DataLine 中的 isRunning() 和 isActibe() 有什么区别？当线路实际处理数据时，这两个标志似乎都已设置。
更新
那里有两对方法:
1) 打开/关闭
2) 启动/停止
还有三个标志
1) 正在打开
2) 正在运行
3) 处于 Activity 状态
有人可以推断出他们之间和/或彼此之间的一些关系吗？例如，很明显，isRunning 意味着 isOpen，isActive 意味着 isOpen，但是 isActive 是否意味着 isRunning，或者反之亦然？或者他们是独立的？
我猜 Line 在调用 open() 后立即变为 isOpen 。所以 isOpen 用于检查是否调用了 open()。
我可以检查一下我是否调用了start()吗？也许一些 isActive 或 isRunning 就是为了这个？但哪一个呢？
更新1
以下代码旨在将音频从默认系统声音输入播放到默认系统声音输出。
public static void main(String[] args) throws LineUnavailableException, InterruptedException {
AudioFormat audioFormat = new AudioFormat(16000f, 16, 1, true, false);
final SourceDataLine outputLine;
final TargetDataLine inputLine;
outputLine = AudioSystem.getSourceDataLine(audioFormat);
inputLine = AudioSystem.getTargetDataLine(audioFormat);
Thread player = new Thread("player") {
@Override
public void run() {
byte[] b = new byte[2048];
int readen;
log.info("Starting transfer");
while( !inputLine.isOpen() ) {
try {
log.info("TargetDataLine is closed, waiting");
sleep(1000);
} catch (InterruptedException e) {
interrupt();
}
}
while( !inputLine.isRunning() ) {
try {
log.info("TargetDataLine is not running, waiting");
sleep(100);
} catch (InterruptedException e) {
interrupt();
}
}
while((readen = inputLine.read(b,0,b.length))>=0 && !isInterrupted()) {
outputLine.write(b,0,readen);
}
}
};
player.start();
outputLine.open();
outputLine.start();
inputLine.open();
inputLine.start();
player.join();
}
代码的输出如下:
15:20:01.369 [player] INFO tests.DataLineFlags01 - Starting transfer
15:20:01.371 [player] INFO tests.DataLineFlags01 - TargetDataLine is closed, waiting
15:20:02.371 [player] INFO tests.DataLineFlags01 - TargetDataLine is not running, waiting
15:20:02.471 [player] INFO tests.DataLineFlags01 - TargetDataLine is not running, waiting
15:20:02.571 [player] INFO tests.DataLineFlags01 - TargetDataLine is not running, waiting
15:20:02.671 [player] INFO tests.DataLineFlags01 - TargetDataLine is not running, waiting
15:20:02.771 [player] INFO tests.DataLineFlags01 - TargetDataLine is not running, waiting
...
这证明 TargetDataLine 在调用 start() 后不会进入“运行”状态。
对于 isActive() 标志也会发生同样的情况。
这意味着
(1) 无法知道是否调用了 start()
(2) isRunning() 和 isActive() 标志没有用
这样对吗？它们对于 SourceDataLine 对象可能有用吗？
更新2
以下应用
package testing.Test_TargetDataLine_01;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.TargetDataLine;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class App
{
private static Logger log = LoggerFactory.getLogger(App.class);
private final AudioFormat audioFormat;
private final TargetDataLine targetDataLine;
private final Thread observer = new Thread("observer") {
{
setDaemon(true);
}
public void run() {
while( !isInterrupted() ) {
if( targetDataLine != null ) {
log.info("targetDataLine: Opened={}, Active={}, Running={}", targetDataLine.isOpen(), targetDataLine.isActive(), targetDataLine.isRunning());
}
else {
log.info("targetDataLine: is null");
}
try {
sleep(10);
} catch (InterruptedException e) {
}
}
};
};
public App() throws LineUnavailableException, InterruptedException {
byte[] buffer = new byte[160*2]; // 1/100 of second
log.info("App starting");
log.info("Observer starting");
observer.start();
log.info("Sleeping 500");
Thread.sleep(500);
log.info("Creating targetDataLine");
audioFormat = new AudioFormat(16000, 16, 1, true, false);
targetDataLine = AudioSystem.getTargetDataLine(audioFormat);
log.info("Sleeping 500");
Thread.sleep(500);
log.info("Opening targetDataLine");
targetDataLine.open();
log.info("Sleeping 500");
Thread.sleep(500);
log.info("Starting targetDataLine");
targetDataLine.start();
log.info("Sleeping 500");
Thread.sleep(500);
log.info("Reading target data line for 5 seconds");
for(int i=0; i<50; ++i) {
targetDataLine.read(buffer, 0, buffer.length);
log.info("Stage " + i);
}
log.info("Stopping targetDataLine");
targetDataLine.stop();
log.info("Sleeping 500");
Thread.sleep(500);
log.info("Closing targetDataLine");
targetDataLine.close();
log.info("Sleeping 500");
Thread.sleep(500);
//log.info("Interrupting observer");
//observer.interrupt();
}
public static void main( String[] args ) throws LineUnavailableException, InterruptedException
{
new App();
}
}
产生以下输出:
20:58:23,360 0 [main] INFO testing.Test_TargetDataLine_01.App - App starting 20:58:23,362 2 [main] INFO testing.Test_TargetDataLine_01.App - Observer starting 20:58:23,362 2 [main] INFO testing.Test_TargetDataLine_01.App - Sleeping 500 20:58:23,362 2 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: is null 20:58:23,372 12 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: is null ... 20:58:23,842 482 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: is null 20:58:23,852 492 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: is null 20:58:23,862 502 [main] INFO testing.Test_TargetDataLine_01.App - Creating targetDataLine 20:58:23,862 502 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: is null 20:58:23,872 512 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: is null ... 20:58:23,912 552 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: is null 20:58:23,922 562 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: is null 20:58:23,929 569 [main] INFO testing.Test_TargetDataLine_01.App - Sleeping 500 20:58:23,933 573 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:23,943 583 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false ... 20:58:24,413 1053 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:24,423 1063 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:24,430 1070 [main] INFO testing.Test_TargetDataLine_01.App - Opening targetDataLine 20:58:24,433 1073 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:24,443 1083 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false ... 20:58:24,483 1123 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:24,493 1133 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:24,501 1141 [main] INFO testing.Test_TargetDataLine_01.App - Sleeping 500 20:58:24,503 1143 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:24,513 1153 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false ... 20:58:24,983 1623 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:24,993 1633 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:25,002 1642 [main] INFO testing.Test_TargetDataLine_01.App - Starting targetDataLine 20:58:25,002 1642 [main] INFO testing.Test_TargetDataLine_01.App - Sleeping 500 20:58:25,003 1643 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:25,013 1653 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false ... 20:58:25,483 2123 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:25,493 2133 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:25,502 2142 [main] INFO testing.Test_TargetDataLine_01.App - Reading target data line for 5 seconds 20:58:25,502 2142 [main] INFO testing.Test_TargetDataLine_01.App - Stage 0 20:58:25,502 2142 [main] INFO testing.Test_TargetDataLine_01.App - Stage 1 20:58:25,503 2143 [main] INFO testing.Test_TargetDataLine_01.App - Stage 2 20:58:25,503 2143 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=true, Running=true 20:58:25,503 2143 [main] INFO testing.Test_TargetDataLine_01.App - Stage 3 20:58:25,503 2143 [main] INFO testing.Test_TargetDataLine_01.App - Stage 4 ... 20:58:25,512 2152 [main] INFO testing.Test_TargetDataLine_01.App - Stage 48 20:58:25,512 2152 [main] INFO testing.Test_TargetDataLine_01.App - Stage 49 20:58:25,512 2152 [main] INFO testing.Test_TargetDataLine_01.App - Stopping targetDataLine 20:58:25,513 2153 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=true, Running=true 20:58:25,521 2161 [main] INFO testing.Test_TargetDataLine_01.App - Sleeping 500 20:58:25,523 2163 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:25,533 2173 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false ... 20:58:26,003 2643 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:26,013 2653 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=true, Active=false, Running=false 20:58:26,021 2661 [main] INFO testing.Test_TargetDataLine_01.App - Closing targetDataLine 20:58:26,023 2663 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:26,026 2666 [main] INFO testing.Test_TargetDataLine_01.App - Sleeping 500 20:58:26,033 2673 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:26,043 2683 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false ... 20:58:26,513 3153 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false 20:58:26,523 3163 [observer] INFO testing.Test_TargetDataLine_01.App - targetDataLine: Opened=false, Active=false, Running=false
这表明两个标志无法区分。
最佳答案
如果你查看 API 文档，它会说:
isRunning():
指示线路是否正在运行。默认为 false。当响应启动方法的调用而呈现第一个数据时，开放线开始运行，并继续运行，直到响应停止调用或因为播放完成而停止呈现为止。
isActive():
指示线路是否正在进行 Activity I/O(例如播放或捕获)。当不活动线路变为 Activity 线路时，它会向其监听器发送 START 事件。同样，当 Activity 线路变为非 Activity 状态时，它会发送 STOP 事件。
查看 start() 方法，我们发现 start() 允许该行变为非 Activity 状态，因此我们可以说 isRunning() 告诉我们线路是否可以激活，isActive() 告诉我们线路是否正在使用(即数据正在以播放或录制的形式传输)
所以，简而言之，
isRunning() - 在使用此行之前我们需要调用start()吗？
isActive() - 此行现在正在使用吗？
如果您必须知道何时调用 start()，请使用:
final HashSet<Line> openLines = new HashSet<Line>();
...
DataLine myLine = getDataLine();
myLine.addListener(new LineListener(){
public void update(LineEvent evt)
{
if(evt.getType().equals(LineEvent.Type.START)) openLines.add(evt.getLine());
else if(evt.getType().equals(LineEvent.Type.STOP)) openLines.remove(evt.getLine());
}
});
...
public boolean isLineStarted(DataLine l)
{
return openLines.contains(l);
}
关于java - DataLine 中的 isRunning() 和 isActive() 有什么区别？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/11384059/