
More than this, please be careful since it's not only 200 to be the success status code, even 201, 204, etc. are often used as success statuses.
Here is an example of how I went to manage it
... connection code code code ...
// Get the response code
int statusCode = connection.getResponseCode();
InputStream is = null;
if (statusCode >= 200 && statusCode < 400) {
// Create an InputStream in order to extract the response object
is = connection.getInputStream();
}
else {
is = connection.getErrorStream();
}
... callback/response to your handler....
In this way, you'll be able to get the needed response in both success and error cases.
Hope this helps!
In .Net you have the Response property of the WebException that gives access to the stream ON an exception. So i guess this is a good way for Java,...
private InputStream dispatch(HttpURLConnection http) throws Exception {
try {
return http.getInputStream();
} catch(Exception ex) {
return http.getErrorStream();
}
}
Or an implementation i used. (Might need changes for encoding or other things. Works in current environment.)
private String dispatch(HttpURLConnection http) throws Exception {
try {
return readStream(http.getInputStream());
} catch(Exception ex) {
readAndThrowError(http);
return null; // <- never gets here, previous statement throws an error
}
}
private void readAndThrowError(HttpURLConnection http) throws Exception {
if (http.getContentLengthLong() > 0 && http.getContentType().contains("application/json")) {
String json = this.readStream(http.getErrorStream());
Object oson = this.mapper.readValue(json, Object.class);
json = this.mapper.writer().withDefaultPrettyPrinter().writeValueAsString(oson);
throw new IllegalStateException(http.getResponseCode() + " " + http.getResponseMessage() + "\n" + json);
} else {
throw new IllegalStateException(http.getResponseCode() + " " + http.getResponseMessage());
}
}
private String readStream(InputStream stream) throws Exception {
StringBuilder builder = new StringBuilder();
try (BufferedReader in = new BufferedReader(new InputStreamReader(stream))) {
String line;
while ((line = in.readLine()) != null) {
builder.append(line); // + "\r\n"(no need, json has no line breaks!)
}
in.close();
}
System.out.println("JSON: " + builder.toString());
return builder.toString();
}
I know that this doesn't answer the question directly, but instead of using the HTTP connection library provided by Sun, you might want to take a look at Commons HttpClient, which (in my opinion) has a far easier API to work with.
First check the response code and then use HttpURLConnection.getErrorStream()
InputStream is = null;
if (httpConn.getResponseCode() !=200) {
is = httpConn.getErrorStream();
} else {
/* error from server */
is = httpConn.getInputStream();
}
My running code.
HttpURLConnection httpConn = (HttpURLConnection) urlConn;
if (httpConn.getResponseCode() < HttpURLConnection.HTTP_BAD_REQUEST) {
in = new InputStreamReader(urlConn.getInputStream());
BufferedReader bufferedReader = new BufferedReader(in);
if (bufferedReader != null) {
int cp;
while ((cp = bufferedReader.read()) != -1) {
sb.append((char) cp);
}
bufferedReader.close();
}
in.close();
} else {
/* error from server */
in = new InputStreamReader(httpConn.getErrorStream());
BufferedReader bufferedReader = new BufferedReader(in);
if (bufferedReader != null) {
int cp;
while ((cp = bufferedReader.read()) != -1) {
sb.append((char) cp);
}
bufferedReader.close();
}
in.close();
}
System.out.println("sb="+sb);
How to read 404 response body in java:
Use Apache library - https://hc.apache.org/httpcomponents-client-4.5.x/httpclient/apidocs/
or
Java 11 - https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html
Snippet given below uses Apache:
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.util.EntityUtils;
CloseableHttpClient client = HttpClients.createDefault();
CloseableHttpResponse resp = client.execute(new HttpGet(domainName + "/blablablabla.html"));
String response = EntityUtils.toString(resp.getEntity());
I am using Jsoup Java HTML parser to fetch images from a particular URL. But some of the images are throwing a status 502 error code and are not saved to my machine. Here is the code snapshot i have used:-
String url = "http://www.jabong.com";
String html = Jsoup.connect(url.toString()).get().html();
Document doc = Jsoup.parse(html, url);
images = doc.select("img");
for (Element element : images) {
String imgSrc = element.attr("abs:src");
log.info(imgSrc);
if (imgSrc != "") {
saveFromUrl(imgSrc, dirPath+"/" + nameCounter + ".jpg");
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
log.error("error in sleeping");
}
nameCounter++;
}
}
And the saveFromURL function looks like this:-
public static void saveFromUrl(String Url, String destinationFile) {
try {
URL url = new URL(Url);
InputStream is = url.openStream();
OutputStream os = new FileOutputStream(destinationFile);
byte[] b = new byte[2048];
int length;
while ((length = is.read(b)) != -1) {
os.write(b, 0, length);
}
is.close();
os.close();
} catch (IOException e) {
log.error("Error in saving file from url:" + Url);
//e.printStackTrace();
}
}
I searched on internet about status code 502 but it says error is due to bad gateway. I don't understand this. One of the possible things i am thinking that this error may be because of I am sending get request to images in loop. May be webserver is not able handle to this much load so denying the request to the images when previous image is not sent.So I tried to put sleep after fetching every image but no luck :(
Some advices please
Here's a full code example that works for me...
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.Authenticator;
import java.net.HttpURLConnection;
import java.net.InetSocketAddress;
import java.net.MalformedURLException;
import java.net.Proxy;
import java.net.SocketAddress;
import java.net.URL;
public class DownloadImage {
public static void main(String[] args) {
// URLs for Images we wish to download
String[] urls = {
"http://cdn.sstatic.net/stackoverflow/img/apple-touch-icon.png",
"http://www.google.co.uk/images/srpr/logo3w.png",
"http://i.microsoft.com/global/en-us/homepage/PublishingImages/sprites/microsoft_gray.png"
};
for(int i = 0; i < urls.length; i++) {
downloadFromUrl(urls[i]);
}
}
/*
Extract the file name from the URL
*/
private static String getOutputFileName(URL url) {
String[] urlParts = url.getPath().split("/");
return "c:/temp/" + urlParts[urlParts.length-1];
}
/*
Assumes there is no Proxy server involved.
*/
private static void downloadFromUrl(String urlString) {
InputStream is = null;
FileOutputStream fos = null;
try {
URL url = new URL(urlString);
System.out.println("Reading..." + url);
HttpURLConnection conn = (HttpURLConnection)url.openConnection(proxy);
is = conn.getInputStream();
String filename = getOutputFileName(url);
fos = new FileOutputStream(filename);
byte[] readData = new byte[1024];
int i = is.read(readData);
while(i != -1) {
fos.write(readData, 0, i);
i = is.read(readData);
}
System.out.println("Created file: " + filename);
}
catch (MalformedURLException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
finally {
if(is != null) {
try {
is.close();
} catch (IOException e) {
System.out.println("Big problems if InputStream cannot be closed");
}
}
if(fos != null) {
try {
fos.close();
} catch (IOException e) {
System.out.println("Big problems if FileOutputSream cannot be closed");
}
}
}
System.out.println("Completed");
}
}
You should see the following ouput on your console...
Reading...http://cdn.sstatic.net/stackoverflow/img/apple-touch-icon.png
Created file: c:/temp/apple-touch-icon.png
Completed
Reading...http://www.google.co.uk/images/srpr/logo3w.png
Created file: c:/temp/logo3w.png
Completed
Reading...http://i.microsoft.com/global/en-us/homepage/PublishingImages/sprites/microsoft_gray.png
Created file: c:/temp/microsoft_gray.png
Completed
So that's a working example without a Proxy server involved.
Only if you require authentication with a proxy server here's an additional Class that you'll need based on this Oracle technote
import java.net.Authenticator;
import java.net.PasswordAuthentication;
public class ProxyAuthenticator extends Authenticator {
private String userName, password;
public ProxyAuthenticator(String userName, String password) {
this.userName = userName;
this.password = password;
}
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(userName, password.toCharArray());
}
}
And to use this new Class you would use the following code in place of the call to openConnection() shown above
...
try {
URL url = new URL(urlString);
System.out.println("Reading..." + url);
Authenticator.setDefault(new ProxyAuthenticator("username", "password");
SocketAddress addr = new InetSocketAddress("proxy.server.com", 80);
Proxy proxy = new Proxy(Proxy.Type.HTTP, addr);
HttpURLConnection conn = (HttpURLConnection)url.openConnection(proxy);
...
Your problem sounds like HTTP communication issues, so you are probably better off trying to use a library to handle the communication side of things. Take a look at Apache Commons HttpClient.
Some notes about your code example. You haven't used a URLConnection object so it's not clear what the behaviour will be in regards to the Web/Proxy servers and closing resources cleanly, etc. The HttpCommon library mentioned will help in this aspect.
There also seems to be some examples of doing what you want using J2ME libararies. Not something I have used personally but may also help you out.
I am making a crawler, and need to get the data from the stream regardless if it is a 200 or not. CURL is doing it, as well as any standard browser.
The following will not actually get the content of the request, even though there is some, an exception is thrown with the http error status code. I want the output regardless, is there a way? I prefer to use this library as it will actually do persistent connections, which is perfect for the type of crawling I am doing.
package test;
import java.net.*;
import java.io.*;
public class Test {
public static void main(String[] args) {
try {
URL url = new URL("http://github.com/XXXXXXXXXXXXXX");
URLConnection connection = url.openConnection();
DataInputStream inStream = new DataInputStream(connection.getInputStream());
String inputLine;
while ((inputLine = inStream.readLine()) != null) {
System.out.println(inputLine);
}
inStream.close();
} catch (MalformedURLException me) {
System.err.println("MalformedURLException: " + me);
} catch (IOException ioe) {
System.err.println("IOException: " + ioe);
}
}
}
Worked, thanks: Here is what I came up with - just as a rough proof of concept:
import java.net.*;
import java.io.*;
public class Test {
public static void main(String[] args) {
//InputStream error = ((HttpURLConnection) connection).getErrorStream();
URL url = null;
URLConnection connection = null;
String inputLine = "";
try {
url = new URL("http://verelo.com/asdfrwdfgdg");
connection = url.openConnection();
DataInputStream inStream = new DataInputStream(connection.getInputStream());
while ((inputLine = inStream.readLine()) != null) {
System.out.println(inputLine);
}
inStream.close();
} catch (MalformedURLException me) {
System.err.println("MalformedURLException: " + me);
} catch (IOException ioe) {
System.err.println("IOException: " + ioe);
InputStream error = ((HttpURLConnection) connection).getErrorStream();
try {
int data = error.read();
while (data != -1) {
//do something with data...
//System.out.println(data);
inputLine = inputLine + (char)data;
data = error.read();
//inputLine = inputLine + (char)data;
}
error.close();
} catch (Exception ex) {
try {
if (error != null) {
error.close();
}
} catch (Exception e) {
}
}
}
System.out.println(inputLine);
}
}
Simple:
URLConnection connection = url.openConnection();
InputStream is = connection.getInputStream();
if (connection instanceof HttpURLConnection) {
HttpURLConnection httpConn = (HttpURLConnection) connection;
int statusCode = httpConn.getResponseCode();
if (statusCode != 200 /* or statusCode >= 200 && statusCode < 300 */) {
is = httpConn.getErrorStream();
}
}
You can refer to Javadoc for explanation. The best way I would handle this is as follows:
URLConnection connection = url.openConnection();
InputStream is = null;
try {
is = connection.getInputStream();
} catch (IOException ioe) {
if (connection instanceof HttpURLConnection) {
HttpURLConnection httpConn = (HttpURLConnection) connection;
int statusCode = httpConn.getResponseCode();
if (statusCode != 200) {
is = httpConn.getErrorStream();
}
}
}
You need to do the following after calling openConnection.
Cast the URLConnection to HttpURLConnection
Call getResponseCode
If the response is a success, use getInputStream, otherwise use getErrorStream
(The test for success should be 200 <= code < 300 because there are valid HTTP success codes apart from than 200.)
I am making a crawler, and need to get the data from the stream regardless if it is a 200 or not.
Just be aware that it if the code is a 4xx or 5xx, then the "data" is likely to be an error page of some kind.
The final point that should be made is that you should always respect the "robots.txt" file ... and read the Terms of Service before crawling / scraping the content of a site whose owners might care. Simply blatting off GET requests is likely to annoy site owners ... unless you've already come to some sort of "arrangement" with them.
In Java, this code throws an exception when the HTTP result is 404 range:
URL url = new URL("http://stackoverflow.com/asdf404notfound");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.getInputStream(); // throws!
In my case, I happen to know that the content is 404, but I'd still like to read the body of the response anyway.
(In my actual case the response code is 403, but the body of the response explains the reason for rejection, and I'd like to display that to the user.)
How can I access the response body?
Here is the bug report (close, will not fix, not a bug).
Their advice there is to code like this:
HttpURLConnection httpConn = (HttpURLConnection)_urlConnection;
InputStream _is;
if (httpConn.getResponseCode() < HttpURLConnection.HTTP_BAD_REQUEST) {
_is = httpConn.getInputStream();
} else {
/* error from server */
_is = httpConn.getErrorStream();
}
It's the same problem I was having:
HttpUrlConnection returns FileNotFoundException if you try to read the getInputStream() from the connection.
You should instead use getErrorStream() when the status code is higher than 400.
More than this, please be careful since it's not only 200 to be the success status code, even 201, 204, etc. are often used as success statuses.
Here is an example of how I went to manage it
... connection code code code ...
// Get the response code
int statusCode = connection.getResponseCode();
InputStream is = null;
if (statusCode >= 200 && statusCode < 400) {
// Create an InputStream in order to extract the response object
is = connection.getInputStream();
}
else {
is = connection.getErrorStream();
}
... callback/response to your handler....
In this way, you'll be able to get the needed response in both success and error cases.
Hope this helps!
In .Net you have the Response property of the WebException that gives access to the stream ON an exception. So i guess this is a good way for Java,...
private InputStream dispatch(HttpURLConnection http) throws Exception {
try {
return http.getInputStream();
} catch(Exception ex) {
return http.getErrorStream();
}
}
Or an implementation i used. (Might need changes for encoding or other things. Works in current environment.)
private String dispatch(HttpURLConnection http) throws Exception {
try {
return readStream(http.getInputStream());
} catch(Exception ex) {
readAndThrowError(http);
return null; // <- never gets here, previous statement throws an error
}
}
private void readAndThrowError(HttpURLConnection http) throws Exception {
if (http.getContentLengthLong() > 0 && http.getContentType().contains("application/json")) {
String json = this.readStream(http.getErrorStream());
Object oson = this.mapper.readValue(json, Object.class);
json = this.mapper.writer().withDefaultPrettyPrinter().writeValueAsString(oson);
throw new IllegalStateException(http.getResponseCode() + " " + http.getResponseMessage() + "\n" + json);
} else {
throw new IllegalStateException(http.getResponseCode() + " " + http.getResponseMessage());
}
}
private String readStream(InputStream stream) throws Exception {
StringBuilder builder = new StringBuilder();
try (BufferedReader in = new BufferedReader(new InputStreamReader(stream))) {
String line;
while ((line = in.readLine()) != null) {
builder.append(line); // + "\r\n"(no need, json has no line breaks!)
}
in.close();
}
System.out.println("JSON: " + builder.toString());
return builder.toString();
}
I know that this doesn't answer the question directly, but instead of using the HTTP connection library provided by Sun, you might want to take a look at Commons HttpClient, which (in my opinion) has a far easier API to work with.
First check the response code and then use HttpURLConnection.getErrorStream()
InputStream is = null;
if (httpConn.getResponseCode() !=200) {
is = httpConn.getErrorStream();
} else {
/* error from server */
is = httpConn.getInputStream();
}
My running code.
HttpURLConnection httpConn = (HttpURLConnection) urlConn;
if (httpConn.getResponseCode() < HttpURLConnection.HTTP_BAD_REQUEST) {
in = new InputStreamReader(urlConn.getInputStream());
BufferedReader bufferedReader = new BufferedReader(in);
if (bufferedReader != null) {
int cp;
while ((cp = bufferedReader.read()) != -1) {
sb.append((char) cp);
}
bufferedReader.close();
}
in.close();
} else {
/* error from server */
in = new InputStreamReader(httpConn.getErrorStream());
BufferedReader bufferedReader = new BufferedReader(in);
if (bufferedReader != null) {
int cp;
while ((cp = bufferedReader.read()) != -1) {
sb.append((char) cp);
}
bufferedReader.close();
}
in.close();
}
System.out.println("sb="+sb);
How to read 404 response body in java:
Use Apache library - https://hc.apache.org/httpcomponents-client-4.5.x/httpclient/apidocs/
or
Java 11 - https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html
Snippet given below uses Apache:
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.util.EntityUtils;
CloseableHttpClient client = HttpClients.createDefault();
CloseableHttpResponse resp = client.execute(new HttpGet(domainName + "/blablablabla.html"));
String response = EntityUtils.toString(resp.getEntity());