Question

有什么方法可以读取jar文件的内容。就像我想读取清单文件，以便找到jar文件和版本的创建者。有没有办法实现同样的目标。

Answer 1

下一段代码应该有所帮助：

JarInputStream jarStream = new JarInputStream(stream);
Manifest mf = jarStream.getManifest();

为您留下异常处理:)

Answer 2

您可以使用以下内容：

public static String getManifestInfo() {
    Enumeration resEnum;
    try {
        resEnum = Thread.currentThread().getContextClassLoader().getResources(JarFile.MANIFEST_NAME);
        while (resEnum.hasMoreElements()) {
            try {
                URL url = (URL)resEnum.nextElement();
                InputStream is = url.openStream();
                if (is != null) {
                    Manifest manifest = new Manifest(is);
                    Attributes mainAttribs = manifest.getMainAttributes();
                    String version = mainAttribs.getValue("Implementation-Version");
                    if(version != null) {
                        return version;
                    }
                }
            }
            catch (Exception e) {
                // Silently ignore wrong manifests on classpath?
            }
        }
    } catch (IOException e1) {
        // Silently ignore wrong manifests on classpath?
    }
    return null; 
}

要获取清单属性，您可以迭代变量“mainAttribs”，或者如果您知道密钥，则直接检索所需的属性。

此代码循环遍历类路径上的每个jar并读取每个jar的MANIFEST。如果您知道jar的名称，您可能只想查看URL，如果它包含（）您感兴趣的jar的名称。

Answer 3

我建议做以下事项：

Package aPackage = MyClassName.class.getPackage();
String implementationVersion = aPackage.getImplementationVersion();
String implementationVendor = aPackage.getImplementationVendor();

MyClassName可以是您编写的应用程序中的任何类。

Answer 4

我根据stackoverflow的一些想法实现了一个AppVersion类，这里我只是分享整个类：

import java.io.File;
import java.net.URL;
import java.util.jar.Attributes;
import java.util.jar.Manifest;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class AppVersion {
  private static final Logger log = LoggerFactory.getLogger(AppVersion.class);

  private static String version;

  public static String get() {
    if (StringUtils.isBlank(version)) {
      Class<?> clazz = AppVersion.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";
        log.debug("manifestPath={}", 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;
  }
}

基本上，此类可以从其自己的JAR文件的清单或其classes文件夹中的清单中读取版本信息。希望它可以在不同的平台上运行，但到目前为止我只在Mac OS X上测试过它。

我希望这对其他人有用。

Answer 5

您可以使用Manifests中的实用工具类jcabi-manifests：

final String value = Manifests.read("My-Version");

该类将找到类路径中可用的所有MANIFEST.MF文件，并从其中一个文件中读取您要查找的属性。另请阅读：http://www.yegor256.com/2014/07/03/how-to-read-manifest-mf.html

Answer 6

保持简单。 JAR也是ZIP，因此任何ZIP代码都可用于阅读MAINFEST.MF：

public static String readManifest(String sourceJARFile) throws IOException
{
    ZipFile zipFile = new ZipFile(sourceJARFile);
    Enumeration entries = zipFile.entries();

    while (entries.hasMoreElements())
    {
        ZipEntry zipEntry = (ZipEntry) entries.nextElement();
        if (zipEntry.getName().equals("META-INF/MANIFEST.MF"))
        {
            return toString(zipFile.getInputStream(zipEntry));
        }
    }

    throw new IllegalStateException("Manifest not found");
}

private static String toString(InputStream inputStream) throws IOException
{
    StringBuilder stringBuilder = new StringBuilder();
    try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream)))
    {
        String line;
        while ((line = bufferedReader.readLine()) != null)
        {
            stringBuilder.append(line);
            stringBuilder.append(System.lineSeparator());
        }
    }

    return stringBuilder.toString().trim() + System.lineSeparator();
}

尽管有灵活性，但只需阅读数据this，答案是最好的。

Answer 7

以简单的方式实现属性

    public static String  getMainClasFromJarFile(String jarFilePath) throws Exception{
    // Path example: "C:\\Users\\GIGABYTE\\.m2\\repository\\domolin\\DeviceTest\\1.0-SNAPSHOT\\DeviceTest-1.0-SNAPSHOT.jar";
    JarInputStream jarStream = new JarInputStream(new FileInputStream(jarFilePath));
    Manifest mf = jarStream.getManifest();
    Attributes attributes = mf.getMainAttributes();
    // Manifest-Version: 1.0
    // Built-By: GIGABYTE
    // Created-By: Apache Maven 3.0.5
    // Build-Jdk: 1.8.0_144
    // Main-Class: domolin.devicetest.DeviceTest
    String mainClass = attributes.getValue("Main-Class");
    //String mainClass = attributes.getValue("Created-By");
    //  Output: domolin.devicetest.DeviceTest
    return mainClass;
}

Answer 8

阅读版本；
我们将MANIFEST.MF从jar复制到了用户家。

    public void processManifestFile() {
        String version = this.getClass().getPackage().getImplementationVersion();
        LOG.info("Version: {}", version);
        Path targetFile = Paths.get(System.getProperty("user.home"), "my-project", "MANIFEST.MF");

        try {
            URL url = this.getClass().getProtectionDomain().getCodeSource().getLocation();
            JarFile jarFile = new JarFile(url.getFile());
            Manifest manifest = jarFile.getManifest();
            try(FileWriter fw = new FileWriter(targetFile.toFile())) {
                manifest.getMainAttributes().entrySet().stream().forEach( x -> {
                    try {
                        fw.write(x.getKey() + ": " + x.getValue() + "\n");
                        LOG.info("{}: {}", x.getKey(), x.getValue());
                    } catch (IOException e) {
                        LOG.error("error in write manifest, {}", e.getMessage());
                    }
                });
            }
            LOG.info("Copy MANIFEST.MF to {}", targetFile);
        } catch (Exception e) {
            LOG.error("Error in processing MANIFEST.MF file", e);
        }
    }

使用JAVA从jar文件中读取MANIFEST.MF文件

8 个答案: