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Groovy example source code file (JsonOutput.groovy)

This example Groovy source code file (JsonOutput.groovy) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

close_bracket, close_bracket, close_curly, comma, float, iterator, json, json, jsonoutput, open_bracket, string, string, stringbuilder, stringbuilder

The Groovy JsonOutput.groovy source code

/*
 * Copyright 2003-2011 the original author or authors.
 *
 * 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 groovy.json

import static JsonTokenType.*

/**
 * Class responsible for the actual String serialization of the possible values of a JSON structure.
 * This class can also be used as a category, so as to add <code>toJson() methods to various types.
 *
 * @author Guillaume Laforge
 * @since 1.8.0
 */
class JsonOutput {

    /**
     * @return "true" or "false" for a boolean value
     */
    static String toJson(Boolean bool) {
        bool.toString()
    }

    /**
     * @return a string representation for a number
     * @throws JsonException if the number is infinite or not a number.
     */
    static String toJson(Number n) {
        if (n.class in [Double, Float] && (n.isInfinite() || n.isNaN())) {
            throw new JsonException("Number ${n} can't be serialized as JSON: infinite or NaN are not allowed in JSON.")
        }
        n.toString()
    }

    /**
     * @return a properly encoded string with escape sequences
     */
    static String toJson(String s) {
        if (!s) {
            '""'
        } else {
            def result = new StringBuilder('"')

            s.each { c ->
                switch (c) {
                    case '"':
                        result.append('\\"')
                        break
                    case '\\':
                        result.append('\\\\')
                        break
                    case '/':
                        result.append('\\/')
                        break
                    case '\b':
                        result.append('\\b')
                        break
                    case '\f':
                        result.append('\\f')
                        break
                    case '\n':
                        result.append('\\n')
                        break
                    case '\r':
                        result.append('\\r')
                        break
                    case '\t':
                        result.append('\\t')
                        break
                    default:
                        // control chars below space
                        if (c < ' ') {
                            result.append('\\u' + Integer.toHexString((int)c).padLeft(4, '0'))
                        } else {
                            result.append(c)
                        }
                }
            }

            result.append('"')
            result.toString()
        }
    }

    /**
     * @return an object representation of a closure
     */
    static String toJson(Closure closure) {
        toJson(JsonDelegate.cloneDelegateAndGetContent(closure))
    }

    /**
     * @return "null" for a null value, or a JSON array representation for a collection, array, iterator or enumeration.
     */
    static String toJson(object) {
        if (object == null) {
            "null"
        } else if (object instanceof Collection ||
                object.class.isArray() ||
                object instanceof Iterator ||
                object instanceof Enumeration) {
            "[" + object.collect { toJson(it) }.join(',') + "]"
        } else if (object instanceof Enum) {
            '"' + object.name() + '"'
        } else {
            def properties = object.properties
            properties.remove('class')
            properties.remove('declaringClass')
            properties.remove('metaClass')
            toJson(properties)
        }
    }

    /**
     * @return a JSON object representation for a map
     */
    static String toJson(Map m) {
        "{" + m.collect { k, v -> toJson(k.toString()) + ':' + toJson(v) }.join(',') + "}"
    }

    /**
     * Pretty print a JSON payload
     * 
     * @param jsonPayload
     * @return
     */
    static String prettyPrint(String jsonPayload) {
        int indent = 0
        def output = new StringBuilder()
        def lexer = new JsonLexer(new StringReader(jsonPayload))

        while (lexer.hasNext()) {
            JsonToken token = lexer.next()
            if (token.type == OPEN_CURLY) {
                indent += 4
                output.append('{\n')
                output.append(' ' * indent)
            } else if (token.type == CLOSE_CURLY) {
                indent -= 4
                output.append('\n')
                output.append(' ' * indent)
                output.append('}')
            } else if(token.type == OPEN_BRACKET) {
                indent += 4
                output.append('[\n')
                output.append(' ' * indent)
            } else if(token.type == CLOSE_BRACKET) {
                indent -= 4
                output.append('\n')
                output.append(' ' * indent)
                output.append(']')
            } else if (token.type == COMMA) {
                output.append(',\n')
                output.append(' ' * indent)
            } else if (token.type == COLON) {
                output.append(': ')
            } else {
                output.append(token.text)
            }
        }

        return output.toString()
    }
}

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