call java class with click on a button

call java class with click on a button - java

I am trying to call another class called HttpUtilityTester.java from Mainactivity.java.
Actually I'd like to test HttpUtility.sendPostRequest from HttpUtility.java with a click on a button.
The spot is marked with this comment: "//here I need help from stackoverflow"
This is already added to my button in the activity_main.xml:
android:onClick="sendMessage1"
here is Mainactivity.java:
package com.example.mythirdapp;
import android.app.Activity;
import android.os.Bundle;
public class MainActivity extends Activity {
//here I need help from stackoverflow
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
here is HttpUtility.java:
package com.example.mythirdapp;
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 {
/**
* Represents an HTTP connection
*/
private static HttpURLConnection httpConn;
/**
* Makes an HTTP request using GET method to the specified URL.
*
* #param requestURL
* the URL of the remote server
* #return An HttpURLConnection object
* #throws IOException
* thrown if any I/O error occurred
*/
public static HttpURLConnection sendGetRequest(String requestURL)
throws IOException {
URL url = new URL(requestURL);
httpConn = (HttpURLConnection) url.openConnection();
httpConn.setUseCaches(false);
httpConn.setDoInput(true); // true if we want to read server's response
httpConn.setDoOutput(false); // false indicates this is a GET request
return httpConn;
}
/**
* Makes an HTTP request using POST method to the specified URL.
*
* #param requestURL
* the URL of the remote server
* #param params
* A map containing POST data in form of key-value pairs
* #return An HttpURLConnection object
* #throws IOException
* thrown if any I/O error occurred
*/
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); // true indicates the server returns response
StringBuffer requestParams = new StringBuffer();
if (params != null && params.size() > 0) {
httpConn.setDoOutput(true); // true indicates POST request
// creates the params string, encode them using URLEncoder
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("&");
}
// sends POST data
OutputStreamWriter writer = new OutputStreamWriter(
httpConn.getOutputStream());
writer.write(requestParams.toString());
writer.flush();
}
return httpConn;
}
/**
* Returns only one line from the server's response. This method should be
* used if the server returns only a single line of String.
*
* #return a String of the server's response
* #throws IOException
* thrown if any I/O error occurred
*/
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;
}
/**
* Returns an array of lines from the server's response. This method should
* be used if the server returns multiple lines of String.
*
* #return an array of Strings of the server's response
* #throws IOException
* thrown if any I/O error occurred
*/
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]);
}
/**
* Closes the connection if opened
*/
public static void disconnect() {
if (httpConn != null) {
httpConn.disconnect();
}
}
}
here is HttpUtilityTester.java:
package com.example.mythirdapp;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
public class HttpUtilityTester {public static void main(String[] args) {
// test sending GET request
String requestURL = "http://www.google.com";
try {
HttpUtility.sendGetRequest(requestURL);
String[] response = HttpUtility.readMultipleLinesRespone();
for (String line : response) {
System.out.println(line);
}
} catch (IOException ex) {
ex.printStackTrace();
}
HttpUtility.disconnect();
System.out.println("=====================================");
// test sending POST request
Map<String, String> params = new HashMap<String, String>();
requestURL = "https://accounts.google.com/ServiceLoginAuth";
params.put("Email", "your_email");
params.put("Passwd", "your_password");
try {
HttpUtility.sendPostRequest(requestURL, params);
String[] response = HttpUtility.readMultipleLinesRespone();
for (String line : response) {
System.out.println(line);
}
} catch (IOException ex) {
ex.printStackTrace();
}
HttpUtility.disconnect();
}
}
I tried to add code of the HttpUtilityTester.java to my Mainactivity.java like this:
...public class MainActivity extends Activity {
public void sendMessage1(View v){
// test sending POST request
Map<String, String> params = new HashMap<String, String>();
requestURL = "https://accounts.google.com/ServiceLoginAuth";
params.put("Email", "your_email");
params.put("Passwd", "your_password");
try {
HttpUtility.sendPostRequest(requestURL, params);
String[] response = HttpUtility.readMultipleLinesRespone();
for (String line : response) {
System.out.println(line);
}
} catch (IOException ex) {
ex.printStackTrace();
}
HttpUtility.disconnect();
}...
But logcat sais: "could not execute method of the activity"

The following will be called when you click that button, so place it in your code where applicable.
public void sendMessage1(View v){
}

Related

Webpage login error-Android App

I'm new to Android and Java. I'm creating an app to login to my ISP. This is the page: http://reliancebroadband.co.in/reliance/login.do
Earlier, I was using a python script, which worked flawlessly. Its like this:
#!/usr/bin/env python
# encoding: utf-8
import urllib2, urllib, cookielib
username = 'my-username'
password = 'my-password'
jar = cookielib.FileCookieJar("cookies")
opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(jar))
response = opener.open("http://reliancebroadband.co.in/reliance/startportal_isg.do")
login_data = urllib.urlencode({'userId' : username, 'password' : password, 'action' : 'doLoginSubmit'})
resp = opener.open('http://reliancebroadband.co.in/reliance/login.do', login_data)
And now i'm trying to create an android app(source: http://www.compiletimeerror.com/2013/01/login-application-for-android.html#.U7AFBPmSz9Y) (Tried contacting the developer there, but he's not responding.)
The app is compiling correctly, but while tring to login, its just returning the source code of the login page in the error dialogue, instead of logging in.
Here's the code:
MainActivity.java:
package com.app.reliancebblogin;
import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
#SuppressLint("NewApi")
public class MainActivity extends Activity
{
EditText un, pw;
TextView error;
Button ok;
private String resp;
private String errorMsg;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
un = (EditText) findViewById(R.id.et_un);
pw = (EditText) findViewById(R.id.et_pw);
ok = (Button) findViewById(R.id.btn_login);
error = (TextView) findViewById(R.id.tv_error);
ok.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
/** According with the new StrictGuard policy, running long tasks on the Main UI thread is not possible
So creating new thread to create and execute http operations */
new Thread(new Runnable()
{
#Override
public void run()
{
ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("username",un.getText().toString()));
postParameters.add(new BasicNameValuePair("password",pw.getText().toString()));
String response = null;
try
{
response = SimpleHttpClient.executeHttpPost("http://reliancebroadband.co.in/reliance/login.do", postParameters);
String res = response.toString();
resp = res.replaceAll("\\s+", "");
}
catch (Exception e)
{
e.printStackTrace();
errorMsg = e.getMessage();
}
}
}).start();
try
{
/** wait a second to get response from server */
Thread.sleep(1000);
/** Inside the new thread we cannot update the main thread
So updating the main thread outside the new thread */
error.setText(resp);
if (null != errorMsg && !errorMsg.isEmpty())
{
error.setText(errorMsg);
}
}
catch (Exception e)
{
error.setText(e.getMessage());
}
}
});
}
}
SimpleHttpClient.java:
package com.app.reliancebblogin;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.util.ArrayList;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
public class SimpleHttpClient
{
/** The time it takes for our client to timeout */
public static final int HTTP_TIMEOUT = 30 * 1000; // milliseconds
/** Single instance of our HttpClient */
private static HttpClient mHttpClient;
/**
* Get our single instance of our HttpClient object.
*
* #return an HttpClient object with connection parameters set
*/
private static HttpClient getHttpClient()
{
if (mHttpClient == null)
{
mHttpClient = new DefaultHttpClient();
final HttpParams params = mHttpClient.getParams();
HttpConnectionParams.setConnectionTimeout(params, HTTP_TIMEOUT);
HttpConnectionParams.setSoTimeout(params, HTTP_TIMEOUT);
ConnManagerParams.setTimeout(params, HTTP_TIMEOUT);
}
return mHttpClient;
}
/**
* Performs an HTTP Post request to the specified url with the
* specified parameters.
*
* #param url The web address to post the request to
* #param postParameters The parameters to send via the request
* #return The result of the request
* #throws Exception
*/
public static String executeHttpPost(String url, ArrayList<NameValuePair> postParameters) throws Exception
{
BufferedReader in = null;
try
{
HttpClient client = getHttpClient();
HttpPost request = new HttpPost(url);
UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(postParameters);
request.setEntity(formEntity);
HttpResponse response = client.execute(request);
in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null)
{
sb.append(line + NL);
}
in.close();
String result = sb.toString();
return result;
}
finally
{
if (in != null)
{
try
{
in.close();
} catch (IOException e)
{
e.printStackTrace();
}
}
}
}
/**
* Performs an HTTP GET request to the specified url.
*
* #param url The web address to post the request to
* #return The result of the request
* #throws Exception
*/
public static String executeHttpGet(String url) throws Exception
{
BufferedReader in = null;
try
{
HttpClient client = getHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI(url));
HttpResponse response = client.execute(request);
in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null)
{
sb.append(line + NL);
}
in.close();
String result = sb.toString();
return result;
}
finally
{
if (in != null)
{
try
{
in.close();
} catch (IOException e)
{
e.printStackTrace();
}
}
}
}
}

Communicate between android Application and java

Every body i am new in program world , I am getting a issue,My Request is related to Communication between Android tablet to Desktop PC using JAVA Code.
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorldServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public HelloWorldServlet() {
super();
}
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = response.getWriter();
out.println("Hello Android !!!!");
}
}
above code is my servlet code which is running in my local system server (Tomcat 6.0 ) here i am sending message through println and i want to reveive same message in my Android app which is running in another system. Now i am going to post my android code which is running on another system.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class HttpGetServletActivity3 extends Activity implements
OnClickListener {
Button button;
TextView outputText;
public static final String URL =
"http://192.168.0.2:9999/HttpGetServlet/HelloWorldServlet";
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
findViewsById();
button.setOnClickListener(this);
}
private void findViewsById() {
button = (Button) findViewById(R.id.button);
outputText = (TextView) findViewById(R.id.outputTxt);
}
public void onClick(View view) {
GetXMLTask task = new GetXMLTask();
task.execute(new String[] { URL });
}
private class GetXMLTask extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... urls) {
String output = null;
for (String url : urls) {
output = getOutputFromUrl(url);
}
return output;
}
private String getOutputFromUrl(String url) {
StringBuffer output = new StringBuffer("");
try {
InputStream stream = getHttpConnection(url);
BufferedReader buffer = new BufferedReader(
new InputStreamReader(stream));
String s = "";
while ((s = buffer.readLine()) != null)
output.append(s);
} catch (IOException e1) {
e1.printStackTrace();
}
return output.toString();
}
// Makes HttpURLConnection and returns InputStream
private InputStream getHttpConnection(String urlString)
throws IOException {
InputStream stream = null;
URL url = new URL(urlString);
URLConnection connection = url.openConnection();
try {
HttpURLConnection httpConnection = (HttpURLConnection) connection;
httpConnection.setRequestMethod("GET");
httpConnection.connect();
if (httpConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
stream = httpConnection.getInputStream();
}
} catch (Exception ex) {
ex.printStackTrace();
}
return stream;
}
#Override
protected void onPostExecute(String output) {
outputText.setText(output);
}
}}
Here 192.68.0.2 is ip address of system where servlet code is running in my local system (Tomcat6.0 server which has port no 9999) .But it is not working for me.Both the system are in same wifi network Any help is really very appreciated. Thanks in advance to all

try this i will work for you. This is android code
protected Integer doInBackground(String... arg0) {
/** According with the new StrictGuard policy, running long tasks on the Main UI thread is not possible
So creating new thread to create and execute http operations */
new Thread(new Runnable() {
#Override
public void run() {
ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("username",un.getText().toString()));
postParameters.add(new BasicNameValuePair("password",pw.getText().toString()));
String response = null;
try {
response = SimpleHttpClient.executeHttpPost("http://XXX.168.1.X:5555/LoginServlet/loginservlet.do", postParameters);
res = response.toString();
System.out.println("response :"+res);
} catch (Exception e) {
// e.printStackTrace();
errorMsg = e.getMessage();
}
}
}).start();
/** Inside the new thread we cannot update the main thread
So updating the main thread outside the new thread */
try {
}catch (Exception e) {
error.setText(e.getMessage());
// e.printStackTrace();
}
return null;
}
Now this is another class for android
public class SimpleHttpClient {
public static String result="";
/** The time it takes for our client to timeout */
public static final int HTTP_TIMEOUT = 30 * 1000; // milliseconds
/** Single instance of our HttpClient */
private static HttpClient mHttpClient;
/**
* Get our single instance of our HttpClient object.
*
* #return an HttpClient object with connection parameters set
*/
private static HttpClient getHttpClient() {
if (mHttpClient == null) {
mHttpClient = new DefaultHttpClient();
final HttpParams params = mHttpClient.getParams();
HttpConnectionParams.setConnectionTimeout(params, HTTP_TIMEOUT);
HttpConnectionParams.setSoTimeout(params, HTTP_TIMEOUT);
ConnManagerParams.setTimeout(params, HTTP_TIMEOUT);
}
return mHttpClient;
}
/**
* Performs an HTTP Post request to the specified url with the
* specified parameters.
*
* #param url The web address to post the request to
* #param postParameters The parameters to send via the request
* #return The result of the request
* #throws Exception
*/
public static String executeHttpPost(String url, ArrayList<NameValuePair> postParameters) throws Exception {
BufferedReader in = null;
try {
HttpClient client = getHttpClient();
HttpPost request = new HttpPost(url);
UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(postParameters);
request.setEntity(formEntity);
// String str1= request.setEntity(formEntity);
System.out.println("actual request"+formEntity);
HttpResponse response = client.execute(request);
System.out.println("response in class"+response);
in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
result = sb.toString();
}catch(Exception e){
e.printStackTrace();
System.out.println("catch");
}
finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return result;
}
/**
* Performs an HTTP GET request to the specified url.
*
* #param url The web address to post the request to
* #return The result of the request
* #throws Exception
*/
public static String executeHttpGet(String url) throws Exception {
String result="";
BufferedReader in = null;
try {
HttpClient client = getHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI(url));
HttpResponse response = client.execute(request);
in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
result = sb.toString();
}
catch(Exception e){
e.printStackTrace();
System.out.println("catch2");
}
finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return result;
}}
And finally this is servlet code for you
public class LoginServlet extends HttpServlet {
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
String un,pw;
un=request.getParameter("username");
pw=request.getParameter("password");
System.out.println("username :"+un);
System.out.println("password :"+pw);
if(un.equals("") || pw.equals("") ){
out.print("null");
}
else if(un.equalsIgnoreCase("hello") && pw.equals("world"))
{
out.print("success");
}
else{
out.print("failed");
}
System.out.println("after :");
request.getAttribute("USER"+un);
request.getAttribute("PASS"+pw);
RequestDispatcher rd=request.getRequestDispatcher("home.jsp");
rd.forward(request, response);
}catch(Exception e){
System.out.println("inside exception");
e.printStackTrace();
}
finally {
out.close();
}
}
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
service(request, response);
}
#Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
service(request, response);
}
#Override
public String getServletInfo() {
return "Short description";
}}

Java, Simulating Browser

I am writing a small java program/api to programatically login/ (do a hthp post with login credentials) to this http://web2sms.ke.airtel.com
For me to post, I need parameter(key and value for the login form). When I render the form via browser, the key/name keep changing everytime to but when I fetch the page via java code below the key is always contact f_1.number, therefore meaning the server in my thinking the server is differentiating if a page is fetched from from a browser or not. How can I simulate a browser and get the figures to be rendered by browser?
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
*
* #author Dell
*/
public class AirtelWeb2Sms {
String link = "http://web2sms.ke.airtel.com";
/**
* #param args the command line arguments
*/
private boolean on = false;
public static void main(String[] args) {
new AirtelWeb2Sms();
}
public AirtelWeb2Sms() {
login();
}
private void login(){
Map <String, String> parameters = new HashMap();
try{
URL url = new URL(link);
URLConnection yc = url.openConnection();
BufferedReader in = new BufferedReader(
new InputStreamReader(
yc.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
{
if(inputLine.contains("<div id=\"loginform\">"))
{
on=true;
}
if(on && (inputLine.contains("input")||inputLine.contains("select"))&& inputLine.contains("name")&& inputLine.contains("value")){
// System.out.println(inputLine);
String[] tokens = inputLine.split("\" ");
String key="", value="";
for(String str: tokens){
if(str.contains("name=")){
key=str.substring(str.indexOf("\"")+1);
}
if(str.startsWith("value")){
value=str.substring(str.indexOf("\"")+1);
}
if(key.contains(".number")){
value="+25473DummyNumber";
}
if(key.contains(".passwd")){
value="dymmerPassword";
}
if(key.contains(".language")){
value="en";
}
}
parameters.put(key, value=value.replace(""", "\""));
System.out.println(key+":"+value);
}
if(inputLine.contains("<input type=\"submit\""))
{
on=false;
}
}
doSubmit(link+"index.hei", parameters);
}
catch(Exception ex){
System.out.println(ex.getLocalizedMessage());
}
}
public void doSubmit(String url, Map<String, String> data) throws Exception
{
URL siteUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection) siteUrl.openConnection();
conn.setRequestMethod("POST"); conn.setDoOutput(true);
conn.setDoInput(true); DataOutputStream out = new DataOutputStream(conn.getOutputStream());
Set keys = data.keySet();
Iterator keyIter = keys.iterator(); String content = "";
for(int i=0; keyIter.hasNext(); i++) {
Object key = keyIter.next();
if(i!=0) {
content += "&";
}
content += key + "=" +data.get(key);
}
System.out.println(content);
out.writeBytes(content);
out.flush();
out.close();
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line = "";
while((line=in.readLine())!=null) {
System.out.println(line); } in.close();
}
}

Try setting the "User-Agent" HTTP header to some value that a real browser would send. You can check what's your browser's user-agent string by visiting http://whatsmyuseragent.com/.

How to send data from java servlet to android client

I am doing a simple application in android. The android application has a simple form and when I click the submit button from Android client the form values goes to servlet. Now I have a problem getting string values from servlet to Android client.
How can I send a string data from servlet? And how can I receive string data in Android client?

You need to make a URLConnection to your servlet page and do it. Example for it: http://www.helloandroid.com/tutorials/how-download-fileimage-url-your-device

Save the code below as CustomHttpClient.java
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.util.ArrayList;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
public class CustomHttpClient {
/** The time it takes for our client to timeout */
public static final int HTTP_TIMEOUT = 30 * 1000; // milliseconds
/** Single instance of our HttpClient */
private static HttpClient mHttpClient;
/**
* Get our single instance of our HttpClient object.
*
* #return an HttpClient object with connection parameters set
*/
private static HttpClient getHttpClient() {
if (mHttpClient == null) {
mHttpClient = new DefaultHttpClient();
final HttpParams params = mHttpClient.getParams();
HttpConnectionParams.setConnectionTimeout(params, HTTP_TIMEOUT);
HttpConnectionParams.setSoTimeout(params, HTTP_TIMEOUT);
ConnManagerParams.setTimeout(params, HTTP_TIMEOUT);
}
return mHttpClient;
}
/**
* Performs an HTTP Post request to the specified url with the
* specified parameters.
*
* #param url The web address to post the request to
* #param postParameters The parameters to send via the request
* #return The result of the request
* #throws Exception
*/
public static String executeHttpPost(String url, ArrayList<NameValuePair> postParameters) throws Exception {
BufferedReader in = null;
try {
HttpClient client = getHttpClient();
HttpPost request = new HttpPost(url);
UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(postParameters);
request.setEntity(formEntity);
HttpResponse response = client.execute(request);
in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
String result = sb.toString();
return result;
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
/**
* Performs an HTTP GET request to the specified url.
*
* #param url The web address to post the request to
* #return The result of the request
* #throws Exception
*/
public static String executeHttpGet(String url) throws Exception {
BufferedReader in = null;
try {
HttpClient client = getHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI(url));
HttpResponse response = client.execute(request);
in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String line = "";
String NL = System.getProperty("line.separator");
while ((line = in.readLine()) != null) {
sb.append(line + NL);
}
in.close();
String result = sb.toString();
return result;
} finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
Now add the code where you want to make the client server communication
ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("username",str2));
//here we are passing a variable str2 to the server.
String response = null;
try {
//address should be the http address of the server side code.
response = CustomHttpClient.executeHttpPost("http://www.xxx.xx/xxx.java", postParameters);
String res=response.toString();
res= res.replaceAll("\\s+","");
//res will be the string that you get from the server.

how to pass data from servlet to android application

I have a form in android upon submit im inserting it into database using servlet i have to show to user that form was inserted successfully. this is my application
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.util.ArrayList;
/**
*
* #author trainee
*/
public class form extends HttpServlet {
String name;
String password;
Connection con = null;
Statement stmt = null;
/**
* Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* #param request servlet request
* #param response servlet response
* #throws ServletException if a servlet-specific error occurs
* #throws IOException if an I/O error occurs
*/
/* TODO output your page here
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet form</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Servlet form at " + request.getContextPath () + "</h1>");
out.println("</body>");
out.println("</html>");
*/
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try
{
}
catch(Exception ex)
{
}
}
/**
* Handles the HTTP <code>POST</code> method.
* #param request servlet request
* #param response servlet response
* #throws ServletException if a servlet-specific error occurs
* #throws IOException if an I/O error occurs
*/
#Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try
{
Class.forName("com.mysql.jdbc.Driver");
con =DriverManager.getConnection ("jdbc:mysql://localhost:3306/Login","root", "");
String nn=request.getParameter("name");
String pass=request.getParameter("pass");
String email=request.getParameter("email");
stmt=con.createStatement();
String query="insert into users values('"+nn+"','"+pass+"','"+email+"');";
int v=stmt.executeUpdate(query);
ArrayList<String> arr=new ArrayList<String>();
arr.add("inserted");
System.out.println("sent response back...");
}
catch(Exception ex)
{
}
}
/**
* Returns a short description of the servlet.
* #return a String containing servlet description
*/
#Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
}
this is my android application
package org.me.loginandroid;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.io.*;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import org.apache.http.client.methods.HttpGet;
public class MainActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btn1 = (Button) findViewById(R.id.submit);
btn1.setOnClickListener(listener_login);
}
private OnClickListener listener_login = new OnClickListener() {
boolean check = false;
public void onClick(View v) {
EditText emailText = (EditText) findViewById(R.id.email);
EditText passText = (EditText) findViewById(R.id.password);
EditText nameText = (EditText) findViewById(R.id.uname);
String name = nameText.getText().toString();
String email = (emailText.getText().toString());
String pass = (passText.getText().toString());
String result = "";
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("name", name));
nameValuePairs.add(new BasicNameValuePair("pass", pass));
nameValuePairs.add(new BasicNameValuePair("email", email));
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://10.0.2.2:8084/Login/form");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
InputStream is = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
TextView lbl = (TextView) findViewById(R.id.lbl);
lbl.setText(result);
} catch (Exception e) {
TextView tv = (TextView) findViewById(R.id.err);
tv.setText("Error parsing data " + e.toString());
System.out.println("Error parsing data " + e.toString());
}
//parse json data
try {
boolean check=false;
ArrayList<String> arrays=new ArrayList<String>();
for(int i=0;i<arrays.size();i++)
{
if(arrays.get(i).equals("Inserted"))
{
check=true;
}
else
{
}
}
if(check)
{
Intent myintent = new Intent(MainActivity.this, welcome.class);
startActivity(myintent);
}
else
{
TextView tv = (TextView) findViewById(R.id.err);
tv.setText("Data was not inserted properly");
}
} catch (Exception e) {
//setContentView(R.layout.notify);
TextView tv = (TextView) findViewById(R.id.err);
tv.setText(e.toString());
System.out.println("log_tag" + "Error parsing data ");
}
}
};
}

You need to make a URLConnection to your servlet page and do it. Example for it: How to download file/image from url to your device

you can get data from servlet to andriod application through json format.
Please go through this
http://wiebe-elsinga.com/blog/?p=405 link to get an idea of how to call Servlet from andriod application and get the response
back in json format.
call to Servlet from Andriod
private InputStream callService(String text) {
InputStream in = null;
SERVLET_URL = http://wizkid.com/web/updateServlet";
try {
URL url = new URL(SERVLET_URL);
URLConnection conn = url.openConnection();
HttpURLConnection httpConn = (HttpURLConnection) conn;
httpConn.setRequestMethod("POST");
httpConn.setDoInput(true);
httpConn.setDoOutput(true);
httpConn.connect();
DataOutputStream dataStream = new DataOutputStream(conn
.getOutputStream());
dataStream.writeBytes(text);
dataStream.flush();
dataStream.close();
int responseCode = httpConn.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
in = httpConn.getInputStream();
}
} catch (Exception ex) {
display("Error: Not not connect");
}
return in;
}
// Get Data from Server to andriod
private String getResultFromServlet(String text) {
String result = "";
InputStream in = callService(text);
if (in != null) {
JSONObject jsonResponse;
try {
jsonResponse = new JSONObject(convertStreamToString(in));
result = jsonResponse.getString("output");
} catch (JSONException e) {
result = "Error: JSON Object couldn't be made";
}
} else {
result = "Error: Service not returning result";
}
return result;
}

first of all,
if your doGet() and doPost() do the same thing, you can call one from the other, sending the request and response
Second, you can pass an ArrayList<E> to the android app.
Both the Servlet and Android APIs have it
edit:
You need to read from a InputStream, generated by a HttpURLConnection object.
http://developer.android.com/reference/java/io/InputStream.html
check out this book:
used book http://www.amazon.com/Professional-Android-Application-Development-Programmer/dp/0470565527)
String input = getString(R.string.input);
try {
URL url = new URL(input);
URLConnection connection = url.openConnection();
HttpURLConnection http = (HttpURLConnection)connection;
int response = http.getResponseCode();
if (response == HttpURLConnection.HTTP_OK) {
InputStream is = http.getInputStream();
//do whatever you want with the stream
}
}
catch (MalformedURLException exception) { }
catch (IOException exception) { }

You can check here. There is a whole description with sample code
Send arraylist from servlet to Android application

Develop Reference

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

call java class with click on a button - java

The following will be called when you click that button, so place it in your code where applicable. public void sendMessage1(View v){ }

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