HttpConnection Class

The HttpConnection class makes a HTTP connection to a given URI. You can use it to make GET and POST requests to other web services.

HTTPS calls are supported only for URIs that have standard security certificates.

When you call the execute method in HttpConnection, it executes the request, gets the response, and closes the connection. This means that a single object cannot be used multiple times. For multiple HTTP requests, instantiate multiple instances.

Note: Make sure that the URL is properly encoded when instantiating an HttpConnection object.

Constructor

You create an instance of HttpConnection using the new operator.

Method signature

HttpConnection con = new HttpConnection(int methodType, String URI)

methodType

Sets the HTTP method type:

• CONSTANTS.HTTP.METHOD.GET for HTTP GET requests
• CONSTANTS.HTTP.METHOD.POST for HTTP POST requests

String URI

URI to which to connect

Methods

The methods are:

• addHeader
• addParameter
• execute
• getResponse
• encode
• getResponseHeaders
• setRequestBody

addHeader

Adds a key-value pair to the request header.

Method signature

void addHeader(String key, String value)

Parameters

• key - The name of the key
• value - The value of the key

Return

None

addParameter

Adds a parameter to an HTTP POST request. This methods throws an exception if it is called for an HTTP GET request.

Method signature

void addParameter(String key, String value)

Parameters

• key - The name of the key
• value - The value of the key

Return

None

execute

Executes the request and returns a standard HTTP response such as "200 - OK" or "404 - not found".

Method signature

int execute()

Parameters

None

Return

Standard HTTP response

getResponse

Returns the response as a String.

Method signature

String getResponse()

Parameters

None

Return

The response from the service

encode

Returns a String encoded from s.

Method signature

String encode(String s)

Parameters

• s - The string to encode

Return

The encoded string

getResponseHeaders

Retrieve the headers from the HTTP Response from an external server. It is a map of String Header Name/Header Value pairs.

For example, if the Header Content-Length is equal to 10008, then "Content-Length" is the Header Name and "10008" is the Header Value.

This method is to be called after execute method of HttpConnection.

Method signature

HashMap<String name, String value> getResponseHeaders()

Parameters

None

Return

A HashMap of Header Name/Header Value string pairs

setRequestBody

Specify the body of the request, the content type, and character set.

Method signature

HashMap<String name, String value> getResponseHeaders()

Parameters

• content-Type - String. One of the valid MIME types for the body of a request. For example: "application/xml".
• charSet - String. The character set used in the request. For example: "utf-8".

Return

None

Learn more:

• MIME types
• CharSets

HttpConnection Example

This example gets the result of a Google search for "IT Leaders".

HttpConnection con = new HttpConnection(CONSTANTS.HTTP.METHOD.GET, "http://www.google.com/search?hl=en&q=IT+Leaders&btnG=Google+Search"); int code= con.execute(); String response = con.getResponse();

Note: The typical response format is JSON. Those libraries are built into the platform. The APIs are documented at JSON.org.