我一直在尝试使用openCSV读取多个csv文件（大约20 MB），但是到目前为止，它的速度很慢。我试图读取我正在设计的4个正在加载到堆中的csv文件。我想知道，是否还有其他方法可以在更短的时间内完成。
private Heap<VOMovingViolations> datosHeap;
public void loadMovingViolations()
{
Runtime garbage = Runtime.getRuntime();
garbage.gc();
try
{
FileReader fileReaderMes1 = new FileReader(FECHAS[0]);
FileReader fileReaderMes2 = new FileReader(FECHAS[1]);
FileReader fileReaderMes3 = new FileReader(FECHAS[2]);
FileReader fileReaderMes4 = new FileReader(FECHAS[3]);
CSVReader enero = new CSVReaderBuilder(fileReaderMes1).withSkipLines(1).build();
CSVReader febrero = new CSVReaderBuilder(fileReaderMes2).withSkipLines(1).build();
CSVReader marzo = new CSVReaderBuilder(fileReaderMes3).withSkipLines(1).build();
CSVReader abril = new CSVReaderBuilder(fileReaderMes4).withSkipLines(1).build();
String[] row;
while((row = enero.readNext()) != null)
{
int objectId = Integer.parseInt(row[0]);
int totalPaid = (int)Double.parseDouble(row[9]);
short fi = Short.parseShort(row[8]);
short penalty1 = Short.parseShort(row[10]);
datosHeap.insert(new VOMovingViolations(objectId, totalPaid, fi, row[2], row[13],
row[12],row[14], row[15], row[4], row[3], penalty1));
}
while((row = febrero.readNext()) != null)
{
int objectId = Integer.parseInt(row[0]);
int totalPaid = (int)Double.parseDouble(row[9]);
short fi = Short.parseShort(row[8]);
short penalty1 = Short.parseShort(row[10]);
datosHeap.insert(new VOMovingViolations(objectId, totalPaid, fi, row[2], row[13],
row[12],row[14], row[15], row[4], row[3], penalty1));
}
while((row = marzo.readNext()) != null)
{
int objectId = Integer.parseInt(row[0]);
int totalPaid = (int)Double.parseDouble(row[9]);
short fi = Short.parseShort(row[8]);
short penalty1 = Short.parseShort(row[10]);
datosHeap.insert(new VOMovingViolations(objectId, totalPaid, fi, row[2], row[13],
row[12],row[14], row[15], row[4], row[3], penalty1));
}
while((row = abril.readNext()) != null)
{
int objectId = Integer.parseInt(row[0]);
int totalPaid = (int)Double.parseDouble(row[9]);
short fi = Short.parseShort(row[8]);
short penalty1 = Short.parseShort(row[10]);
datosHeap.insert(new VOMovingViolations(objectId, totalPaid, fi, row[2], row[13],
row[12],row[14], row[15], row[4], row[3], penalty1));
}
}
catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
如果有人可以给我任何帮助或想法，我将不胜感激。
答案 0 :(得分：3)
读取20 MB CSV文件并实例化每行一个对象，所花费的总时间少于 1秒。
您没有定义术语“慢”。所以我做了一个实验，一个随意的基准测试。
首先，我们创建一个20 MB的文件，包含40,000 Person个记录。每个Person都具有法文的名字和姓氏，UUID和一些任意文字作为说明。数据在CSV的UTF-8文件中被分为四列。我使用Apache Commons CSV库进行读写。
第二，读取该写入文件。每行数据都被读取到内存中，然后用于实例化和收集Person对象。
读取此文件并实例化每一行的Person对象花费的总时间不到一秒。每行大约需要20K nanoseconds。实际上，这包括读取文件两次，因为我们进行了一次扫描以计算数据的行数以设置所收集实例的初始容量。另外，我们将输入的十六进制字符串解析为UUID的128位值，因此我们花了一些时间在数据处理上（不仅仅是读取）。
这里是Person类。
package work.basil.example;
import java.util.UUID;
public class Person
{
// Static
static public String LOREM_IPSUM = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
// Member variables.
public String givenName, surname, description;
public UUID id;
public Person ( String givenName , String surname , UUID id , String description)
{
this.givenName = givenName;
this.surname = surname;
this.id = id;
this.description = description ;
}
@Override
public String toString ()
{
return "Person{ " +
"givenName='" + givenName + '\'' +
" | surname='" + surname + '\'' +
" | id='" + id + '\'' +
" }";
}
}
这是编写并读取20 MB文件的完整应用程序。请研究和批评，因为我对此轻描淡写。我没有仔细检查我的工作。
您将找到一个write方法和一个read方法。 main方法同时调用和跟踪时间。
package work.basil.example;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;
import org.apache.commons.csv.CSVRecord;
import java.io.BufferedReader;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.Duration;
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.ThreadLocalRandom;
public class CsvSpeed
{
public List < Person > read ( Path path )
{
// TODO: Add a check for valid file existing.
List < Person > list = List.of(); // Default to empty list.
try
{
// Prepare list.
int initialCapacity = ( int ) Files.lines( path ).count();
list = new ArrayList <>( initialCapacity );
// Read CSV file. For each row, instantiate and collect `DailyProduct`.
BufferedReader reader = Files.newBufferedReader( path );
Iterable < CSVRecord > records = CSVFormat.RFC4180.withFirstRecordAsHeader().parse( reader );
for ( CSVRecord record : records )
{
String givenName = record.get( "givenName" );
String surname = record.get( "surname" );
UUID id = UUID.fromString( record.get( "id" ) );
String description = record.get( "description" );
// Instantiate `Person` object, and collect it.
Person person = new Person( givenName , surname , id , description );
list.add( person );
}
} catch ( IOException e )
{
e.printStackTrace();
}
return list;
}
public void write ( final Path path )
{
ThreadLocalRandom random = ThreadLocalRandom.current();
try ( final CSVPrinter printer = CSVFormat.RFC4180.withHeader( "givenName" , "surname" , "id" , "description" ).print( path , StandardCharsets.UTF_8 ) ; )
{
int limit = 40_000; // 40_000 yields about 20 MB of data.
List < String > givenNames = List.of( "Adrien" , "Aimon" , "Alerion" , "Alexis" , "Alezan" , "Ancil" , "Andre" , "Antoine" , "Archard" , "Aurélien" , "Averill" , "Baptiste" , "Barnard" , "Bartelemy" , "Bastien" , "Baylee" , "Beale" , "Beau" , "Beaumont" , "Beauregard" , "Bellamy" , "Berger" , "Blaize" , "Blondel" , "Boyce" , "Bruce" , "Brunelle" , "Brys" , "Burcet" , "Burnell" , "Burrell" , "Byron" , "Canaan" , "Carden" , "Carolas" , "Cavell" , "Chace" , "Chanler" , "Chante" , "Chappel" , "Charles" , "Chasen" , "Chason" , "Chemin" , "Chene" , "Cher" , "Chevalier" , "Cheyne" , "Clément" , "Clemence" , "Corbin" , "Coty" , "Cygne" , "Damien" , "Dandre" , "Dariel" , "Darl" , "Dauphine" , "Davet" , "Dax" , "Dean" , "Delice" , "Delmon" , "Destin" , "Dominique" , "Donatien" , "Duke" , "Eliott" , "Elroy" , "Enzo" , "Erwan" , "Etalon" , "Ethan" , "Fabron" , "Ferrand" , "Filberte" , "Florent" , "Florian" , "Fontaine" , "Forest" , "Fortune" , "Franchot" , "Francois" , "Fraser" , "Frayne" , "Gaëtan" , "Gabin" , "Gage" , "Gaige" , "Garland" , "Garner" , "Gaston" , "Gauge" , "Gaylord" , "Germain" , "Germaine" , "German" , "Gervaise" , "Giles" , "Gilles" , "Gitan" , "Grosvener" , "Guifford" , "Guion" , "Guy" , "Guzman" , "Henri" , "Holland" , "Hugo" , "Hugues" , "Hyacinthe" , "Jérémy" , "Jacquan" , "Jacques" , "Jacquez" , "Janvier" , "Jardan" , "Jay" , "Jaye" , "Jehan" , "Jemond" , "Jocquez" , "Jonathan" , "Jules" , "Julien" , "Justus" , "Karoly" , "Lado" , "Lafayette" , "Lamond" , "Lancelin" , "Landis" , "Landry" , "Laron" , "Larrimore" , "Laurent" , "LaValle" , "Leandre" , "Leggett" , "Leonce" , "Leron" , "Leverett" , "Lilian" , "Loïc" , "Lorenzo" , "Louis" , "Lowell" , "Luc" , "Lucien" , "Lukas" , "Macaire" , "Mace" , "Mahieu" , "Maison" , "Malleville" , "Manneville" , "Mantel" , "Marc" , "Marcel" , "Marion" , "Marius" , "Markez" , "Markis" , "Marmion" , "Marquis" , "Marquise" , "Marshall" , "Martial" , "Maslin" , "Mason" , "Matheo" , "Mathias" , "Mathys" , "Matthieu" , "Maxence" , "Mayson" , "Mehdi" , "Merle" , "Merville" , "Montague" , "Montaigu" , "Monte" , "Montgomery" , "Montreal" , "Montrel" , "Moore" , "Morel" , "Mortimer" , "Nerville" , "Neuveville" , "Nicolas" , "Noë" , "Noah" , "Noe" , "Norman" , "Norville" , "Nouel" , "Olivier" , "Onfroi" , "Paien" , "Parfait" , "Parnell" , "Pascal" , "Patrice" , "Paul" , "Peppin" , "Percival" , "Percy" , "Pernell" , "Peverell" , "Philipe" , "Pierpont" , "Pierre" , "Pomeroy" , "Prewitt" , "Purvis" , "Quennell" , "Quentin" , "Quincey" , "Quincy" , "Quintin" , "Rémi" , "Rafaelle" , "Ranger" , "Raoul" , "Raphaël" , "Rapier" , "Rawlins" , "Ray" , "Raynard" , "Remi" , "René" , "Renard" , "Rene" , "Reule" , "Reynard" , "Robin" , "Romain" , "Rondel" , "Roy" , "Royal" , "Ruff" , "Rush" , "Russel" , "Rustin" , "Sabastien" , "Sacha" , "Salomon" , "Samuel" , "Satordi" , "Saville" , "Scoville" , "Sebastien" , "Sennett" , "Severin" , "Shant" , "Shantae" , "Sidney" , "Siffre" , "Simeon" , "Simon" , "Sinclair" , "Sofiane" , "Somer" , "Stephane" , "Sully" , "Sydney" , "Sylvain" , "Talbot" , "Talon" , "Telford" , "Tempest" , "Teppo" , "Théo" , "Thayer" , "Thibault" , "Thibaut" , "Thiery" , "Tiennan" , "Tiennot" , "Titouan" , "Toussaint" , "Travaris" , "Tyson" , "Urson" , "Vachel" , "Valentin" , "Valere" , "Vallis" , "Verdun" , "Victoir" , "Victor" , "Waltier" , "William" , "Wyatt" , "Yanis" , "Yann" , "Yves" , "Yvon" , "Zosime" , "Abrial" , "Abrielle" , "Abril" , "Adele" , "Alair" , "Alerion" , "Amee" , "Angelique" , "Annette" , "Antonella" , "Arian" , "Ariane" , "Armandina" , "Aubree" , "Aubrielle" , "Audra" , "Avril" , "Bella" , "Berneta" , "Bette" , "Blaise" , "Blanche" , "Blasa" , "Bonte" , "Brie" , "Brienne" , "Brigit" , "Cachay" , "Calice" , "Camille" , "Camylle" , "Caprice" , "Caressa" , "Caroline" , "Catin" , "Celesta" , "Celeste" , "Cera" , "Cerise" , "Chablis" , "Chalice" , "Chambray" , "Champagne" , "Chandell" , "Chaney" , "Chantal" , "Chante" , "Chanterelle" , "Chantile" , "Chantilly" , "Chantrice" , "Charla" , "Charlotte" , "Charmane" , "Chaton" , "Chemin" , "Chenetta" , "Cher" , "Chere" , "Cheri" , "Cheryl" , "Christine" , "Cidney" , "Cinderella" , "Claire" , "Claudette" , "Colette" , "Cordelle" , "Cydnee" , "Daeja" , "Daija" , "Daja" , "Damzel" , "Darelle" , "Darlene" , "Darselle" , "Dejanelle" , "Deleena" , "Delice" , "Demeri" , "Deni" , "Denise" , "Desgracias" , "Desire" , "Desiree" , "Destanee" , "Destiny" , "Dior" , "Domanique" , "Dominique" , "Elaina" , "Elaine" , "Elayna" , "Elise" , "Eloisa" , "Elyse" , "Emeline" , "Emmaline" , "Emmeline" , "Estella" , "Estrella" , "Etiennette" , "Evette" , "Fabienne" , "Fabrienne" , "Fanchon" , "Fancy" , "Fawna" , "Fayana" , "Fayette" , "Fifi" , "Fleur" , "Fleurette" , "Fontanna" , "Fosette" , "Francine" , "Frederique" , "Gabriel" , "Gabriele" , "Gabrielle" , "Gaby" , "Garcelle" , "Gena" , "Genie" , "Georgette" , "Germaine" , "Gervaise" , "Gitana" , "Harriet" , "Heloisa" , "Holland" , "Honnetta" , "Isabelle" , "Ivette" , "Ivonne" , "Jacqueena" , "Jacquetta" , "Jacquiline" , "Jacyline" , "Jaime" , "Jakqueline" , "Janeen" , "Janelly" , "Janina" , "Janiqua" , "Janique" , "Jannnelle" , "Jaquita" , "Jardena" , "Jeanetta" , "Jermaine" , "Jessamine" , "Jewel" , "Jewell" , "Joli" , "Jolie" , "Josephine" , "Jozephine" , "Julieta" , "Karessa" , "Karmaine" , "Klara" , "Laine" , "Lanelle" , "Laramie" , "Layne" , "Layney" , "Leala" , "Leonette" , "Lissette" , "Lizette" , "Lourdes" , "Lucienne" , "Ly" , "Lyla" , "Lysette" , "Madelaine" , "Malerie" , "Manette" , "Marais" , "Marcelle" , "Marché" , "Mardi" , "Margo" , "Marguerite" , "Marie" , "Marie Claude" , "Marie Frances" , "Marie Joelle" , "Marie Pascale" , "Marie Sophie" , "Marjolaine" , "Marquise" , "Marvella" , "Mathieu" , "Matisse" , "Maurelle" , "Maurissa" , "Mavis" , "Melisande" , "Michelle" , "Miette" , "Mignon" , "Mimi" , "Mirya" , "Monet" , "Moniqua" , "Monteen" , "Musetta" , "Myrlie" , "Nadeen" , "Nadia" , "Nadiyah" , "Naeva" , "Nanon" , "Natalle" , "Naudia" , "Nettie" , "Nicholas" , "Nicki" , "Nicky" , "Nicole" , "Nicolette" , "Nicolina" , "Nicolle" , "Nikolette" , "Ninette" , "Ninon" , "Noelle" , "Nycole" , "Odelette" , "Opaline" , "Orane" , "Orva" , "Page" , "Parisa" , "Parnel" , "Parris" , "Patrice" , "Peridot" , "Pippi" , "Prairie" , "Rachele" , "Rachelle" , "Racquel" , "Raphaelle" , "Raquelle" , "Remi" , "Renée" , "Renea" , "Renelle" , "Renita" , "Risette" , "Rochelle" , "Romy" , "Rosabel" , "Rosiclara" , "Ruba" , "Russhell" , "Saleena" , "Salina" , "Satin" , "Sedona" , "Serene" , "Shandelle" , "Shanta" , "Shante" , "Shariah" , "Sharita" , "Sharleen" , "Sheree" , "Shereen" , "Sherell" , "Sherice" , "Sherry" , "Sidnee" , "Sidney" , "Sidnie" , "Sidonie" , "Sinclaire" , "Solange" , "Solen" , "Sorrel" , "Suzette" , "Sydnee" , "Sydney" , "Tallis" , "Tempest" , "Toinette" , "Turquoise" , "Veronique" , "Vignette" , "Villette" , "Violeta" , "Virginie" , "Voleta" , "Vonny" );
List < String > surnames = List.of( "Arceneau" , "Aucoin" , "Babin" , "Babineaux" , "Benoit" , "Bergeron" , "Bernard" , "Bertrand" , "Bessette" , "Blanc" , "Blanchard" , "Bonnet" , "Boucher" , "Bourg" , "Bourque" , "Boutin" , "Bouvier" , "Braud" , "Broussard" , "Brun" , "Chevalier" , "David" , "Depaul" , "Desmarais" , "Disney" , "Dubois" , "Dupont" , "Dupuis" , "Durand" , "Fortescue" , "Fournier" , "Garnier" , "Gaudet" , "Gillet" , "Gillette" , "Girard" , "Gravois" , "Grosvenor" , "Lambert" , "Landry" , "Laroche" , "Laurent" , "Lefevre" , "Leroy" , "Leveque" , "Lisle" , "Martin" , "Michel" , "Molyneux" , "Moreau" , "Morel" , "Neville" , "Pelletier" , "Petit" , "Prideux" , "Renard" , "Richard" , "Robert" , "Rousseau" , "Roux" , "Rufus" , "Simon" , "Thomas" );
for ( int i = 1 ; i <= limit ; i++ )
{
String givenName = givenNames.get( random.nextInt( 0 , givenNames.size() ) );
String surname = surnames.get( random.nextInt( 0 , surnames.size() ) );
UUID id = UUID.randomUUID();
String description = Person.LOREM_IPSUM;
printer.printRecord( givenName , surname , id , description );
}
} catch ( IOException e )
{
e.printStackTrace();
}
}
public static void main ( final String[] args )
{
// Launch the app.
CsvSpeed app = new CsvSpeed();
// Write.
String when = Instant.now().truncatedTo( ChronoUnit.SECONDS ).toString().replace( ":" , "•" );
Path pathOutput = Paths.get( "/Users/basilbourque/persons.csv" );
app.write( pathOutput );
System.out.println( "Writing file: " + pathOutput );
// Read.
long start = System.nanoTime();
Path pathInput = Paths.get( "/Users/basilbourque/persons.csv" );
List < Person > list = app.read( pathInput );
long stop = System.nanoTime();
// Time.
long elapsed = ( stop - start );
Duration d = Duration.ofNanos( elapsed );
System.out.println( "Reading elapsed: " + d );
System.out.println( "Reading took nanos per row: " + ( elapsed / list.size() ) );
System.out.println( "nanos elapsed: " + elapsed + " | list.size: " + list.size() );
}
}
运行时：
编写文件：/Users/basilbourque/persons.csv
已阅读时间：PT0.857816234S
读取数据每行花费了nanos：21445
经过的Nanos：857816234 | list.size：40000
技术栈：
答案 1 :(得分：2)
除了使用@Basil建议的java.nio外，将FileReader用BufferedReader包裹起来也可以大大提高速度。
FileReader fileReaderMes1 = new BufferedReader( new FileReader(FECHAS[0]));
答案 2 :(得分：2)
在csv-parsers-comparison上，我们可以找到CSV Reader / Writer-s之间的比较。最快的是uniVocity CSV parser。第三是我个人更喜欢的Jackson。通过使用@Basil Bourque很好的示例，我做了一些改动，并使用了Jackson类。读取方法返回MappingIterator，可用于初始化堆对象（请参阅如何向List添加元素）。我没有提供时间详细信息，但您可以自己使用Basil的解决方案和以下解决方案：
import com.fasterxml.jackson.databind.MappingIterator;
import com.fasterxml.jackson.databind.ObjectReader;
import com.fasterxml.jackson.databind.ObjectWriter;
import com.fasterxml.jackson.dataformat.csv.CsvMapper;
import com.fasterxml.jackson.dataformat.csv.CsvSchema;
import java.io.File;
import java.io.FileWriter;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.ThreadLocalRandom;
public class CsvSpeed {
public static void main(String[] args) throws Exception {
File csvFile = new File("./resource/persons.csv").getAbsoluteFile();
CsvSchema schema = CsvSchema.builder()
.addColumn("givenName")
.addColumn("surname")
.addColumn("id")
.addColumn("description")
.build().withHeader();
CsvSpeed csvSpeed = new CsvSpeed();
csvSpeed.write(csvFile, schema);
// Read.
long start = System.nanoTime();
MappingIterator<Person> personMappingIterator = csvSpeed.read(csvFile, schema);
List<Person> persons = new ArrayList<>(40_000);
personMappingIterator.forEachRemaining(persons::add);
long stop = System.nanoTime();
System.out.println(persons.size());
// Time.
long elapsed = (stop - start);
Duration d = Duration.ofNanos(elapsed);
System.out.println("Reading elapsed: " + d);
System.out.println("Reading took nanos per row: " + (elapsed / persons.size()));
System.out.println("nanos elapsed: " + elapsed + " | list.size: " + persons.size());
}
public MappingIterator<Person> read(final File path, CsvSchema schema) throws Exception {
CsvMapper csvMapper = new CsvMapper();
ObjectReader reader = csvMapper.readerFor(Person.class).with(schema);
return reader.readValues(path);
}
public void write(final File path, CsvSchema schema) throws Exception {
ThreadLocalRandom random = ThreadLocalRandom.current();
CsvMapper csvMapper = new CsvMapper();
ObjectWriter writer = csvMapper.writerFor(Person.class).with(schema);
try (FileWriter fileWriter = new FileWriter(path)) {
List<String> givenNames = Arrays.asList("Adrien", "Aimon", "Alerion", "Alexis", "Alezan", "Ancil", "Andre", "Antoine", "Archard", "Aurélien", "Averill", "Baptiste", "Barnard", "Bartelemy", "Bastien", "Baylee", "Beale", "Beau", "Beaumont", "Beauregard", "Bellamy", "Berger", "Blaize", "Blondel", "Boyce", "Bruce", "Brunelle", "Brys", "Burcet", "Burnell", "Burrell", "Byron", "Canaan", "Carden", "Carolas", "Cavell", "Chace", "Chanler", "Chante", "Chappel", "Charles", "Chasen", "Chason", "Chemin", "Chene", "Cher", "Chevalier", "Cheyne", "Clément", "Clemence", "Corbin", "Coty", "Cygne", "Damien", "Dandre", "Dariel", "Darl", "Dauphine", "Davet", "Dax", "Dean", "Delice", "Delmon", "Destin", "Dominique", "Donatien", "Duke", "Eliott", "Elroy", "Enzo", "Erwan", "Etalon", "Ethan", "Fabron", "Ferrand", "Filberte", "Florent", "Florian", "Fontaine", "Forest", "Fortune", "Franchot", "Francois", "Fraser", "Frayne", "Gaëtan", "Gabin", "Gage", "Gaige", "Garland", "Garner", "Gaston", "Gauge", "Gaylord", "Germain", "Germaine", "German", "Gervaise", "Giles", "Gilles", "Gitan", "Grosvener", "Guifford", "Guion", "Guy", "Guzman", "Henri", "Holland", "Hugo", "Hugues", "Hyacinthe", "Jérémy", "Jacquan", "Jacques", "Jacquez", "Janvier", "Jardan", "Jay", "Jaye", "Jehan", "Jemond", "Jocquez", "Jonathan", "Jules", "Julien", "Justus", "Karoly", "Lado", "Lafayette", "Lamond", "Lancelin", "Landis", "Landry", "Laron", "Larrimore", "Laurent", "LaValle", "Leandre", "Leggett", "Leonce", "Leron", "Leverett", "Lilian", "Loïc", "Lorenzo", "Louis", "Lowell", "Luc", "Lucien", "Lukas", "Macaire", "Mace", "Mahieu", "Maison", "Malleville", "Manneville", "Mantel", "Marc", "Marcel", "Marion", "Marius", "Markez", "Markis", "Marmion", "Marquis", "Marquise", "Marshall", "Martial", "Maslin", "Mason", "Matheo", "Mathias", "Mathys", "Matthieu", "Maxence", "Mayson", "Mehdi", "Merle", "Merville", "Montague", "Montaigu", "Monte", "Montgomery", "Montreal", "Montrel", "Moore", "Morel", "Mortimer", "Nerville", "Neuveville", "Nicolas", "Noë", "Noah", "Noe", "Norman", "Norville", "Nouel", "Olivier", "Onfroi", "Paien", "Parfait", "Parnell", "Pascal", "Patrice", "Paul", "Peppin", "Percival", "Percy", "Pernell", "Peverell", "Philipe", "Pierpont", "Pierre", "Pomeroy", "Prewitt", "Purvis", "Quennell", "Quentin", "Quincey", "Quincy", "Quintin", "Rémi", "Rafaelle", "Ranger", "Raoul", "Raphaël", "Rapier", "Rawlins", "Ray", "Raynard", "Remi", "René", "Renard", "Rene", "Reule", "Reynard", "Robin", "Romain", "Rondel", "Roy", "Royal", "Ruff", "Rush", "Russel", "Rustin", "Sabastien", "Sacha", "Salomon", "Samuel", "Satordi", "Saville", "Scoville", "Sebastien", "Sennett", "Severin", "Shant", "Shantae", "Sidney", "Siffre", "Simeon", "Simon", "Sinclair", "Sofiane", "Somer", "Stephane", "Sully", "Sydney", "Sylvain", "Talbot", "Talon", "Telford", "Tempest", "Teppo", "Théo", "Thayer", "Thibault", "Thibaut", "Thiery", "Tiennan", "Tiennot", "Titouan", "Toussaint", "Travaris", "Tyson", "Urson", "Vachel", "Valentin", "Valere", "Vallis", "Verdun", "Victoir", "Victor", "Waltier", "William", "Wyatt", "Yanis", "Yann", "Yves", "Yvon", "Zosime", "Abrial", "Abrielle", "Abril", "Adele", "Alair", "Alerion", "Amee", "Angelique", "Annette", "Antonella", "Arian", "Ariane", "Armandina", "Aubree", "Aubrielle", "Audra", "Avril", "Bella", "Berneta", "Bette", "Blaise", "Blanche", "Blasa", "Bonte", "Brie", "Brienne", "Brigit", "Cachay", "Calice", "Camille", "Camylle", "Caprice", "Caressa", "Caroline", "Catin", "Celesta", "Celeste", "Cera", "Cerise", "Chablis", "Chalice", "Chambray", "Champagne", "Chandell", "Chaney", "Chantal", "Chante", "Chanterelle", "Chantile", "Chantilly", "Chantrice", "Charla", "Charlotte", "Charmane", "Chaton", "Chemin", "Chenetta", "Cher", "Chere", "Cheri", "Cheryl", "Christine", "Cidney", "Cinderella", "Claire", "Claudette", "Colette", "Cordelle", "Cydnee", "Daeja", "Daija", "Daja", "Damzel", "Darelle", "Darlene", "Darselle", "Dejanelle", "Deleena", "Delice", "Demeri", "Deni", "Denise", "Desgracias", "Desire", "Desiree", "Destanee", "Destiny", "Dior", "Domanique", "Dominique", "Elaina", "Elaine", "Elayna", "Elise", "Eloisa", "Elyse", "Emeline", "Emmaline", "Emmeline", "Estella", "Estrella", "Etiennette", "Evette", "Fabienne", "Fabrienne", "Fanchon", "Fancy", "Fawna", "Fayana", "Fayette", "Fifi", "Fleur", "Fleurette", "Fontanna", "Fosette", "Francine", "Frederique", "Gabriel", "Gabriele", "Gabrielle", "Gaby", "Garcelle", "Gena", "Genie", "Georgette", "Germaine", "Gervaise", "Gitana", "Harriet", "Heloisa", "Holland", "Honnetta", "Isabelle", "Ivette", "Ivonne", "Jacqueena", "Jacquetta", "Jacquiline", "Jacyline", "Jaime", "Jakqueline", "Janeen", "Janelly", "Janina", "Janiqua", "Janique", "Jannnelle", "Jaquita", "Jardena", "Jeanetta", "Jermaine", "Jessamine", "Jewel", "Jewell", "Joli", "Jolie", "Josephine", "Jozephine", "Julieta", "Karessa", "Karmaine", "Klara", "Laine", "Lanelle", "Laramie", "Layne", "Layney", "Leala", "Leonette", "Lissette", "Lizette", "Lourdes", "Lucienne", "Ly", "Lyla", "Lysette", "Madelaine", "Malerie", "Manette", "Marais", "Marcelle", "Marché", "Mardi", "Margo", "Marguerite", "Marie", "Marie Claude", "Marie Frances", "Marie Joelle", "Marie Pascale", "Marie Sophie", "Marjolaine", "Marquise", "Marvella", "Mathieu", "Matisse", "Maurelle", "Maurissa", "Mavis", "Melisande", "Michelle", "Miette", "Mignon", "Mimi", "Mirya", "Monet", "Moniqua", "Monteen", "Musetta", "Myrlie", "Nadeen", "Nadia", "Nadiyah", "Naeva", "Nanon", "Natalle", "Naudia", "Nettie", "Nicholas", "Nicki", "Nicky", "Nicole", "Nicolette", "Nicolina", "Nicolle", "Nikolette", "Ninette", "Ninon", "Noelle", "Nycole", "Odelette", "Opaline", "Orane", "Orva", "Page", "Parisa", "Parnel", "Parris", "Patrice", "Peridot", "Pippi", "Prairie", "Rachele", "Rachelle", "Racquel", "Raphaelle", "Raquelle", "Remi", "Renée", "Renea", "Renelle", "Renita", "Risette", "Rochelle", "Romy", "Rosabel", "Rosiclara", "Ruba", "Russhell", "Saleena", "Salina", "Satin", "Sedona", "Serene", "Shandelle", "Shanta", "Shante", "Shariah", "Sharita", "Sharleen", "Sheree", "Shereen", "Sherell", "Sherice", "Sherry", "Sidnee", "Sidney", "Sidnie", "Sidonie", "Sinclaire", "Solange", "Solen", "Sorrel", "Suzette", "Sydnee", "Sydney", "Tallis", "Tempest", "Toinette", "Turquoise", "Veronique", "Vignette", "Villette", "Violeta", "Virginie", "Voleta", "Vonny");
List<String> surnames = Arrays.asList("Arceneau", "Aucoin", "Babin", "Babineaux", "Benoit", "Bergeron", "Bernard", "Bertrand", "Bessette", "Blanc", "Blanchard", "Bonnet", "Boucher", "Bourg", "Bourque", "Boutin", "Bouvier", "Braud", "Broussard", "Brun", "Chevalier", "David", "Depaul", "Desmarais", "Disney", "Dubois", "Dupont", "Dupuis", "Durand", "Fortescue", "Fournier", "Garnier", "Gaudet", "Gillet", "Gillette", "Girard", "Gravois", "Grosvenor", "Lambert", "Landry", "Laroche", "Laurent", "Lefevre", "Leroy", "Leveque", "Lisle", "Martin", "Michel", "Molyneux", "Moreau", "Morel", "Neville", "Pelletier", "Petit", "Prideux", "Renard", "Richard", "Robert", "Rousseau", "Roux", "Rufus", "Simon", "Thomas");
Iterable<Person> persons = () -> {
return new Iterator<Person>() {
int counter = 40_000; //0_000; // 40_000 yields about 20 MB of data.
@Override
public boolean hasNext() {
return counter-- > 0;
}
@Override
public Person next() {
String givenName = givenNames.get(random.nextInt(0, givenNames.size()));
String surname = surnames.get(random.nextInt(0, surnames.size()));
UUID id = UUID.randomUUID();
String description = Person.LOREM_IPSUM;
return new Person(givenName, surname, id, description);
}
};
};
writer.writeValues(fileWriter).writeAll(persons);
}
}
}
class Person {
// Static
static public String LOREM_IPSUM = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
// Member variables.
private String givenName, surname, description;
private UUID id;
public Person() {
}
public Person(String givenName, String surname, UUID id, String description) {
this.givenName = givenName;
this.surname = surname;
this.id = id;
this.description = description;
}
public String getGivenName() {
return givenName;
}
public void setGivenName(String givenName) {
this.givenName = givenName;
}
public String getSurname() {
return surname;
}
public void setSurname(String surname) {
this.surname = surname;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public UUID getId() {
return id;
}
public void setId(UUID id) {
this.id = id;
}
@Override
public String toString() {
return "Person{ " +
"givenName='" + givenName + '\'' +
" | surname='" + surname + '\'' +
" | id='" + id + '\'' +
" }";
}
}
答案 3 :(得分：2)
这是Basil提供的解决方案的我的版本，但这使用了univocity-parsers：
public class CsvSpeed {
public static class Person {
// Static
static public String LOREM_IPSUM = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
// Member variables.
@Parsed
public String givenName, surname, description;
public UUID id;
@Parsed
public void id(String id) {
this.id = UUID.fromString(id);
}
@Override
public String toString() {
return "Person{ " +
"givenName='" + givenName + '\'' +
" | surname='" + surname + '\'' +
" | id='" + id + '\'' +
" }";
}
}
public List<Person> read(Path path) {
return new CsvRoutines(Csv.parseRfc4180()).parseAll(Person.class, path.toFile(), "UTF-8", 40_000);
}
public void write(final Path path) {
ThreadLocalRandom random = ThreadLocalRandom.current();
CsvWriter writer = new CsvWriter(path.toFile(), "UTF-8", Csv.writeRfc4180());
writer.writeHeaders("givenName" , "surname" , "id" , "description");
int limit = 40_000; // 40_000 yields about 20 MB of data.
List<String> givenNames = List.of("Adrien", "Aimon", "Alerion", "Alexis", "Alezan", "Ancil", "Andre", "Antoine", "Archard", "Aurélien", "Averill", "Baptiste", "Barnard", "Bartelemy", "Bastien", "Baylee", "Beale", "Beau", "Beaumont", "Beauregard", "Bellamy", "Berger", "Blaize", "Blondel", "Boyce", "Bruce", "Brunelle", "Brys", "Burcet", "Burnell", "Burrell", "Byron", "Canaan", "Carden", "Carolas", "Cavell", "Chace", "Chanler", "Chante", "Chappel", "Charles", "Chasen", "Chason", "Chemin", "Chene", "Cher", "Chevalier", "Cheyne", "Clément", "Clemence", "Corbin", "Coty", "Cygne", "Damien", "Dandre", "Dariel", "Darl", "Dauphine", "Davet", "Dax", "Dean", "Delice", "Delmon", "Destin", "Dominique", "Donatien", "Duke", "Eliott", "Elroy", "Enzo", "Erwan", "Etalon", "Ethan", "Fabron", "Ferrand", "Filberte", "Florent", "Florian", "Fontaine", "Forest", "Fortune", "Franchot", "Francois", "Fraser", "Frayne", "Gaëtan", "Gabin", "Gage", "Gaige", "Garland", "Garner", "Gaston", "Gauge", "Gaylord", "Germain", "Germaine", "German", "Gervaise", "Giles", "Gilles", "Gitan", "Grosvener", "Guifford", "Guion", "Guy", "Guzman", "Henri", "Holland", "Hugo", "Hugues", "Hyacinthe", "Jérémy", "Jacquan", "Jacques", "Jacquez", "Janvier", "Jardan", "Jay", "Jaye", "Jehan", "Jemond", "Jocquez", "Jonathan", "Jules", "Julien", "Justus", "Karoly", "Lado", "Lafayette", "Lamond", "Lancelin", "Landis", "Landry", "Laron", "Larrimore", "Laurent", "LaValle", "Leandre", "Leggett", "Leonce", "Leron", "Leverett", "Lilian", "Loïc", "Lorenzo", "Louis", "Lowell", "Luc", "Lucien", "Lukas", "Macaire", "Mace", "Mahieu", "Maison", "Malleville", "Manneville", "Mantel", "Marc", "Marcel", "Marion", "Marius", "Markez", "Markis", "Marmion", "Marquis", "Marquise", "Marshall", "Martial", "Maslin", "Mason", "Matheo", "Mathias", "Mathys", "Matthieu", "Maxence", "Mayson", "Mehdi", "Merle", "Merville", "Montague", "Montaigu", "Monte", "Montgomery", "Montreal", "Montrel", "Moore", "Morel", "Mortimer", "Nerville", "Neuveville", "Nicolas", "Noë", "Noah", "Noe", "Norman", "Norville", "Nouel", "Olivier", "Onfroi", "Paien", "Parfait", "Parnell", "Pascal", "Patrice", "Paul", "Peppin", "Percival", "Percy", "Pernell", "Peverell", "Philipe", "Pierpont", "Pierre", "Pomeroy", "Prewitt", "Purvis", "Quennell", "Quentin", "Quincey", "Quincy", "Quintin", "Rémi", "Rafaelle", "Ranger", "Raoul", "Raphaël", "Rapier", "Rawlins", "Ray", "Raynard", "Remi", "René", "Renard", "Rene", "Reule", "Reynard", "Robin", "Romain", "Rondel", "Roy", "Royal", "Ruff", "Rush", "Russel", "Rustin", "Sabastien", "Sacha", "Salomon", "Samuel", "Satordi", "Saville", "Scoville", "Sebastien", "Sennett", "Severin", "Shant", "Shantae", "Sidney", "Siffre", "Simeon", "Simon", "Sinclair", "Sofiane", "Somer", "Stephane", "Sully", "Sydney", "Sylvain", "Talbot", "Talon", "Telford", "Tempest", "Teppo", "Théo", "Thayer", "Thibault", "Thibaut", "Thiery", "Tiennan", "Tiennot", "Titouan", "Toussaint", "Travaris", "Tyson", "Urson", "Vachel", "Valentin", "Valere", "Vallis", "Verdun", "Victoir", "Victor", "Waltier", "William", "Wyatt", "Yanis", "Yann", "Yves", "Yvon", "Zosime", "Abrial", "Abrielle", "Abril", "Adele", "Alair", "Alerion", "Amee", "Angelique", "Annette", "Antonella", "Arian", "Ariane", "Armandina", "Aubree", "Aubrielle", "Audra", "Avril", "Bella", "Berneta", "Bette", "Blaise", "Blanche", "Blasa", "Bonte", "Brie", "Brienne", "Brigit", "Cachay", "Calice", "Camille", "Camylle", "Caprice", "Caressa", "Caroline", "Catin", "Celesta", "Celeste", "Cera", "Cerise", "Chablis", "Chalice", "Chambray", "Champagne", "Chandell", "Chaney", "Chantal", "Chante", "Chanterelle", "Chantile", "Chantilly", "Chantrice", "Charla", "Charlotte", "Charmane", "Chaton", "Chemin", "Chenetta", "Cher", "Chere", "Cheri", "Cheryl", "Christine", "Cidney", "Cinderella", "Claire", "Claudette", "Colette", "Cordelle", "Cydnee", "Daeja", "Daija", "Daja", "Damzel", "Darelle", "Darlene", "Darselle", "Dejanelle", "Deleena", "Delice", "Demeri", "Deni", "Denise", "Desgracias", "Desire", "Desiree", "Destanee", "Destiny", "Dior", "Domanique", "Dominique", "Elaina", "Elaine", "Elayna", "Elise", "Eloisa", "Elyse", "Emeline", "Emmaline", "Emmeline", "Estella", "Estrella", "Etiennette", "Evette", "Fabienne", "Fabrienne", "Fanchon", "Fancy", "Fawna", "Fayana", "Fayette", "Fifi", "Fleur", "Fleurette", "Fontanna", "Fosette", "Francine", "Frederique", "Gabriel", "Gabriele", "Gabrielle", "Gaby", "Garcelle", "Gena", "Genie", "Georgette", "Germaine", "Gervaise", "Gitana", "Harriet", "Heloisa", "Holland", "Honnetta", "Isabelle", "Ivette", "Ivonne", "Jacqueena", "Jacquetta", "Jacquiline", "Jacyline", "Jaime", "Jakqueline", "Janeen", "Janelly", "Janina", "Janiqua", "Janique", "Jannnelle", "Jaquita", "Jardena", "Jeanetta", "Jermaine", "Jessamine", "Jewel", "Jewell", "Joli", "Jolie", "Josephine", "Jozephine", "Julieta", "Karessa", "Karmaine", "Klara", "Laine", "Lanelle", "Laramie", "Layne", "Layney", "Leala", "Leonette", "Lissette", "Lizette", "Lourdes", "Lucienne", "Ly", "Lyla", "Lysette", "Madelaine", "Malerie", "Manette", "Marais", "Marcelle", "Marché", "Mardi", "Margo", "Marguerite", "Marie", "Marie Claude", "Marie Frances", "Marie Joelle", "Marie Pascale", "Marie Sophie", "Marjolaine", "Marquise", "Marvella", "Mathieu", "Matisse", "Maurelle", "Maurissa", "Mavis", "Melisande", "Michelle", "Miette", "Mignon", "Mimi", "Mirya", "Monet", "Moniqua", "Monteen", "Musetta", "Myrlie", "Nadeen", "Nadia", "Nadiyah", "Naeva", "Nanon", "Natalle", "Naudia", "Nettie", "Nicholas", "Nicki", "Nicky", "Nicole", "Nicolette", "Nicolina", "Nicolle", "Nikolette", "Ninette", "Ninon", "Noelle", "Nycole", "Odelette", "Opaline", "Orane", "Orva", "Page", "Parisa", "Parnel", "Parris", "Patrice", "Peridot", "Pippi", "Prairie", "Rachele", "Rachelle", "Racquel", "Raphaelle", "Raquelle", "Remi", "Renée", "Renea", "Renelle", "Renita", "Risette", "Rochelle", "Romy", "Rosabel", "Rosiclara", "Ruba", "Russhell", "Saleena", "Salina", "Satin", "Sedona", "Serene", "Shandelle", "Shanta", "Shante", "Shariah", "Sharita", "Sharleen", "Sheree", "Shereen", "Sherell", "Sherice", "Sherry", "Sidnee", "Sidney", "Sidnie", "Sidonie", "Sinclaire", "Solange", "Solen", "Sorrel", "Suzette", "Sydnee", "Sydney", "Tallis", "Tempest", "Toinette", "Turquoise", "Veronique", "Vignette", "Villette", "Violeta", "Virginie", "Voleta", "Vonny");
List<String> surnames = List.of("Arceneau", "Aucoin", "Babin", "Babineaux", "Benoit", "Bergeron", "Bernard", "Bertrand", "Bessette", "Blanc", "Blanchard", "Bonnet", "Boucher", "Bourg", "Bourque", "Boutin", "Bouvier", "Braud", "Broussard", "Brun", "Chevalier", "David", "Depaul", "Desmarais", "Disney", "Dubois", "Dupont", "Dupuis", "Durand", "Fortescue", "Fournier", "Garnier", "Gaudet", "Gillet", "Gillette", "Girard", "Gravois", "Grosvenor", "Lambert", "Landry", "Laroche", "Laurent", "Lefevre", "Leroy", "Leveque", "Lisle", "Martin", "Michel", "Molyneux", "Moreau", "Morel", "Neville", "Pelletier", "Petit", "Prideux", "Renard", "Richard", "Robert", "Rousseau", "Roux", "Rufus", "Simon", "Thomas");
for (int i = 1; i <= limit; i++) {
String givenName = givenNames.get(random.nextInt(0, givenNames.size()));
String surname = surnames.get(random.nextInt(0, surnames.size()));
UUID id = UUID.randomUUID();
String description = Person.LOREM_IPSUM;
writer.writeRow(givenName, surname, id, description);
}
writer.close();
}
public static void main(final String[] args) {
// Launch the app.
CsvSpeed app = new CsvSpeed();
// Write.
String when = Instant.now().truncatedTo(ChronoUnit.SECONDS).toString().replace(":", "•");
Path pathOutput = Paths.get("/tmp/persons.csv");
app.write(pathOutput);
System.out.println("Writing file: " + pathOutput);
// Read.
long start = System.nanoTime();
Path pathInput = Paths.get("/tmp/persons.csv");
List<Person> list = app.read(pathInput);
long stop = System.nanoTime();
// Time.
long elapsed = (stop - start);
Duration d = Duration.ofNanos(elapsed);
System.out.println("Reading elapsed: " + d);
System.out.println("Reading took nanos per row: " + (elapsed / list.size()));
System.out.println("nanos elapsed: " + elapsed + " | list.size: " + list.size());
}
}
在我的计算机上运行时，我得到了以下计时信息：
Writing file: /tmp/persons.csv
Reading elapsed: PT0.230395859S
Reading took nanos per row: 5759
nanos elapsed: 230395859 | list.size: 40000
它没有显示出将JIT引入并优化代码后，解析器可以获得多快的速度。我已经更改了代码以生成40万条记录（导致200 MB文件）。现在代码显示：
Reading elapsed: PT0.993483883S
Reading took nanos per row: 2483
nanos elapsed: 993483883 | list.size: 400000
具有4M行（几乎2GB的数据）：
Reading elapsed: PT7.961481755S
Reading took nanos per row: 1990
nanos elapsed: 7961481755 | list.size: 4000000