tidying up and add comments

Author: Psilo

src/main/java/info/unterrainer/commons/httpserver/GenericHandlerGroupBuilder.java

@@ -100,6 +100,15 @@ public GenericHandlerGroupBuilder<P, J, E> getListInterceptor(final GetListInter
 		return this;
 	}
 
+	/**
+	 * Gives you a {@link InterceptorParamBuilder} object that allows you to declare
+	 * an interceptor with minimal code.<br>
+	 * You can specify every important part of it (select-clause, where-clause,
+	 * join-clause and order-by-clause) and utilizes its own parser for the
+	 * where-clause ({@link InterceptorParamBuilder#query(String)}).
+	 * 
+	 * @return
+	 */
 	public InterceptorParamBuilder<P, J, E> getListInterceptor() {
 		return new InterceptorParamBuilder<>(this, (passedData, query) -> {
 			getListInterceptors.add((ctx, hu) -> {

src/main/java/info/unterrainer/commons/httpserver/interceptors/InterceptorParamBuilder.java

@@ -33,6 +33,37 @@ public InterceptorParamBuilder<P, J, E> orderBy(final String orderByClause) {
 		return this;
 	}
 
+	/**
+	 * This is where you declare your rules that will construct your query.
+	 * <p>
+	 * - The operators are 'AND' and 'OR' and you may use parentheses '(' and ')' to
+	 * group your sub-expressions.<br>
+	 * {@code Example: 'term1 AND (term2 OR term3)'}<br>
+	 * - Operator precedence automatically is AND before OR.<br>
+	 * - A term starts with a DB-field followed by either an operator and a
+	 * JSON-field, or a null-operator.<br>
+	 * - JSON-fields start with ':' and end on a bracket-expression containing the
+	 * type of field.<br>
+	 * - Allowed fields are:
+	 * {@code string, boolean, int, long, float, double and datetime} (The system
+	 * knows how to convert these to DB-values).<br>
+	 * {@code Example: 'dbFieldName = :jsonName[string] AND dbId = :id[long] OR otherDbField IS NOT NULL AND anotherDbField IS NULL'}<br>
+	 * - When using Enums you have to specify the type of the Enum to cast to
+	 * preceded by a '~'.<br>
+	 * {@code Example: 'dbEnumField = :jsonField[~MyEnumClass]'}<br>
+	 * <p>
+	 * - Term operators are: >, <, >=, <=, = or ==, <> or != and LIKE (which
+	 * automatically adds the wildcards like %yourvalue% before going to the
+	 * database).<br>
+	 * - Every term may be optional when you precede the DB-field-name with a
+	 * '?'.<br>
+	 * {@code Example: '?dbFieldName = :jsonName[string] AND dbId = :id[long]' requested with an empty 'jsonName' will result in 'dbId = :id[long]'}
+	 * Everything is case-insensitive except for the parameters of course.
+	 *
+	 * @param query a string that will be parsed constructing your where-clause and
+	 *              all parameter-assignments
+	 * @return itself in order to provide a fluent interface.
+	 */
 	public InterceptorParamBuilder<P, J, E> query(final String query) {
 		this.query = query;
 		return this;