Reading HTTP
• In this lesson, you will learn to launch a HTTP request on
a Web server.
• For this, you will use the DefaultHttpClient, HttpGet /
HttpPost and an InputStream.

Reading HTTP
• To do a request of type GET, use the class HttpGet :
HttpGet http = new HttpGet (new URI (url));
• To do a request of type POST, use the class HttpPost :
HttpPost http = new HttpPost (new URI (url));
• To add a HTTP header, use the method addHeader() :
http.addHeader("pragma","no-cache");

Reading HTTP
• To add data, use the object List <NameValuePair> in orderto store them
then call the method setEntity :
http.setEntity(new UrlEncodedFormEntity (headers, HTTP.UTF_8));
• To run the HTTP request, use the method execute() :
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpResponse httpResponse = httpClient.execute(http);
• To read the data returned by the server, use an InputStream :
InputStream inputStream = httpResponse.getEntity().getContent();

Reading HTTP
• To read a stream InputStream, use an InputStreamReader :
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
• Read the data line by line thanks to a BufferedReader :
BufferedReader bufferedReader = new BufferedReader (inputStreamReader);
StringBuilder stringBuilder = new StringBuilder();
String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line).append("n");
}

Reading HTTP
• Then you have to close the InputStream :
inputStream.close();
• The read text is in the StringBuilder :
String html = stringBuilder.toString();

Layout main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="URL" />
<EditText
android:id="@+id/et_url"
android:ems="10"
android:text="http://www.google.com" />

Layout main.xml
<Button
android:id="@+id/btnDownload"
android:text="Download" />
<EditText
android:id="@+id/et_output"
android:ems="10" />
</LinearLayout>

File Main.java
public class Main extends Activity {
EditText et_output;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
et_output = (EditText)findViewById (R.id.et_output);
Button btnDownload = (Button)findViewById (R.id.btnDownload);
btnDownload.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
EditText et_url = (EditText)findViewById (R.id.et_url);
et_output.setText (getURL ("" + et_url.getText(), null));
}
});
}

File Main.java
public String getURL (String url, List <NameValuePair> headers) {
try {
HttpGet httpGet = new HttpGet (new URI (url));
httpGet.addHeader("pragma","no-cache");
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpResponse httpResponse = httpClient.execute(httpGet);
InputStream inputStream = httpResponse.getEntity().getContent();
return inputStreamToString (inputStream);
} catch (Exception e) {
Toast.makeText(this, e.getMessage(), 5000).show();
}
return "";
}

File Main.java
public String inputStreamToString (InputStream inputStream) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader (inputStreamReader);
StringBuilder stringBuilder = new StringBuilder();
try {
String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line).append("n");
}
inputStream.close();
} catch (IOException e) {
}
return stringBuilder.toString();
}
}

Test on your mobile
Network_Http

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Android Lab Test : Using the network with HTTP (english)