www.pudn.com > cryptix-asn1-0.1.11.zip > ASNString.java

/* $Id: ASNString.java,v 1.4 2001/05/26 07:10:24 raif Exp $ 
 * 
 * Copyright (C) 1997-2001 The Cryptix Foundation Limited. All rights reserved. 
 * 
 * Use, modification, copying and distribution of this software is subject to 
 * the terms and conditions of the Cryptix General Licence. You should have 
 * received a copy of the Cryptix General Licence along with this library; if 
 * not, you can download a copy from http://www.cryptix.org/ 
 */ 
package cryptix.asn1.lang; 
 
import cryptix.asn1.io.ASNReader; 
import cryptix.asn1.io.ASNWriter; 
import cryptix.asn1.io.BlankElementException; 
import cryptix.asn1.io.ElementNotFoundException; 
 
import org.apache.log4j.Category; 
 
import java.io.EOFException; 
import java.io.IOException; 
 
/** 
 * The abstract implementation of all ASN.1 string types.
 
 * 
 * @version $Revision: 1.4 $ 
 * @author  Raif S. Naffah 
 */ 
public abstract class ASNString extends Type implements IType { 
 
	// Constants and vars 
	// ....................................................................... 
 
	static Category cat = Category.getInstance(ASNString.class.getName()); 
 
	// Constructor(s) 
	// ....................................................................... 
 
	public ASNString(String name, Tag tag) { 
		super(name, tag); 
	} 
 
	// Redefinition of methods in superclass Type 
	// ....................................................................... 
 
	/** 
	 * Decodes a String from an input stream. 
	 * 
	 * @param is the ASN.1 stream to read from. 
	 * @exception IOException if an exception occurs during the operation. 
	 */ 
	public abstract void decode(ASNReader is) throws IOException; 
 
	/** 
	 * Encodes a PrintableString to an output stream. 
	 * 
	 * @param os the ASN.1 stream to write to. 
	 * @exception IOException if an exception occurs during the operation. 
	 */ 
	public abstract void encode(ASNWriter os) throws IOException; 
 
	/** 
	 * Sets the current value of this instance to the designated one. 
	 * 
	 * @param value the designated value. Allowed types are: 
	 * java.lang.String, and any subclass of cryptix.asn1.lang.ASNString. 
	 * @exception ClassCastException if the designated value is not appropriate. 
	 */ 
	public void value(Object value) { 
		if (value == null) 
			return; 
 
		if (value instanceof String) 
			this.value = (String) value; 
		else if (value instanceof ASNString) 
			this.value = ((ASNString) value).stringValue(); 
		else 
			throw new ClassCastException(); 
	} 
 
	// other instance methods 
	// ....................................................................... 
 
	/** 
	 * Convenience method to facilitate type casting. 
	 * 
	 * @return the current value as a java.lang.String. 
	 */ 
	public String stringValue() { 
		return ((String) this.value); 
	} 
 
   /** 
    * Returns true if the designated value is equal to the value of 
    * this instance.
 
    * 
    * @param obj a value to compare with the value of this instance. 
    * @return true if this instance has an equal, non-null value to 
    * the designated one; false otherwise. 
    */ 
   protected boolean sameValue(Object obj) { 
      String val = this.stringValue(); 
      return (val == null) ? false : val.equals(obj); 
   } 
 
   // java.lang.Object overloaded methods 
   // ....................................................................... 
 
	/** 
	 * Returns a string representation of this instance. 
	 * 
	 * @return a string representation of this instance. 
	 */ 
	public String toString() { 
		StringBuffer sb = new StringBuffer("-- "); 
		if (value != null) 
			sb.append("\"").append(stringValue()).append("\""); 
		else 
			sb.append("N/A"); 
 
		return sb.toString(); 
	} 
 
	// Protected methods invoked by subclasses 
	// ....................................................................... 
 
	void decodeInternal(ASNReader is, int tagValue) throws IOException { 
		String cn = this.getClass().getName(); 
		cat.debug("==> "+cn+".decodeInternal("+tagValue+")"); 
 
		is.mark(Integer.MAX_VALUE); 
		try { 
			String result = is.decodeString(tagValue, this); 
			if (result == null) 
				throw new ElementNotFoundException(cn); 
			else 
				this.value(result); 
		} catch (IOException x) { 
			cat.warn("Exception ("+String.valueOf(x)+") encountered while decoding a "+cn); 
			if (x instanceof ASNException || x instanceof EOFException) { 
				cat.warn("Resetting stream..."); 
				is.reset(); 
			} 
			throw x; 
		} 
 
		cat.debug("<== "+cn+".decodeInternal()"); 
	} 
 
	void encodeInternal(ASNWriter os, int tagValue) throws IOException { 
		String cn = this.getClass().getName(); 
		cat.debug("==> "+cn+".encodeInternal("+tagValue+")"); 
 
		Object val = this.value(); 
		if (val != null) 
			os.encodeString(tagValue, this, (String) val); 
		else { 
			val = this.defaultValue(); 
			if (val != null) { 
				cat.warn("Encoding default value for "+cn); 
				os.encodeString(tagValue, this, (String) val); 
			} else if (!this.isOptional()) 
				throw new BlankElementException(cn); 
//			else { 
//				cat.warn("Encoding a NULL for "+cn); 
//				new Null(this.name()).encode(os); 
//			} 
		} 
 
		cat.debug("<== "+cn+".encodeInternal()"); 
	} 
}