HttpConnection Class
About the 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.
- Considerations
-
- 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.
- Make sure that the URL is properly encoded when instantiating an HttpConnection object.
Learn more:
Constructor
You create an instance of HttpConnection using the new operator.
- Method signature
HttpConnection con = new HttpConnection(int methodType, String encoded_URI)
- methodType
- Sets the HTTP method type:
- CONSTANTS.HTTP.METHOD.GET for an HTTP GET request
- CONSTANTS.HTTP.METHOD.POST for an HTTP POST request
- String encoded_URI
- Properly encoded URI to connect to
Learn more: URL Encoding
Methods
The methods are:
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:
HttpConnection Example
This example gets the result of a Google search for "IT Leaders".
<syntaxhighlight lang="java" enclose="div"> 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(); </syntaxhighlight >
Note: The typical response format is JSON. Those libraries are built into the platform. The APIs are documented at JSON.org.
