Question

正在使用的技术：Java 1.8和Maven

我有一个模块（A）引用另一个模块（B），我希望在运行时获得B的模块版本。

下面的代码是在运行时返回A的版本而不是B的版本。

我也引用了另一个问题： reading MANIFEST.MF file from jar file using JAVA

模块（B）中返回其版本的代码：

public static String getVersion() {
    if (StringUtils.isBlank(version)) {
        Class<?> clazz = Runner.class;
        String className = clazz.getSimpleName() + ".class";
        String classPath = clazz.getResource(className).toString();
        if (!classPath.startsWith("jar")) {
            // Class not from JAR
            String relativePath = clazz.getName().replace('.', File.separatorChar) + ".class";
            String classFolder = classPath.substring(0, classPath.length() - relativePath.length() - 1);
            String manifestPath = classFolder + "/META-INF/MANIFEST.MF";
            //log.debug("manifestPath={}", manifestPath);
            version = readVersionFrom(manifestPath);
        } else {
            String manifestPath = classPath.substring(0, classPath.lastIndexOf("!") + 1) + "/META-INF/MANIFEST.MF";
            System.out.println(String.format("manifestPath={%s}", manifestPath));
            version = readVersionFrom(manifestPath);
        }
    }
    return version;
}

private static String readVersionFrom(String manifestPath) {
    Manifest manifest = null;
    try {
        manifest = new Manifest(new URL(manifestPath).openStream());
        Attributes attrs = manifest.getMainAttributes();

        String implementationVersion = attrs.getValue("Implementation-Version");
        implementationVersion = StringUtils.replace(implementationVersion, "-SNAPSHOT", "");
        //log.debug("Read Implementation-Version: {}", implementationVersion);

        String implementationBuild = attrs.getValue("Implementation-Build");
        //log.debug("Read Implementation-Build: {}", implementationBuild);

        String version = implementationVersion;
        if (StringUtils.isNotBlank(implementationBuild)) {
            version = StringUtils.join(new String[] { implementationVersion, implementationBuild }, '.');
        }
        return version;
    } catch (Exception e) {
        //log.error(e.getMessage(), e);
    }
    return StringUtils.EMPTY;
}

模块（A）中的代码从模块（B）获取版本：

moduleB.getVersion()

命令我用来运行模块（A）打包的jar：

java -jar test.jar

Answer 1

public static Manifest manifest(Class<?> clazz) throws IOException {
        URL resource = clazz.getResource("/" + clazz.getName().replace(".", "/") + ".class");
        System.out.println(resource);
        String resourceBase = resource.toString().replace(clazz.getName().replace(".", "/") + ".class", "");
        System.out.println(resourceBase);
        Enumeration<URL> resources = clazz.getClassLoader().getResources("META-INF/MANIFEST.MF");
        while (resources.hasMoreElements()) {
            try {
                URL nextElement = resources.nextElement();
                if (nextElement.toString().equals(resourceBase + "META-INF/MANIFEST.MF")) {
                    System.out.println(nextElement);
                    Manifest manifest = new Manifest(nextElement.openStream());
                    return manifest;
                }
            } catch (IOException E) {
                //
            }
        }
        return null;
    }

的System.out.println（清单（T.class）.getMainAttributes（）的getValue（＆＃34;实施-版＆＃34））;

不要忘记检查是否有清单，它会返回null

使用Java从引用的模块获取版本

1 个答案: