com.workday.autoparse.json.context.JsonParserSettingsBuilder Maven / Gradle / Ivy

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A java library built specifically for Android that uses code generation to parse JSON into custom objects in your project.
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/*
 * Copyright 2016 Workday, Inc.
 *
 * This software is available under the MIT license.
 * Please see the LICENSE.txt file in this project.
 */

package com.workday.autoparse.json.context;

import com.workday.autoparse.json.annotations.JsonObject;
import com.workday.autoparse.json.annotations.JsonParserPartition;
import com.workday.autoparse.json.parser.JsonObjectParser;
import com.workday.autoparse.json.parser.JsonObjectParserTable;
import com.workday.autoparse.json.updater.InstanceUpdaterTable;
import com.workday.meta.ConcreteTypeNames;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * @author nathan.taylor
 * @since 2014-10-29.
 */
public class JsonParserSettingsBuilder {

    public static final String DEFAULT_INSTANCE_UPDATER_PACKAGE =
            InstanceUpdaterTable.class.getPackage().getName();
    public static final String DEFAULT_OBJECT_PARSER_PACKAGE =
            JsonObjectParserTable.class.getPackage().getName();
    private String discriminationName;
    private JsonObjectParser unknownObjectParser;
    private Class unknownObjectClass;
    private List partitionPackages = new ArrayList<>();

    public JsonParserSettingsBuilder withDiscriminationName(String discriminationName) {
        this.discriminationName = discriminationName;
        return this;
    }

    public  JsonParserSettingsBuilder withUnknownObjectParser(JsonObjectParser
                                                                         unknownObjectParser,
                                                                 Class unknownObjectType) {
        this.unknownObjectParser = unknownObjectParser;
        this.unknownObjectClass = unknownObjectType;
        return this;
    }

    /**
     * Indicate which partitions the {@link JsonParserSettings} should use. If no partitions are
     * indicated, the default partition is assumed. To include explicit partitions and the default
     * partition, include {@link #DEFAULT_INSTANCE_UPDATER_PACKAGE} in the list.
     * 
     * When the {@link JsonParserSettings} instance is created, a validation is performed to ensure
     * that there are no name collisions (multiple classes mapping to the same discrimination name)
     * among the partitions. If there are, an {@link IllegalArgumentException} is thrown.
     *
     * @param partitionPackages The fully qualified names of the packages that hold the partitions.
     * These are packages annotated with {@literal@}{@link JsonParserPartition}.
     *
     * @return This JsonParserSettingsBuilder.
     */
    public JsonParserSettingsBuilder withPartitions(String... partitionPackages) {
        this.partitionPackages.addAll(Arrays.asList(partitionPackages));
        return this;
    }

    /**
     * You can use this method to set the unknown object parser if that parser was generated by
     * Autoparse.
     *
     * @param unknownObjectClass The type of object that will be created when an unknown object is
     * encountered in the JSON document. This class must be annotated with {@literal@}{@link
     * JsonObject}.
     */
    public JsonParserSettingsBuilder withUnknownObjectClass(Class unknownObjectClass) {
        this.unknownObjectClass = unknownObjectClass;
        String parserName = ConcreteTypeNames.constructClassName(unknownObjectClass,
                                                                 GeneratedClassNames.PARSER_SUFFIX);
        try {
            @SuppressWarnings("unchecked")
            Class> parserClass =
                    (Class>) Class.forName(parserName);
            Object instance = parserClass.getDeclaredField("INSTANCE").get(null);
            if (!(instance instanceof JsonObjectParser)) {
                throw new RuntimeException(
                        "Public constant INSTANCE must be of type JsonObjectParser");
            }
            unknownObjectParser = (JsonObjectParser) instance;
        } catch (ClassNotFoundException e) {
            throw new RuntimeException("No JsonObjectParser found for class of type "
                                               + unknownObjectClass, e);
        } catch (NoSuchFieldException e) {
            throw new RuntimeException("Parser does not have static field named INSTANCE.", e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException("Field INSTANCE is not public.", e);
        } catch (NullPointerException e) {
            throw new RuntimeException("Field INSTANCE is not static", e);
        }
        return this;
    }

    public JsonParserSettings build() {
        return new JsonParserSettings(discriminationName,
                                      unknownObjectParser,
                                      unknownObjectClass,
                                      partitionPackages);
    }
}