Play Framework/Scala example source code file (Json.java)

This example Play Framework source code file (Json.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Play Framework (and Scala) source code examples by using tags.

All credit for the original source code belongs to Play Framework; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Play Framework tags/keywords

a, defaultprettyprinter, ioexception, jsongenerator, jsonnode, lib, library, objectmapper, objectnode, play, play framework, runtimeexception, string, stringwriter

The Json.java Play Framework example source code

/*
 * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
 */
package play.libs;

import java.io.IOException;
import java.io.StringWriter;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator.Feature;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;

/**
 * Helper functions to handle JsonNode values.
 */
public class Json {
    private static final ObjectMapper defaultObjectMapper = new ObjectMapper();
    private static volatile ObjectMapper objectMapper = null;

    /**
     * Get the ObjectMapper used to serialize and deserialize objects to and from JSON values.
     *
     * This can be set to a custom implementation using Json.setObjectMapper.
     *
     * @return the ObjectMapper currently being used
     */
    public static ObjectMapper mapper() {
        if (objectMapper == null) {
            return defaultObjectMapper;
        } else {
            return objectMapper;
        }
    }

    private static String generateJson(Object o, boolean prettyPrint, boolean escapeNonASCII) {
        try {
            StringWriter sw = new StringWriter();
            JsonGenerator jgen = new JsonFactory(mapper()).createGenerator(sw);
            if (prettyPrint) {
                jgen.setPrettyPrinter(new DefaultPrettyPrinter());
            }
            if (escapeNonASCII) {
                jgen.enable(Feature.ESCAPE_NON_ASCII);
            }
            mapper().writeValue(jgen, o);
            sw.flush();
            return sw.toString();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Convert an object to JsonNode.
     *
     * @param data Value to convert in Json.
     */
    public static JsonNode toJson(final Object data) {
        try {
            return mapper().valueToTree(data);
        } catch(Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Convert a JsonNode to a Java value
     *
     * @param json Json value to convert.
     * @param clazz Expected Java value type.
     */
    public static <A> A fromJson(JsonNode json, Class<A> clazz) {
        try {
            return mapper().treeToValue(json, clazz);
        } catch(Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Creates a new empty ObjectNode.
     */
    public static ObjectNode newObject() {
        return mapper().createObjectNode();
    }

    /**
     * Creates a new empty ArrayNode.
     */
    public static ArrayNode newArray() {
        return mapper().createArrayNode();
    }

    /**
     * Convert a JsonNode to its string representation.
     */
    public static String stringify(JsonNode json) {
        return generateJson(json, false, false);
    }

    /**
     * Convert a JsonNode to its string representation, escaping non-ascii characters.
     */
    public static String asciiStringify(JsonNode json) {
        return generateJson(json, false, true);
    }

    /**
     * Convert a JsonNode to its string representation.
     */
    public static String prettyPrint(JsonNode json) {
        return generateJson(json, true, false);
    }

    /**
     * Parse a String representing a json, and return it as a JsonNode.
     */
    public static JsonNode parse(String src) {
        try {
            return mapper().readTree(src);
        } catch(Throwable t) {
            throw new RuntimeException(t);
        }
    }

    /**
     * Parse a InputStream representing a json, and return it as a JsonNode.
     */
    public static JsonNode parse(java.io.InputStream src) {
        try {
            return mapper().readTree(src);
        } catch(Throwable t) {
            throw new RuntimeException(t);
        }
    }

    /**
     * Parse a byte array representing a json, and return it as a JsonNode.
     */
    public static JsonNode parse(byte[] src) {
        try {
            return mapper().readTree(src);
        } catch(Throwable t) {
            throw new RuntimeException(t);
        }
    }

    /**
     * Inject the object mapper to use.
     *
     * This is intended to be used when Play starts up.  By default, Play will inject its own object mapper here,
     * but this mapper can be overridden either by a custom plugin or from Global.onStart.
     */
    public static void setObjectMapper(ObjectMapper mapper) {
        objectMapper = mapper;
    }

}