所以，我正在從 BufferedReader 中閱讀。一切都很好，直到我添加一個條件。我需要從 BufferedReader 讀取特定的持續(xù)時間。這就是我現(xiàn)在正在做的事情。while ((line = br.readLine()) != null && System.currentTimeMillis() - start < maxReadTime.toMillis()) { // doingSomethingHere()}問題： InputStream 即使在時間過去后仍處于活動狀態(tài)。例如 - maxReadTime 是 30 秒。輸入在 20 秒內(nèi)不斷出現(xiàn)。在接下來的 12 秒內(nèi)，沒有任何活動。現(xiàn)在，當(dāng)下一個輸入到達時，流打開并僅在讀取輸入后關(guān)閉。但是，我不處理此輸入，因為 while 循環(huán)終止。我的預(yù)期或我需要的是：Stream 將在 30 秒后關(guān)閉。也就是說，當(dāng)輸入到達第 32 秒時，流被關(guān)閉并且不監(jiān)聽任何輸入。我對 ExecutorService 知之甚少。我不確定這是否是正確的方法。
2 回答
慕俠2389804
TA貢獻1719條經(jīng)驗 獲得超6個贊
只需在從流中讀取之前設(shè)置您的計時器條件
while ((line = br.readLine()) != null) {
boolean active = System.currentTimeMillis() - start < maxReadTime.toMillis();
if (!active) {
br.close();
}
// doingSomethingHere()
}
在這種情況下，如果第一個條件是false（時間已到），則根本不會執(zhí)行第二個條件
DIEA
TA貢獻1820條經(jīng)驗 獲得超3個贊
readLine()基本上，您必須在調(diào)用方法之前檢查緩沖區(qū)是否準(zhǔn)備就緒ready()，InputStream檢查available()方法返回您可以在沒有阻塞的情況下讀取多少字節(jié)。
這里有一個例子
import java.io.*;
import java.time.Duration;
public class Main {
public static void main(String[] args) {
final InputStream in = System.in; //new FileInputStream(new File("/tmp/x"));
final String out = readInput(in, Duration.ofSeconds(5));
System.out.printf("m=main, status=complete, out=%s%n", out);
}
public static String readInput(InputStream in, Duration duration) {
final long timestamp = System.currentTimeMillis();
final BufferedReader reader = new BufferedReader(new InputStreamReader(in));
final StringBuilder out = new StringBuilder();
try {
String line = null;
while (true){
if(Duration.ofMillis(System.currentTimeMillis() - timestamp).compareTo(duration) >=0 ){
System.out.println("m=readInput, status=timeout");
break;
}
if(!reader.ready()){
System.out.println("m=readInput, status=not ready");
sleep(1000);
continue;
}
line = reader.readLine();
if(line == null){
System.out.println("m=readInput, status=null line");
break;
}
out.append(line);
out.append('\n');
System.out.printf("m=readInput status=read, line=%s%n" , line);
}
return out.toString();
} catch (IOException e){
throw new RuntimeException(e);
} finally {
System.out.println("m=readInput, status=complete");
}
}
static void sleep(int millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {}
}
}
如果您想在后臺執(zhí)行此操作，可以按照此示例進行操作
package com.mageddo;
import java.io.*;
import java.util.concurrent.*;
public class Main {
public static void main(String[] args) throws IOException, ExecutionException, InterruptedException {
final InputStream in = System.in; //new FileInputStream(new File("/tmp/x"));
final StringBuilder out = new StringBuilder();
final ExecutorService executor = Executors.newFixedThreadPool(1);
final Future<String> promise = executor.submit(() -> readInput(in, out));
try {
final String result = promise.get(5, TimeUnit.SECONDS);
System.out.printf("m=main, status=success, result=%s%n", result);
} catch (TimeoutException e) {
System.out.println("m=main, status=timeout");
in.close();
promise.cancel(true);
System.out.println("Failed output: " + promise.get());
e.printStackTrace();
} finally {
executor.shutdown();
System.out.println("m=main, status=shutdown, out=" + out);
}
}
public static String readInput(InputStream in, StringBuilder out) {
final BufferedReader reader = new BufferedReader(new InputStreamReader(in));
try {
String line = null;
while (true){
if(Thread.currentThread().isInterrupted()){
System.out.println("m=readInput status=interrupt signal");
break;
}
if(!reader.ready()){
System.out.println("m=readInput, status=not ready");
sleep(1000);
continue;
}
line = reader.readLine();
if(line == null){
System.out.println("m=readInput, status=null line");
break;
}
out.append(line);
out.append('\n');
System.out.printf("m=readInput status=read, line=%s%n" , line);
}
return out.toString();
} catch (IOException e){
throw new RuntimeException(e);
} finally {
System.out.println("m=readInput, status=complete");
}
}
static void sleep(int millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
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