JsonBuilder.java

/*
 * Copyright 2014 Rick Grashel.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.sourceforge.stripes.action;

import com.fasterxml.jackson.annotation.JsonFilter;
import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ser.FilterProvider;
import com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter;
import com.fasterxml.jackson.databind.ser.impl.SimpleFilterProvider;
import java.io.Writer;

/**
 * This class converts an object to JSON. This implementation initially
 * uses Jackson.  In the future, this will be a pluggable implementation for
 * building JSON.
 *
 * @author Rick Grashel
 */
public class JsonBuilder extends ObjectOutputBuilder<JsonBuilder> {

    /**
     * Constructs a new JsonBuilder object which is used to convert the passed
     * Java object into JSON.  The optional list of properties will be excluded
     * from serialization.
     *
     * @param root - Root object to convert to JSON
     * @param propertiesToExclude - List of property names to exclude from serialization
     * marshaling
     */
    public JsonBuilder(Object root, String... propertiesToExclude) {
        super(root);
        addPropertyExclusion(propertiesToExclude);
    }

    @Override
    public void build(Writer writer) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        mapper.setSerializationInclusion(Include.NON_NULL);
        mapper.addMixInAnnotations(Object.class, DynamicPropertyFilterMixin.class);
        FilterProvider filterProvider = new SimpleFilterProvider()
                .addFilter("dynamicPropertyFilter",
                        SimpleBeanPropertyFilter.serializeAllExcept(getExcludedProperties()));
        mapper.writer(filterProvider).writeValue(writer, getRootObject());
    }

    /**
     * This is an empty class which is used to do dynamic exclusion of property
     * names from serialization.
     */
    @JsonFilter("dynamicPropertyFilter")
    class DynamicPropertyFilterMixin {
    }

}