我试图从MANIFEST.MF文件中获取一些属性,但它们返回null。
歧管
Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Built-By: jenkins
Build-Time: 2016-04-09T18:02:46Z Class-Path: spigot-1.8-R0.1-SNAPSHOT.jar Created-By: Apache Maven 3.3.9
Build-Jdk: 1.8.0_77
Name: Build Details
Implementation-SCM-Revision: SomeCommit
Implementation-Build-Number: SomeBuildNumber
Implementation-Title: SomeTitle
Implementation-Version: 4.0.0-SNAPSHOT
代码(此代码不是使用的确切代码,但几乎相同)
首次尝试
public void doStuff() {
String version;
InputStream stream = Main.class.getClassLoader().getResourceAsStream("META-INF/MANIFEST.MF");
Properties properties = new Properties();
if (stream != null) {
try {
properties.load(stream);
version = properties.getProperty("Implementation-SCM-Revision"); //This is null
} catch (IOException ex) {
//TODO handle exception
}
}
第二次尝试
public void doStuff() {
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-SCM-Revision"); //This is null
}
}
catch (Exception e) {
}
}
} catch (IOException e1) {
}
}
问题是,当Attributes#getMainAttributes()中的所有键都打印出来时,它会打印[Archiver-Version, Implementation-Title, Sealed, Specification-Version, Implementation-Version, Created-By, Manifest-Version, Build-Jdk, Specification-Vendor, Implementation-Vendor, Ant-Version, Specification-Title, Built-By, Main-Class]
,而不包括Implementation-SCM-Revision
之类的东西。这就是我想要得到的。
没有生成stacktrace,它只是在打印Implementation-SCM-Revision
属性时在控制台中打印null
Oracle成功地破坏了Manifest类,尽管它很难:
JDK-8201636尝试读取清单文件属性时为空值
另请参阅MANIFEST实体的类似错误:
JDK-8031748澄清jar文件中的jar条目顺序:
从一开始,jar文件就有一个"未记录"的假设MANIFEST.MF文件和签名相关文件(块和SF)应该出现在开头(除了目录条目,META-INF/)。
当前的答案是错误的。虽然它提到的错误报告并非无关,但问题中提供的代码中存在明显错误。因此,它并没有提供错误的信息,但它表明了一个错误的结论。
属性Implementation-SCM-Revision
不是主属性,而是清单条目Build Details
的属性。
简化后,清单具有以下形式
# fixed
Manifest-Version: 1.0
# Main Attributes
Implementation-Version: 1.0
# 'Name:' marks the beginning of an entry
Name: com.example.Foo
# all following lines belong to the previously started entry
# this line therefore applies to com.example.Foo
Checksum: 76652367792347
因此,要检索Implementation-SCM-Revision
的值,必须执行
manifest.getAttributes("Build Details").getValue("Implementation-SCM-Revision");
反过来,为了通过manifest.getMainAttributes()
检索Implementation-SCM-Revision
,它必须高于Name:
Manifest-Version: 1.0
# other main attributes
Implementation-SCM-Revision: SomeCommit
Name: Build Details
# other entry-related attributes