我现在不在 IDE 面前，只是查看 API 规范。
CodeSource src = MyClass.class.getProtectionDomain().getCodeSource();
if (src != null) {
URL jar = src.getLocation();
}
我想确定一个类来自哪个 JAR 文件。是这样的吗？
【问题讨论】：
java -findjar -cp /some/path/with/libs/*.jar my.java.Class -> my.jar。
标签： java jar class classloader
是的。它适用于除引导类加载器加载的类之外的所有类。另一种判断方法是：
Class klass = String.class;
URL location = klass.getResource('/' + klass.getName().replace('.', '/') + ".class");
正如notnoop 指出的klass.getResource() 方法返回类文件本身的位置。例如：
jar:file:/jdk/jre/lib/rt.jar!/java/lang/String.class
file:/projects/classes/pkg/MyClass$1.class
getProtectionDomain().getCodeSource().getLocation()方法返回jar文件或CLASSPATH的位置
file:/Users/home/java/libs/ejb3-persistence-1.0.2.GA.jar
file:/projects/classes
【讨论】：
klass.getResource()？
从Lombok Patcher LiveInjector.java 签出LiveInjector.findPathJar()。请注意，文件实际上并不存在于 jar 中的特殊情况，您可能需要更改它。
/**
* If the provided class has been loaded from a jar file that is on the local file system, will find the absolute path to that jar file.
*
* @param context The jar file that contained the class file that represents this class will be found. Specify {@code null} to let {@code LiveInjector}
* find its own jar.
* @throws IllegalStateException If the specified class was loaded from a directory or in some other way (such as via HTTP, from a database, or some
* other custom classloading device).
*/
public static String findPathJar(Class<?> context) throws IllegalStateException {
if (context == null) context = LiveInjector.class;
String rawName = context.getName();
String classFileName;
/* rawName is something like package.name.ContainingClass$ClassName. We need to turn this into ContainingClass$ClassName.class. */ {
int idx = rawName.lastIndexOf('.');
classFileName = (idx == -1 ? rawName : rawName.substring(idx+1)) + ".class";
}
String uri = context.getResource(classFileName).toString();
if (uri.startsWith("file:")) throw new IllegalStateException("This class has been loaded from a directory and not from a jar file.");
if (!uri.startsWith("jar:file:")) {
int idx = uri.indexOf(':');
String protocol = idx == -1 ? "(unknown)" : uri.substring(0, idx);
throw new IllegalStateException("This class has been loaded remotely via the " + protocol +
" protocol. Only loading from a jar on the local file system is supported.");
}
int idx = uri.indexOf('!');
//As far as I know, the if statement below can't ever trigger, so it's more of a sanity check thing.
if (idx == -1) throw new IllegalStateException("You appear to have loaded this class from a local jar file, but I can't make sense of the URL!");
try {
String fileName = URLDecoder.decode(uri.substring("jar:file:".length(), idx), Charset.defaultCharset().name());
return new File(fileName).getAbsolutePath();
} catch (UnsupportedEncodingException e) {
throw new InternalError("default charset doesn't exist. Your VM is borked.");
}
}
【讨论】：
private String resourceLookup(String lookupResourceName) {
try {
if (lookupResourceName == null || lookupResourceName.length()==0) {
return "";
}
// "/java/lang/String.class"
// Check if entered data was in java class name format
if (lookupResourceName.indexOf("/")==-1) {
lookupResourceName = lookupResourceName.replaceAll("[.]", "/");
lookupResourceName = "/" + lookupResourceName + ".class";
}
URL url = this.getClass().getResource(lookupResourceName);
if (url == null) {
return("Unable to locate resource "+ lookupResourceName);
}
String resourceUrl = url.toExternalForm();
Pattern pattern =
Pattern.compile("(zip:|jar:file:/)(.*)!/(.*)", Pattern.CASE_INSENSITIVE);
String jarFilename = null;
String resourceFilename = null;
Matcher m = pattern.matcher(resourceUrl);
if (m.find()) {
jarFilename = m.group(2);
resourceFilename = m.group(3);
} else {
return "Unable to parse URL: "+ resourceUrl;
}
if (!jarFilename.startsWith("C:") ){
jarFilename = "/"+jarFilename; // make absolute path on Linux
}
File file = new File(jarFilename);
Long jarSize=null;
Date jarDate=null;
Long resourceSize=null;
Date resourceDate=null;
if (file.exists() && file.isFile()) {
jarSize = file.length();
jarDate = new Date(file.lastModified());
try {
JarFile jarFile = new JarFile(file, false);
ZipEntry entry = jarFile.getEntry(resourceFilename);
resourceSize = entry.getSize();
resourceDate = new Date(entry.getTime());
} catch (Throwable e) {
return ("Unable to open JAR" + jarFilename + " "+resourceUrl +"\n"+e.getMessage());
}
return "\nresource: "+resourceFilename+"\njar: "+jarFilename + " \nJarSize: " +jarSize+" \nJarDate: " +jarDate.toString()+" \nresourceSize: " +resourceSize+" \nresourceDate: " +resourceDate.toString()+"\n";
} else {
return("Unable to load jar:" + jarFilename+ " \nUrl: " +resourceUrl);
}
} catch (Exception e){
return e.getMessage();
}
}
【讨论】：
使用
String path = <Any of your class within the jar>.class.getProtectionDomain().getCodeSource().getLocation().getPath();
如果这包含多个条目，则执行一些子字符串操作。
【讨论】：
对于 Linux，我正在使用一个小脚本来帮助我找到可以在 find -exec 中使用的类所在的 jar：
findclass.sh:
unzip -l "$1" 2>/dev/null | grep $2 >/dev/null 2>&1 && echo "$1"
基本上，由于 jar 是 zip，unzip -l 将打印类资源列表，因此您必须将 . 转换为 /。你可以在脚本中用tr进行替换，但调用脚本时自己做也不会太麻烦。
这个想法是在类路径的根目录上使用 find 来定位所有 jar，然后在所有找到的 jar 上运行 findclass.sh 以查找匹配项。
它不处理多目录，但如果你仔细选择根目录，你可以让它工作。
现在，找到哪个 jar 包含类 org.apache.commons.lang3.RandomUtils 以便您取消项目 (...)：
$ find ~/.m2/repository/ -type f -name '*.jar' -exec findclass.sh {} org/apache/commons/lang3/RandomUtils \;
.m2/repository/org/apache/commons/commons-lang3/3.7/commons-lang3-3.7.jar
.m2/repository/org/apache/commons/commons-lang3/3.6/commons-lang3-3.6.jar
.m2/repository/org/apache/commons/commons-lang3/3.6/commons-lang3-3.6-sources.jar
$
【讨论】：