Develop Reference

Reading REST Request Output using HttpURLConnection

I am trying to do REST request on the StackExchange API on java and I have some problems to read the output. I made a small code example to see if I can read properly:
package Utils;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class RestClient
{
public static void main(String[] args)
{
try
{
URL url = new URL("https://api.stackexchange.com/2.2/questions?order=desc&sort=activity&site=stackoverflow");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
System.out.println(conn.getResponseCode());
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String output;
while ((output = reader.readLine()) != null)
{
System.out.println(output);
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
Below is a sample output from the website:
{"items":[{"tags":["c++","templates","covariant"],"owner":{"reputation":3,"user_id":7447292,"user_type":"registered","profile_image":"https://www.gravatar.com/avatar/8979f1b328b9b0f786dec8b4edd514bc?s=128&d=identicon&r=PG&f=1","display_name":"B.Oudot","link":"http://stackoverflow.com/users/7447292/b-oudot"}
However when I print the output of my java program, I get the status code 200 and then the rest is just bunch of non-ascii characters. I am new with REST and JSON. I would like to not use any 3rd party library if possible.
EDIT
I have put the output of my program as an image.

you need to use GZIPInputStream api, when the content encoding used gZip. it is also an inputstream.
i used gipinput stream to your response and i see output in json.
public static void main(String[] args){
try
{
URL url = new URL("https://api.stackexchange.com/2.2/questions?order=desc&sort=activity&site=stackoverflow");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
System.out.println(conn.getResponseCode());
GZIPInputStream gzis = new GZIPInputStream(conn.getInputStream());
InputStreamReader reader = new InputStreamReader(gzis);
BufferedReader in = new BufferedReader(reader);
String readed;
while ((readed = in.readLine()) != null) {
System.out.println(readed);
}
//BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String output;
while ((output = in.readLine()) != null)
{
System.out.println(output);
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
it worked for me.

How to Read from and Post to a Remote Server using Java

I am new to this type of problems. Here I want to make a request to a website API and get response in JSON format.
I then want to send this response directly to a a different remote URL.

See the below sample code
PostMethod post = new PostMethod("Your URL");
post.setRequestBody("your json data");
post.setRequestHeader("Content-type", "application/json;charset=utf-8");
// Get HTTP client
HttpClient httpclient = new HttpClient();
// Execute request
try
{
int result = httpclient.executeMethod(post);
s_log.info("Response status code: " + result);
s_log.info(post.getResponseBodyAsString());
}
catch (HttpException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
post.releaseConnection();
}

Reading from and writing to a remote URL can be done using the standard Java API and is detailed in the official Java tutorials:
https://docs.oracle.com/javase/tutorial/networking/urls/readingWriting.html
Reading:
import java.net.*;
import java.io.*;
public class URLConnectionReader {
public static void main(String[] args) throws Exception {
URL oracle = new URL("http://www.oracle.com/");
URLConnection yc = oracle.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(
yc.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
in.close();
}
}
Writing
import java.io.*;
import java.net.*;
public class Reverse {
public static void main(String[] args) throws Exception {
if (args.length != 2) {
System.err.println("Usage: java Reverse "
+ "http://<location of your servlet/script>"
+ " string_to_reverse");
System.exit(1);
}
String stringToReverse = URLEncoder.encode(args[1], "UTF-8");
URL url = new URL(args[0]);
URLConnection connection = url.openConnection();
connection.setDoOutput(true);
OutputStreamWriter out = new OutputStreamWriter(
connection.getOutputStream());
out.write("string=" + stringToReverse);
out.close();
BufferedReader in = new BufferedReader(
new InputStreamReader(
connection.getInputStream()));
String decodedString;
while ((decodedString = in.readLine()) != null) {
System.out.println(decodedString);
}
in.close();
}
}

eRRORServer returned HTTP response code: 503 for URL: https://ipv4.google.com/

import java.io.*;
import java.net.URL;
import java.net.URLConnection;
public class Rough_Program
{
public static void main(String[] args) throws IOException
{
String inputLine = null;
String contant = null;
System.setProperty("java.net.useSystemProxies", "true");
System.setProperty("http.proxyHost", "10.10.10.1");
System.setProperty("http.proxyPort", "3128");
URL oracle = new URL("https://www.google.co.in/search?q=Old%20Trafford");
StringBuffer str1 = new StringBuffer();
URLConnection yc = oracle.openConnection();
yc.addRequestProperty("User-Agent", "Mozilla/4.76");
BufferedReader in = new BufferedReader(new InputStreamReader(
yc.getInputStream()));
while ((inputLine = in.readLine()) != null) {
str1.append(inputLine);
}
contant = str1.toString();
System.out.println(contant);
}
}

try to add proxy settings for https:
System.setProperty("https.proxyHost", "10.10.10.1");
System.setProperty("https.proxyPort", "3128");

C drive memory overloading by running swing

I'm making a management software in java for a book store. There is a database on my server. I get my database data by php code.which is also in my server.I use the code below to get data by running the php code.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
public class HttpUtility {
private static HttpURLConnection httpConn;
public static HttpURLConnection sendGetRequest(String requestURL)
throws IOException {
URL url = new URL(requestURL);
httpConn = (HttpURLConnection) url.openConnection();
httpConn.setUseCaches(false);
httpConn.setDoInput(true);
httpConn.setDoOutput(false);
return httpConn;
}
public static HttpURLConnection sendPostRequest(String requestURL,
Map<String, String> params) throws IOException {
URL url = new URL(requestURL);
httpConn = (HttpURLConnection) url.openConnection();
httpConn.setUseCaches(false);
httpConn.setDoInput(true);
StringBuffer requestParams = new StringBuffer();
if (params != null && params.size() > 0) {
httpConn.setDoOutput(true);
Iterator<String> paramIterator = params.keySet().iterator();
while (paramIterator.hasNext()) {
String key = paramIterator.next();
String value = params.get(key);
requestParams.append(URLEncoder.encode(key, "UTF-8"));
requestParams.append("=").append(
URLEncoder.encode(value, "UTF-8"));
requestParams.append("&");
}
OutputStreamWriter writer = new OutputStreamWriter(
httpConn.getOutputStream());
writer.write(requestParams.toString());
writer.flush();
}
return httpConn;
}
public static String readSingleLineRespone() throws IOException {
InputStream inputStream = null;
if (httpConn != null) {
inputStream = httpConn.getInputStream();
} else {
throw new IOException("Connection is not established.");
}
BufferedReader reader = new BufferedReader(new InputStreamReader(
inputStream));
String response = reader.readLine();
reader.close();
return response;
}
public static String[] readMultipleLinesRespone() throws IOException {
InputStream inputStream = null;
if (httpConn != null) {
inputStream = httpConn.getInputStream();
} else {
throw new IOException("Connection is not established.");
}
BufferedReader reader = new BufferedReader(new InputStreamReader(
inputStream));
List<String> response = new ArrayList<String>();
String line = "";
while ((line = reader.readLine()) != null) {
response.add(line);
}
reader.close();
return (String[]) response.toArray(new String[0]);
}
public static void disconnect() {
if (httpConn != null) {
httpConn.disconnect();
}
}
}
Now I'm facing a problem like the image link (don't have enough reputation for the upload)below.There are 3 image link.
before log in
After the log in and before the search query
Another link is in the comment.
After every request making my C:// drive is loosing 10 MB space and I don't know why(Very noob coder sorry.)
Can anyone help me.

Reading source code from a webpage in java

I am trying to read source code from a webpage. My java code is
import java.net.*;
import java.io.*;
import java.util.*;
import javax.swing.JOptionPane;
class Testing{
public static void Connect() throws Exception{
URL url = new URL("http://excite.com/education");
URLConnection spoof = url.openConnection();
spoof.setRequestProperty( "User-Agent", "Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 5.0; H010818)" );
BufferedReader in = new BufferedReader(new InputStreamReader(spoof.getInputStream()));
String strLine = "";
while ((strLine = in.readLine()) != null){
System.out.println(strLine);
}
System.out.println("End of page.");
}
public static void main(String[] args){
try{
Connect();
}catch(Exception e){
}
}
When i compile and run this code, it gives the following output:
�I�%&/m�{J�J��t�$ؐ#������iG#)�*��eVe]f#�흼��{���{���;�N'���?\fdl��J�ɞ!���?~|?"~�$}�>�������4�����7N�����+�ӲM�N��?J�tZfM��G�j����R��!�9�?>JgE��Ge[����ⳏ���W�?�����8������
�|8�
���������ho����0׳���|փ:--�|�L�Uο�׫��m�zt�n3��l\�w��O^f�G[�CG<�y6K��gM�rg��ǟy�Eִy����h˜��ؗ˲X���l=�ڢZ�/����(կ^O�UU6�����&�6_�#yC}�p�y���lAH�ͯ��zF#�V�6_��}��)�v=J+�$��̤�G�Y�L�b���wS"�7�y^����Z�m���Y:ɛ���J<N_�Y=���U�f���,���y�Q2(J٩P!ͨ�i����1&F0&ૼn�?�x�T��h�Qzw�+����n�)�h��K��2����8g����⮥��A0
���1I�%����Q�Z����{��������w���?x����N�?�<d�S��۫�%a|4�j��z���k�Bak��k-�c�z�g��z���l>���֎s^,��5��/B�{����]]����Ý�ֳ���y{�_l�8g�k�ӫ�b���"+|��(��M��^[���J�P��_�..?������x�Z�$������E>��느�u���E~����{媘���f�e1ͷ�QZ,�����f��e�3Jٻb�^��4��۴���>��y��;��<렛{�l��ZfW
S# {�]��1��Q�����n[�,t�?����~�n�S�u#SL��n�^��������EC��q�/�y���FE�tpm������e&��oB���z9eY��������P��IK?����̦����w�N��;�;J?����;�/��5���M���rZ��q��]��C�dᖣ��F�nd���}���A5���M�5�.�:��/�_D�?�3����'�c�Z7��}��(OI),ۏi����{�<�w�������DZ?e����'q���eY]=���kj���߬������\qhrRn���l�o-��.���k��_���oD8��GA�P�r��|$��ȈPv~Y�:�[q?�sH�� <��C��ˬ�^N�[ v(��S��l�c�C����3���E5&5�VӪL�T��۔���oQrĈ��/���#[f�5�5"����[���t�vm�\��.0�nh����aڌWYM
^T�|\,��퓜�L�u����B�̌�C�r������ �������'�%�{��)�);�fV�]��g,�>�C �c2���p�4��}H���P��(�%j"�}�&�:�Oh\5I�l�氪��{�/�]�LB�l��2��I"��=��Y�|�>�֏n�������}�����~�[��'��O��
��:/�)�Wz�3��lo�.5�k�&����H[ji�����b������WWy}�5�֝Q�|f�����]�KjH5��}yNm�����g�ӷ�ǣ��>��'o��泏��<���G�g���>->�xQM�����%<�|����u�.��3���[�[r���ٝ;���]4E��6[����]����1���*�8}��n�w�������ݽ����|����}|qo|�~u����w|�i�i���Z�`z�ŧ����Q}�u��!���w �O���R9�)�~��g~߻w6��{���wd�o��/Z�uUS��݄l��I^�����>��[�U1�o�_��J��}��#�#�U�/��/?���i�7|CZT?(�2b~����c�W�c5'����EeFĿꇙ�0��T��{��W�2����/���O���YJj����K/���>��:'_l�
Other than URLs from this directory i.e. "excite.com/education" all URLs are giving correct source codes but these URLs are creating problems.
Anyone Please Help.
Thanks in advance.

It works for me.
private static String getWebPabeSource(String sURL) throws IOException {
URL url = new URL(sURL);
URLConnection urlCon = url.openConnection();
BufferedReader in = null;
if (urlCon.getHeaderField("Content-Encoding") != null
&& urlCon.getHeaderField("Content-Encoding").equals("gzip")) {
in = new BufferedReader(new InputStreamReader(new GZIPInputStream(
urlCon.getInputStream())));
} else {
in = new BufferedReader(new InputStreamReader(
urlCon.getInputStream()));
}
String inputLine;
StringBuilder sb = new StringBuilder();
while ((inputLine = in.readLine()) != null)
sb.append(inputLine);
in.close();
return sb.toString();
}

Try reading it this way:
private static String getUrlSource(String url) throws IOException {
URL url = new URL(url);
URLConnection urlConn = url.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(
urlConn.getInputStream(), "UTF-8"));
String inputLine;
StringBuilder a = new StringBuilder();
while ((inputLine = in.readLine()) != null)
a.append(inputLine);
in.close();
return a.toString();
}
and set your encoding according to the web page - notice this line:
BufferedReader in = new BufferedReader(new InputStreamReader(
urlConn.getInputStream(), "UTF-8"));

First you have to uncompress the content using GZIPInputStream. Then put the uncompressed stream to Input Stream and read it using BufferedReader
Use Apache HTTP Client 4.1.1
Maven dependency
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.1.1</version>
</dependency>
Sample Code to parse gzip content.
package com.gzip.simple;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.zip.GZIPInputStream;
import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
public class GZIPFetcher {
public static void main(String[] args) {
try {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet getRequest = new HttpGet("http://excite.com/education");
getRequest.addHeader("accept", "application/json");
HttpResponse response = httpClient.execute(getRequest);
if (response.getStatusLine().getStatusCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : "
+ response.getStatusLine().getStatusCode());
}
InputStream instream = response.getEntity().getContent();
// Check whether the content-encoding is gzip or not.
Header contentEncoding = response
.getFirstHeader("Content-Encoding");
if (contentEncoding != null
&& contentEncoding.getValue().equalsIgnoreCase("gzip")) {
instream = new GZIPInputStream(instream);
}
BufferedReader in = new BufferedReader(new InputStreamReader(
instream));
String content;
System.out.println("Output from Server .... \n");
while ((content = in.readLine()) != null)
System.out.println(content);
httpClient.getConnectionManager().shutdown();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}