java - 从当前运行的 jar 中提取一个 jar

Question

我正在尝试从当前运行的 jar 中提取 2 个 jar 文件，但是它们总是以 2kb 结束，即使它们的大小是 104kb 和 1.7m，这是我得到的

public static boolean extractFromJar(String fileName, String dest) {
    if (Configuration.getRunningJarPath() == null) {
        return false;
    }
    File file = new File(dest + fileName);
    if (file.exists()) {
        return false;
    }

    if (file.isDirectory()) {
        file.mkdir();
        return false;
    }
    try {
        JarFile jar = new JarFile(Configuration.getRunningJarPath());
        Enumeration<JarEntry> e = jar.entries();
        while (e.hasMoreElements()) {
            JarEntry je = e.nextElement();
            InputStream in = new BufferedInputStream(jar.getInputStream(je));
            OutputStream out = new BufferedOutputStream(
                    new FileOutputStream(file));
            copyInputStream(in, out);
        }
        return true;
    } catch (Exception e) {
        Methods.debug(e);
        return false;
    }
}

private final static void copyInputStream(InputStream in, OutputStream out)
        throws IOException {
    while (in.available() > 0) {
        out.write(in.read());
    }
    out.flush();
    out.close();
    in.close();
}

Answer 1

这应该比依赖 InputStream.available() 方法效果更好:

private final static void copyInputStream(InputStream in, OutputStream out)
        throws IOException {
    byte[] buff = new byte[4096];
    int n;
    while ((n = in.read(buff)) > 0) {
        out.write(buff, 0, n);
    }
    out.flush();
    out.close();
    in.close();
}