Java tutorial
/* * Copyright (c) 2013-2016 Cinchapi Inc. * * 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 com.cinchapi.concourse.importer.util; import java.io.IOException; import java.util.Collection; import java.util.List; import javax.annotation.Nullable; import org.apache.commons.lang.StringUtils; import com.cinchapi.concourse.importer.Transformer; import com.cinchapi.concourse.util.KeyValue; import com.cinchapi.concourse.util.QuoteAwareStringSplitter; import com.cinchapi.concourse.util.SplitOption; import com.cinchapi.concourse.util.StringBuilderWriter; import com.cinchapi.concourse.util.StringSplitter; import com.cinchapi.concourse.util.Strings; import com.google.common.annotations.VisibleForTesting; import com.google.common.base.Throwables; import com.google.common.collect.Lists; import com.google.gson.stream.JsonWriter; /** * Helper functions to aid in the process of importing data from files or * strings. * * @author Jeff Nelson */ public class Importables { /** * Given a string of {@code lines}, where is line has tokens that are * separated by a {@code delimiter} character, covert each line to a JSON * object and return a single string that contains a JSON array of the * objects. * * @param lines the data to convert * @param resolveKey a key that the * {@link com.cinchapi.concourse.importer.Importer importer} uses * to determine the existing records into which the data should * be imported. The method places the appropriate resolve * instruction in the JSON blob so Concourse Server can perform * the resolution during the import * @param delimiter the delimiter character * @param header the list of header keys. If this list is empty, it is * assumed that the first line of {@code lines} contains the * header * @param transformer the {@link Transformer} that is used to potentially * alter key/value pairs before import * @return a JSON string that contains the raw {@code lines} in the new * format * @throws IndexOutOfBoundsException if a line has more columns that there * are header keys; it is fine for a line to have fewer columns * that header keys */ public static String delimitedStringToJsonArray(String lines, @Nullable String resolveKey, char delimiter, List<String> header, @Nullable Transformer transformer) { header = header == null ? Lists.<String>newArrayList() : header; StringSplitter it = createStringSplitter(lines, delimiter); StringBuilderWriter out = new StringBuilderWriter(); int hcount = 0; try (JsonWriter json = new JsonWriter(out)) { json.beginArray(); while (it.hasNext()) { if (header.isEmpty()) { do { header.add(it.next()); } while (it.hasNext() && !it.atEndOfLine()); } else { json.beginObject(); hcount = 0; do { String key = header.get(hcount); ++hcount; String value = it.next(); Object jvalue = value; KeyValue<String, Object> kv = transformer == null ? null : transformer.transform(key, value); if (kv != null) { key = kv.getKey(); jvalue = kv.getValue(); value = jvalue.toString(); } // TODO process resolve key json.name(key); if (StringUtils.isBlank(value)) { json.nullValue(); } else if (jvalue instanceof Collection) { json.beginArray(); for (Object jitem : (Collection<?>) jvalue) { writeJsonValue(json, jitem.toString()); } json.endArray(); } else { writeJsonValue(json, value); } } while (it.hasNext() && !it.atEndOfLine()); json.endObject(); } } json.endArray(); return out.toString(); } catch (IOException e) { throw Throwables.propagate(e); } } /** * Given a {@code line} that is separated by a {@code delimiter} character, * convert each token to fields within a single JSON object. * * @param line the data to convert * @param resolveKey a key that the * {@link com.cinchapi.concourse.importer.Importer importer} uses * to determine the existing records into which the data should * be imported. The method places the appropriate resolve * instruction in the JSON blob so Concourse Server can perform * the resolution during the import * @param delimiter the delimiter character * @param header the list of header keys. If this list is empty, this method * will return {@code null} and instead place the tokens from the * {@code line} into the list * @param transformer the {@link Transformer} that is used to potentially * alter key/value pairs before import * @return a JSON string that contains the raw {@code line} in the new * format or {@code null} if {@code header} is * {@link List#isEmpty() empty} * @throws IndexOutOfBoundsException if the line has more columns that there * are header keys (as long as the number of header keys is > * 0); it is fine for a line to have fewer columns that header * keys */ @Nullable public static String delimitedStringToJsonObject(String line, @Nullable String resolveKey, char delimiter, List<String> header, @Nullable Transformer transformer) { StringBuilder builder = new StringBuilder(); delimitedStringToJsonObject(line, resolveKey, delimiter, header, transformer, builder); return builder.length() == 0 ? null : builder.toString(); } /** * Given a {@code line} that is separated by a {@code delimiter} character, * convert each token to fields within a single JSON object. * <p> * This method does not return anything. It writes the JSON blob to the * provided {@code builder}. * </p> * * @param line the data to convert * @param resolveKey a key that the * {@link com.cinchapi.concourse.importer.Importer importer} uses * to determine the existing records into which the data should * be imported. The method places the appropriate resolve * instruction in the JSON blob so Concourse Server can perform * the resolution during the import * @param delimiter the delimiter character * @param header the list of header keys. If this list is empty, this method * will return {@code null} and instead place the tokens from the * {@code line} into the list * @param transformer the {@link Transformer} that is used to potentially * alter key/value pairs before import * @param builder the {@link StringBuilder} where the JSON blob should be * written * @throws IndexOutOfBoundsException if the line has more columns that there * are header keys (as long as the number of header keys is > * 0); it is fine for a line to have fewer columns that header * keys */ public static void delimitedStringToJsonObject(String line, @Nullable String resolveKey, char delimiter, List<String> header, @Nullable Transformer transformer, StringBuilder builder) { StringSplitter it = createStringSplitter(line, delimiter); if (header.isEmpty()) { while (it.hasNext()) { header.add(it.next()); } } else { int hcount = 0; StringBuilderWriter out = new StringBuilderWriter(builder); try (JsonWriter json = new JsonWriter(out)) { json.beginObject(); while (it.hasNext()) { String key = header.get(hcount); ++hcount; String value = it.next(); Object jvalue = value; KeyValue<String, Object> kv = transformer == null ? null : transformer.transform(key, value); if (kv != null) { key = kv.getKey(); jvalue = kv.getValue(); value = jvalue.toString(); } // TODO process resolve key json.name(key); if (StringUtils.isBlank(value)) { json.nullValue(); } else if (jvalue instanceof Collection) { json.beginArray(); for (Object jitem : (Collection<?>) jvalue) { writeJsonValue(json, jitem.toString()); } json.endArray(); } else { writeJsonValue(json, value); } } json.endObject(); } catch (IOException e) { throw Throwables.propagate(e); } } } /** * Intelligently write the appropriate JSON representation for {@code value} * to {@code out}. * * @param out the {@link JsonWriter} to use for writing * @param value the value to write * @throws IOException */ @VisibleForTesting protected static void writeJsonValue(JsonWriter out, String value) throws IOException { Object parsed; if ((parsed = Strings.tryParseNumberStrict(value)) != null) { out.value((Number) parsed); } else if ((parsed = Strings.tryParseBoolean(value)) != null) { out.value((boolean) parsed); } else { value = Strings.ensureWithinQuotes(value); value = Strings.escapeInner(value, value.charAt(0), '\n'); out.jsonValue(value); } } /** * Return a {@link StringSplitter} for {@code string} and {@code delimiter} * with all the appropriate {@link SplitOption options}. * * @param string the string over which to split * @param delimiter the delimiter on which to split * @return an appropriately configured {@link StringSplitter} */ private static StringSplitter createStringSplitter(String string, char delimiter) { return new QuoteAwareStringSplitter(string, delimiter, SplitOption.TRIM_WHITESPACE, SplitOption.SPLIT_ON_NEWLINE); } }