se.itu.systemet.rest

Interface Query

All Known Implementing Classes:

RestQuery

public interface Query

Defines a Query for an API access fetch operation.

Typically, when accessing a data API, you send along some kind of query which contains a set of conditions or criteria for the stuff you want to fetch.

For instance, an ApiAccess object in this library has a fetch method which accepts a Query as the sole argument.

A Query object is a holder of a set of parameters (Param objects). Conequently, there is an addParam method for Query objects which you use while building up your Query in increments (stepwise).

The ApiAccess, for instance, will make use of the toQueryString() method found in this interface, which will return a String representation of the query and all its parameters. It's up to the implementing class to produce a correct query string. A query string can be the GET parameters of a URL or the WHERE clause of an SQL query SELECT, for instance.

For convenience, this interface also declares a get(String key) method which will return the value of any parameter whose key matches the key parameter, or null if no such key is available in any of the Query's parameters. It is up to the implementing class to implement this method in an efficient manner, but one obvious way would be to hold a private Map of some sort for quick access of the values from any parameter key. Note that a Map would only permit unique keys, and if multiple keys are to be permitted (if the query would allow more than one paramter to use the same key), a Map won't solve this, unless you use a Map of String keys and values that are always a list.

Method Summary

Modifier and Type	Method and Description
void	addParam(Param param) Adds a Param object to this Query.
String	get(String key) Returns the value (as a String) of the parameter whose key is the key provided by the key argument.
String	toQueryString() Returns this Query as a String, in the format suitable for the target API.

Method Detail

addParam

void addParam(Param param)

Adds a Param object to this Query.

Parameters:

param - The Param object to be added

toQueryString

String toQueryString()

Returns this Query as a String, in the format suitable for the target API.

Returns:

This Query as a String, in the format suitable for the target

get

String get(String key)

Returns the value (as a String) of the parameter whose key is the key provided by the key argument.

Parameters:

key - The key to the parameter whose value is requested

Returns:

The value of the parameter in this request whose key matches the argument, or null if no parameter has a matching key