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[英]ClassNotFoundException in ObjectInputStream.readObject()
[英]ObjectInputStream#readObject raises ClassNotFoundException with External Jar classes
所以我有一個 Spring 引導應用程序,它從以下路徑加載外部 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 在編譯時不知道外部 jars。 通過指定外部 jars 像“插件”或“插件”一樣加載
-Dloader.path=...
所有外部 jars 都依賴於來自“main-0.0.1-SNAPSHOT.jar”的接口,它們應該或多或少地進行 object 序列化。 該接口稱為Configurable
,它提供了兩種默認方法,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 中的類實現了這個接口,它們調用readFile()
和writeFile()
。
writeFile()
工作得很好,似乎沒有引起任何問題; 但是, readFile()
會拋出ClassNotFoundException
,這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)
經過一些測試,在我看來ClassNotFoundException
是由 Class.forName() 引發的,因為默認的 ClassLoader 很難找到moe.ofs.addon.navdata.domain.Navaid
,這是我正在嘗試反序列化的 class 。
Navaid implements Serializable
,它還有一個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());
這在打印出來時會給出類似的東西
Thread.currentThread().getContextClassLoader() = org.springframework.boot.loader.LaunchedURLClassLoader@7a0b4753
除了ObjectInputStream#readObject
仍然拋出ClassNotFoundException
。 如果我明確調用從 Spring 引導加載程序加載 Navaid class ,例如:
getClass().getClassLoader().loadClass("moe.ofs.addon.navdata.domain.Navaid");
它返回一個Navaid
實例,沒有任何問題。
正如預期的那樣,直接調用時
Class.forName("moe.ofs.addon.navdata.domain.Navaid")
即使線程上下文加載器已顯式設置為LaunchedURLClassLoader
,也會引發ClassNotFoundException
; ObjectInputStream#readObject
總是嘗試通過調用系統默認類加載器來加載 class 來解析 class。
然后我嘗試使用LaunchedURLClassLoader
加載ObjectInputStream
,但該實例仍然使用系統默認 class 加載器中的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
任何輸入表示贊賞。 提前致謝。
據我所知,您應該覆蓋ObjectInputStream
上的方法resolveClass
像這樣的東西:
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();
}
自己從未嘗試過,但值得一試。
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.
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