Java文件和ByteArray或InputStream

Question

我想使用jFugue在小程序中播放一些MIDI音乐。有一个用于MIDI模式的类- Pattern -加载模式的唯一方法是从文件。现在，我不知道applet是如何加载文件的，但我使用的是一个框架(PulpCore)，它使加载资产成为一项简单的任务。如果我需要从ZIP目录中获取资产，我可以使用提供get()和getAsStream()方法的Assets类。get()以ByteArray的形式返回给定的资产，另一个以InputStream的形式返回。

我需要jFugue从ByteArray或InputStream加载模式。在伪代码中，我想这样做：

Pattern.load(new File(Assets.get("mymidifile.midi")));

但是，没有可以接受ByteArray的文件构造函数。有什么建议吗？

Answer 1

确实，jFugue只允许加载文件，这很遗憾，因为没有什么可以阻止使用任何其他类型的流：

public static final String TITLE = "Title";

public static Pattern loadPattern(File file) throws IOException {
    InputStream in = new FileInputStream(file);
    try {
        return loadPattern(in);
    } finally {
        in.close();
    }
}

public static Pattern loadPattern(URL url) throws IOException {
    InputStream in = url.openStream();
    try {
        return loadPattern(in);
    } finally {
        in.close();
    }
}

public static Pattern loadPattern(InputStream in) throws IOException {
    return loadPattern(new InputStreamReader(in, "UTF-8")); // or ISO-8859-1 ?
}

public static Pattern loadPattern(Reader reader) throws IOException {
    if (reader instanceof BufferedReader) {
        return loadPattern(reader);
    } else {
        return loadPattern(new BufferedReader(reader));
    }
}

public static Pattern loadPattern(BufferedReader bread) throws IOException {
    StringBuffer buffy = new StringBuffer();

    Pattern pattern = new Pattern();
    while (bread.ready()) {
        String s = bread.readLine();
        if ((s != null) && (s.length() > 1)) {
            if (s.charAt(0) != '#') {
                buffy.append(" ");
                buffy.append(s);
            } else {
                String key = s.substring(1, s.indexOf(':')).trim();
                String value = s.substring(s.indexOf(':')+1, s.length()).trim();
                if (key.equalsIgnoreCase(TITLE)) {
                    pattern.setTitle(value);
                } else {
                    pattern.setProperty(key, value);
                }
            }
        }
    }
    return pattern;
}

更新(用于loadMidi)

public static Pattern loadMidi(InputStream in) throws IOException, InvalidMidiDataException
{
    MidiParser parser = new MidiParser();
    MusicStringRenderer renderer = new MusicStringRenderer();
    parser.addParserListener(renderer);
    parser.parse(MidiSystem.getSequence(in));
    Pattern pattern = new Pattern(renderer.getPattern().getMusicString());
    return pattern;
}

public static Pattern loadMidi(URL url) throws IOException, InvalidMidiDataException
{
    MidiParser parser = new MidiParser();
    MusicStringRenderer renderer = new MusicStringRenderer();
    parser.addParserListener(renderer);
    parser.parse(MidiSystem.getSequence(url));
    Pattern pattern = new Pattern(renderer.getPattern().getMusicString());
    return pattern;
}

Answer 2

如果我没记错的话，模式文件包含纯文本。使用getAsStream()加载文件，然后使用

BufferedReader br = new BufferedReader(new InputStreamReader(yourStream));
//...
String pattern = convertToString(br); // you should implement convertToString yourself. It's easy. Read the java.io APIs.

其中yourStream是getAsStream()返回的InputStream。然后使用add(字符串...patterns)方法来加载模式：

add(pattern);

Answer 3

您可以使用以下代码(取自Pattern.loadPattern()方法的实现)：

    InputStream is = ...; // Get a stream from the Asset object

    // Prepare a pattern object
    Pattern pattern = new Pattern();

    // Now start reaing from the stream
    StringBuffer buffy = new StringBuffer();
    BufferedReader bread = new BufferedReader(new InputStreamReader(is));
    while (bread.ready()) {
        String s = bread.readLine();
        if ((s != null) && (s.length() > 1)) {
            if (s.charAt(0) != '#') {
                buffy.append(" ");
                buffy.append(s);
            } else {
                String key = s.substring(1, s.indexOf(':')).trim();
                String value = s.substring(s.indexOf(':')+1, s.length()).trim();
                if (key.equalsIgnoreCase(TITLE)) {
                    pattern.setTitle(value);
                } else {
                    pattern.setProperty(key, value);
                }
            }
        }
    }
    bread.close();
    pattern.setMusicString(buffy.toString());

    // Your pattern is now ready