[英]ClassNotFoundException in ObjectInputStream.readObject()
[英]ObjectInputStream#readObject raises ClassNotFoundException with External Jar classes
所以我有一个 Spring 引导应用程序,它从以下路径加载外部 jars:
java -cp "main-0.0.1-SNAPSHOT.jar" -Dloader.path="%USERPROFILE%\Addons\" -Dloader.main=moe.ofs.backend.BackendApplication org.springframework.boot.loader.PropertiesLauncher
主 jar 在编译时不知道外部 jars。 通过指定外部 jars 像“插件”或“插件”一样加载
-Dloader.path=...
所有外部 jars 都依赖于来自“main-0.0.1-SNAPSHOT.jar”的接口,它们应该或多或少地进行 object 序列化。 该接口称为Configurable
,它提供了两种默认方法,如下所示:
default <T extends Serializable> void writeFile(T object, String fileName) throws IOException {
Path configFilePath = configPath.resolve(fileName + ".data");
FileOutputStream fileOutputStream = new FileOutputStream(configFilePath.toFile());
ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
objectOutputStream.writeObject(object);
objectOutputStream.close();
}
default <T extends Serializable> T readFile(String fileName) throws IOException, ClassNotFoundException {
Path configFilePath = configPath.resolve(fileName + ".data");
FileInputStream fileInputStream = new FileInputStream(configFilePath.toFile());
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
return (T) objectInputStream.readObject();
}
外部 jars 中的类实现了这个接口,它们调用readFile()
和writeFile()
。
writeFile()
工作得很好,似乎没有引起任何问题; 但是, readFile()
会抛出ClassNotFoundException
,这就是我想要弄清楚的。
java.lang.ClassNotFoundException: moe.ofs.addon.navdata.domain.Navaid
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355)
at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:719)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1922)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1805)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2096)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1624)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:464)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:422)
at java.util.ArrayList.readObject(ArrayList.java:797)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1170)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:2232)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2123)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1624)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:464)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:422)
at moe.ofs.backend.Configurable.lambda$readFile$0(Configurable.java:186)
at java.lang.Thread.run(Thread.java:748)
经过一些测试,在我看来ClassNotFoundException
是由 Class.forName() 引发的,因为默认的 ClassLoader 很难找到moe.ofs.addon.navdata.domain.Navaid
,这是我正在尝试反序列化的 class 。
Navaid implements Serializable
,它还有一个static final long serialVersionUID
。
I had hoped that I could solve this by setting a context class loader for current thread, so that ObjectInputStream
will use Spring Boot class loader to resolve Navaid
class:
Thread.currentThread().setContextClassLoader(getClass().getClassLoader());
这在打印出来时会给出类似的东西
Thread.currentThread().getContextClassLoader() = org.springframework.boot.loader.LaunchedURLClassLoader@7a0b4753
除了ObjectInputStream#readObject
仍然抛出ClassNotFoundException
。 如果我明确调用从 Spring 引导加载程序加载 Navaid class ,例如:
getClass().getClassLoader().loadClass("moe.ofs.addon.navdata.domain.Navaid");
它返回一个Navaid
实例,没有任何问题。
正如预期的那样,直接调用时
Class.forName("moe.ofs.addon.navdata.domain.Navaid")
即使线程上下文加载器已显式设置为LaunchedURLClassLoader
,也会引发ClassNotFoundException
; ObjectInputStream#readObject
总是尝试通过调用系统默认类加载器来加载 class 来解析 class。
然后我尝试使用LaunchedURLClassLoader
加载ObjectInputStream
,但该实例仍然使用系统默认 class 加载器中的Class.forName()
。
ClassLoader cl = getClass().getClassLoader();
Thread.currentThread().setContextClassLoader(cl);
System.out.println("Thread.currentThread().getContextClassLoader() = " + Thread.currentThread().getContextClassLoader());
Class<?> tClass = getClass().getClassLoader().loadClass("java.io.ObjectInputStream");
System.out.println("tClass = " + tClass);
Path configFilePath = configPath.resolve(fileName + ".data");
FileInputStream fileInputStream = new FileInputStream(configFilePath.toFile());
Constructor<?> constructor = tClass.getConstructor(InputStream.class);
ObjectInputStream objectInputStream = (ObjectInputStream) constructor.newInstance(fileInputStream);
objectInputStream.readObject(); // throws ClassNotFoundException
任何输入表示赞赏。 提前致谢。
据我所知,您应该覆盖ObjectInputStream
上的方法resolveClass
像这样的东西:
default <T extends Serializable> T readFile(String fileName, ClassLoader loader) throws IOException, ClassNotFoundException {
Path configFilePath = configPath.resolve(fileName + ".data");
FileInputStream fileInputStream = new FileInputStream(configFilePath.toFile());
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream){
protected Class<?> resolveClass(ObjectStreamClass desc)
throws IOException, ClassNotFoundException {
try {
return Class.forName(desc.getName(), false, loader);
} catch(ClassNotFoundException cnfe) {
return super.resolveClass(desc);
}
}
};
return (T) objectInputStream.readObject();
}
自己从未尝试过,但值得一试。
There is also http://commons.apache.org/proper/commons-io/javadocs/api-2.4/org/apache/commons/io/input/ClassLoaderObjectInputStream.html if you aready have commons-io in your project.
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.