在不支持PagedResultsControl的LDAP服务器上分页 [英] Paginate on LDAP server which does not support PagedResultsControl
问题描述
我正在尝试使用Spring LDAP(版本2.3.2)在LDAP服务器上获取所有条目.在我的代码中，我使用PagedResultsDirContextProcessor对所有结果进行分页.在支持PagedResultsControl的服务器上，这可以正常工作.
I'm trying to get all entries on an LDAP server using Spring LDAP (version 2.3.2). Within my code, I make use of PagedResultsDirContextProcessor to paginate through all the result. This works fine on the servers which support PagedResultsControl.
但是，我现在需要连接到不支持PagedResultsControl的LDAP服务器.如何在不使用PagedResultsControl的情况下获取所有条目?
However, I now need to connect to an LDAP server which does not support PagedResultsControl. How can I get all entries without using PagedResultsControl?
推荐答案
您可以通过JNDI使用VirtualListView.您必须检索并重新提供'contextID'才能进行分页，如下所示:
You can use VirtualListView via JNDI. You have to retrieve and re-supply the 'contextID' to paginate, as follows:
static final int LIST_SIZE = 20; // Adjust to suit
@Test
public void TestVLV() throws NamingException, IOException
{
Hashtable<String,Object> env = new Hashtable<>();
env.put(Context.INITIAL_CONTEXT_FACTORY,
"com.sun.jndi.ldap.LdapCtxFactory");
env.put(Context.PROVIDER_URL, "ldap://localhost");
env.put(Context.SECURITY_AUTHENTICATION, "simple");
env.put(Context.SECURITY_PRINCIPAL, "cn=XXXXXXX");
env.put(Context.SECURITY_CREDENTIALS, "YYYYYYY");
try
{
/* Create initial context with no connection request controls */
LdapContext ctx = new InitialLdapContext(env, null);
/* Sort Control is required for VLV to work */
SortKey[] sortKeys =
{
// sort by cn
new SortKey("cn", true, "caseIgnoreOrderingMatch")
};
// Note: the constructors for SortControl that take String or String[]
// as the first argument produce 'no ordering rule' errors with OpenLDAP.
SortControl sctl = new SortControl(
// "cn",
// new String[]{"cn"},
sortKeys,
Control.CRITICAL);
/* VLV that returns the first 20 answers */
VirtualListViewControl vctl =
new VirtualListViewControl(1, 0, 0, LIST_SIZE-1, Control.CRITICAL);
/* Set context's request controls */
ctx.setRequestControls(new Control[]
{
sctl,
vctl
});
int count = 0;
SearchControls sc = new SearchControls(SearchControls.SUBTREE_SCOPE, 0, 0, null, false, false);
for (;;)
{
/* Perform search */
// System.out.println("namespace="+ctx.getNameInNamespace());
// System.out.println("count limit="+sc.getCountLimit());
// System.out.println("search scope="+sc.getSearchScope());
NamingEnumeration<SearchResult> ne =
ctx.search("ou=Users,dc=xxxx,dc=com", "(objectClass={0})", new String[]{"inetOrgPerson"}, sc);
/* Enumerate search results */
while (ne.hasMore())
{
count++;
SearchResult sr = ne.next();
// System.out.println(i+": "+sr.getName());
System.out.println(count+": "+sr.getNameInNamespace());
}
ne.close();
// Get the contextID.
Control[] controls = ctx.getResponseControls();
VirtualListViewResponseControl vlvrc = null;
byte[] contextID = null;
for (int j = 0; j < controls.length; j++)
{
if (controls[j] instanceof VirtualListViewResponseControl)
{
vlvrc = (VirtualListViewResponseControl)controls[j];
contextID = vlvrc.getContextID();
System.out.println("contextID=0x"+new BigInteger(1,contextID).toString(16));
if (contextID != null)
{
vctl = new VirtualListViewControl(vlvrc.getTargetOffset()+LIST_SIZE, 0, 0, LIST_SIZE-1, Control.CRITICAL);
vctl.setContextID(contextID);
ctx.setRequestControls(new Control[]
{
sctl,
vctl
});
}
break; // there should only be one VLV response control, and we're not interested in anything else.
}
}
if (vlvrc != null && contextID != null && count < vlvrc.getListSize())
{
System.out.println("Continuing");
}
else
{
System.out.println("Finished");
break;
}
}
ctx.close();
}
finally
{
}
}
当然可以调整身份验证并搜索根目录和过滤器以适合自己.
Adjust the authentication and search root and filter to suit yourself, of course.
并测试它是否受支持(尽管上面代码中的不受支持的关键控制"异常也会告诉您):
And to test whether it is supported (although an 'unsupported critical control' exception from the above code will tell you just as well):
/**
* Is VLV Control supported?
*
* Query the rootDSE object to find out if VLV Control is supported.
* @return true if it is supported.
*/
static boolean isVLVControlSupported(LdapContext ctx)
throws NamingException
{
String[] returningAttributes =
{
"supportedControl"
};
// Fetch the supportedControl attribute of the rootDSE object.
Attributes attrs = ctx.getAttributes("", returningAttributes);
Attribute attr = attrs.get("supportedControl");
System.out.println("supportedControls="+attr);
if (attr != null)
{
// Fast way to check. add() would have been just as good. Does no damage to the DIT.
return attr.remove(VLV_CONTROL_OID);
}
return false;
}
VirtualListViewControl和VirtualListViewResponseControl是Sun/Oracle LDAP Booster Pack的一部分，您可以通过Maven通过以下方式获得它:
The VirtualListViewControl and VirtualListViewResponseControl are part of the Sun/Oracle LDAP Booster Pack, which you can obtain via Maven as:
<dependency>
<groupId>com.sun</groupId>
<artifactId>ldapbp</artifactId>
<version>1.0</version>
<type>jar</type>
</dependency>
这篇关于在不支持PagedResultsControl的LDAP服务器上分页的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
