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SortControl.javaAPI DocJava SE 5 API7648Fri Aug 26 14:57:40 BST 2005javax.naming.ldap

SortControl

public final class SortControl extends BasicControl
Requests that the results of a search operation be sorted by the LDAP server before being returned. The sort criteria are specified using an ordered list of one or more sort keys, with associated sort parameters. Search results are sorted at the LDAP server according to the parameters supplied in the sort control and then returned to the requestor. If sorting is not supported at the server (and the sort control is marked as critical) then the search operation is not performed and an error is returned.

The following code sample shows how the class may be used: 


// Open an LDAP association
LdapContext ctx = new InitialLdapContext();

// Activate sorting
String sortKey = "cn";
ctx.setRequestControls(new Control[]{
new SortControl(sortKey, Control.CRITICAL) });

// Perform a search
NamingEnumeration results =
ctx.search("", "(objectclass=*)", new SearchControls());

// Iterate over search results
while (results != null && results.hasMore()) {
// Display an entry
SearchResult entry = (SearchResult)results.next();
System.out.println(entry.getName());
System.out.println(entry.getAttributes());

// Handle the entry's response controls (if any)
if (entry instanceof HasControls) {
// ((HasControls)entry).getControls();
}
}
// Examine the sort control response
Control[] controls = ctx.getResponseControls();
if (controls != null) {
for (int i = 0; i < controls.length; i++) {
if (controls[i] instanceof SortResponseControl) {
SortResponseControl src = (SortResponseControl)controls[i];
if (! src.isSorted()) {
throw src.getException();
}
} else {
// Handle other response controls (if any)
}
}
}

// Close the LDAP association
ctx.close();
...

This class implements the LDAPv3 Request Control for server-side sorting as defined in RFC 2891. The control's value has the following ASN.1 definition: 


SortKeyList ::= SEQUENCE OF SEQUENCE {
attributeType AttributeDescription,
orderingRule [0] MatchingRuleId OPTIONAL,
reverseOrder [1] BOOLEAN DEFAULT FALSE }
since
1.5
see
SortKey
see
SortResponseControl
author
Vincent Ryan

Fields Summary
public static final String
OID
The server-side sort control's assigned object identifier is 1.2.840.113556.1.4.473.
private static final long
serialVersionUID
Constructors Summary
public SortControl(String sortBy, boolean criticality)
Constructs a control to sort on a single attribute in ascending order. Sorting will be performed using the ordering matching rule defined for use with the specified attribute.

param
sortBy An attribute ID to sort by.
param
criticality If true then the server must honor the control and return the search results sorted as requested or refuse to perform the search. If false, then the server need not honor the control.
exception
IOException If an error was encountered while encoding the supplied arguments into a control.


                                  		                                                                                                                                                                                                  
           

	super(OID, criticality, null);
	super.value = setEncodedValue(new SortKey[]{ new SortKey(sortBy) });
public SortControl(String[] sortBy, boolean criticality)
Constructs a control to sort on a list of attributes in ascending order. Sorting will be performed using the ordering matching rule defined for use with each of the specified attributes.

param
sortBy A non-null list of attribute IDs to sort by. The list is in order of highest to lowest sort key precedence.
param
criticality If true then the server must honor the control and return the search results sorted as requested or refuse to perform the search. If false, then the server need not honor the control.
exception
IOException If an error was encountered while encoding the supplied arguments into a control.


	super(OID, criticality, null);
	SortKey[] sortKeys = new SortKey[sortBy.length];
	for (int i = 0; i < sortBy.length; i++) {
	    sortKeys[i] = new SortKey(sortBy[i]);
	}
	super.value = setEncodedValue(sortKeys);
public SortControl(SortKey[] sortBy, boolean criticality)
Constructs a control to sort on a list of sort keys. Each sort key specifies the sort order and ordering matching rule to use.

param
sortBy A non-null list of keys to sort by. The list is in order of highest to lowest sort key precedence.
param
criticality If true then the server must honor the control and return the search results sorted as requested or refuse to perform the search. If false, then the server need not honor the control.
exception
IOException If an error was encountered while encoding the supplied arguments into a control.


	super(OID, criticality, null);
	super.value = setEncodedValue(sortBy);
Methods Summary
private byte[]setEncodedValue(javax.naming.ldap.SortKey[] sortKeys)


	// build the ASN.1 BER encoding
	BerEncoder ber = new BerEncoder(30 * sortKeys.length + 10);
	String matchingRule;

	ber.beginSeq(Ber.ASN_SEQUENCE | Ber.ASN_CONSTRUCTOR);

	for (int i = 0; i < sortKeys.length; i++) {
	    ber.beginSeq(Ber.ASN_SEQUENCE | Ber.ASN_CONSTRUCTOR);
	    ber.encodeString(sortKeys[i].getAttributeID(), true); // v3

	    if ((matchingRule = sortKeys[i].getMatchingRuleID()) != null) {
		ber.encodeString(matchingRule, (Ber.ASN_CONTEXT | 0), true);
	    }
	    if (! sortKeys[i].isAscending()) {
		ber.encodeBoolean(true, (Ber.ASN_CONTEXT | 1));
	    }
	    ber.endSeq();
	}
	ber.endSeq();

	return ber.getTrimmedBuf();