JAVA basics: Find the class name from the. class File

JAVA basics: Find the class name-general Linux technology-Linux programming and kernel information from the. class file. The following is a detailed description. You can determine the name of a class in multiple ways:

Assume that all classes start with com, org, or net.
Search for a class named Hack by classpath.
Search for classpath to find the Directory Entry mapped to this file
Directly view the class itself. In all cases, this is the most direct
The Java specification specifies how to view a class file. The first value stored in the class file is the complete class description in the format of the Java internal delimiter.

The following code returns the file C: \ code \ hacks \ research \ com \ generationjava \ Hack. class internal class name com/generationjava/Hack, readers can further write code to convert "/" to ". ":

Static final public int MAGIC = 0 xCAFEBABE;
// Pass C: \ code \ hacks \ research \ com \ generationjava \ Hack. class
// Assume that such a class exists.
Public String getFullyQualifiedName (String filename) throws IOException {
String name = null;

Try {
DataInputStream in = new
DataInputStream (new FileInputStream (filename ));
If (in. readInt ()! = MAGIC ){
// Not a. class File
Thrownew IOException ("Not a class file ");
}

In. readUnsignedShort (); // version number
In. readUnsignedShort (); // main version number
In. readUnsignedShort (); // Length
In. readByte (); // CLASS = 7
In. readUnsignedShort (); // ignore this location
In. readByte (); // UTF8 = 1
Name = in. readUTF (); // class name !!!
In. close ();
} Catch (IOException ioe ){
Ioe. printStackTrace ();
}

Return name;
}
When you directly obtain class information from the. class file, the development is simplified. Finding the complete class name of an anonymous. class file is an important part of any. class file-based application.