以编程方式分析jar文件 [英] analyze jar file programmatically
问题描述
我需要以编程方式计算给定jar文件中已编译的类,接口和枚举的数量(因此我需要三个单独的数字)。哪种API对我有帮助? (我不能使用第三方库。)
I need to count the number of compiled classes, interfaces and enums in a given jar file programmatically (so I need three separate numbers). Which API would help me? (I can't use third party libraries.)
我已经尝试了相当棘手的方案,似乎并不总是正确的。也就是说,我将每个ZipEntry读入一个byte [],然后将结果提供给我的自定义类加载器,它扩展了标准的CalssLoader,并将此byte []发送到ClassLoader.defineClass(这是保护,无法直接从应用程序代码调用)。完整代码是在Pastebin上。
I've already tried quite tricky scheme which seems not always correct. Namely, I read each ZipEntry into a byte[] and then feed the result to my custom class loader which extends standard CalssLoader and just sends this byte[] to ClassLoader.defineClass (which is protect and couldn't be called from application code directly). Full code is on the Pastebin.
推荐答案
jar文件是具有特定模式的zip文件。
您可以使用ZipFile和ZipEntry或他们的子类JarFile和JarEntry。
A jar file is a zip file with a specific pattern. You may use a ZipFile and a ZipEntry or their children classes JarFile and JarEntry.
此代码(自定义类加载器的方法)将返回一个Map您需要的每种类型类的数组。
This code (a method of a custom classloader) will return a Map with arrays of each type of "class" you need.
public Map<String, List<Class<?>>> loadAndScanJar(File jarFile)
throws ClassNotFoundException, ZipException, IOException {
// Load the jar file into the JVM
// You can remove this if the jar file already loaded.
super.addURL(jarFile.toURI().toURL());
Map<String, List<Class<?>>> classes = new HashMap<String, List<Class<?>>>();
List<Class<?>> interfaces = new ArrayList<Class<?>>();
List<Class<?>> clazzes = new ArrayList<Class<?>>();
List<Class<?>> enums = new ArrayList<Class<?>>();
List<Class<?>> annotations = new ArrayList<Class<?>>();
classes.put("interfaces", interfaces);
classes.put("classes", clazzes);
classes.put("annotations", annotations);
classes.put("enums", enums);
// Count the classes loaded
int count = 0;
// Your jar file
JarFile jar = new JarFile(jarFile);
// Getting the files into the jar
Enumeration<? extends JarEntry> enumeration = jar.entries();
// Iterates into the files in the jar file
while (enumeration.hasMoreElements()) {
ZipEntry zipEntry = enumeration.nextElement();
// Is this a class?
if (zipEntry.getName().endsWith(".class")) {
// Relative path of file into the jar.
String className = zipEntry.getName();
// Complete class name
className = className.replace(".class", "").replace("/", ".");
// Load class definition from JVM
Class<?> clazz = this.loadClass(className);
try {
// Verify the type of the "class"
if (clazz.isInterface()) {
interfaces.add(clazz);
} else if (clazz.isAnnotation()) {
annotations.add(clazz);
} else if (clazz.isEnum()) {
enums.add(clazz);
} else {
clazzes.add(clazz);
}
count++;
} catch (ClassCastException e) {
}
}
}
System.out.println("Total: " + count);
return classes;
}
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