Android How to - Access Web Services Using the GET Method

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To Access Web Services Using the GET Method involves the following steps:

• download XML files
• parse the contents

Example

The following code shows how to Access Web Services Using the GET Method.

Add the following statement to the AndroidManifest.xml file:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.java2s.myapplication3.app" >
    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />
    <uses-permission android:name="android.permission.INTERNET"/>
    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="java2s.com"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.java2s.myapplication3.app.MainActivity"
            android:label="java2s.com"
            >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Layout xml file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center" />

</LinearLayout>

Main Activity Java code

package com.java2s.myapplication3.app;
/*  w  w w .j  av a2s . c o  m*/
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.ImageView;
import android.widget.Toast;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

public class MainActivity extends Activity {
    ImageView img;

    private InputStream OpenHttpConnection(String urlString) throws IOException {
        InputStream in = null;
        int response = -1;

        URL url = new URL(urlString);
        URLConnection conn = url.openConnection();

        if (!(conn instanceof HttpURLConnection))
            throw new IOException("Not an HTTP connection");
        try {
            HttpURLConnection httpConn = (HttpURLConnection) conn;
            httpConn.setAllowUserInteraction(false);
            httpConn.setInstanceFollowRedirects(true);
            httpConn.setRequestMethod("GET");
            httpConn.connect();
            response = httpConn.getResponseCode();
            if (response == HttpURLConnection.HTTP_OK) {
                in = httpConn.getInputStream();
            }
        } catch (Exception ex) {
            throw new IOException("Error connecting");
        }
        return in;
    }

    private String WordDefinition(String word) {
        InputStream in = null;
        String strDefinition = "";
        try {
            in = OpenHttpConnection("http://your server.com/query?word=" + word);
            Document doc = null;
            DocumentBuilderFactory dbf =
                    DocumentBuilderFactory.newInstance();
            DocumentBuilder db;
            try {
                db = dbf.newDocumentBuilder();
                doc = db.parse(in);
            } catch (ParserConfigurationException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            doc.getDocumentElement().normalize();

            //---retrieve all the <Definition> elements---
            NodeList definitionElements =
                    doc.getElementsByTagName("Definition");

            //---iterate through each <Definition> elements---
            for (int i = 0; i < definitionElements.getLength(); i++) {
                Node itemNode = definitionElements.item(i);
                if (itemNode.getNodeType() == Node.ELEMENT_NODE) {
                    //---convert the Definition node into an Element---
                    Element definitionElement = (Element) itemNode;


                }
            }
        } catch (IOException e1) {
            Log.d("NetworkingActivity", e1.getLocalizedMessage());
        }
        //---return the definitions of the word---
        return strDefinition;
    }

    private class AccessWebServiceTask extends AsyncTask<String, Void, String> {
        protected String doInBackground(String... urls) {
            return WordDefinition(urls[0]);
        }

        protected void onPostExecute(String result) {
            Toast.makeText(getBaseContext(), result, Toast.LENGTH_LONG).show();
        }
    }

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //---access a Web Service using GET---
        new AccessWebServiceTask().execute("apple");
    }
}

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