I am currently working on a J2ME polish application, just enhancing it. I am finding difficulties to get the exact version of the jar file.
Is there any way to find the version of the jar file for the imports done in the class? I mean if you have some thing, import x.y.z; can we know the version of the jar x.y package belongs to?

我目前正在开发一个J2ME波兰语应用程序，只是对其进行了增强。我发现很难获得JAR文件的准确版本。有没有办法为类中完成的导入找到JAR文件的版本？我的意思是，如果您有什么东西，导入x.y.z；我们可以知道JAR X.Y包的版本吗？

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Decompress the JAR file and look for the manifest file (META-INF\MANIFEST.MF). The manifest file of JAR file might contain a version number (but not always a version is specified).

解压缩JAR文件并查找清单文件(META-INF\MANIFEST.MF)。JAR文件的清单文件可能包含版本号(但并不总是指定版本)。

You need to unzip it and check its META-INF/MANIFEST.MF file, e.g.

您需要将其解压缩并检查其META-INF/MANIFEST.MF文件，例如

unzip -p file.jar | head

or more specific:

或者更具体地说：

unzip -p file.jar META-INF/MANIFEST.MF

Just to expand on the answers above, inside the META-INF/MANIFEST.MF file in the JAR, you will likely see a line: Manifest-Version: 1.0 ← This is NOT the jar versions number!

在JAR中的META-INF/MANIFEST.MF文件中，您可能会看到一行：MANIFEST-VERSION：1.0JAR←这不是JAR版本号！

You need to look for Implementation-Version which, if present, is a free-text string so entirely up to the JAR's author as to what you'll find in there.
See also Oracle docs and Package Version specificaion

您需要查找Implementation-Version，如果存在的话，它是一个自由文本字符串，因此完全取决于您在其中找到的内容。另请参阅Oracle文档和包版本规范

Just to complete the above answer.

只是为了完成上面的答案。

Manifest file is located inside jar at META-INF\MANIFEST.MF path.

清单文件位于JAR内的META-INF\MANIFEST.MF路径下。

You can examine jar's contents in any archiver that supports zip.

您可以在任何支持Zip的归档程序中检查JAR的内容。

Each jar version has a unique checksum. You can calculate the checksum for you jar (that had no version info) and compare it with the different versions of the jar. We can also search a jar using checksum.

每个JAR版本都有一个唯一的校验和。您可以计算JAR(没有版本信息)的校验和，并将其与JAR的不同版本进行比较。我们还可以使用校验和来搜索JAR。

Refer this Question to calculate checksum:
What is the best way to calculate a checksum for a file that is on my machine?

请参考以下问题来计算校验和：为我的计算机上的文件计算校验和的最佳方法是什么？

Basically you should use the java.lang.Package class which use the classloader to give you informations about your classes.

基本上，您应该使用java.lang.Package类，它使用类加载器为您提供有关类的信息。

example:

示例：

String.class.getPackage().getImplementationVersion();
Package.getPackage(this).getImplementationVersion();
Package.getPackage("java.lang.String").getImplementationVersion();

I think logback is known to use this feature to trace the JAR name/version of each class in its produced stacktraces.

我认为众所周知，Logback使用此功能来跟踪其生成的堆栈跟踪中每个类的JAR名称/版本。

see also http://docs.oracle.com/javase/8/docs/technotes/guides/versioning/spec/versioning2.html#wp90779

另请参阅http://docs.oracle.com/javase/8/docs/technotes/guides/versioning/spec/versioning2.html#wp90779

Thought I would give a more recent answer as this question still comes up pretty high on searches.

我想我会给出一个更新的答案，因为这个问题在搜索量上仍然很高。

Checking CLi JAR Version:

检查CLi版本：

Run the following on the CLi jar file:

对CLI JAR文件运行以下命令：

unzip -p jenkins-cli.jar META-INF/MANIFEST.MF

Example Output:

输出示例：

Manifest-Version: 1.0
Built-By: kohsuke
Jenkins-CLI-Version: 2.210  <--- Jenkins CLI Version
Created-By: Apache Maven 3.6.1
Build-Jdk: 1.8.0_144
Main-Class: hudson.cli.CLI

The CLi version is listed above.

上面列出了CLI版本。

To get the Server Version, run the following:

要获取服务器版本，请运行以下命令：

java -jar ./jenkins-cli.jar -s https://<Server_URL> -auth <email>@<domain>.com:<API Token> version

(the above will vary based on your implementation of authentication, please change accordingly)

(以上内容将根据您的身份验证实施情况而有所不同，请相应更改)

Example Output:

输出示例：

Dec 23, 2019 4:42:55 PM org.apache.sshd.common.util.security.AbstractSecurityProviderRegistrar getOrCreateProvider
INFO: getOrCreateProvider(EdDSA) created instance of net.i2p.crypto.eddsa.EdDSASecurityProvider
2.210  <-- Jenkins Server Version

This simple program will list all the cases for version of jar namely

这个简单的程序将列出JAR版本的所有情况，即

• Version found in Manifest file


• No version found in Manifest and even from jar name



• Manifest file not found

  找不到清单文件

  
  
  

  Map<String, String> jarsWithVersionFound   = new LinkedHashMap<String, String>();
  List<String> jarsWithNoManifest     = new LinkedList<String>();
  List<String> jarsWithNoVersionFound = new LinkedList<String>();
  
  //loop through the files in lib folder
  //pick a jar one by one and getVersion()
  //print in console..save to file(?)..maybe later
  
  File[] files = new File("path_to_jar_folder").listFiles();
  
  for(File file : files)
  {
      String fileName = file.getName();
  
  
      try
      {
          String jarVersion = new Jar(file).getVersion();
  
          if(jarVersion == null)
              jarsWithNoVersionFound.add(fileName);
          else
              jarsWithVersionFound.put(fileName, jarVersion);
  
      }
      catch(Exception ex)
      {
          jarsWithNoManifest.add(fileName);
      }
  }
  
  System.out.println("******* JARs with versions found *******");
  for(Entry<String, String> jarName : jarsWithVersionFound.entrySet())
      System.out.println(jarName.getKey() + " : " + jarName.getValue());
  
  System.out.println("\n \n ******* JARs with no versions found *******");
  for(String jarName : jarsWithNoVersionFound)
      System.out.println(jarName);
  
  System.out.println("\n \n ******* JARs with no manifest found *******");
  for(String jarName : jarsWithNoManifest)
      System.out.println(jarName);
  

It uses the javaxt-core jar which can be downloaded from http://www.javaxt.com/downloads/

它使用的是可以从http://www.javaxt.com/downloads/下载的Java-core JAR

I'm late this but you can try the following two methods

我这次迟到了，但你可以尝试以下两种方法

using these needed classes

使用这些所需的类

import java.util.jar.Attributes;
import java.util.jar.Manifest;

These methods let me access the jar attributes. I like being backwards compatible and use the latest. So I used this

这些方法允许我访问JAR属性。我喜欢向后兼容，并使用最新的。所以我用了这个

public Attributes detectClassBuildInfoAttributes(Class sourceClass) throws MalformedURLException, IOException {
    String className = sourceClass.getSimpleName() + ".class";
    String classPath = sourceClass.getResource(className).toString();
    if (!classPath.startsWith("jar")) {
      // Class not from JAR
      return null;
    }
    String manifestPath = classPath.substring(0, classPath.lastIndexOf("!") + 1) + 
        "/META-INF/MANIFEST.MF";
    Manifest manifest = new Manifest(new URL(manifestPath).openStream());
    return manifest.getEntries().get("Build-Info");
}

public String retrieveClassInfoAttribute(Class sourceClass, String attributeName) throws MalformedURLException, IOException {
    Attributes version_attr = detectClassBuildInfoAttributes(sourceClass);

    String attribute = version_attr.getValue(attributeName);

    return attribute;
}

This works well when you are using maven and need pom details for known classes. Hope this helps.

当您使用maven并且需要已知类的pom细节时，这很有效。希望这能帮上忙。

For Linux, try following:

对于Linux，请尝试以下操作：

find . -name "YOUR_JAR_FILE.jar" -exec zipgrep "Implementation-Version:" '{}' \;|awk -F ': ' '{print $2}'

找到。-name“Your_JAR_FILE.jar”-exec zipgrep“Implementation-Version：”‘{}’\；|awk-F‘：’‘{print$2}’

If you have winrar, open the jar with winrar, double-click to open folder META-INF. Extract MANIFEST.MF and CHANGES files to any location (say desktop).

如果你有WinRar，用WinRar打开JAR，双击打开META-INF文件夹。解压缩MANIFEST.MF并将文件更改到任何位置(例如桌面)。

Open the extracted files in a text editor: You will see Implementation-Version or release version.

在文本编辑器中打开解压缩文件：您将看到Implementation-Version或Release Version。

You can filter version from the MANIFEST file using

您可以使用以下命令从清单文件中筛选版本

unzip -p my.jar META-INF/MANIFEST.MF | grep 'Bundle-Version'

解压缩-p my.jar META-INF/MANIFEST.MF|grep‘Bundle-Version’

best solution that does not involve extracting the jar files is to run the following command. If the jar file does not contain a manifest file you will get a "WARNING: Manifest file not found"

不需要解压缩JAR文件的最佳解决方案是运行以下命令。如果JAR文件不包含清单文件，您将收到“警告：未找到清单文件”

java -jar file.jar -v

JAVA-JAR文件.jar-v

You could execute this script, it will find all versions of jar files in a directory:

您可以执行此脚本，它将在一个目录中找到所有版本的JAR文件：

find /directory -maxdepth 3 -name "*.jar" | xargs -l % sh -c "JAR=\"\$(basename % .jar)"; VERSION=\"\$(unzip -q -c % META-INF/MANIFEST.MF | grep 'Implementation-Version' cut -d' ' -f2)\"; echo \"\$JAR \$VERSION\";" | sort

[A] Manually we can extract/unzip the jar file and check Bundle-Version or Implementation-Version keyword in META-INF/MANIFEST.MF file.

[A]我们可以手动解压/解压缩JAR文件，并检查META-INF/MANIFEST.MF文件中的Bundle-Version或Implementation-Version关键字。

[B] In Unix environment ,
you can easily use the grep command in combination with unzip and then cut command to get the version.
[This soluction does assume that there will be version mentioned in META-INF/MANIFEST.MF . (80% chances)]

[B]在Unix环境下，你可以很容易地使用grep命令与unzip命令结合，然后再使用cut命令来获取版本。[This solvent确实假定在META-INF/MANIFEST.MF中会有提到版本。(80% chances）]

Run below command to get the VERSION.

运行下面的命令以获取版本。

VERSION=unzip -p "javaPackage.jar" "META-INF/MANIFEST.MF" | grep -m1 -E "Bundle-Version|Implementation-Version:" | cut -d':' -f2 | awk '{$1=$1;print}' 2>/dev/null;

VERSION=unzip -p“javaPackage.jar”“META-INF/MANIFEST.MF”|grep -m1 -E“Bundle-Version|实施版本：“|cut -d'：' -f2| awk '{$1=$1;print}' 2>/dev/null;

Explanation :

解释：

1. unzip -> Get content of META-INF/MANIFEST.MF file from your java jar, This can be done without extracting the jar.


2. grep -> Search matching word against either "Bundle-Version" or "Implementation-Version:" keyword


3. cut -> Split based on hyphen and get 2nd part


4. awk -> Trim space present around the jar-version


5. 2>/dev/null -> Error redirection to /dev/null

Note : - If you want to find version of multiple jars , then run a for loop and call above script.

注意：-如果你想找到多个JAR的版本，那么运行一个for循环并调用上面的脚本。

Just rename the extension with .zip instead of .jar. Then go to META-INF/MANIFEST.MF and open the MANIFEST.MF file with notepad. You can find the implementation version there.

只需将扩展名重命名为.zip，而不是.jar。然后转到META-INF/MANIFEST.MF并使用记事本打开MANIFEST.MF文件。您可以在那里找到实现版本。

It can be checked with a command java -jar jarname

可以使用命令Java-jar jarname进行检查