嘿，我认为标题总结了它，但仍然如此。
我需要从其编译的.class文件中提取对象的完全限定名称，有人能指出我正确的方向吗？
谢谢，
亚当。
问问题
11668 次
6 回答
12
getClass().getName()
更新：您可以将类文件加载到byte[]（使用标准 i/o）中，然后使用getClass().getClassLoader().defineClass(...)
于 2010-07-21T12:07:04.380 回答
5
public String getFullClassName(String classFileName) throws IOException {
File file = new File(classFileName);
FileChannel roChannel = new RandomAccessFile(file, "r").getChannel();
ByteBuffer bb = roChannel.map(FileChannel.MapMode.READ_ONLY, 0, (int)roChannel.size());
Class<?> clazz = defineClass((String)null, bb, (ProtectionDomain)null);
return clazz.getName();
}
于 2010-07-21T13:00:22.243 回答
2
使用像 BCEL 这样的库将类文件读入内存并查询类名。
于 2010-07-21T12:08:32.847 回答
0
根据您使用的 IDE，可能会有执行此操作的机制。例如，在 Eclipse 中，您可以深入到 .class 文件并右键单击它并选择“复制完全限定名称”。
老版本的eclipse可能没有这个功能，但是我之前用过这个插件：
http://www.jave.de/eclipse/copyfully/index.html
它的工作方式几乎相同。希望这可以帮助。
于 2010-07-21T12:06:58.680 回答
0
您可以查看 JSF 实现中的 AnnotationScanner 示例，它们确实手动加载类（以避免永久空间污染）以查找 JSF 注释。特别看这个：
/**
* This class is encapsulating binary .class file information as defined at
* http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html
* <p/>
* This is used by the annotation frameworks to quickly scan .class files
* for the presence of annotations. This avoid the annotation framework
* having to load each .class file in the class loader.
* <p/>
* Taken from the GlassFish V2 source base.
*/
@SuppressWarnings({"UnusedDeclaration"})
private static final class ClassFile {
private static final int magic = 0xCAFEBABE;
public static final int ACC_PUBLIC = 0x1;
public static final int ACC_PRIVATE = 0x2;
public static final int ACC_PROTECTED = 0x4;
public static final int ACC_STATIC = 0x8;
public static final int ACC_FINAL = 0x10;
public static final int ACC_SYNCHRONIZED = 0x20;
public static final int ACC_THREADSAFE = 0x40;
public static final int ACC_TRANSIENT = 0x80;
public static final int ACC_NATIVE = 0x100;
public static final int ACC_INTERFACE = 0x200;
public static final int ACC_ABSTRACT = 0x400;
public short majorVersion;
public short minorVersion;
public ConstantPoolInfo constantPool[];
public short accessFlags;
public ConstantPoolInfo thisClass;
public ConstantPoolInfo superClass;
public ConstantPoolInfo interfaces[];
/**
* bunch of stuff I really don't care too much for now.
* <p/>
* FieldInfo fields[]; MethodInfo methods[];
* AttributeInfo attributes[];
*/
ByteBuffer header;
ConstantPoolInfo constantPoolInfo = new ConstantPoolInfo();
// ------------------------------------------------------------ Constructors
/**
* Creates a new instance of ClassFile
*/
public ClassFile() {
header = ByteBuffer.allocate(12000);
}
// ---------------------------------------------------------- Public Methods
public void setConstantPoolInfo(ConstantPoolInfo poolInfo) {
constantPoolInfo = poolInfo;
}
/**
* Read the input channel and initialize instance data structure.
*
* @param in a <code>ReadableByteChannel</code> that provides the bytes
* of the classfile
*
* @return <code>true</code> if the bytes representing this classfile include
* one of the annotations we're looking for.
*
* @throws IOException if an I/O error occurs while reading the class
*/
public boolean containsAnnotation(ReadableByteChannel in)
throws IOException {
/**
* this is the .class file layout
*
ClassFile {
u4 magic;
u2 minor_version;
u2 major_version;
u2 constant_pool_count;
cp_info constant_pool[constant_pool_count-1];
u2 access_flags;
u2 this_class;
u2 super_class;
u2 interfaces_count;
u2 interfaces[interfaces_count];
u2 fields_count;
field_info fields[fields_count];
u2 methods_count;
method_info methods[methods_count];
u2 attributes_count;
attribute_info attributes[attributes_count];
}
**/
header.clear();
long read = (long) in.read(header);
if (read == -1) {
return false;
}
header.rewind();
if (header.getInt() != magic) {
return false;
}
minorVersion = header.getShort();
majorVersion = header.getShort();
int constantPoolSize = header.getShort();
return constantPoolInfo
.containsAnnotation(constantPoolSize, header, in);
}
} // END ClassFile
于 2010-07-21T12:49:45.033 回答