at java.net.urlclassloader.findclass

java.net.URLClassLoader.findClass是Java中的一个方法，用于在指定的URL路径中查找指定的类。它是Java中的一个类加载器，用于从指定的URL路径中加载类。当Java程序需要使用某个类时，它会首先尝试从系统类路径中查找该类，如果找不到，则会使用URLClassLoader来查找该类。

相关问题

at java.net.URLClassLoader.findClass(URLClassLoader.java:382)

This exception is thrown when the Java Virtual Machine (JVM) is unable to find a class using a URLClassLoader. The URLClassLoader is used to load classes from a specified set of URLs.

The exception is typically caused by one of the following reasons:

1. The class is not present in the specified URLs.
2. The class is present in the specified URLs but is not in the correct package or directory structure.
3. The class is present in the specified URLs but has not been compiled or packaged correctly.
4. There is a conflict between different versions of the same class.

To resolve this exception, you should check the following:

1. Check that the class is present in the specified URLs.
2. Check that the class is in the correct package or directory structure.
3. Check that the class has been compiled and packaged correctly.
4. Check for conflicts between different versions of the same class.

If you are still unable to resolve the issue, you should seek help from a Java developer or post a question on a Java forum.

[root@localhost jx]# java -jar haikongweishi-1.0-SNAPSHOT.jar Exception in thread "main" java.lang.NoClassDefFoundError: com/sun/jna/Library at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:756) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:468) at java.net.URLClassLoader.access$100(URLClassLoader.java:74) at java.net.URLClassLoader$1.run(URLClassLoader.java:369) at java.net.URLClassLoader$1.run(URLClassLoader.java:363) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:362) at java.lang.ClassLoader.loadClass(ClassLoader.java:418) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355) at java.lang.ClassLoader.loadClass(ClassLoader.java:351) at client.LinuxClientDemo.<clinit>(LinuxClientDemo.java:8) Caused by: java.lang.ClassNotFoundException: com.sun.jna.Library at java.net.URLClassLoader.findClass(URLClassLoader.java:382) at java.lang.ClassLoader.loadClass(ClassLoader.java:418) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355) at java.lang.ClassLoader.loadClass(ClassLoader.java:351) ... 13 more [root@localhost jx]#

这个错误提示显示找不到 `com.sun.jna.Library` 类，可能是因为你的程序依赖了 JNA 库，但是在运行时没有找到这个库。你可以尝试将 JNA 库添加到你的 classpath 中，具体步骤如下：

1. 下载 JNA 库，可以从官方网站下载：https://github.com/java-native-access/jna
2. 将 JNA 的 jar 包添加到你的工程中，可以在 Maven 中添加以下依赖：

<dependency>
    <groupId>net.java.dev.jna</groupId>
    <artifactId>jna</artifactId>
    <version>5.7.0</version>
</dependency>

3. 重新打包你的程序，并使用 `java -jar` 命令运行。如果你使用的是 Maven，可以使用以下命令打包：

mvn clean package

这个命令会在 `target` 目录下生成一个名为 `haikongweishi-1.0-SNAPSHOT.jar` 的文件，可以使用 `java -jar haikongweishi-1.0-SNAPSHOT.jar` 命令运行。