server/protocols/webadmin/webadmin-core/src/main/java/org/apache/james/webadmin/utils/JsonTransformer.java

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 * regarding copyright ownership.  The ASF licenses this file   *
 * to you under the Apache License, Version 2.0 (the            *
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package org.apache.james.webadmin.utils;

import java.text.SimpleDateFormat;
import java.time.ZoneId;
import java.util.Collection;
import java.util.Set;
import java.util.TimeZone;
import java.util.stream.Collectors;

import javax.inject.Inject;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.Module;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.datatype.guava.GuavaModule;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.google.common.collect.ImmutableSet;

import spark.ResponseTransformer;

public class JsonTransformer implements ResponseTransformer {

    private final ObjectMapper objectMapper;

    public JsonTransformer(JsonTransformerModule... modules) {
        this(ImmutableSet.copyOf(modules));
    }

    @Inject
    public JsonTransformer(Set<JsonTransformerModule> jsonTransformerModules) {
        this(jsonTransformerModules
            .stream()
            .map(JsonTransformerModule::asJacksonModule)
            .collect(Collectors.toList()));
    }

    private JsonTransformer(Collection<Module> modules) {
        objectMapper = new ObjectMapper()
            .configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false)
            .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
            .registerModule(new Jdk8Module())
            .registerModule(new JavaTimeModule())
            .registerModule(new GuavaModule())
            .registerModules(modules);
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ"));
        objectMapper.setTimeZone(TimeZone.getTimeZone(ZoneId.of("UTC")));
    }

    @Override
    public String render(Object o) throws JsonProcessingException {
        return objectMapper.writeValueAsString(o);
    }
}