用不同的包名称动态加载java中的类

如Pete所述，可以使用ASM字节码库来完成此操作。实际上，该库实际上带有一个专门用于处理这些类名重新映射（

RemappingClassAdapter

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[] bytepre = ...; // I will leave this part up to you        byte[] remappedBytepre;        try { remappedBytepre = rewriteDefaultPackageClassNames(bytepre);        } catch (IOException e) { throw new RuntimeException("Could not rewrite class " + name);        }        return defineClass(name, remappedBytepre, 0, remappedBytepre.length);    }    public byte[] rewriteDefaultPackageClassNames(byte[] bytepre) throws IOException {        ClassReader classReader = new ClassReader(bytepre);        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; }        }    }}

为了说明这一点，我创建了两个类，它们都属于默认包：

public class Customer {}

和

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;    }}

这是任何重新映射

Order

> javap -private -c命令从“ Order.java”编译公共类Order扩展java.lang.Object {私人客户客户；公共秩序（客户）；  码：   0：加载_0   1：调用特殊＃10; //方法java / lang / Object。“” :(）V   4：aload_0   5：aload_1   6：普特菲尔德＃13；//字段客户：LCustomer;   9：返回公共客户getCustomer（）;  码：   0：加载_0   1：getfield＃13；//字段客户：LCustomer;   4：阿伦public void setCustomer（Customer）;  码：   0：加载_0   1：aload_1   2：putfield＃13；//字段客户：LCustomer;   5：返回}

这是重新映射

Order

com.mycompany

> javap -private -c命令从“ Order.java”编译公共类com.mycompany.Order扩展了com.mycompany.java.lang.Object {私人com.mycompany.Customer客户；公共com.mycompany.Order（com.mycompany.Customer）;  码：   0：加载_0   1：调用特殊＃30; //方法“ com.mycompany.java/lang/Object"."":()V   4：aload_0   5：aload_1   6：普特菲尔德＃32；//字段客户：Lcom.mycompany.Customer;   9：返回公共com.mycompany.Customer getCustomer（）;  码：   0：加载_0   1：getfield＃32；//字段客户：Lcom.mycompany.Customer;   4：阿伦公共无效setCustomer（com.mycompany.Customer）;  码：   0：加载_0   1：aload_1   2：putfield＃32；//字段客户：Lcom.mycompany.Customer;   5：返回}

如您所见，重新映射更改了

Order

com.mycompany.Order

Customer

com.mycompany.Customer

该类加载器将必须加载以下任一类的所有类：

• 属于默认软件包，或
• 使用属于默认软件包的其他类。