Package com.alibaba.dcm

Class DnsCacheManipulator

java.lang.Object

com.alibaba.dcm.DnsCacheManipulator

public class DnsCacheManipulator
extends Object

Setting dns (in fact dns cache).

Throw DnsCacheManipulatorException if operation fail for all methods.

Author:

Jerry Lee (oldratlee at gmail dot com)

See Also:

DnsCacheEntry, DnsCacheManipulatorException

Method Summary

Modifier and Type	Method	Description
static void	clearDnsCache()	Clear all dns cache entries, cause lookup dns server for all host after.
static List<DnsCacheEntry>	getAllDnsCache()	Deprecated. use listDnsCache() instead.
static DnsCacheEntry	getDnsCache(String host)	Get dns cache.
static int	getDnsCachePolicy()	Get JVM DNS cache policy.
static int	getDnsNegativeCachePolicy()	JVM DNS negative cache policy
static DnsCache	getWholeDnsCache()	Get whole dns cache info.
static List<DnsCacheEntry>	listDnsCache()	Get all dns cache entries.
static void	loadDnsCacheConfig()	Load dns config from properties file dns-cache.properties on classpath, then set to dns cache.
static void	loadDnsCacheConfig(String propertiesFileName)	Load dns config from the specified properties file on classpath, then set dns cache.
static void	removeDnsCache(String host)	Remove dns cache entry, cause lookup dns server for host after.
static void	setDnsCache(long expireMillis, String host, String... ips)	Set a dns cache entry.
static void	setDnsCache(String host, String... ips)	Set a never expired dns cache entry
static void	setDnsCache(Properties properties)	Set dns cache entries by properties
static void	setDnsCachePolicy(int cacheSeconds)	Set JVM DNS cache policy
static void	setDnsNegativeCachePolicy(int negativeCacheSeconds)	Set JVM DNS negative cache policy

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

setDnsCache

public static void setDnsCache(@Nonnull
                               String host,
                               @Nonnull
                               String... ips)

Set a never expired dns cache entry

Parameters:

host - host

ips - ips

Throws:

DnsCacheManipulatorException - Operation fail

See Also:

setDnsCache(long, java.lang.String, java.lang.String...)

setDnsCache

public static void setDnsCache(long expireMillis,
                               @Nonnull
                               String host,
                               @Nonnull
                               String... ips)

Set a dns cache entry.

Parameters:

expireMillis - expire time in milliseconds.

host - host

ips - ips

Throws:

DnsCacheManipulatorException - Operation fail

setDnsCache

public static void setDnsCache(@Nonnull
                               Properties properties)

Set dns cache entries by properties

Parameters:

properties - input properties. e.g. www.example.com=42.42.42.42, or www.example.com=42.42.42.42,43.43.43.43

Throws:

DnsCacheManipulatorException - Operation fail

loadDnsCacheConfig

public static void loadDnsCacheConfig()

Load dns config from properties file dns-cache.properties on classpath, then set to dns cache.

dns-cache.properties can be reset/customized by JVM -D option dcm.config.filename

Throws:

DnsCacheManipulatorException - Operation fail

See Also:

setDnsCache(java.util.Properties), loadDnsCacheConfig(java.lang.String)

loadDnsCacheConfig

public static void loadDnsCacheConfig(@Nonnull
                                      String propertiesFileName)

Load dns config from the specified properties file on classpath, then set dns cache.

Parameters:

propertiesFileName - specified properties file name on classpath.

Throws:

DnsCacheManipulatorException - Operation fail

See Also:

setDnsCache(java.util.Properties)

getDnsCache

@Nullable
public static DnsCacheEntry getDnsCache(@Nonnull
                                        String host)

Get dns cache.

Returns:

dns cache. return null if no entry for host or dns cache is expired.

Throws:

DnsCacheManipulatorException - Operation fail

getAllDnsCache

@Deprecated
@Nonnull
public static List<DnsCacheEntry> getAllDnsCache()

Deprecated.

use listDnsCache() instead.

Get all dns cache entries.

Returns:

dns cache entries

Throws:

DnsCacheManipulatorException - Operation fail

listDnsCache

@Nonnull
public static List<DnsCacheEntry> listDnsCache()

Get all dns cache entries.

Returns:

dns cache entries

Throws:

DnsCacheManipulatorException - Operation fail

Since:

1.2.0

See Also:

getWholeDnsCache()

getWholeDnsCache

@Nonnull
public static DnsCache getWholeDnsCache()

Get whole dns cache info.

Returns:

dns cache entries

Throws:

DnsCacheManipulatorException - Operation fail

Since:

1.2.0

removeDnsCache

public static void removeDnsCache(@Nonnull
                                  String host)

Remove dns cache entry, cause lookup dns server for host after.

Parameters:

host - host

Throws:

DnsCacheManipulatorException - Operation fail

See Also:

clearDnsCache()

clearDnsCache

public static void clearDnsCache()

Clear all dns cache entries, cause lookup dns server for all host after.

Throws:

DnsCacheManipulatorException - Operation fail

getDnsCachePolicy

public static int getDnsCachePolicy()

Get JVM DNS cache policy.

Returns:

cache seconds.

• -1 means never expired.(In effect, all negative value)
• 0 never cached.

Throws:

DnsCacheManipulatorException - Operation fail

Since:

1.3.0

setDnsCachePolicy

public static void setDnsCachePolicy(int cacheSeconds)

Set JVM DNS cache policy

NOTE: if Security Manage is turn on, JVM DNS cache policy set will not take effective. You can check by method getDnsCachePolicy().

Parameters:

cacheSeconds - set default dns cache time. Special input case:

• -1 means never expired.(In effect, all negative value)
• 0 never cached.

Throws:

DnsCacheManipulatorException - Operation fail

Since:

1.3.0

getDnsNegativeCachePolicy

public static int getDnsNegativeCachePolicy()

JVM DNS negative cache policy

Returns:

negative cache seconds.

• -1 means never expired.(In effect, all negative value)
• 0 never cached.

Throws:

DnsCacheManipulatorException - Operation fail

Since:

1.3.0

setDnsNegativeCachePolicy

public static void setDnsNegativeCachePolicy(int negativeCacheSeconds)

Set JVM DNS negative cache policy

Parameters:

negativeCacheSeconds - set default dns cache time. Special input case:

• -1 means never expired.(In effect, all negative value)
• 0 never cached.

Throws:

DnsCacheManipulatorException - Operation fail

Since:

1.3.0