import org.xbill.DNS.MXRecord; //导入依赖的package包/类
/**
 * Returns an ordered host name list based on the MX records of the domain.
 * The first has the highest priority. If the domain has no MX records, then
 * it returns the host itself. Records with the same priority are shuffled
 * randomly.
 * 
 * @see <a href="http://tools.ietf.org/html/rfc5321#section-5.1">RFC 5321
 *      Simple Mail Transfer Protocol - Locating the Target Host</a>
 */
public Name[] queryMxTargets(Domain domain) throws MxLookupException {
    MXRecord[] records = queryMxRecords(domain);
    if (records.length == 0) {
        logger.debug("Domain {} has no MX records, using an implicit "
                + "MX record targetting the host", domain);
        return implicitMxTargetForDomain(domain);
    } else {
        //
        ArrayList<MXRecord> list =
                new ArrayList<MXRecord>(Arrays.asList(records));
        Collections.shuffle(list);
        // This sort is guaranteed to be stable: equal elements will not be
        // reordered as a result of the sort, so shuffle remains in effect
        Collections.sort(list, mxRecordPriorityComparator);
        list.toArray(records);
        return convertMxRecordsToHostNames(records);
    }
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
@Test()
public void testSamePriorityReallyShuffled() throws MxLookupException {
    new Expectations() {
        {
            lookup.run();
            result =
                    new MXRecord[] { HOST1_PRIORITY10, HOST2_PRIORITY10,
                            HOST3_PRIORITY10, HOST4_PRIORITY10 };
        }

    };

    final int COUNT_OF_TEST_RUNS = 4;
    List<Name[]> listOfResults = new ArrayList<Name[]>();
    for (int i = 0; i < COUNT_OF_TEST_RUNS; i++) {
        listOfResults.add(mxLookup.queryMxTargets(EXAMPLE_COM_DOMAIN));
    }

    assertTrue(reallyShuffled(listOfResults));
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
@Override
public int compare(MXRecord o1, MXRecord o2) {
    int p1 = o1.getPriority();
    int p2 = o2.getPriority();
    if (p1 < p2)
        return -1;
    else if (p1 > p2)
        return +1;
    else
        return 0;
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
@Test()
public void testDifferentPriority() throws MxLookupException {
    new Expectations() {
        {
            lookup.run();
            result = new MXRecord[] { HOST2_PRIORITY20, HOST1_PRIORITY10 };
        }

    };

    Name[] targets = mxLookup.queryMxTargets(EXAMPLE_COM_DOMAIN);

    assertArrayEquals(new Name[] { HOST1_EXAMPLE_COM_NAME,
            HOST2_EXAMPLE_COM_NAME }, targets);
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
public static ArrayList<MXRecord> mxLookup(String server) throws Exception {

        ArrayList<MXRecord> mxServers = new ArrayList<MXRecord>();

        Lookup lookup = new Lookup(server, Type.MX);
        Record[] records = lookup.run();

        for (int i = 0; i < records.length; i++) {
            mxServers.add((MXRecord)records[i]);
        }

        Collections.sort(mxServers, new MXCompare());
        return mxServers;
    }
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
public static String getMxServer(String server) throws Exception {

        ArrayList<MXRecord> servers = MXExchange.mxLookup(server);
        if (servers.isEmpty()) {
            return null;
        }

        String serverName = servers.get(0).getTarget().toString();
        return serverName.substring(0, serverName.length() - 1);
    }
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
private Name[] convertMxRecordsToHostNames(MXRecord[] records) {
    Name[] result = new Name[records.length];
    for (int i = result.length; --i >= 0;)
        result[i] = records[i].getTarget();
    return result;
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
@Override
public int compare(Object arg0, Object arg1) {
    return Integer.compare(((MXRecord) arg0).getPriority(), ((MXRecord) arg1).getPriority());
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
public static MXRecord getMXRecord(String domainName) {
    return null;
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
public MXRecord getMXRecord(String domainName) {
    return null;
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
/**
 * Return a prioritized unmodifiable list of MX records obtained from the
 * server.
 * 
 * @param hostname
 *            domain name to look up
 * 
 * @return a list of MX records corresponding to this mail domain
 * @throws TemporaryResolutionException
 *             get thrown on temporary problems
 */
private List<String> findMXRecordsRaw(String hostname) throws TemporaryResolutionException {
    Record answers[] = lookup(hostname, Type.MX, "MX");
    List<String> servers = new ArrayList<String>();
    if (answers == null) {
        return servers;
    }

    MXRecord[] mxAnswers = new MXRecord[answers.length];

    for (int i = 0; i < answers.length; i++) {
        mxAnswers[i] = (MXRecord) answers[i];
    }
    // just sort for now.. This will ensure that mx records with same prio
    // are in sequence
    Arrays.sort(mxAnswers, mxComparator);

    // now add the mx records to the right list and take care of shuffle
    // mx records with the same priority
    int currentPrio = -1;
    List<String> samePrio = new ArrayList<String>();
    for (int i = 0; i < mxAnswers.length; i++) {
        boolean same = false;
        boolean lastItem = i + 1 == mxAnswers.length;
        MXRecord mx = mxAnswers[i];
        if (i == 0) {
            currentPrio = mx.getPriority();
        } else {
            if (currentPrio == mx.getPriority()) {
                same = true;
            } else {
                same = false;
            }
        }
        
        String mxRecord = mx.getTarget().toString();
        if (same) {
            samePrio.add(mxRecord);
        } else {
            // shuffle entries with same prio
            // JAMES-913
            Collections.shuffle(samePrio);
            servers.addAll(samePrio);
                
            samePrio.clear();
            samePrio.add(mxRecord);
            
        }
        
        if (lastItem) {
            // shuffle entries with same prio
            // JAMES-913
            Collections.shuffle(samePrio);
            servers.addAll(samePrio);
        }
        logger.debug(new StringBuffer("Found MX record ").append(mxRecord).toString());
    }
    return servers;
}
 

import org.xbill.DNS.MXRecord; //导入依赖的package包/类
public int compare(MXRecord a, MXRecord b) {
    int pa = a.getPriority();
    int pb = b.getPriority();
    return pa - pb;
}