below I include some of my code:
Here is my code:
int responseCode = httpCon.getResponseCode();
if (responseCode==-1) { httpCon.connect(); }
InputStream is = httpCon.getInputStream();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
String line;
StringBuffer response = new StringBuffer();
while((line = rd.readLine()) != null) {
response.append(line);
}
rd.close();
try {
OutputStream file = openFileOutput("configND", Context.MODE_PRIVATE);
DataOutputStream wrf = new DataOutputStream(file);
wrf.writeBytes(line);
wrf.close();
} catch (Exception e){
e.printStackTrace();
}
I'm trying receive data (JSON string) from PHP file and then create a file with a content but something is wrong. I can't receive a JSON string and the file can not be created.
I use HttpURLconnection and I don't use apache library. I might add that sending JSON is working properly.
Help!
If you receive nothing from the server, the problem might be simply in your PHP script.
For the Android part of the "problem", if you don't want to use Volley and simply handle this with Android APIs, these two links should make your day :)
http://www.androidhive.info/2012/05/how-to-connect-android-with-php-mysql/
http://www.codeproject.com/Articles/267023/Send-and-receive-json-between-android-and-php
Personnally, when I learned Android some years ago, I followed AndroidHive ressources and it works pretty well.
Related
I have an assignment for school that involves writing a simple web crawler that crawls Wikipedia. The assignment stipulates that I can't use any external libraries so I've been playing around with the java.net.URL class. Based on the official tutorial and some code given by my professor I have:
public static void main(String[] args) {
System.setProperty("sun.net.client.defaultConnectTimeout", "500");
System.setProperty("sun.net.client.defaultReadTimeout", "1000");
try {
URL url = new URL(BASE_URL + "/wiki/Physics");
InputStream is = url.openStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String inputLine;
int lineNum = 0;
while ((inputLine = br.readLine()) != null && lineNum < 10) {
System.out.println(inputLine);
lineNum++;
}
is.close();
}
catch (MalformedURLException e) {
System.out.println(e.getMessage());
}
catch (IOException e) {
System.out.println(e.getMessage());
}
}
In addition, the assignment requires that:
Your program should not continuously send requests to wiki. Your program
must wait for at least 1 second after every 10 requests
So my question is, where exactly in the above code is the "request" being sent? And how does this connection work? Is the entire webpage being loaded in one go? or is it being downloaded line by line?
I honestly don't really understand much about networking at all so apologies if I'm misunderstanding something fundamental. Any help would be much appreciated.
InputStream is = url.openStream();
at the above line you will be sending request
BufferedReader br = new BufferedReader(new InputStreamReader(is));
at this line getting the input stream and reading.
Calling url.openStream() initiates a new TCP connection to the server that the URL resolves to. An HTTP GET request is then sent over the connection. If all goes right (i.e., 200 OK), the server sends back the HTTP response message that carries the data payload that is served up at the specified URL. You then need to read the bytes from the InputStream that the openStream() method returns in order to retrieve the data payload into your program.
I'm a newbie in android programming and I want to sent data to php server and receive data to show in android
but I have no idea to create it, I don't no to use library? and Can give some example for me to practice about it.
ps. sorry my english is not good.
example Myphp "xxx.xxx.x.x/api.php"
$keyword = $_GET['keyword'];
$index= $_GET['index'];
$path = "http://xxxxxxx/webservice/&query=".urlencode($keyword)."&index=".$index."";
$jsondata = file_get_contents($path);
$jsons = json_decode($jsondata,true);
echo json_encode($jsons);
I want to send keyword and index from edittext to php server and receive json data to show listview.
HttpURLConnection can be used for get,put,post,delete requests :
try {
// Construct the URL
URL url = new URL("http://xxxxxxx/webservice/&query="
+keyword.getText().toString()
+"&index="+index.getText().toString());
// Create the request
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// Read the input stream into a String
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
// Nothing to do.
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
// Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
// But it does make debugging a *lot* easier if you print out the completed
// buffer for debugging.
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
// Stream was empty. No point in parsing.
}
JsonStr = buffer.toString(); //result
} catch (IOException e) {
}
where keyword and index will be your EditText Variables.
I'm trying to replace a Netcat command that I'm running in my terminal that will reset some data on a server. The netcat command looks like this:
echo '{"id":1, "method":"object.deleteAll", "params":["subscriber"]} ' | nc x.x.x.x 3994
I've been trying to implement it in Java since I would like to be able to call this command from an application I'm developing. I'm having issues with it though, the command is never executed on the server.
This is my java code:
try {
Socket socket = new Socket("x.x.x.x", 3994);
String string = "{\"id\":1,\"method\":\"object.deleteAll\",\"params\":[\"subscriber\"]}";
DataInputStream is = new DataInputStream(socket.getInputStream());
DataOutputStream os = new DataOutputStream(socket.getOutputStream());
os.write(string.getBytes());
os.flush();
BufferedReader in = new BufferedReader(new InputStreamReader(is));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
is.close();
os.close();
} catch (IOException e) {
e.printStackTrace();
}
The code also hangs on the while loop that should read the InputStream, I have no idea why. I've been using Wireshark to capture the packets and the data that is going out looks the same:
{"id":1,"method":"object.deleteAll","params":["subscriber"]}
Perhaps the rest of the packets are not shaped in the same way but I really can't understand why that would be. Perhaps I am writing the string in a faulty way to the OutputStream? I have no idea :(
Note that I posted a question similar to this yesterday when I didn't properly understand the problem:
Can't post JSON to server with HTTP Client in Java
EDIT:
These are the possible results I get from running the nc command, I would expect to get the same messages to the InputStream if the OutputStream sends correct data in a correct way:
Wrong arguments:
{"id":1,"error":{"code":-32602,"message":"Invalid entity type: subscribe"}}
Ok, successful:
{"id":1,"result":100}
Nothing to delete:
{"id":1,"result":0}
Wow, I really had no idea. I experimented with some different Writers like "buffered writer" and "print writer" and it seems the PrintWriter was the solution. Although I couldn't use the PrintWriter.write() nor the PrintWriter.print() methods. I had to use PrintWriter.println().
If someone has the answer to why other writers wouldn't work and explain how they would impact the data sent to the server I will gladly accept that as the solution.
try {
Socket socket = new Socket(InetAddress.getByName("x.x.x.x"), 3994);
String string = "{\"id\":1,\"method\":\"object.deleteAll\",\"params\":[\"subscriber\"]}";
DataInputStream is = new DataInputStream(socket.getInputStream());
DataOutputStream os = new DataOutputStream(socket.getOutputStream());
PrintWriter pw = new PrintWriter(os);
pw.println(string);
pw.flush();
BufferedReader in = new BufferedReader(new InputStreamReader(is));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
is.close();
os.close();
} catch (IOException e) {
e.printStackTrace();
}
I think the server is expecting newline at the end of the message. Try to use your original code with write() and add \n at the end to confirm this.
I request a web page that sends a Content-Encoding: gzip header, but got stuck how to read it..
My code:
try {
URLConnection connection = new URL("http://jquery.org").openConnection();
String html = "";
BufferedReader in = null;
connection.setReadTimeout(10000);
in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null){
html+=inputLine+"\n";
}
in.close();
System.out.println(html);
System.exit(0);
} catch (IOException ex) {
Logger.getLogger(Crawler.class.getName()).log(Level.SEVERE, null, ex);
}
The output looks very messy.. (I was unable to paste it here, a sort of symbols..)
I believe this is a compressed content, how to parse it?
Note:
If I change jquery.org to jquery.com (which don't send that header, my code works well)
Actually, this is pb2q's answer, but I post the full code for future readers
try {
URLConnection connection = new URL("http://jquery.org").openConnection();
String html = "";
BufferedReader in = null;
connection.setReadTimeout(10000);
//The changed part
if (connection.getHeaderField("Content-Encoding")!=null && connection.getHeaderField("Content-Encoding").equals("gzip")){
in = new BufferedReader(new InputStreamReader(new GZIPInputStream(connection.getInputStream())));
} else {
in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
}
//End
String inputLine;
while ((inputLine = in.readLine()) != null){
html+=inputLine+"\n";
}
in.close();
System.out.println(html);
System.exit(0);
} catch (IOException ex) {
Logger.getLogger(Crawler.class.getName()).log(Level.SEVERE, null, ex);
}
There is a class for this: GZIPInputStream. It is an InputStream and so is very transparent to use.
there are two cases with Content-Encoding:gzip header
if data already compressed(by application), Content-Encoding:gizp header will cause data to compressed again.so its double compressed.it's because http compression
if data is not compressed by application, Content-Encoding:gizp will cause data to compress(gzip mostly) and it will automatically uncompressed(un-zip) before it reaches to client. un-zip is default feature available in most of web browsers. browser will do un-zip if it finds Content-Encoding:gizp header in the response.
Im on quite a basic level of android development.
I would like to get text from a page such as "http://www.google.com". (The page i will be using will only have text, so no pictures or something like that)
So, to be clear: I want to get the text written on a page into etc. a string in my application.
I tried this code, but im not even sure if it does what i want.
URL url = new URL(/*"http://www.google.com");
URLConnection connection = url.openConnection();
// Get the response
BufferedReader rd = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String line = "";
I cant get any text from it anyhow. How should I do this?
From the sample code you gave you are not even reading the response from the request. I would get the html with the following code
URL u = new URL("http://www.google.com");
URLConnection conn = u.openConnection();
BufferedReader in = new BufferedReader(
new InputStreamReader(
conn.getInputStream()));
StringBuffer buffer = new StringBuffer();
String inputLine;
while ((inputLine = in.readLine()) != null)
buffer.append(inputLine);
in.close();
System.out.println(buffer.toString());
From there you would need to pass the string into some kind of html parser if you want only the text. From what I've heard JTidy would is a good library for this however I have never used any Java html parsing libraries.
You want to extract text from HTML file? You can make use of specialized tool such as the Jericho HTML parser library. I'm not sure if it can be used directly in Android app, it is quite big, but it is open source so you can make use of its code and take only what you need for your task.
Here is one way:
public String scrape(String urlString) throws Exception {
URL url = new URL(urlString);
URLConnection connection = url.openConnection();
BufferedReader reader = new BufferedReader(new InputStreamReader(
connection.getInputStream()));
String line = null, data = "";
while ((line = reader.readLine()) != null) {
data += line + "\n";
}
return data;
}
Here is another.