Develop Reference

How do I change this try-finally to try-with-resources?

This is the code.
Most of the examples do not let me to use response variable which I got with the function's parameter.
Is there anyone who can help me with this question?
Or is it better to use try-finally than try-with-resources in this case?
public void func(HttpServletResponse response) throws IOException {
OutputStream out = null;
InputStream in = null;
try {
out = response.getOutputStream();
ResponseEntity<Resource> url = getUrl();
Resource body = url.getBody();
in = body.getInputStream();
FileCopyUtils.copy(in, out);
} finally {
if (out != null) {
try {
out.close();
}catch (IOException e) {
}
}
if (in != null) {
try {
in.close();
}catch (IOException e) {
}
}
}
}

You can do it this way using try-with-resources construct
public void func(HttpServletResponse response) throws IOException {
try (OutputStream out = response.getOutputStream) {
out = response.getOutputStream();
ResponseEntity<Resource> url = getUrl();
Resource body = url.getBody();
try(InputStream in = body.getInputStream()) {
FileCopyUtils.copy(in, out);
}
}
}

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.io.IOException: Stream closed in HandlerInterceptor

I have a problem with Interceptor in SpringBoot I am trying to read the body in a request at preHandle() method.
public class LogInterceptor extends HandlerInterceptorAdapter {
#Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
try {
InputStream inputStream = request.getInputStream();
if (inputStream != null) {
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
char[] charBuffer = new char[128];
int bytesRead = -1;
while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
} else {
stringBuilder.append("");
}
} catch (IOException ex) {
System.out.println("Error reading the request body...");
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException ex) {
System.out.println("Error closing bufferedReader...");
}
}
}
String body = stringBuilder.toString();
System.out.println("--Body--"+body);
}
}
This code print body correctly but when I try to made a POST petition with Postman I receive the following error.
I/O error while reading input message; nested exception is java.io.IOException: Stream closed
If I do the same petition witouth this code the petition works correctly.
Could anyone help to me ? Or said a better solution to intercept body ?

How to rewrite POST request body on HttpServletRequest

I'm working on a Filter in which I have to get the request payload, decrypt it, check if it's a valid JSON and if it is go on with the chain and go to my service. The thing is that, so far I haven't been able to find a way to rewrite the body. Why I want to rewrite it? As the service expects a JSON and the request has an encrypted text in the body, once I decrypt it I want the body to be the decrypted JSON. Also, once I return from the service, I should rewrite the response to have the json encrypted. I've read a lot of forums and questions but couldn't get to a working solution.
Here's my code:
RequestLoginFilter.java
#WebFilter("/RequestLoginFilter")
public class RequestLoginFilter implements Filter{
protected final static Log logger = LogFactory.getLog(RequestLoginFilter.class);
private ServletContext context;
private CryptoUtil crypto;
public void init(FilterConfig fConfig) throws ServletException {
this.context = fConfig.getServletContext();
this.context.log("RequestLoggingFilter initialized");
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
// use wrapper to read multiple times the content
AuthenticationRequestWrapper req = new AuthenticationRequestWrapper((HttpServletRequest) request);
HttpServletResponse resp = (HttpServletResponse) response;
String payload = req.getPayload();
try {
String decryptedPayload = crypto.decrypt(payload);
JSONUtils.convertJSONStringToObject(decryptedPayload, LoginTokenTO.class);
} catch (GeneralSecurityException e) {
logger.error("Error when trying to decrypt payload '"+payload+"'");
throw new ServletException("Error when trying to decrypt payload '"+payload+"'", e);
}
chain.doFilter(req, resp);
System.out.println("a ver");
}
#Override
public void destroy() {
// TODO Auto-generated method stub
}
}
And also the wrapper, just in case:
AuthenticationRequestWrapper.java
public class AuthenticationRequestWrapper extends HttpServletRequestWrapper {
protected final static Log logger = LogFactory.getLog(AuthenticationRequestWrapper.class);
private final String payload;
public AuthenticationRequestWrapper (HttpServletRequest request) throws AuthenticationException {
super(request);
// read the original payload into the payload variable
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
try {
// read the payload into the StringBuilder
InputStream inputStream = request.getInputStream();
if (inputStream != null) {
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
char[] charBuffer = new char[128];
int bytesRead = -1;
while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
} else {
// make an empty string since there is no payload
stringBuilder.append("");
}
} catch (IOException ex) {
logger.error("Error reading the request payload", ex);
throw new AuthenticationException("Error reading the request payload", ex);
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException iox) {
// ignore
}
}
}
payload = stringBuilder.toString();
}
#Override
public ServletInputStream getInputStream () throws IOException {
final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(payload.getBytes());
ServletInputStream inputStream = new ServletInputStream() {
public int read ()
throws IOException {
return byteArrayInputStream.read();
}
};
return inputStream;
}
public String getPayload() {
return payload;
}
}
Hopefully somebody here knows how I can get to get this working.
Thanks in advance guys.

Whilst what you are asking is probably technically possible, it doesn't sound like the right approach to me.
What you need is a security layer that sits between the incoming request (endpoint) and your service. Re-writing the body of the request is a strange thing to be doing (which probably explains why you're having issues). Is there a reason you want this to be done in a Filter? After all, filters are designed to filter requests, not rewrite them ;)
A more logical/transparent solution would be to have your endpoint accept all incoming requests, decrypt and validate them before passing the request onto your service tier. Something like this:
public void handleRequest(Request request) {
try {
IncomingRequest x = securityManager.decrypt(request);
Response r = myService.handleRequest(x);
handleResponse(securityManager.encrypt(r));
}catch(InvlidateMessage x) {
handleInvalidMessage...
}catch(BusinessException x) {
handleBusinessException...
}
}

Having problems retrieving response from a servlet in J2ME

I am trying to retreive a response from a servlet to a midlet using the code below
public String receiveData() {
HttpConnection connection = null;
String url = "http://localhost:8084/MCastServer/Create";
DataInputStream is = null;
OutputStream os = null;
StringBuffer stringBuffer = new StringBuffer();
String res = null;
try {
connection = (HttpConnection) Connector.open(url);
connection.setRequestMethod(HttpConnection.GET);
connection.setRequestProperty("IF-Modified-Since", "20 Jan 2001 16:19:14 GMT");
connection.setRequestProperty("User-Agent", "Profile/MIDP-2.0 Confirguration/CLDC-1.0");
connection.setRequestProperty("Content-Language", "en-CA");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
os = connection.openOutputStream();
is = connection.openDataInputStream();
System.out.println(url);
int ch = 0;
while ((ch = is.read()) == -1) {
stringBuffer.append((char) ch);
System.out.println(stringBuffer);
}
res = stringBuffer.toString();
System.out.println(res);
//ByteArrayOutputStream bos = new ByteArrayOutputStream();
} catch (Exception e) {
} finally {
try {
if (is != null) {
is.close();
}
if (os != null) {
os.close();
}
if (connection != null) {
connection.close();
}
//display.setCurrent(textBox);
} catch (Exception e) {
}
}
return res;
}
But it keeps returning a null output. I have searched and tried various means but it still returns the same.
Below is the Servlet which I wrote
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/plain");
PrintWriter out = response.getWriter();
String groupNames = "SELECT phone_group_name FROM phone_group_name";
InteractToDB dbCall = new InteractToDB("org.postgresql.Driver");
dbCall.connect("jdbc:postgresql://localhost:5432/mcast", "postgres", "mimi");
out.print(dbCall.getNames());
System.out.println(dbCall.getNames() + " call");
try {
} finally {
out.close();
}
}

You have an empty catch block - that's not a good idea. You should print the stack trace at minimum.
I also think it's a terrible idea to put database code in a servlet. I'd write an interface-based POJO, test out the code thoroughly without the servlet, and then call its methods in the servlet. It decomposes the problem into smaller ones and helps your unit testing efforts.
Why are you creating a connection per request? Why aren't you using a connection pool to amortize the cost of creating connections?
Why are you hard-wiring your information in plain text in the class? What happens if dbCall is null? What if a SQLException is thrown?
The more I look at this code, the worst it gets. I'd better stop now.