is it possible to proccess JSON responses with the JDK or HttpComponents only?

we are upgrading our web app to use Facebook's Graph API, which returns JSON responses. However we don't want to add dependecy to a JSON library unless we have no other choice. For server-side http requests we use Apache HttpComponents.

Thus, my question is what are the classes (if any) in the JDK and/or in HttpComponents that I can use to process JSON responses? Code snippets are welcome :)

Solution 1:

Unfortunately, native JSON support was delayed past Java 9.

But for the sake of sportmanship here is plain Java 8 hacky solution using Nashorn JavaScript engine without any external dependency:

String json = "{\"foo\":1, \"bar\":\"baz\"}";
ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
Object o = engine.eval(String.format("JSON.parse('%s')", json));
Map<String, String> map = (Map<String, String>) o;
System.out.println(Arrays.toString(map.entrySet().toArray()));
// [foo=1, bar=baz]

Since Java 8u60 JSON.parse can be substituted with Java.asJSONCompatible which does better handling of JSON arrays.

Credits:

Effective way to pass JSON between java and javascript

https://dzone.com/articles/mapping-complex-json-structures-with-jdk8-nashorn

Solution 2:

It is possible. Because JSON is valid JavaScript syntax, you can use the built-in JavaScript interpreter via the scripting API to create and object graph, walk that (using the visitor pattern to push data into a Java object, for example).

However, you need to trust the data or you leave yourself open to code injection attacks. To me, this would not be an adequate substitute for a proper JSON parser.