softsettingshash.html

用JAVA编写的,在做实验的时候留下来的,本来想删的,但是传上来,大家分享吧

<a name="158" href="#158">158</a> <em>     * hash map, or &lt;tt>null&lt;/tt> if the map contains no mapping for</em>
<a name="159" href="#159">159</a> <em>     * this key. Null is also returned if the element has been GC'ed.</em>
<a name="160" href="#160">160</a> <em>     *</em>
<a name="161" href="#161">161</a> <em>     * @param   key the key whose associated settings object is to be returned.</em>
<a name="162" href="#162">162</a> <em>     * @return  the settings object represented by the key, or</em>
<a name="163" href="#163">163</a> <em>     *          &lt;tt>null&lt;/tt> if the map contains no mapping for this key.</em>
<a name="164" href="#164">164</a> <em>     * @see #put(String, CrawlerSettings)</em>
<a name="165" href="#165">165</a> <em>     */</em>
<a name="166" href="#166">166</a>     <strong>public</strong> <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> get(String key) {
<a name="167" href="#167">167</a>         <strong>if</strong> (key == <strong>null</strong>) {
<a name="168" href="#168">168</a>             <strong>throw</strong> <strong>new</strong> NullPointerException(<span class="string">"Null key"</span>);
<a name="169" href="#169">169</a>         }
<a name="170" href="#170">170</a>         <strong>int</strong> hash = hash(key);
<a name="171" href="#171">171</a>         expungeStaleEntries();
<a name="172" href="#172">172</a>         <strong>int</strong> index = indexFor(hash, table.length);
<a name="173" href="#173">173</a>         SettingsEntry e = table[index];
<a name="174" href="#174">174</a>         <strong>while</strong> (e != <strong>null</strong>) {
<a name="175" href="#175">175</a>             <strong>if</strong> (e.hash == hash &amp;&amp; eq(key, e.get()))
<a name="176" href="#176">176</a>                 <strong>return</strong> e.settings;
<a name="177" href="#177">177</a>             e = e.next;
<a name="178" href="#178">178</a>         }
<a name="179" href="#179">179</a>         <strong>return</strong> <strong>null</strong>;
<a name="180" href="#180">180</a>     }
<a name="181" href="#181">181</a> 
<a name="182" href="#182">182</a>     <em>/**<em>*</em></em>
<a name="183" href="#183">183</a> <em>     * Associates the specified settings object with the specified key in this</em>
<a name="184" href="#184">184</a> <em>     * hash.</em>
<a name="185" href="#185">185</a> <em>     *</em>
<a name="186" href="#186">186</a> <em>     * If the hash previously contained a settings object for this key, the old</em>
<a name="187" href="#187">187</a> <em>     * object is replaced.</em>
<a name="188" href="#188">188</a> <em>     *</em>
<a name="189" href="#189">189</a> <em>     * @param key key with which the specified settings object is to be</em>
<a name="190" href="#190">190</a> <em>     *            associated.</em>
<a name="191" href="#191">191</a> <em>     * @param settings settings object to be associated with the specified key.</em>
<a name="192" href="#192">192</a> <em>     * @return previous value associated with specified key, or &lt;tt>null&lt;/tt></em>
<a name="193" href="#193">193</a> <em>     *         if there was no mapping for key.</em>
<a name="194" href="#194">194</a> <em>     */</em>
<a name="195" href="#195">195</a>     <strong>public</strong> <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> put(String key, <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> settings) {
<a name="196" href="#196">196</a>         <strong>if</strong> (settings == <strong>null</strong>) {
<a name="197" href="#197">197</a>             <strong>throw</strong> <strong>new</strong> NullPointerException(<span class="string">"Settings object was null"</span>);
<a name="198" href="#198">198</a>         }
<a name="199" href="#199">199</a>         <strong>if</strong> (key == <strong>null</strong>) {
<a name="200" href="#200">200</a>             <strong>throw</strong> <strong>new</strong> NullPointerException(<span class="string">"Null key"</span>);
<a name="201" href="#201">201</a>         }
<a name="202" href="#202">202</a>         <strong>int</strong> hash = hash(key);
<a name="203" href="#203">203</a>         expungeStaleEntries();
<a name="204" href="#204">204</a>         <strong>int</strong> i = indexFor(hash, table.length);
<a name="205" href="#205">205</a> 
<a name="206" href="#206">206</a>         <strong>for</strong> (SettingsEntry entry = table[i]; entry != <strong>null</strong>; entry = entry.next) {
<a name="207" href="#207">207</a>             <strong>if</strong> (hash == entry.hash &amp;&amp; eq(key, entry.get())) {
<a name="208" href="#208">208</a>                 <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> oldValue = entry.settings;
<a name="209" href="#209">209</a>                 <strong>if</strong> (settings != oldValue)
<a name="210" href="#210">210</a>                     entry.settings = settings;
<a name="211" href="#211">211</a>                 <strong>return</strong> oldValue;
<a name="212" href="#212">212</a>             }
<a name="213" href="#213">213</a>         }
<a name="214" href="#214">214</a> 
<a name="215" href="#215">215</a>         modCount++;
<a name="216" href="#216">216</a>         table[i] = <strong>new</strong> SettingsEntry(key, settings, queue, hash, table[i]);
<a name="217" href="#217">217</a>         <strong>if</strong> (++size >= threshold)
<a name="218" href="#218">218</a>             resize(table.length * 2);
<a name="219" href="#219">219</a>         <strong>return</strong> <strong>null</strong>;
<a name="220" href="#220">220</a>     }
<a name="221" href="#221">221</a> 
<a name="222" href="#222">222</a>     <strong>public</strong> <a href="../../../../org/archive/crawler/settings/CrawlerSettings.html">CrawlerSettings</a> put(SettingsEntry entry) {
<a name="223" href="#223">223</a>         <strong>return</strong> put(entry.getKey(), entry.getValue());
<a name="224" href="#224">224</a>     }
<a name="225" href="#225">225</a> 
<a name="226" href="#226">226</a>     <em>/**<em>*</em></em>
<a name="227" href="#227">227</a> <em>     * Rehashes the contents of this hash into a new &lt;tt>HashMap&lt;/tt> instance</em>
<a name="228" href="#228">228</a> <em>     * with a larger capacity. This method is called automatically when the</em>
<a name="229" href="#229">229</a> <em>     * number of keys in this map exceeds its capacity and load factor.</em>
<a name="230" href="#230">230</a> <em>     *</em>
<a name="231" href="#231">231</a> <em>     * Note that this method is a no-op if it's called with newCapacity ==</em>
<a name="232" href="#232">232</a> <em>     * 2*MAXIMUM_CAPACITY (which is Integer.MIN_VALUE).</em>
<a name="233" href="#233">233</a> <em>     *</em>
<a name="234" href="#234">234</a> <em>     * @param newCapacity the new capacity, MUST be a power of two.</em>
<a name="235" href="#235">235</a> <em>     */</em>
<a name="236" href="#236">236</a>     <strong>void</strong> resize(<strong>int</strong> newCapacity) {
<a name="237" href="#237">237</a>         expungeStaleEntries();
<a name="238" href="#238">238</a>         SettingsEntry[] oldTable = table;
<a name="239" href="#239">239</a>         <strong>int</strong> oldCapacity = oldTable.length;
<a name="240" href="#240">240</a> 
<a name="241" href="#241">241</a>         <em class="comment">// check if needed</em>
<a name="242" href="#242">242</a>         <strong>if</strong> (size &lt; threshold || oldCapacity > newCapacity)
<a name="243" href="#243">243</a>             <strong>return</strong>;
<a name="244" href="#244">244</a> 
<a name="245" href="#245">245</a>         SettingsEntry[] <strong>new</strong>Table = <strong>new</strong> SettingsEntry[<strong>new</strong>Capacity];
<a name="246" href="#246">246</a> 
<a name="247" href="#247">247</a>         transfer(oldTable, newTable);
<a name="248" href="#248">248</a>         table = newTable;
<a name="249" href="#249">249</a> 
<a name="250" href="#250">250</a>         <em class="comment">/*</em>
<a name="251" href="#251">251</a> <em class="comment">         * If ignoring null elements and processing ref queue caused massive</em>
<a name="252" href="#252">252</a> <em class="comment">         * shrinkage, then restore old table.  This should be rare, but avoids</em>
<a name="253" href="#253">253</a> <em class="comment">         * unbounded expansion of garbage-filled tables.</em>
<a name="254" href="#254">254</a> <em class="comment">         */</em>
<a name="255" href="#255">255</a>         <strong>if</strong> (size >= threshold / 2) {
<a name="256" href="#256">256</a>             threshold = (<strong>int</strong>)(newCapacity * LOAD_FACTOR);
<a name="257" href="#257">257</a>         } <strong>else</strong> {
<a name="258" href="#258">258</a>             expungeStaleEntries();
<a name="259" href="#259">259</a>             transfer(newTable, oldTable);
<a name="260" href="#260">260</a>             table = oldTable;
<a name="261" href="#261">261</a>         }
<a name="262" href="#262">262</a>     }
<a name="263" href="#263">263</a> 
<a name="264" href="#264">264</a>     <em>/**<em>* Transfer all entries from src to dest tables */</em></em>
<a name="265" href="#265">265</a>     <strong>private</strong> <strong>void</strong> transfer(SettingsEntry[] src, SettingsEntry[] dest) {
<a name="266" href="#266">266</a>         <strong>for</strong> (<strong>int</strong> j = 0; j &lt; src.length; ++j) {
<a name="267" href="#267">267</a>             SettingsEntry entry = src[j];
<a name="268" href="#268">268</a>             src[j] = <strong>null</strong>;
<a name="269" href="#269">269</a>             <strong>while</strong> (entry != <strong>null</strong>) {
<a name="270" href="#270">270</a>                 SettingsEntry next = entry.next;
<a name="271" href="#271">271</a>                 Object key = entry.get();
<a name="272" href="#272">272</a>                 <strong>if</strong> (key == <strong>null</strong>) {
<a name="273" href="#273">273</a>                     entry.next = <strong>null</strong>;  <em class="comment">// Help GC</em>
<a name="274" href="#274">274</a>                     entry.settings = <strong>null</strong>; <em class="comment">//  "   "</em>
<a name="275" href="#275">275</a>                     size--;
<a name="276" href="#276">276</a>                 } <strong>else</strong> {
<a name="277" href="#277">277</a>                     <strong>int</strong> i = indexFor(entry.hash, dest.length);
<a name="278" href="#278">278</a>                     entry.next = dest[i];
<a name="279" href="#279">279</a>                     dest[i] = entry;
<a name="280" href="#280">280</a>                 }
<a name="281" href="#281">281</a>                 entry = next;
<a name="282" href="#282">282</a>             }
<a name="283" href="#283">283</a>         }
<a name="284" href="#284">284</a>     }
<a name="285" href="#285">285</a> 
<a name="286" href="#286">286</a>     <em>/**<em>*</em></em>
<a name="287" href="#287">287</a> <em>     * Removes the settings object identified by the key from this hash if</em>
<a name="288" href="#288">288</a> <em>     * present.</em>
<a name="289" href="#289">289</a> <em>     *</em>
<a name="290" href="#290">290</a> <em>     * @param key key whose element is to be removed from the hash.</em>
<a name="291" href="#291">291</a> <em>     * @return previous value associated with specified key, or &lt;tt>null&lt;/tt></em>
<a name="292" href="#292">292</a> <em>     *         if there was no mapping for key.</em>
<a name="293" href="#293">293</a> <em>     */</em>
<a name="294" href="#294">294</a>     <strong>public</strong> Object remove(String key) {
<a name="295" href="#295">295</a>         <strong>if</strong> (key == <strong>null</strong>) {
<a name="296" href="#296">296</a>             <strong>throw</strong> <strong>new</strong> NullPointerException(<span class="string">"Null key"</span>);
<a name="297" href="#297">297</a>         }
<a name="298" href="#298">298</a>         <strong>int</strong> hash = hash(key);
<a name="299" href="#299">299</a>         expungeStaleEntries();
<a name="300" href="#300">300</a>         <strong>int</strong> i = indexFor(hash, table.length);
<a name="301" href="#301">301</a>         SettingsEntry prev = table[i];
<a name="302" href="#302">302</a>         SettingsEntry entry = prev;
<a name="303" href="#303">303</a> 
<a name="304" href="#304">304</a>         <strong>while</strong> (entry != <strong>null</strong>) {
<a name="305" href="#305">305</a>             SettingsEntry next = entry.next;
<a name="306" href="#306">306</a>             <strong>if</strong> (hash == entry.hash &amp;&amp; eq(key, entry.get())) {
<a name="307" href="#307">307</a>                 modCount++;
<a name="308" href="#308">308</a>                 size--;
<a name="309" href="#309">309</a>                 <strong>if</strong> (prev == entry)
<a name="310" href="#310">310</a>                     table[i] = next;
<a name="311" href="#311">311</a>                 <strong>else</strong>
<a name="312" href="#312">312</a>                     prev.next = next;
<a name="313" href="#313">313</a>                 <strong>return</strong> entry.settings;
<a name="314" href="#314">314</a>             }
<a name="315" href="#315">315</a>             prev = entry;
<a name="316" href="#316">316</a>             entry = next;
<a name="317" href="#317">317</a>         }
<a name="318" href="#318">318</a> 
<a name="319" href="#319">319</a>         <strong>return</strong> <strong>null</strong>;
<a name="320" href="#320">320</a>     }
<a name="321" href="#321">321</a> 
<a name="322" href="#322">322</a>     <em>/**<em>*</em></em>
<a name="323" href="#323">323</a> <em>     * Removes all settings object from this hash.</em>