|
1
52
53 package com.go.trove.net;
54
55 import java.net.*;
56 import java.util.*;
57 import java.lang.ref.*;
58 import com.go.trove.util.SoftHashMap;
59
60
71 public class InetAddressResolver {
72 private static final long RESOLVE_PERIOD = 10 * 60 * 1000;
74 private static Timer cResolveTimer;
75
76 private static Map cResolvers = new SoftHashMap();
77
78 private static Timer getResolveTimer() {
79 Timer timer = cResolveTimer;
80 if (timer == null) {
81 timer = new Timer(true);
82 timer.schedule(new TimerTask() {
83 public void run() {
84 Thread.currentThread().setName("InetAddressResolver");
85 }
86 }, 0);
87 cResolveTimer = timer;
88 }
89 return timer;
90 }
91
92
100 public static InetAddressResolver listenFor(String  host,
101 InetAddressListener listener) {
102 synchronized (cResolvers) {
103 InetAddressResolver resolver =
104 (InetAddressResolver)cResolvers.get(host);
105 if (resolver == null) {
106 resolver = new InetAddressResolver(host);
107 cResolvers.put(host, resolver);
108 }
109 resolver.addListener(listener);
110 return resolver;
111 }
112 }
113
114 private final String mHost;
115
116 private List mListeners = new ArrayList();
117
118 private Object mResolutionResults;
120
121 private InetAddressResolver(String host) {
122 mHost = host;
123
124 long delay = (long)(Math.random() * RESOLVE_PERIOD);
127 getResolveTimer().schedule(new Resolver(this), delay, RESOLVE_PERIOD);
128 }
129
130 private synchronized void addListener(InetAddressListener listener) {
131 mListeners.add(listener);
132 if (!resolveAddresses()) {
133 notifyListener(listener);
135 }
136 }
137
138 private synchronized void notifyListener(InetAddressListener listener) {
139 if (mResolutionResults instanceof UnknownHostException) {
140 listener.unknown((UnknownHostException)mResolutionResults);
141 }
142 else {
143 InetAddress[] addresses = (InetAddress[])mResolutionResults;
144 addresses = (InetAddress[])addresses.clone();
145 listener.resolved(addresses);
146 }
147 }
148
149 private synchronized boolean resolveAddresses() {
151 boolean changed;
152 try {
153 InetAddress[] addresses = InetAddress.getAllByName(mHost);
154 if (mResolutionResults instanceof UnknownHostException) {
155 changed = true;
156 }
157 else {
158 Arrays.sort(addresses, new Comparator() {
160 public int compare(Object a, Object b) {
161 return ((InetAddress)a).getHostAddress()
162 .compareTo(((InetAddress)b).getHostAddress());
163 }
164 });
165
166 changed = !Arrays.equals
167 (addresses, (InetAddress[])mResolutionResults);
168 }
169 mResolutionResults = addresses;
170 }
171 catch (UnknownHostException e) {
172 changed = !(mResolutionResults instanceof UnknownHostException);
173 mResolutionResults = e;
174 }
175
176 if (changed) {
177 int size = mListeners.size();
178 for (int i=0; i<size; i++) {
179 notifyListener((InetAddressListener)mListeners.get(i));
180 }
181 }
182
183 return changed;
184 }
185
186 private class Resolver extends TimerTask {
187 private final Reference mOwner;
190
191 public Resolver(InetAddressResolver owner) {
192 mOwner = new WeakReference(owner);
193 }
194
195 public void run() {
196 InetAddressResolver owner = (InetAddressResolver)mOwner.get();
197 if (owner == null) {
198 cancel();
199 }
200 Thread t = Thread.currentThread();
201 String originalName = t.getName();
202 t.setName("InetAddressResolver:" + owner.mHost);
203 try {
204 owner.resolveAddresses();
205 }
206 finally {
207 t.setName(originalName);
208 }
209 }
210 }
211 }
212 |
Popular Tags |
Java API By Example, From Geeks To Geeks.