Add query parameters Apache HttpClient

Suppose you want to send request to a URL with below format

Here,
param1, param2 and param3 are called Query parameters or Request parameters.

In this article, we will look at adding query parameters to a request URL in Apache HttpClient library in java.
If you do know how to send an HTTP request with HttpClient, refer this article.

URIBuilder
Apache HttpClient provides a URIBuilder class which accepts a base URL as constructor argument.
For adding query parameters, it provides addParameter() method, which takes two string arguments representing parameter name and value.

After the parameters are added to the URIBuilder, call its build() method to create an object of URI class.
This URI object is provided to the request using its setURI() method.

Example,

HttpPost post = new HttpPost("https://app-url");
URI uriBuilder = new URIBuilder(post.getURI()).
                     addParameter("id", "10").
                     addParameter("name", "abc").build();
post.setURI(uriBuilder);

If you look at the logs, then you would see below line

Note that in above example, base URL for URIBuilder is taken from request object using its getURI() method.
But, we can also set the base URL directly in the URIBuilder constructor as shown below

HttpPost post = new HttpPost(); 
URI uriBuilder = new URIBuilder("https://app-url").
addParameter("id", "10").
addParameter("name", "abc").build();
post.setURI(uriBuilder);

This also has the same result.

This method is applicable to both GET and POST request objects of HttpClient.
Adding all parameters
URIBuilder provides an option to add multiple query parameters at once, instead of calling addParameter() multiple times.
It has an addParameters() method which takes a list of NameValuePair objects. Example,

HttpPost post = new HttpPost("https://app-url"); 
// define a list
List<NameValuePair> parameters = new ArrayList<>();
// add new parameters
parameters.add(new BasicNameValuePair("id", "10"));
parameters.add(new BasicNameValuePair("name", "abc"));
URI uriBuilder = new URIBuilder(post.getURI()).
                     addParameters(parameters).
                     build();
post.setURI(uriBuilder);

NameValuePair is an interface, so we create object of BasicNameValuePair, which implements it.