java - 从 JarInputStream 读取类到列表时出现 ClassNotFoundException

Question

我正在读取 Jar 文件，并使用 JarInputStream 将文件分成单独的类。如果我在控制台中打印出名称，它工作正常，但是当我尝试使用 Class.forName(name) 并将其添加到我的列表中时，程序会抛出 ClassNotFoundException。

 list = new ClassList();

    JarInputStream in = new JarInputStream(new FileInputStream(new File("test-jar.jar")));

    JarEntry next = in.getNextJarEntry();

    while (next != null) 
    {
         if (next.getName().endsWith(".class")) 
         {
             String name = next.getName().replaceAll("/", "\\.");

             name = name.replaceAll(".class", "");

             if (!name.contains("$")) name.substring(0, name.length() - ".class".length());

             System.out.println(name);

             Class queryClass;

             try {
                 queryClass = Class.forName(name);
                 list.add(queryClass);
             } catch (ClassNotFoundException e) {
                 e.printStackTrace();
             }

             System.out.println(list.size());
         }
         next = in.getNextJarEntry();

    }

包名称:
ie.gmit.sw

类名
工匠、Galaxian玩家、业余爱好者、律师、Pastimable、玩家、扑克玩家、运行者、科学家、 worker 、斯诺克玩家、集邮者、学生

堆栈跟踪

java.lang.ClassNotFoundException: ie.gmit.sw.Playerable
ie.gmit.sw.Runner
1
ie.gmit.sw.Playerable
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at ie.gmit.sw.ReadinJarFile.main(ReadinJarFile.java:39)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
1
ie.gmit.sw.Scientist
1
ie.gmit.sw.PokerPlayer
1
ie.gmit.sw.SnookerPlayer
1
ie.gmit.sw.Lawyer
1
ie.gmit.sw.Worker
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
java.lang.ClassNotFoundException: ie.gmit.sw.Scientist
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at ie.gmit.sw.ReadinJarFile.main(ReadinJarFile.java:39)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
java.lang.ClassNotFoundException: ie.gmit.sw.PokerPlayer
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at ie.gmit.sw.ReadinJarFile.main(ReadinJarFile.java:39)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
java.lang.ClassNotFoundException: ie.gmit.sw.SnookerPlayer
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at ie.gmit.sw.ReadinJarFile.main(ReadinJarFile.java:39)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
java.lang.ClassNotFoundException: ie.gmit.sw.Lawyer
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at ie.gmit.sw.ReadinJarFile.main(ReadinJarFile.java:39)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
java.lang.ClassNotFoundException: ie.gmit.sw.Worker
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at ie.gmit.sw.ReadinJarFile.main(ReadinJarFile.java:39)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
1

Answer 1

如果您想从 jar 文件加载任何 class，则该 jar 文件应存在于您的应用程序classpath<中。使用 JarInputStream 读取 jar 文件不会将该 jar 添加到您的类路径中。在您的应用程序classpath中添加该jar，此异常就会消失。