我正在尝试处理任意 CSV 文件，其范围可以从 10 条记录到数百万条记录。 CSV 文件有 4 个固定列(例如 a、b、c、d)和 2 个来自外部 REST API 的附加列(e、f)。
我的目标是从 CSV 中读取所有记录，并为每条记录调用外部 REST API 以添加 2 个附加列，并将生成的 CSV 作为合并的 CSV 输出。输出应该是包含列(a、b、c、d、e、f)的相同 csv 文件。
我使用 Spring Integration 使用 EIP 的内容丰富器模式实现了此场景，并且能够实现预期的输出，但是当我顺序读取 CSV 文件时，该解决方案适用于少量记录，但一旦没有。记录数量增加，执行程序的时间也会以 O(n) 的方式增加。
我进一步开始实现生产者 - 消费者设计模式，并尝试以这样的方式实现代码:从 CSV 读取的每条记录然后使用 put() 放入队列中，然后多个消费者读取使用 BlockingQueue 的 take() 方法从同一个共享队列中获取。主程序使用 Executors.newFixedSizedThreadPool(3) 实例化具有 1 个生产者和多个消费者的 ExecutorService，但是我面临着几个挑战:
take() 方法永远不会退出。我尝试通过添加一个终结器对象来实现“毒丸”，然后检查消费者循环中是否有相同的毒丸爆发，但它仍然永远不会爆发(我在循环中添加了一个系统，看看它是否达到“毒丸”并且它确实打印出我的语句)，那么为什么它不退出呢？
CSV 文件仅保留从最后执行的消费者线程读取的数据，并覆盖其他消费者写入的所有内容 - 我正在使用 OpenCSV 读取/写入 CSV 数据。
这是我到目前为止的代码。有人可以指导我在这段代码中哪里错了以及需要改进的地方吗？
主程序
**
BlockingQueue<Account> queue = new ArrayBlockingQueue<>(100);
AccountProducer readingThread = new AccountProducer(inputFileName, queue);
//new Thread(readingThread).start();
ExecutorService producerExecutor = Executors.newFixedThreadPool(1);
producerExecutor.submit(readingThread);
AccountConsumer normalizers = new AccountConsumer(outputFileName, queue, accountService );
ExecutorService consumerExecutor = Executors.newFixedThreadPool(3);
for (int i = 1; i <= 3; i++) {
consumerExecutor.submit(normalizers);
}
producerExecutor.shutdown();
consumerExecutor.shutdown();
AccountProducer
public class AccountProducer implements Runnable {
private String inputFileName;
private BlockingQueue<Account> blockingQueue;
private static final String TERMINATOR = "TERMINATOR";
public AccountProducer (String inputFileName, BlockingQueue<Account> blockingQueue) {
this.inputFileName = inputFileName;
this.blockingQueue = blockingQueue;
}
@Override
public void run() {
try (Reader reader = Files.newBufferedReader(Paths.get(inputFileName));) {
PropertyEditorManager.registerEditor(java.util.Date.class, DateEditor.class);
ColumnPositionMappingStrategy<Account> strategy = new ColumnPositionMappingStrategy<>();
strategy.setType(Account.class);
String[] memberFieldsToBindTo = { "accountId", "accountName", "firstName", "createdOn" };
strategy.setColumnMapping(memberFieldsToBindTo);
CsvToBean<Account> csvToBean = new CsvToBeanBuilder<Account>(reader).withMappingStrategy(strategy)
.withSkipLines(1).withIgnoreLeadingWhiteSpace(true).build();
Iterator<Account> csvAccountIterator = csvToBean.iterator();
while (csvAccountIterator.hasNext()) {
Account account = csvAccountIterator.next();
// Checking if the Account Id in the csv is blank / null - If so, we skip the
// row for processing and hence avoiding API call..
if (null == account.getAccountId() || account.getAccountId().isEmpty()) {
continue;
} else {
// This call will send the extracted Account Object down the Enricher to get
// additional details from API
blockingQueue.put(account);
}
}
} catch (InterruptedException | IOException ex) {
System.out.println(ex);
} finally {
while (true) {
try {
Account account = new Account();
account.setAccountId(TERMINATOR);
blockingQueue.put(account);
break;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
帐户消费者
public class AccountConsumer implements Runnable {
private String outputFileLocation;
private BlockingQueue<Account> blockingQueue;
private AccountService accountService;
public AccountConsumer(String outputFileLocation, BlockingQueue<Account> blockingQueue, AccountService accountService) {
this.blockingQueue = blockingQueue;
this.outputFileLocation = outputFileLocation;
this.accountService = accountService;
}
@Override
public void run() {
List<Account> accounts = new ArrayList<>();
try {
while (true) {
Account account = blockingQueue.poll();
account = accountService.populateAccount(account);
accounts.add(account);
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} catch (Exception ex) {
System.out.println(ex);
}
processOutput(accounts, outputFileLocation);
}
/**
* The method processOutput simply takes the list of Accounts and writes them to
* CSV.
*
* @param outputFileName
* @param accounts
* @throws Exception
*/
private void processOutput(List<Account> accounts, String outputFileName) {
System.out.println("List Size is : " + accounts.size());
// Using try with Resources block to make sure resources are released properly
try (Writer writer = new FileWriter(outputFileName, true);) {
StatefulBeanToCsv<Account> beanToCsv = new StatefulBeanToCsvBuilder(writer).build();
beanToCsv.write(accounts);
} catch (CsvDataTypeMismatchException | CsvRequiredFieldEmptyException ex) {
System.out.println(ex);
//logger.error("Unable to write the output CSV File : " + ex);
//throw ex;
} catch (IOException e) {
e.printStackTrace();
}
}
}
这是我正在使用的 Spring Integration XML:
<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/integration"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/task
http://www.springframework.org/schema/task/spring-task.xsd
http://www.springframework.org/schema/integration
http://www.springframework.org/schema/integration/spring-integration.xsd"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:task="http://www.springframework.org/schema/task">
<channel id="accountChannel" />
<!-- accountOutputChannel is used for putting the Account object on the
Channel which will then be consumed by accountAPIChannel as Input to the API
-->
<channel id="accountOutputChannel" />
<!-- accountAPIChannel will take 1 accountId at a time and invoke REST API
Service to get additional details required to fill the Content Enricher -->
<channel id="accountAPIChannel" />
<!-- accountGateway is the entry point to the utility -->
<gateway id="accountGateway" default-request-timeout="5000"
default-reply-timeout="5000"
service-interface="com.epe.service.AccountService"
default-request-channel="accountChannel">
</gateway>
<!--Content enricher is used here for enriching an existing message with
additional data from External API
This is based on EIP Pattern - Content Enricher -->
<enricher id="enricher" input-channel="accountOutputChannel"
request-channel="accountAPIChannel">
<property name="status" expression="payload.status" />
<property name="statusSetOn" expression="payload.createdOn" />
</enricher>
<beans:bean id="accountService"
class="com.epe.service.impl.AccountServiceImpl" />
<!-- Below service-activator is used to actually invoke the external REST
API which will provide the additional fields for enrichment -->
<service-activator id="fetchAdditionalAccountInfoServiceActivator"
ref="accountInfoService" method="getAdditionalAccountInfoService"
input-channel="accountAPIChannel"
/>
<!-- accountInfoService is a bean which will be used for fetching
additional information from REST API Service -->
<beans:bean id="accountInfoService"
class="com.epe.service.impl.AccountInfoServiceImpl" />
</beans:beans>
最佳答案
您在代码中使用的是 poll()，而不是 take()。
您应该使用带有超时的poll()，例如poll(10, TimeUnit.SECONDS) 这样您就可以优雅地终止每个线程。
但是，您不需要所有这些逻辑；您可以使用 Spring 集成组件 - ExecutorChannel 和附加模式下的文件出站 channel 适配器来实现所有这些。
编辑
我没有时间写你的整个申请，但本质上你需要......
<file:inbound-channel-adapter />
<file:splitter output-channel="execChannel"/>
<int:channel id="execChannel">
<int:dispatcher task-executor="exec" />
</int:channel>
<int:transformer /> <!-- OpenCSV -->
<int:enricher ... />
<int:transformer /> <!-- OpenCSV -->
<int:resequencer /> <!== restore order -->
<file:outbound-channel-adapter />
您可以在引用手册中阅读有关所有这些组件的信息。
您可能还想考虑使用 Java DSL 而不是 xml；类似...
@Bean
public IntegrationFlow flow() {
return IntegrationFlows.from(File.inboundChannelAdapter(...))
.split(Files.splitter())
.channel(MessageChannels.executor(exec())
.transform(...)
.enrich(...)
.transform(...)
.resequence()
.handle(File.outboundCHannelAdapter(...))
.get();
关于java - 使用生产者-消费者模式处理巨大的 CSV 文件，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/57488846/