用不同的包名动态加载java中的类
是否可以在Java中加载一个类并“伪造”类的包名/规范名？我尝试过这样做，很明显，但是我在用不同的包名动态加载java中的类,java,class,dynamic-class-loaders,Java,Class,Dynamic Class Loaders,是否可以在Java中加载一个类并“伪造”类的包名/规范名？我尝试过这样做，很明显，但是我在ClassDefNotFoundException中得到了一条“类名不匹配”的消息 我这样做的原因是我试图加载一个在默认包中编写的API，这样我就可以直接使用它而不用使用反射。代码将针对表示包和包名导入的文件夹结构中的类进行编译。即： ./com/DefaultPackageClass.class 我目前的代码如下： public Class loadClass(String name) throws Cl
ClassDefNotFoundExceptionpublic Class loadClass(String name) throws ClassNotFoundException {
if(!CLASS_NAME.equals(name))
return super.loadClass(name);
try {
URL myUrl = new URL(fileUrl);
URLConnection connection = myUrl.openConnection();
InputStream input = connection.getInputStream();
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int data = input.read();
while(data != -1){
buffer.write(data);
data = input.read();
}
input.close();
byte[] classData = buffer.toByteArray();
return defineClass(CLASS_NAME,
classData, 0, classData.length);
} catch (MalformedURLException e) {
throw new UndeclaredThrowableException(e);
} catch (IOException e) {
throw new UndeclaredThrowableException(e);
}
}
也许将API从默认包移动到更合理的位置会更容易？听起来你好像没有访问源代码的权限。我不确定包是否被编码到类文件中，因此简单地移动API类可能值得一试。否则，像JAD这样的Java反编译器通常会做得很好，因此您可以在反编译的源代码中更改包名并重新编译它。您应该能够完成一些工作，尽管在构建时重命名包比在加载时重命名包更容易。，这可以使用ASM字节码库来完成。事实上，该库实际上附带了一个专门用于处理这些类名重新映射（）的类。下面是使用此类的类装入器示例：
public class MagicClassLoader extends ClassLoader {
private final String defaultPackageName;
public MagicClassLoader(String defaultPackageName) {
super();
this.defaultPackageName = defaultPackageName;
}
public MagicClassLoader(String defaultPackageName, ClassLoader parent) {
super(parent);
this.defaultPackageName = defaultPackageName;
}
@Override
public Class<?> loadClass(String name) throws ClassNotFoundException {
byte[] bytecode = ...; // I will leave this part up to you
byte[] remappedBytecode;
try {
remappedBytecode = rewriteDefaultPackageClassNames(bytecode);
} catch (IOException e) {
throw new RuntimeException("Could not rewrite class " + name);
}
return defineClass(name, remappedBytecode, 0, remappedBytecode.length);
}
public byte[] rewriteDefaultPackageClassNames(byte[] bytecode) throws IOException {
ClassReader classReader = new ClassReader(bytecode);
ClassWriter classWriter = new ClassWriter(classReader, 0);
Remapper remapper = new DefaultPackageClassNameRemapper();
classReader.accept(
new RemappingClassAdapter(classWriter, remapper),
0
);
return classWriter.toByteArray();
}
class DefaultPackageClassNameRemapper extends Remapper {
@Override
public String map(String typeName) {
boolean hasPackageName = typeName.indexOf('.') != -1;
if (hasPackageName) {
return typeName;
} else {
return defaultPackageName + "." + typeName;
}
}
}
}
Ordercom.mycompany.OrderCustomercom.mycompany.Customer- 属于默认包，或
- 使用属于默认包的其他类
public class Customer {
}
public class Order {
private Customer customer;
public Order(Customer customer) {
this.customer = customer;
}
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
}