我需要频繁调用一个音乐文件,有什么方法可以只从磁盘读取一次,然后重复加以利用吗?

[mumasgw]

程序如下:
FileInputStream fis = new FileInputStream(url);
AudioStream music = new AudioStream(fis);
AudioPlayer.player.start(music);

因为需要重复播放文件,如何才能重磁盘获取一次,后面几次播放不再读磁盘呢?怎样把这个文件流定为到文件头呢?

[qybao]

AudioStream有没有AudioStream(InputStream stream)这样的构造函数，如果有的话，还有可能，否则，估计做不到，FileInputStream不支持mark，所以也不能reset, 要构造FileInputStream就必须通过文件或文件路径。

如果有AudioStream(InputStream stream)的构造函数的话，可以把文件信息保存在一个byte数组里

FileInputStream   fis   =   new   FileInputStream(url); 

//保存文件信息到byte数组中
byte[] bt = new byte[(int)new File(url).length()];
fis.read(bt);

//用个管道连接
InputStream is = new PipedInputStream();
PipedOutputStream pos = new PipedOutputStream((PipedInputStream)is);
pos.write(bt, 0, bt.length);
pos.flush();

AudioStream music = new AudioStream(is); 
AudioPlayer.player.start(music); 

//反复调用
pos.write(bt, 0, bt.length);
pos.flush();

AudioStream music = new AudioStream(is); 
AudioPlayer.player.start(music);

如果AudioStream是自己写的class的话，建议修改一下构造函数。

[mumasgw]

很奇怪,我用楼上的方法,执行到pos.write(bt, 0, bt.length);这步就会死掉,没有任何出错信息?

[sht_123]

FileInputStream fis = new FileInputStream(url);
AudioStream music = new AudioStream(fis);
AudioPlayer.player.start(music);


我觉得mumsgw,你的这三行代码就可以实现啊!
如你的:
FileInputStream fis = new FileInputStream(url);
AudioStream music = new AudioStream(fis);

代码已经创建了一个 music对象,你可以在你需要的地方多次调用
AudioPlayer.player.start(music);
即已实现一次读取到多次播放的了.

[sht_123]

刚才考虑的不很全面,这是在一个类里而言,要是在多个类里调用我认为 5 楼的可以实现.

[jinxfei]

import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.InputStream;


public class ByteArrayTest {

public static void main(String[] args) throws Exception{
File audioFile=new File("");
InputStream in=new FileInputStream(audioFile);
byte[] bt = new byte[(int)audioFile.length()];

//大文件的话，可能一次读不完，需要多次循环来读出全部内容
in.read(bt);

ByteArrayInputStream bin=new ByteArrayInputStream(bt);

while(true){
AudioStream music = new AudioStream(bin);
AudioPlayer.player.start(music);
bin.reset();

}

}
}

[mumasgw]

楼上会出现如下错误
java.io.IOException: could not create audio stream from input stream
at sun.audio.AudioStream.<init>(AudioStream.java:65)
at ByteArrayTest.main(ByteArrayTest.java:32)
声音只播放了一次

[ziqing_1_2_3]

存在本地%temp%目录下，重复播放时再调就得了。

[qybao]

估计是reset造成的问题，你把LS的代码改成

import   java.io.ByteArrayInputStream; 
import   java.io.FileInputStream; 
import   java.io.InputStream; 


public   class   ByteArrayTest   { 

public   static   void   main(String[]   args)   throws   Exception{ 
File   audioFile=new   File(""); 
InputStream   in=new   FileInputStream(audioFile); 
byte[]   bt   =   new   byte[(int)audioFile.length()]; 

//大文件的话，可能一次读不完，需要多次循环来读出全部内容 
in.read(bt); 

//ByteArrayInputStream   bin=new   ByteArrayInputStream(bt); //remove this

while(true){ 
ByteArrayInputStream   bin=new   ByteArrayInputStream(bt); //move to here
AudioStream       music       =       new       AudioStream(bin);   
AudioPlayer.player.start(music); 
//bin.reset(); //remove this

} 

} 
}

用管道会死掉，奇怪了，这样试试看

FileInputStream   fis   =   new   FileInputStream(url); 

//保存文件信息到byte数组中
byte[] bt = new byte[(int)new File(url).length()];
fis.read(bt);

//用个管道连接
InputStream is = new PipedInputStream();
PipedOutputStream pos = new PipedOutputStream((PipedInputStream)is);
PrintStream ps = new PrintStream(pos);

while (true) {
    ps.write(bt, 0, bt.length);
    AudioStream music = new AudioStream(is); 
    AudioPlayer.player.start(music); 
}

[jinxfei]

upgrade:

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

import sun.audio.AudioPlayer;
import sun.audio.AudioStream;


public class ByteArrayTest {

public static void main(String[] args) throws Exception{
File audioFile=new File("d:/alarm.wav");
InputStream in=new FileInputStream(audioFile);
byte[] bt = new byte[(int)audioFile.length()];

//大文件的话，可能一次读不完，需要多次循环来读出全部内容
in.read(bt);

ByteArrayInputStream bin=new ByteArrayInputStream(bt);
AudioStream music = new AudioStream(bin);
AudioPlayer.player.start(music);
int lastAvail=bin.available();
while(true){
while(bin.available()!=lastAvail){
lastAvail=bin.available();
Thread.sleep(1000);
}
bin.reset();
AudioPlayer.player.stop(bin);
AudioPlayer.player.start(bin);
}

}
}

[cursor_wang]

我认为可能是文件格式的关系，要用.mid,不能用其他格式．你们试下．我这里可以运行．

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

import sun.audio.AudioPlayer;
import sun.audio.AudioStream;

public class ByteArrayTest {
	public ByteArrayTest(){
		FileInputStream fis = null;
		AudioStream music = null;
		try {
			fis = new   FileInputStream("F:/95.mid");
			music = new   AudioStream(fis);
		} catch (FileNotFoundException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		AudioPlayer.player.start(music); 
	}
	public static void main(String[] args) throws FileNotFoundException{
		new ByteArrayTest();
	}
}

[mumasgw]

没人知道吗?好逮也凑点人气吗:)

[hoo428]

用对象序列化行不？

[jinxfei]

可不可以这样，把文件内容全部读到一个byte[]中，然后再建一个ByteArrayInputStream()给你的播放器用？

[guojie1689]

不能把他放到缓存里吗？
然后一直放着，用的时候取

[jinxfei]

不一定非要MID