Classes and resources with a single letter component in their package name cannot be loaded from jar files with /./ or /../ in their path

[bes2008]

our project load mysql 8 class fail:

package config:

<plugin>
      <groupId>org.spring.framework.boot</groupId>
      <artifactId>spring-boot-maven-plugin</artifactId>
      <executions>
             <execution>
                    <goals>
                         <goal>repackage</goal>
                    </goals>
             </execution>
      </executions>
      <configuration>
            <mainClass>our main class</mainClass>
            <layout>ZIP</layout>
            <excludes>
                  <exclude>
                         <groupId>mysql</groupId>
                         <artifactId>mysql-connector-java</artifactId>
                  </exclude>
            </excludes>
      </configuration>
</plugin>

project dist directory:

/--bin/
 --config/
 --lib/
     --drivers/
          -- mysql-connector-java-8.0.15.jar
     --bootstrap.jar
 --scripts/

by debug, I found when load 'com/mysql/cj/protocol/a/result/NativeResultset.class'，
the spring boot custom URLStremHandler (org/springframework/boot/loader/jar/Handler.java
Handler.java ) will parse 'com/mysql/cj/protocol/a/result/NativeResultset.class' as 'com/mysql/cj/protocol/result/NativeResultset.class' 。

In other words, every single letter directory will be parse as empty string "";

[wilkinsona]

Thanks for the report. Which version of Spring Boot are you using?

[bes2008]

1. we can reproduce this bug in 2.1.3.RELEASE ~ 2.1.6.RELEASE versions
2. only windows has the bug
3. JDK 8

[wilkinsona]

I've just noticed that your using a zip layout and a custom dist directory structure. To ensure that we are looking at the same situation as you, please provide a minimal sample that reproduces the problem, either as a zip attached to this issue or in a separate repository on GitHub.

[springborland]

Fix this issue at springborland@b67c714.

[wilkinsona]

Thanks, @springborland. Before we consider a fix, I'd like to make sure the problem is fully understood. To do that, I'd really like to see a sample from @fangjinuo that reproduces the problem.

[bes2008]

Based on debug, I simplify the reproduction of the issue:

step1 : create an empty maven project, with spring-boot-loader dependency:

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-loader</artifactId>
            <version>2.1.6.RELEASE</version>
        </dependency>
    </dependencies>

step2: create a test case:

import org.springframework.boot.loader.LaunchedURLClassLoader;
import org.springframework.boot.loader.jar.JarFile;

import java.io.File;
import java.net.URL;

public class SpringBootClassLoaderBugReproduce extends LaunchedURLClassLoader {
    public SpringBootClassLoaderBugReproduce(URL[] urls, ClassLoader parent) {
        super(urls, parent);
    }

    public static void main(String[] args) throws Exception {
        // mysql jdbc driver should not in the classpath of a project
        // To reproduce the issue, the path should has " /../ "
        File file = new File("E:/springbootbugreproduce/drivers/../drivers/mysql-connector-java-8.0.15.jar");
        System.out.println(file.exists());
        // spring boot's JarFile class
        JarFile jarFile = new JarFile(file);
        SpringBootClassLoaderBugReproduce reproduceCL = new SpringBootClassLoaderBugReproduce(new URL[]{jarFile.getUrl()}, SpringBootClassLoaderBugReproduce.class.getClassLoader());
        Class clazz = reproduceCL.findClass("com.mysql.cj.protocol.a.result.NativeResultset");
        System.out.println(clazz);
    }

}

step 3: put a mysql 8 jdbc driver in the specified directory:

step 4: execute the test case, the CLI result is:

true
Exception in thread "main" java.lang.ClassNotFoundException: com.mysql.cj.protocol.a.result.NativeResultset
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at SpringBootClassLoaderBugReproduce.main(SpringBootClassLoaderBugReproduce.java:20)