{"id":262,"date":"2017-01-11T19:34:23","date_gmt":"2017-01-11T11:34:23","guid":{"rendered":"http:\/\/www.prayerlaputa.com\/?p=262"},"modified":"2017-01-11T19:34:23","modified_gmt":"2017-01-11T11:34:23","slug":"%e3%80%90%e6%ba%90%e7%a0%81%e5%88%86%e6%9e%90%e3%80%91java-sdk%e7%af%87-copyonwrite%e5%ae%b9%e5%99%a8","status":"publish","type":"post","link":"http:\/\/prayerlaputa.com\/?p=262","title":{"rendered":"\u3010\u6e90\u7801\u5206\u6790\u3011java sdk\u7bc7\u2013CopyOnWrite\u5bb9\u5668"},"content":{"rendered":"<p>\u5de5\u4f5c\u4e2d\u9047\u5230CopyOnWriteArrayList\u8fd9\u4e2a\u7c7b\uff0c\u7565\u597d\u5947\uff0c\u7b80\u5355\u5b66\u4e60\u4e86\u4e00\u4e0b\uff0c\u8fd9\u91cc\u505a\u4e2a\u7b14\u8bb0\u3002<\/p>\n<h2>\u4e00\u3001\u6982\u5ff5<\/h2>\n<p>CopyOnWrite\u5bb9\u5668\u662f\u5728JDK 1.5 \u7684java.uti.concurrent\u5305\u4e2d\u51fa\u73b0\u7684\uff0c\u76ee\u524d\u53ea\u6709\u4e24\u4e2a\u7c7b<\/p>\n<ul>\n<li>CopyOnWriteArrayList<\/li>\n<li>CopyOnWriteSet<\/li>\n<\/ul>\n<p><!--more--><br \/>\n\u8fd9\u4e9b\u5bb9\u5668\u7c7b\u4e0e\u5e73\u65f6\u7528\u5230\u7684ArrayList\/Set\u7684\u533a\u522b\u4e4b\u5904\u5728\u4e8e\uff1a<\/p>\n<blockquote><p>CopyOnWrite\u5bb9\u5668\u5373\u5199\u65f6\u590d\u5236\u7684\u5bb9\u5668\u3002\u901a\u4fd7\u7684\u7406\u89e3\u662f\u5f53\u6211\u4eec\u5f80\u4e00\u4e2a\u5bb9\u5668\u6dfb\u52a0\u5143\u7d20\u7684\u65f6\u5019\uff0c\u4e0d\u76f4\u63a5\u5f80\u5f53\u524d\u5bb9\u5668\u6dfb\u52a0\uff0c\u800c\u662f\u5148\u5c06\u5f53\u524d\u5bb9\u5668\u8fdb\u884cCopy\uff0c\u590d\u5236\u51fa\u4e00\u4e2a\u65b0\u7684\u5bb9\u5668\uff0c\u7136\u540e\u65b0\u7684\u5bb9\u5668\u91cc\u6dfb\u52a0\u5143\u7d20\uff0c\u6dfb\u52a0\u5b8c\u5143\u7d20\u4e4b\u540e\uff0c\u518d\u5c06\u539f\u5bb9\u5668\u7684\u5f15\u7528\u6307\u5411\u65b0\u7684\u5bb9\u5668\u3002\u8fd9\u6837\u505a\u7684\u597d\u5904\u662f\u6211\u4eec\u53ef\u4ee5\u5bf9CopyOnWrite\u5bb9\u5668\u8fdb\u884c\u5e76\u53d1\u7684\u8bfb\uff0c\u800c\u4e0d\u9700\u8981\u52a0\u9501\uff0c\u56e0\u4e3a\u5f53\u524d\u5bb9\u5668\u4e0d\u4f1a\u6dfb\u52a0\u4efb\u4f55\u5143\u7d20\u3002\u6240\u4ee5CopyOnWrite\u5bb9\u5668\u4e5f\u662f\u4e00\u79cd\u8bfb\u5199\u5206\u79bb\u7684\u601d\u60f3\uff0c\u8bfb\u548c\u5199\u4e0d\u540c\u7684\u5bb9\u5668\u3002<\/p><\/blockquote>\n<h2>\u4e8c\u3001\u6e90\u7801\u5206\u6790<\/h2>\n<p>\u4e0eArrayList\u7c7b\u4f3c\uff0cCopyOnWriteArrayList\u5185\u90e8\u540c\u6837\u662f\u57fa\u4e8e\u6570\u7ec4\u5b9e\u73b0\uff0c\u5982\u4e0b\uff1a<\/p>\n<pre class=\"brush: java; title: ; notranslate\" title=\"\">\n\/** The array, accessed only via getArray\/setArray. *\/\nprivate transient volatile Object[] array;\n<\/pre>\n<p>array\u6570\u7ec4\u88abtransient\u5173\u952e\u5b57\u4fee\u9970\uff0c\u4fdd\u8bc1\u8be5\u6570\u7ec4\u4e0d\u80fd\u4f7f\u7528Serializable\u63a5\u53e3\u81ea\u52a8\u5e8f\u5217\u5316\uff1b\u88abvolatile\u4fee\u9970\uff0c\u4fdd\u8bc1\u4e86\u591a\u7ebf\u7a0b\u8bbf\u95ee\u65f6\u7684\u53ef\u89c1\u6027\uff0c\u5373\u4fdd\u8bc1\u6bcf\u6b21\u8bfb\u53d6\u7684\u662f\u6700\u65b0\u7684\u503c\uff0c\u4f46\u662f\u6ca1\u4fdd\u8bc1\u5bf9\u53d8\u91cf\u7684\u64cd\u4f5c\u7684\u539f\u5b50\u6027\uff08\u6709\u5173volatile\u5173\u952e\u7684\u5206\u6790\uff0c\u53c2\u89c1\uff1a<a id=\"cb_post_title_url\" class=\"postTitle2\" href=\"http:\/\/www.cnblogs.com\/dolphin0520\/p\/3920373.html\">Java\u5e76\u53d1\u7f16\u7a0b\uff1avolatile\u5173\u952e\u5b57\u89e3\u6790<\/a>\uff09\u3002\u4e0eArrayList\u76f8\u6bd4\uff0cCopyOnWriteArrayList\u591a\u51fa\u4e86volatile\u5173\u952e\u5b57\u3002<br \/>\n\u800cCopyOnWriteArrayList\u533a\u522b\u4e8eArrayList\u7684\u4e3b\u8981\u5730\u65b9\u5728\u4e8eadd\/set\/remove\u7b49\u6d89\u53ca\u5230\u5199\u6570\u636e\u7684\u65b9\u6cd5\uff1a<\/p>\n<pre class=\"brush: java; title: ; notranslate\" title=\"\">\npublic E set(int index, E element) {\n        final ReentrantLock lock = this.lock;\n        lock.lock();\n        try {\n            Object[] elements = getArray();\n            E oldValue = get(elements, index);\n            if (oldValue != element) {\n                int len = elements.length;\n                Object[] newElements = Arrays.copyOf(elements, len);\n                newElements[index] = element;\n                setArray(newElements);\n            } else {\n                \/\/ Not quite a no-op; ensures volatile write semantics\n                setArray(elements);\n            }\n            return oldValue;\n        } finally {\n            lock.unlock();\n        }\n    }\npublic boolean add(E e) {\n        final ReentrantLock lock = this.lock;\n        lock.lock();\n        try {\n            Object[] elements = getArray();\n            int len = elements.length;\n            Object[] newElements = Arrays.copyOf(elements, len + 1);\n            newElements[len] = e;\n            setArray(newElements);\n            return true;\n        } finally {\n            lock.unlock();\n        }\n    }\npublic E remove(int index) {\n        final ReentrantLock lock = this.lock;\n        lock.lock();\n        try {\n            Object[] elements = getArray();\n            int len = elements.length;\n            E oldValue = get(elements, index);\n            int numMoved = len - index - 1;\n            if (numMoved == 0)\n                setArray(Arrays.copyOf(elements, len - 1));\n            else {\n                Object[] newElements = new Object[len - 1];\n                System.arraycopy(elements, 0, newElements, 0, index);\n                System.arraycopy(elements, index + 1, newElements, index,\n                                 numMoved);\n                setArray(newElements);\n            }\n            return oldValue;\n        } finally {\n            lock.unlock();\n        }\n    }\n<\/pre>\n<p>ArrayList\u5728add\/set\/remove\u65f6\uff0c\u53ea\u9700\u8981\u8003\u8651\u5185\u90e8\u7684\u6570\u7ec4\u5c31\u53ef\u4ee5\uff0c\u4e0d\u7528\u8003\u8651\u5e76\u53d1\u3002\u800cCopyOnWriteArrayList\u5219\u91c7\u7528\u53ef\u91cd\u5165\u9501\uff0c\u907f\u514d\u591a\u7ebf\u7a0b\u5199\u64cd\u4f5c\uff0c\u5e76\u4e14\u5199\u7684\u65f6\u5019\u662f\u91cd\u65b0\u62f7\u8d1d\u4e00\u4e2a\u65b0\u7684\u6570\u7ec4\uff0c\u7b49\u62f7\u8d1d\u7ed3\u675f\u3001\u5c06\u4fee\u6539\u5f15\u7528\u540e\u518d\u91ca\u653e\u9501\u3002\u56e0\u6b64\uff0cCopyOnWriteArrayList\u82e5\u4fdd\u5b58\u5bf9\u8c61\u8f83\u5927\u3001\u5360\u7528\u5185\u5b58\u8f83\u591a\u65f6\u53ef\u80fd\u9020\u6210JVM\u9891\u7e41\u8fdb\u884cgc\u3002\u53e6\u5916\uff0cCopyOnWriteArrayList\u53ea\u4fdd\u8bc1\u4e86\u6570\u636e\u7684\u6700\u7ec8\u4e00\u81f4\u6027\uff0c\u5e76\u6ca1\u6709\u4fdd\u8bc1\u6570\u636e\u7684\u5b9e\u65f6\u4e00\u81f4\u6027\u3002<\/p>\n<h2>\u4e09\u3001\u573a\u666f\u5e94\u7528\u5e38\u89c1<\/h2>\n<blockquote><p>CopyOnWrite\u5e76\u53d1\u5bb9\u5668\u7528\u4e8e\u8bfb\u591a\u5199\u5c11\u7684\u5e76\u53d1\u573a\u666f\u3002\u6bd4\u5982\u767d\u540d\u5355\uff0c\u9ed1\u540d\u5355\uff0c\u5546\u54c1\u7c7b\u76ee\u7684\u8bbf\u95ee\u548c\u66f4\u65b0\u573a\u666f<\/p><\/blockquote>\n<h2>\u56db\u3001\u53c2\u8003<\/h2>\n<p><a href=\"http:\/\/coolshell.cn\/articles\/11175.html\">JAVA\u4e2d\u7684COPYONWRITE\u5bb9\u5668<\/a><br \/>\n<a id=\"cb_post_title_url\" class=\"postTitle2\" href=\"http:\/\/www.cnblogs.com\/java-zhao\/p\/5121944.html\">CopyOnWriteArrayList\u6e90\u7801\u89e3\u6790<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5de5\u4f5c\u4e2d\u9047\u5230CopyOnWriteArrayList\u8fd9\u4e2a\u7c7b\uff0c\u7565\u597d\u5947\uff0c\u7b80\u5355\u5b66\u4e60\u4e86\u4e00\u4e0b\uff0c\u8fd9\u91cc\u505a\u4e2a\u7b14\u8bb0\u3002 \u4e00\u3001\u6982\u5ff5 C <a href='http:\/\/prayerlaputa.com\/?p=262' class='excerpt-more'>[&#8230;]<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0},"categories":[6,18,23],"tags":[33,50],"_links":{"self":[{"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=\/wp\/v2\/posts\/262"}],"collection":[{"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=262"}],"version-history":[{"count":0,"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=\/wp\/v2\/posts\/262\/revisions"}],"wp:attachment":[{"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=262"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=262"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/prayerlaputa.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=262"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}