basicattconstraint.java

一个完整的XACML工程,学习XACML技术的好例子!

/*
* Copyright (c) 2006, University of Kent
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*
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* 5. This license is governed, except to the extent that local laws
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*/

/*
 * BasicAttConstraint.java
 *
 * Created on March 23, 2005, 11:20 AM
 */

package issrg.ac.attributes;

import iaik.asn1.*;

import java.math.BigInteger;

/**
 *
 * @author  anhnt
 */
public class BasicAttConstraint extends issrg.ac.Extension {
    
    /**
     *The string stores the standard OID for the basicAttConstraints: 2.5.29.41
     */
    public static final String BASIC_ATT_CONSTRAINT_OID = "2.5.29.41";

    private int depth;
    
    /**
   * This method registers this extension as an extension with a specific
   * OID. After it has been registered, Extensions can recognise 
   * the extension with this OID.
   */  
    
    public static void registerMe() {
       issrg.ac.Extensions.registerExtension(BASIC_ATT_CONSTRAINT_OID, BasicAttConstraint.class); 
    }
    
       
    /**
     *Constructor for the class from an existing basicAttConstraints object
     *@param e is a basicAttConstraint object
     */
       
    public BasicAttConstraint(BasicAttConstraint e) throws CodingException {
      super(BASIC_ATT_CONSTRAINT_OID, e.isCritical());
      setDepth(e.getDepth());
    }
    
    /**
     * This constructor builds a BasicAttributeConstraint extension with no limit on Delegation depth.
     * This is the same as calling BasicAttConstraint(critical, null).
     *@param critical is a boolean value that specifies the critical of the object
     */
    public BasicAttConstraint (boolean critical) {
        this(critical, -1); //unlimited delegation depth
    }
    
    /**
     * This constructor builds a BasicAttributeConstraint extension with the specified limit on Delegation depth.
     * If delegation depth is null or is a negative number, an unlimited delegation is assumed.
     *
     * @param critical - the criticality flag; if true, the extension is marked critical
     * @param depth - the depth of delegation; if null or negative, no delegation limit is assumed.
     */
    public BasicAttConstraint (boolean critical, int depth) {
        super(BASIC_ATT_CONSTRAINT_OID, critical);
        setDepth(depth);
    }
    
    /**
     *This method returns the delegation depth of the basicAttConstraints object
     *@return an integer that represents the delegation depth of the object
     */
    
    public int getDepth(){
      return depth;
    }

    /**
     *This method set the delegation depth for the object
     *@param d is an integer. Is is used for setting the delegation depth for the object
     */
    public void setDepth(int d){
      depth=d;
    }

    /**
     *This method encodes the extension value of this extension
     *to an ASN1Object.
     *
     *@return an ASN1Object
     */
    public ASN1Object encodeValue() throws CodingException{
      ASN1Object extnValue = new SEQUENCE();
      extnValue.addComponent(new BOOLEAN(true));      
      if (getDepth()>=0) {
        extnValue.addComponent(new INTEGER(getDepth()));
      }

      return extnValue;
    }
    
    public Object clone(){
        try {
            return new BasicAttConstraint(this);
        } catch (CodingException ce) {return null;}
    }
    
    /**
     * This method constructs an BasicAttConstraints object from an
     *ASN1Object.
     *
     *@param ao is an ASN1Object.
     */
    
  public BasicAttConstraint(ASN1Object ao) throws CodingException{
    super(ao);
  }
  
  /**
   *This method decodes an ASN1Object to get an extension value 
   *for the BasicAttConstraint object.
   *
   *@param ao is the ASN1Object.
   */

  public void decodeValue(ASN1Object ao) throws CodingException{
    if (!(ao.getComponentAt(0) instanceof BOOLEAN)){
      throw new CodingException("Invalid format of BasicAttConstraint extension: BOOLEAN was expected");
    }

    setDepth((ao.countComponents()==2)?((BigInteger)((INTEGER) ao.getComponentAt(1)).getValue()).intValue():-1);
  }

  /**
   *This method returns a string that represents the object 
   *@param ident is a string that used for seperating the critical value and the delegation depth of the object 
   */
  public String extensionValueToString(String ident){
    return "TRUE, "+(getDepth()<0?"(unlimited)":(""+getDepth()));
  }
}