{"id":10020541,"date":"2024-12-23T20:14:50","date_gmt":"2024-12-23T12:14:50","guid":{"rendered":"https:\/\/itmax.cn\/?p=10020541"},"modified":"2024-12-23T20:14:50","modified_gmt":"2024-12-23T12:14:50","slug":"%e5%bf%ab%e6%89%8b%e5%90%8e%e7%ab%af%e9%9d%a2%e8%af%95%ef%bc%8c%e8%a2%ab%e9%9d%a2%e8%af%95%e5%ae%98%e7%a7%92%e6%8c%82%e4%ba%86%ef%bc%81","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10020541","title":{"rendered":"\u5feb\u624b\u540e\u7aef\u9762\u8bd5\uff0c\u88ab\u9762\u8bd5\u5b98\u79d2\u6302\u4e86\uff01"},"content":{"rendered":"<p>\u4f60\u597d\uff0c\u6211\u662f Guide\u3002\u5f88\u4e45\u6ca1\u6709\u5206\u4eab\u51c9\u7ecf\u4e86\uff0c\u4eca\u5929\u6765\u5206\u4eab\u4e00\u4f4d\u897f\u5317\u5de5\u4e1a\u5927\u5b66\u7684\u8bfb\u8005\u9762\u8bd5\u5feb\u624b\uff0c\u4e00\u9762\u5c31\u76f4\u63a5\u79d2\u6302\u7684\u9762\u7ecf\u3002<\/p>\n<p>\u5feb\u624b\u4e00\u9762\u4e3b\u8981\u4f1a\u95ee\u4e00\u4e9b\u57fa\u7840\u95ee\u9898\uff0c\u4e5f\u5c31\u662f\u6bd4\u8f83\u7b80\u5355\u4e14\u5bb9\u6613\u51c6\u5907\u7684\u5e38\u89c4\u516b\u80a1\uff0c\u901a\u5e38\u4e0d\u4f1a\u95ee\u9879\u76ee\u6216\u8005\u95ee\u7684\u6bd4\u8f83\u5c11\u3002\u5230\u4e86\u4e8c\u9762\uff0c\u4f1a\u5f00\u59cb\u95ee\u9879\u76ee\uff0c\u5404\u79cd\u95ee\u9898\u4e5f\u6316\u6398\u7684\u66f4\u6df1\u4e00\u4e9b\u3002<\/p>\n<p>\u5f88\u591a\u540c\u5b66\u89c9\u5f97\u8fd9\u79cd\u57fa\u7840\u95ee\u9898\u7684\u8003\u67e5\u610f\u4e49\u4e0d\u5927\uff0c\u5b9e\u9645\u4e0a\u8fd8\u662f\u5f88\u6709\u610f\u4e49\u7684\uff0c\u8fd9\u79cd\u57fa\u7840\u6027\u7684\u77e5\u8bc6\u5728\u65e5\u5e38\u5f00\u53d1\u4e2d\u4e5f\u4f1a\u9700\u8981\u7ecf\u5e38\u7528\u5230\u3002\u4f8b\u5982\uff0c\u7ebf\u7a0b\u6c60\u8fd9\u5757\u7684\u62d2\u7edd\u7b56\u7565\u3001\u6838\u5fc3\u53c2\u6570\u914d\u7f6e\u4ec0\u4e48\u7684\uff0c\u5982\u679c\u4f60\u4e0d\u4e86\u89e3\uff0c\u5b9e\u9645\u9879\u76ee\u4e2d\u4f7f\u7528\u7ebf\u7a0b\u6c60\u53ef\u80fd\u5c31\u7528\u7684\u4e0d\u662f\u5f88\u660e\u767d\uff0c\u5bb9\u6613\u51fa\u73b0\u95ee\u9898\u3002\u800c\u4e14\uff0c\u5176\u5b9e\u8fd9\u79cd\u57fa\u7840\u6027\u7684\u95ee\u9898\u662f\u6700\u5bb9\u6613\u51c6\u5907\u7684\uff0c\u50cf\u5404\u79cd\u5e95\u5c42\u539f\u7406\u3001\u7cfb\u7edf\u8bbe\u8ba1\u3001\u573a\u666f\u9898\u4ee5\u53ca\u6df1\u6316\u4f60\u7684\u9879\u76ee\u8fd9\u7c7b\u624d\u662f\u6700\u96be\u7684\uff01<\/p>\n<p>\u4e0b\u9762\u662f\u6b63\u6587\u3002<\/p>\n<p>\u4e00\u9762\u6ca1\u6709\u95ee\u9879\u76ee\uff0c\u5c31\u662f\u4e00\u4e9b\u5f88\u57fa\u7840\u7684\u516b\u80a1\u3002\u9762\u8bd5\u5b98\u8bf4\u6211\u7684\u57fa\u7840\u77e5\u8bc6\u592a\u8584\u5f31\uff0c\u5f88\u591a\u9762\u8bd5\u9898\u56de\u7b54\u7684\u50cf\u662f\u5728\u786c\u80cc\uff0c\u6ca1\u6709\u81ea\u5df1\u7684\u7406\u89e3\u3002\u53e6\u5916\uff0c\u4ed6\u5efa\u8bae\u6211\u63d0\u9ad8\u4e00\u4e0b\u81ea\u5df1\u7684\u8868\u8fbe\u80fd\u529b\uff0c\u5410\u8bcd\u5c3d\u91cf\u8981\u6e05\u6670\u4e00\u4e9b\u3002<\/p>\n<h3>1\u3001Java \u5f02\u5e38\u7c7b\u5206\u4e3a\u54ea\u4e24\u79cd\uff1f\u6709\u4ec0\u4e48\u533a\u522b\uff1f<\/h3>\n<p>Java \u5f02\u5e38\u7c7b\u5c42\u6b21\u7ed3\u6784\u56fe\u6982\u89c8\uff1a<\/p>\n<p><img decoding=\"async\"   referrerpolicy=\"no-referrer\" src=\"https:\/\/oss.javaguide.cn\/github\/javaguide\/java\/basis\/types-of-exceptions-in-java.png\" alt=\"Java \u5f02\u5e38\u7c7b\u5c42\u6b21\u7ed3\u6784\u56fe\" title=\"Java \u5f02\u5e38\u7c7b\u5c42\u6b21\u7ed3\u6784\u56fe\"><\/p>\n<p>\u5728 Java \u4e2d\uff0c\u6240\u6709\u7684\u5f02\u5e38\u90fd\u6709\u4e00\u4e2a\u5171\u540c\u7684\u7956\u5148 <code>java.lang<\/code> \u5305\u4e2d\u7684 <code>Throwable<\/code> \u7c7b\u3002<code>Throwable<\/code> \u7c7b\u6709\u4e24\u4e2a\u91cd\u8981\u7684\u5b50\u7c7b:<\/p>\n<ul>\n<li><strong><code>Exception<\/code><\/strong> :\u7a0b\u5e8f\u672c\u8eab\u53ef\u4ee5\u5904\u7406\u7684\u5f02\u5e38\uff0c\u53ef\u4ee5\u901a\u8fc7 <code>catch<\/code> \u6765\u8fdb\u884c\u6355\u83b7\u3002<code>Exception<\/code> \u53c8\u53ef\u4ee5\u5206\u4e3a Checked Exception (\u53d7\u68c0\u67e5\u5f02\u5e38\uff0c\u5fc5\u987b\u5904\u7406) \u548c Unchecked Exception (\u4e0d\u53d7\u68c0\u67e5\u5f02\u5e38\uff0c\u53ef\u4ee5\u4e0d\u5904\u7406)\u3002<\/li>\n<li><strong><code>Error<\/code><\/strong> \uff1a<code>Error<\/code> \u5c5e\u4e8e\u7a0b\u5e8f\u65e0\u6cd5\u5904\u7406\u7684\u9519\u8bef \uff0c<del>\u6211\u4eec\u6ca1\u529e\u6cd5\u901a\u8fc7 <code>catch<\/code> \u6765\u8fdb\u884c\u6355\u83b7<\/del>\u4e0d\u5efa\u8bae\u901a\u8fc7<code>catch<\/code>\u6355\u83b7 \u3002\u4f8b\u5982 Java \u865a\u62df\u673a\u8fd0\u884c\u9519\u8bef\uff08<code>Virtual MachineError<\/code>\uff09\u3001\u865a\u62df\u673a\u5185\u5b58\u4e0d\u591f\u9519\u8bef(<code>OutOfMemoryError<\/code>)\u3001\u7c7b\u5b9a\u4e49\u9519\u8bef\uff08<code>NoClassDefFoundError<\/code>\uff09\u7b49 \u3002\u8fd9\u4e9b\u5f02\u5e38\u53d1\u751f\u65f6\uff0cJava \u865a\u62df\u673a\uff08JVM\uff09\u4e00\u822c\u4f1a\u9009\u62e9\u7ebf\u7a0b\u7ec8\u6b62\u3002<\/li>\n<\/ul>\n<h3>2\u3001try-with-resources \u600e\u4e48\u4f7f\u7528\uff1f<\/h3>\n<ol>\n<li><strong>\u9002\u7528\u8303\u56f4\uff08\u8d44\u6e90\u7684\u5b9a\u4e49\uff09\uff1a<\/strong> \u4efb\u4f55\u5b9e\u73b0 <code>java.lang.AutoCloseable<\/code>\u6216\u8005 <code>java.io.Closeable<\/code> \u7684\u5bf9\u8c61<\/li>\n<li><strong>\u5173\u95ed\u8d44\u6e90\u548c finally \u5757\u7684\u6267\u884c\u987a\u5e8f\uff1a<\/strong> \u5728 <code>try-with-resources<\/code> \u8bed\u53e5\u4e2d\uff0c\u4efb\u4f55 catch \u6216 finally \u5757\u5728\u58f0\u660e\u7684\u8d44\u6e90\u5173\u95ed\u540e\u8fd0\u884c<\/li>\n<\/ol>\n<p>\u300aEffective Java\u300b\u4e2d\u660e\u786e\u6307\u51fa\uff1a<\/p>\n<blockquote><p>\u9762\u5bf9\u5fc5\u987b\u8981\u5173\u95ed\u7684\u8d44\u6e90\uff0c\u6211\u4eec\u603b\u662f\u5e94\u8be5\u4f18\u5148\u4f7f\u7528 <code>try-with-resources<\/code> \u800c\u4e0d\u662f<code>try-finally<\/code>\u3002\u968f\u4e4b\u4ea7\u751f\u7684\u4ee3\u7801\u66f4\u7b80\u77ed\uff0c\u66f4\u6e05\u6670\uff0c\u4ea7\u751f\u7684\u5f02\u5e38\u5bf9\u6211\u4eec\u4e5f\u66f4\u6709\u7528\u3002<code>try-with-resources<\/code>\u8bed\u53e5\u8ba9\u6211\u4eec\u66f4\u5bb9\u6613\u7f16\u5199\u5fc5\u987b\u8981\u5173\u95ed\u7684\u8d44\u6e90\u7684\u4ee3\u7801\uff0c\u82e5\u91c7\u7528<code>try-finally<\/code>\u5219\u51e0\u4e4e\u505a\u4e0d\u5230\u8fd9\u70b9\u3002<\/p><\/blockquote>\n<p>Java \u4e2d\u7c7b\u4f3c\u4e8e<code>InputStream<\/code>\u3001<code>OutputStream<\/code>\u3001<code>Scanner<\/code>\u3001<code>PrintWriter<\/code>\u7b49\u7684\u8d44\u6e90\u90fd\u9700\u8981\u6211\u4eec\u8c03\u7528<code>close()<\/code>\u65b9\u6cd5\u6765\u624b\u52a8\u5173\u95ed\uff0c\u4e00\u822c\u60c5\u51b5\u4e0b\u6211\u4eec\u90fd\u662f\u901a\u8fc7<code>try-catch-finally<\/code>\u8bed\u53e5\u6765\u5b9e\u73b0\u8fd9\u4e2a\u9700\u6c42\uff0c\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"java\">\/\/\u8bfb\u53d6\u6587\u672c\u6587\u4ef6\u7684\u5185\u5bb9\nScanner scanner = null;\ntry {\n    scanner = new Scanner(new File(&quot;D:\/\/read.txt&quot;));\n    while (scanner.hasNext()) {\n        System.out.println(scanner.nextLine());\n    }\n} catch (FileNotFoundException e) {\n    e.printStackTrace();\n} finally {\n    if (scanner != null) {\n        scanner.close();\n    }\n}<\/code><\/pre>\n<p>\u4f7f\u7528 Java 7 \u4e4b\u540e\u7684 <code>try-with-resources<\/code> \u8bed\u53e5\u6539\u9020\u4e0a\u9762\u7684\u4ee3\u7801:<\/p>\n<pre><code class=\"java\">try (Scanner scanner = new Scanner(new File(&quot;test.txt&quot;))) {\n    while (scanner.hasNext()) {\n        System.out.println(scanner.nextLine());\n    }\n} catch (FileNotFoundException fnfe) {\n    fnfe.printStackTrace();\n}<\/code><\/pre>\n<p>\u5f53\u7136\u591a\u4e2a\u8d44\u6e90\u9700\u8981\u5173\u95ed\u7684\u65f6\u5019\uff0c\u4f7f\u7528 <code>try-with-resources<\/code> \u5b9e\u73b0\u8d77\u6765\u4e5f\u975e\u5e38\u7b80\u5355\uff0c\u5982\u679c\u4f60\u8fd8\u662f\u7528<code>try-catch-finally<\/code>\u53ef\u80fd\u4f1a\u5e26\u6765\u5f88\u591a\u95ee\u9898\u3002<\/p>\n<p>\u901a\u8fc7\u4f7f\u7528\u5206\u53f7\u5206\u9694\uff0c\u53ef\u4ee5\u5728<code>try-with-resources<\/code>\u5757\u4e2d\u58f0\u660e\u591a\u4e2a\u8d44\u6e90\u3002<\/p>\n<pre><code class=\"java\">try (BufferedInputStream bin = new BufferedInputStream(new FileInputStream(new File(&quot;test.txt&quot;)));\n     BufferedOutputStream bout = new BufferedOutputStream(new FileOutputStream(new File(&quot;out.txt&quot;)))) {\n    int b;\n    while ((b = bin.read()) != -1) {\n        bout.write(b);\n    }\n}\ncatch (IOException e) {\n    e.printStackTrace();\n}<\/code><\/pre>\n<p>\u66f4\u591a Java \u57fa\u7840\u76f8\u5173\u7684\u9762\u8bd5\u9898\uff0c\u53ef\u4ee5\u53c2\u8003\u8fd9\u51e0\u7bc7\u6587\u7ae0\uff1a<\/p>\n<ul>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=znlYoFDtRdJFGeXhSN8JUQ%3D%3D.MKOfxHCxVt6tO0mzCKXve7SbfpxwqVLPALdLL71s1rxN4J89yY6eYo6O0YSJ%2FkREJfiAVCufDNWUVcM2N%2FgVzg%3D%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u57fa\u7840\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e0a\uff09<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=l5rTMukeyxQ%2BNE3E1D10%2Fw%3D%3D.Vn7ZaRuzq3KRQ3pUOFAiqNZLmokRSbY9IifAW3wHjY0BNzP7gUNXxoGWvd2tnXZiWp4yBwjP8Qg0LxO3spnA8A%3D%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u57fa\u7840\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e2d\uff09<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=FGoBkH9Ti9561tZvpmfJ%2BA%3D%3D.zhu4eUhJ7Ec1zoETllqr3ylewNw7PW5Hy%2FW7VSiTtjx3krSH2JhiCxCFu%2BKVPPt9VQtH6COYc%2BvcFIpsJ%2F4Now%3D%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u57fa\u7840\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e0b\uff09<\/a><\/li>\n<\/ul>\n<h3>3\u3001HashMap \u4e3a\u4ec0\u4e48\u4e0d\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff1f<\/h3>\n<p>JDK1.7 \u53ca\u4e4b\u524d\u7248\u672c\uff0c\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\uff0c<code>HashMap<\/code> \u6269\u5bb9\u65f6\u4f1a\u9020\u6210\u6b7b\u5faa\u73af\u548c\u6570\u636e\u4e22\u5931\u7684\u95ee\u9898\u3002<\/p>\n<p>\u6570\u636e\u4e22\u5931\u8fd9\u4e2a\u5728 JDK1.7 \u548c JDK 1.8 \u4e2d\u90fd\u5b58\u5728\uff0c\u8fd9\u91cc\u4ee5 JDK 1.8 \u4e3a\u4f8b\u8fdb\u884c\u4ecb\u7ecd\u3002<\/p>\n<p>JDK 1.8 \u540e\uff0c\u5728 <code>HashMap<\/code> \u4e2d\uff0c\u591a\u4e2a\u952e\u503c\u5bf9\u53ef\u80fd\u4f1a\u88ab\u5206\u914d\u5230\u540c\u4e00\u4e2a\u6876\uff08bucket\uff09\uff0c\u5e76\u4ee5\u94fe\u8868\u6216\u7ea2\u9ed1\u6811\u7684\u5f62\u5f0f\u5b58\u50a8\u3002\u591a\u4e2a\u7ebf\u7a0b\u5bf9 <code>HashMap<\/code> \u7684 <code>put<\/code> \u64cd\u4f5c\u4f1a\u5bfc\u81f4\u7ebf\u7a0b\u4e0d\u5b89\u5168\uff0c\u5177\u4f53\u6765\u8bf4\u4f1a\u6709\u6570\u636e\u8986\u76d6\u7684\u98ce\u9669\u3002<\/p>\n<p>\u4e3e\u4e2a\u4f8b\u5b50\uff1a<\/p>\n<ul>\n<li>\u4e24\u4e2a\u7ebf\u7a0b 1,2 \u540c\u65f6\u8fdb\u884c put \u64cd\u4f5c\uff0c\u5e76\u4e14\u53d1\u751f\u4e86\u54c8\u5e0c\u51b2\u7a81\uff08hash \u51fd\u6570\u8ba1\u7b97\u51fa\u7684\u63d2\u5165\u4e0b\u6807\u662f\u76f8\u540c\u7684\uff09\u3002<\/li>\n<li>\u4e0d\u540c\u7684\u7ebf\u7a0b\u53ef\u80fd\u5728\u4e0d\u540c\u7684\u65f6\u95f4\u7247\u83b7\u5f97 CPU \u6267\u884c\u7684\u673a\u4f1a\uff0c\u5f53\u524d\u7ebf\u7a0b 1 \u6267\u884c\u5b8c\u54c8\u5e0c\u51b2\u7a81\u5224\u65ad\u540e\uff0c\u7531\u4e8e\u65f6\u95f4\u7247\u8017\u5c3d\u6302\u8d77\u3002\u7ebf\u7a0b 2 \u5148\u5b8c\u6210\u4e86\u63d2\u5165\u64cd\u4f5c\u3002<\/li>\n<li>\u968f\u540e\uff0c\u7ebf\u7a0b 1 \u83b7\u5f97\u65f6\u95f4\u7247\uff0c\u7531\u4e8e\u4e4b\u524d\u5df2\u7ecf\u8fdb\u884c\u8fc7 hash \u78b0\u649e\u7684\u5224\u65ad\uff0c\u6240\u6709\u6b64\u65f6\u4f1a\u76f4\u63a5\u8fdb\u884c\u63d2\u5165\uff0c\u8fd9\u5c31\u5bfc\u81f4\u7ebf\u7a0b 2 \u63d2\u5165\u7684\u6570\u636e\u88ab\u7ebf\u7a0b 1 \u8986\u76d6\u4e86\u3002<\/li>\n<\/ul>\n<pre><code class=\"java\">public V put(K key, V value) {\n    return putVal(hash(key), key, value, false, true);\n}\n\nfinal V putVal(int hash, K key, V value, boolean onlyIfAbsent,\n                   boolean evict) {\n    \/\/ ...\n    \/\/ \u5224\u65ad\u662f\u5426\u51fa\u73b0 hash \u78b0\u649e\n    \/\/ (n - 1) &amp; hash \u786e\u5b9a\u5143\u7d20\u5b58\u653e\u5728\u54ea\u4e2a\u6876\u4e2d\uff0c\u6876\u4e3a\u7a7a\uff0c\u65b0\u751f\u6210\u7ed3\u70b9\u653e\u5165\u6876\u4e2d(\u6b64\u65f6\uff0c\u8fd9\u4e2a\u7ed3\u70b9\u662f\u653e\u5728\u6570\u7ec4\u4e2d)\n    if ((p = tab[i = (n - 1) &amp; hash]) == null)\n        tab[i] = newNode(hash, key, value, null);\n    \/\/ \u6876\u4e2d\u5df2\u7ecf\u5b58\u5728\u5143\u7d20\uff08\u5904\u7406hash\u51b2\u7a81\uff09\n    else {\n    \/\/ ...\n}<\/code><\/pre>\n<p>\u8fd8\u6709\u4e00\u79cd\u60c5\u51b5\u662f\u8fd9\u4e24\u4e2a\u7ebf\u7a0b\u540c\u65f6 <code>put<\/code> \u64cd\u4f5c\u5bfc\u81f4 <code>size<\/code> \u7684\u503c\u4e0d\u6b63\u786e\uff0c\u8fdb\u800c\u5bfc\u81f4\u6570\u636e\u8986\u76d6\u7684\u95ee\u9898\uff1a<\/p>\n<ol>\n<li>\u7ebf\u7a0b 1 \u6267\u884c <code>if(++size &gt; threshold)<\/code> \u5224\u65ad\u65f6\uff0c\u5047\u8bbe\u83b7\u5f97 <code>size<\/code> \u7684\u503c\u4e3a 10\uff0c\u7531\u4e8e\u65f6\u95f4\u7247\u8017\u5c3d\u6302\u8d77\u3002<\/li>\n<li>\u7ebf\u7a0b 2 \u4e5f\u6267\u884c <code>if(++size &gt; threshold)<\/code> \u5224\u65ad\uff0c\u83b7\u5f97 <code>size<\/code> \u7684\u503c\u4e5f\u4e3a 10\uff0c\u5e76\u5c06\u5143\u7d20\u63d2\u5165\u5230\u8be5\u6876\u4f4d\u4e2d\uff0c\u5e76\u5c06 <code>size<\/code> \u7684\u503c\u66f4\u65b0\u4e3a 11\u3002<\/li>\n<li>\u968f\u540e\uff0c\u7ebf\u7a0b 1 \u83b7\u5f97\u65f6\u95f4\u7247\uff0c\u5b83\u4e5f\u5c06\u5143\u7d20\u653e\u5165\u6876\u4f4d\u4e2d\uff0c\u5e76\u5c06 size \u7684\u503c\u66f4\u65b0\u4e3a 11\u3002<\/li>\n<li>\u7ebf\u7a0b 1\u30012 \u90fd\u6267\u884c\u4e86\u4e00\u6b21 <code>put<\/code> \u64cd\u4f5c\uff0c\u4f46\u662f <code>size<\/code> \u7684\u503c\u53ea\u589e\u52a0\u4e86 1\uff0c\u4e5f\u5c31\u5bfc\u81f4\u5b9e\u9645\u4e0a\u53ea\u6709\u4e00\u4e2a\u5143\u7d20\u88ab\u6dfb\u52a0\u5230\u4e86 <code>HashMap<\/code> \u4e2d\u3002<\/li>\n<\/ol>\n<pre><code class=\"java\">public V put(K key, V value) {\n    return putVal(hash(key), key, value, false, true);\n}\n\nfinal V putVal(int hash, K key, V value, boolean onlyIfAbsent,\n                   boolean evict) {\n    \/\/ ...\n    \/\/ \u5b9e\u9645\u5927\u5c0f\u5927\u4e8e\u9608\u503c\u5219\u6269\u5bb9\n    if (++size &gt; threshold)\n        resize();\n    \/\/ \u63d2\u5165\u540e\u56de\u8c03\n    afterNodeInsertion(evict);\n    return null;\n}<\/code><\/pre>\n<h3>4\u3001\u90a3 HashMap \u7ebf\u7a0b\u5b89\u5168\u7684\u66ff\u4ee3\u54c1\u662f\uff1f<\/h3>\n<p>\u6211\u4eec\u77e5\u9053\uff0c<code>HashMap<\/code> \u662f\u7ebf\u7a0b\u4e0d\u5b89\u5168\u7684\uff0c\u5982\u679c\u5728\u5e76\u53d1\u573a\u666f\u4e0b\u4f7f\u7528\uff0c\u4e00\u79cd\u5e38\u89c1\u7684\u89e3\u51b3\u65b9\u5f0f\u662f\u901a\u8fc7 <code>Collections.synchronizedMap()<\/code> \u65b9\u6cd5\u5bf9 <code>HashMap<\/code> \u8fdb\u884c\u5305\u88c5\uff0c\u4f7f\u5176\u53d8\u4e3a\u7ebf\u7a0b\u5b89\u5168\u3002\u4e0d\u8fc7\uff0c\u8fd9\u79cd\u65b9\u5f0f\u662f\u901a\u8fc7\u4e00\u4e2a\u5168\u5c40\u9501\u6765\u540c\u6b65\u4e0d\u540c\u7ebf\u7a0b\u95f4\u7684\u5e76\u53d1\u8bbf\u95ee\uff0c\u4f1a\u5bfc\u81f4\u4e25\u91cd\u7684\u6027\u80fd\u74f6\u9888\uff0c\u5c24\u5176\u662f\u5728\u9ad8\u5e76\u53d1\u573a\u666f\u4e0b\u3002<\/p>\n<p>\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e00\u95ee\u9898\uff0c<code>ConcurrentHashMap<\/code> \u5e94\u8fd0\u800c\u751f\uff0c\u4f5c\u4e3a <code>HashMap<\/code> \u7684\u7ebf\u7a0b\u5b89\u5168\u7248\u672c\uff0c\u5b83\u63d0\u4f9b\u4e86\u66f4\u9ad8\u6548\u7684\u5e76\u53d1\u5904\u7406\u80fd\u529b\u3002<\/p>\n<p>\u5728 JDK1.7 \u7684\u65f6\u5019\uff0c<code>ConcurrentHashMap<\/code> \u5bf9\u6574\u4e2a\u6876\u6570\u7ec4\u8fdb\u884c\u4e86\u5206\u5272\u5206\u6bb5(<code>Segment<\/code>\uff0c\u5206\u6bb5\u9501)\uff0c\u6bcf\u4e00\u628a\u9501\u53ea\u9501\u5bb9\u5668\u5176\u4e2d\u4e00\u90e8\u5206\u6570\u636e\uff08\u4e0b\u9762\u6709\u793a\u610f\u56fe\uff09\uff0c\u591a\u7ebf\u7a0b\u8bbf\u95ee\u5bb9\u5668\u91cc\u4e0d\u540c\u6570\u636e\u6bb5\u7684\u6570\u636e\uff0c\u5c31\u4e0d\u4f1a\u5b58\u5728\u9501\u7ade\u4e89\uff0c\u63d0\u9ad8\u5e76\u53d1\u8bbf\u95ee\u7387\u3002<\/p>\n<p><img decoding=\"async\"   referrerpolicy=\"no-referrer\" src=\"https:\/\/oss.javaguide.cn\/github\/javaguide\/java\/collection\/java7_concurrenthashmap.png\" alt=\"Java7 ConcurrentHashMap \u5b58\u50a8\u7ed3\u6784\" title=\"Java7 ConcurrentHashMap \u5b58\u50a8\u7ed3\u6784\" loading=\"lazy\"><\/p>\n<p>\u5230\u4e86 JDK1.8 \u7684\u65f6\u5019\uff0c<code>ConcurrentHashMap<\/code> \u53d6\u6d88\u4e86 <code>Segment<\/code> \u5206\u6bb5\u9501\uff0c\u91c7\u7528 <code>Node + CAS + synchronized<\/code> \u6765\u4fdd\u8bc1\u5e76\u53d1\u5b89\u5168\u3002\u6570\u636e\u7ed3\u6784\u8ddf <code>HashMap<\/code> 1.8 \u7684\u7ed3\u6784\u7c7b\u4f3c\uff0c\u6570\u7ec4+\u94fe\u8868\/\u7ea2\u9ed1\u4e8c\u53c9\u6811\u3002Java 8 \u5728\u94fe\u8868\u957f\u5ea6\u8d85\u8fc7\u4e00\u5b9a\u9608\u503c\uff088\uff09\u65f6\u5c06\u94fe\u8868\uff08\u5bfb\u5740\u65f6\u95f4\u590d\u6742\u5ea6\u4e3a O(N)\uff09\u8f6c\u6362\u4e3a\u7ea2\u9ed1\u6811\uff08\u5bfb\u5740\u65f6\u95f4\u590d\u6742\u5ea6\u4e3a O(log(N))\uff09\u3002<\/p>\n<p>Java 8 \u4e2d\uff0c\u9501\u7c92\u5ea6\u66f4\u7ec6\uff0c<code>synchronized<\/code> \u53ea\u9501\u5b9a\u5f53\u524d\u94fe\u8868\u6216\u7ea2\u9ed1\u4e8c\u53c9\u6811\u7684\u9996\u8282\u70b9\uff0c\u8fd9\u6837\u53ea\u8981 hash \u4e0d\u51b2\u7a81\uff0c\u5c31\u4e0d\u4f1a\u4ea7\u751f\u5e76\u53d1\uff0c\u5c31\u4e0d\u4f1a\u5f71\u54cd\u5176\u4ed6 Node \u7684\u8bfb\u5199\uff0c\u6548\u7387\u5927\u5e45\u63d0\u5347\u3002<\/p>\n<p><img decoding=\"async\"   referrerpolicy=\"no-referrer\" src=\"https:\/\/oss.javaguide.cn\/github\/javaguide\/java\/collection\/java8_concurrenthashmap.png\" alt=\"Java8 ConcurrentHashMap \u5b58\u50a8\u7ed3\u6784\" title=\"Java8 ConcurrentHashMap \u5b58\u50a8\u7ed3\u6784\" loading=\"lazy\"><\/p>\n<p>\u66f4\u591a Java \u96c6\u5408\u76f8\u5173\u7684\u9762\u8bd5\u9898\uff0c\u53ef\u4ee5\u53c2\u8003\u8fd9\u51e0\u7bc7\u6587\u7ae0\uff1a<\/p>\n<ul>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=V5k1s%2B8PFbvJCfDgOisahA%3D%3D.72wMxnpeNw%2B4MIZ5M2mC00T2eZnNbHk6U7fDVjJ9biUpHCRYrFnCGQBmL4rWW0AZVg8Sjb7HHpjw4x5teLCwy%2Bzr7j%2FBf%2Bz76yrU7rR4uxI%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u96c6\u5408\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e0a\uff09<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=LPC7pOYXdZW0DGqWXJv2hg%3D%3D.TO7%2FQzVnjVQYFE%2FmAfMq1uKI3D4fFXH7wiQ1%2FqRDQZE9WAhOjvMWEA7ZkSodoGvEf4gpfZbxCicWKaN%2FmAcVRNMYbNQfh15E3R%2FChpRY0uQ%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u96c6\u5408\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e2d\uff09<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=UG5NlfLUEBsriIZKMm8fqQ%3D%3D.KxoMK%2FGI2YwQI0xykLLCuCYz065sFQET8YkO0fMMydIJl6NN4p2Ib1PgmOXxiP%2FvWn058u38CcK2G3ioIF2PmpPTUyzHE9HYJckWoJvCfTg%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u96c6\u5408\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e0b\uff09<\/a><\/li>\n<\/ul>\n<h3>5\u3001\u53ef\u91cd\u5165\u9501\u6307\u7684\u662f\uff1f<\/h3>\n<p><strong>\u53ef\u91cd\u5165\u9501<\/strong> \u4e5f\u53eb\u9012\u5f52\u9501\uff0c\u6307\u7684\u662f\u7ebf\u7a0b\u53ef\u4ee5\u518d\u6b21\u83b7\u53d6\u81ea\u5df1\u7684\u5185\u90e8\u9501\u3002\u6bd4\u5982\u4e00\u4e2a\u7ebf\u7a0b\u83b7\u5f97\u4e86\u67d0\u4e2a\u5bf9\u8c61\u7684\u9501\uff0c\u6b64\u65f6\u8fd9\u4e2a\u5bf9\u8c61\u9501\u8fd8\u6ca1\u6709\u91ca\u653e\uff0c\u5f53\u5176\u518d\u6b21\u60f3\u8981\u83b7\u53d6\u8fd9\u4e2a\u5bf9\u8c61\u7684\u9501\u7684\u65f6\u5019\u8fd8\u662f\u53ef\u4ee5\u83b7\u53d6\u7684\uff0c\u5982\u679c\u662f\u4e0d\u53ef\u91cd\u5165\u9501\u7684\u8bdd\uff0c\u5c31\u4f1a\u9020\u6210\u6b7b\u9501\u3002<\/p>\n<h3>6\u3001synchronized \u662f\u53ef\u91cd\u5165\u9501\u5417\uff1f<\/h3>\n<p>JDK \u63d0\u4f9b\u7684\u6240\u6709\u73b0\u6210\u7684 <code>Lock<\/code> \u5b9e\u73b0\u7c7b\uff0c\u5305\u62ec <code>synchronized<\/code> \u5173\u952e\u5b57\u9501\u90fd\u662f\u53ef\u91cd\u5165\u7684\u3002<\/p>\n<p>\u5728\u4e0b\u9762\u7684\u4ee3\u7801\u4e2d\uff0c<code>method1()<\/code> \u548c <code>method2()<\/code>\u90fd\u88ab <code>synchronized<\/code> \u5173\u952e\u5b57\u4fee\u9970\uff0c<code>method1()<\/code>\u8c03\u7528\u4e86<code>method2()<\/code>\u3002<\/p>\n<pre><code class=\"java\">public class SynchronizedDemo {\n    public synchronized void method1() {\n        System.out.println(&quot;\u65b9\u6cd51&quot;);\n        method2();\n    }\n\n    public synchronized void method2() {\n        System.out.println(&quot;\u65b9\u6cd52&quot;);\n    }\n}<\/code><\/pre>\n<p>\u7531\u4e8e <code>synchronized<\/code>\u9501\u662f\u53ef\u91cd\u5165\u7684\uff0c\u540c\u4e00\u4e2a\u7ebf\u7a0b\u5728\u8c03\u7528<code>method1()<\/code> \u65f6\u53ef\u4ee5\u76f4\u63a5\u83b7\u5f97\u5f53\u524d\u5bf9\u8c61\u7684\u9501\uff0c\u6267\u884c <code>method2()<\/code> \u7684\u65f6\u5019\u53ef\u4ee5\u518d\u6b21\u83b7\u53d6\u8fd9\u4e2a\u5bf9\u8c61\u7684\u9501\uff0c\u4e0d\u4f1a\u4ea7\u751f\u6b7b\u9501\u95ee\u9898\u3002\u5047\u5982<code>synchronized<\/code>\u662f\u4e0d\u53ef\u91cd\u5165\u9501\u7684\u8bdd\uff0c\u7531\u4e8e\u8be5\u5bf9\u8c61\u7684\u9501\u5df2\u88ab\u5f53\u524d\u7ebf\u7a0b\u6240\u6301\u6709\u4e14\u65e0\u6cd5\u91ca\u653e\uff0c\u8fd9\u5c31\u5bfc\u81f4\u7ebf\u7a0b\u5728\u6267\u884c <code>method2()<\/code>\u65f6\u83b7\u53d6\u9501\u5931\u8d25\uff0c\u4f1a\u51fa\u73b0\u6b7b\u9501\u95ee\u9898\u3002<\/p>\n<p>\u66f4\u591a Java \u5e76\u53d1\u76f8\u5173\u7684\u9762\u8bd5\u9898\uff0c\u53ef\u4ee5\u53c2\u8003\u8fd9\u51e0\u7bc7\u6587\u7ae0\uff1a<\/p>\n<ul>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=%2Fy10iZvGP6qUoKgjT78mOw%3D%3D.w%2BkHVT9dR5SG7rwTYlLQMDweDWKrDOym4rEbTJX%2FxenTsGEZ%2FUMX9MpmoyTZiBwhz8q0rSRTfMyQf2SwuqCrP%2B0leQf7l8oFI0%2BUFgZGIkc%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u5e76\u53d1\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e0a\uff09<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=lFNe5m%2FjjjlS%2B5ckXkuzGw%3D%3D.tlA%2BzF%2BxcJ3fvHmi2WcleKE2CO1ByIr5y3gMnBPpY%2FTTq3Lx6zAyCUwfT%2FkIKW6yw7wGNKKLl%2BtaCXcJDKc76THaufaKoPn77IXhhadrBb4%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u5e76\u53d1\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e2d\uff09<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=rR%2FU5pFiDaOY%2Bvdi5EXYeg%3D%3D.mnuga3L5Zc90uxV9nE6M0VWrnqKpIbT287cudqSp2NTWQiZtRxqS7sYQ1tD1SGyV5MdxKEiMlNZNRGJiZjHE%2BHej1EGASFQJ3L4rjJW6pUI%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u5e76\u53d1\u5e38\u89c1\u9762\u8bd5\u9898\u603b\u7ed3\uff08\u4e0b\uff09<\/a><\/li>\n<\/ul>\n<h3>7\u3001\u5806\u5185\u5b58\u7684\u7ed3\u6784\u662f\uff1f<\/h3>\n<p>\u5728 JDK 7 \u7248\u672c\u53ca JDK 7 \u7248\u672c\u4e4b\u524d\uff0c\u5806\u5185\u5b58\u88ab\u901a\u5e38\u5206\u4e3a\u4e0b\u9762\u4e09\u90e8\u5206\uff1a<\/p>\n<ol>\n<li>\u65b0\u751f\u4ee3\u5185\u5b58(Young Generation)<\/li>\n<li>\u8001\u751f\u4ee3(Old Generation)<\/li>\n<li>\u6c38\u4e45\u4ee3(Permanent Generation)<\/li>\n<\/ol>\n<p>\u4e0b\u56fe\u6240\u793a\u7684 Eden \u533a\u3001\u4e24\u4e2a Survivor \u533a S0 \u548c S1 \u90fd\u5c5e\u4e8e\u65b0\u751f\u4ee3\uff0c\u4e2d\u95f4\u4e00\u5c42\u5c5e\u4e8e\u8001\u5e74\u4ee3\uff0c\u6700\u4e0b\u9762\u4e00\u5c42\u5c5e\u4e8e\u6c38\u4e45\u4ee3\u3002<\/p>\n<p><img decoding=\"async\"   referrerpolicy=\"no-referrer\" src=\"https:\/\/oss.javaguide.cn\/github\/javaguide\/java\/jvm\/hotspot-heap-structure.png\" alt=\"\u5806\u5185\u5b58\u7ed3\u6784\" title=\"\u5806\u5185\u5b58\u7ed3\u6784\" loading=\"lazy\"><\/p>\n<p><strong>JDK 8 \u7248\u672c\u4e4b\u540e PermGen(\u6c38\u4e45) \u5df2\u88ab Metaspace(\u5143\u7a7a\u95f4) \u53d6\u4ee3\uff0c\u5143\u7a7a\u95f4\u4f7f\u7528\u7684\u662f\u76f4\u63a5\u5185\u5b58<\/strong> \u3002<\/p>\n<h3>8\u3001\u5bf9\u8c61\u4f1a\u88ab\u5206\u914d\u90fd\u54ea\u4e2a\u533a\u57df\uff1f<\/h3>\n<p>\u5927\u90e8\u5206\u60c5\u51b5\uff0c\u5bf9\u8c61\u90fd\u4f1a\u9996\u5148\u5728 Eden \u533a\u57df\u5206\u914d\u3002\u5982\u679c\u5bf9\u8c61\u5728 Eden \u51fa\u751f\u5e76\u7ecf\u8fc7\u7b2c\u4e00\u6b21 Minor GC \u540e\u4ecd\u7136\u80fd\u591f\u5b58\u6d3b\uff0c\u5e76\u4e14\u80fd\u88ab Survivor \u5bb9\u7eb3\u7684\u8bdd\uff0c\u5c06\u88ab\u79fb\u52a8\u5230 Survivor \u7a7a\u95f4\uff08s0 \u6216\u8005 s1\uff09\u4e2d\uff0c\u5e76\u5c06\u5bf9\u8c61\u5e74\u9f84\u8bbe\u4e3a 1(Eden \u533a-&gt;Survivor \u533a\u540e\u5bf9\u8c61\u7684\u521d\u59cb\u5e74\u9f84\u53d8\u4e3a 1)\u3002<\/p>\n<p>\u5bf9\u8c61\u5728 Survivor \u4e2d\u6bcf\u71ac\u8fc7\u4e00\u6b21 MinorGC,\u5e74\u9f84\u5c31\u589e\u52a0 1 \u5c81\uff0c\u5f53\u5b83\u7684\u5e74\u9f84\u589e\u52a0\u5230\u4e00\u5b9a\u7a0b\u5ea6\uff08\u9ed8\u8ba4\u4e3a 15 \u5c81\uff09\uff0c\u5c31\u4f1a\u88ab\u664b\u5347\u5230\u8001\u5e74\u4ee3\u4e2d\u3002\u5bf9\u8c61\u664b\u5347\u5230\u8001\u5e74\u4ee3\u7684\u5e74\u9f84\u9608\u503c\uff0c\u53ef\u4ee5\u901a\u8fc7\u53c2\u6570 <code>-XX:MaxTenuringThreshold<\/code> \u6765\u8bbe\u7f6e\u3002<\/p>\n<h3>9\u3001JDK \u9ed8\u8ba4\u5783\u573e\u56de\u6536\u5668\u662f\uff1f<\/h3>\n<ul>\n<li><strong>JDK 1.8 \u9ed8\u8ba4\u5783\u573e\u56de\u6536\u5668<\/strong>\uff1aParallel Scanvenge\uff08\u65b0\u751f\u4ee3\uff09+ Parallel Old\uff08\u8001\u5e74\u4ee3\uff09\u3002 \u8fd9\u4e2a\u7ec4\u5408\u4e5f\u88ab\u79f0\u4e3a Parallel GC \u6216 Throughput GC\uff0c\u4fa7\u91cd\u4e8e\u541e\u5410\u91cf\u3002<\/li>\n<li><strong>JDK 1.9 \u53ca\u4ee5\u540e\u9ed8\u8ba4\u5783\u573e\u56de\u6536\u5668<\/strong>\uff1aG1 GC (Garbage-First Garbage Collector)\u3002 G1 GC \u662f\u4e00\u4e2a\u66f4\u73b0\u4ee3\u5316\u7684\u5783\u573e\u56de\u6536\u5668\uff0c\u65e8\u5728\u5e73\u8861\u541e\u5410\u91cf\u548c\u505c\u987f\u65f6\u95f4\uff0c\u5c24\u5176\u9002\u7528\u4e8e\u5806\u5185\u5b58\u8f83\u5927\u7684\u5e94\u7528\u3002<\/li>\n<\/ul>\n<p>\u66f4\u591a JVM \u76f8\u5173\u7684\u9762\u8bd5\u9898\uff0c\u53ef\u4ee5\u53c2\u8003\u8fd9\u51e0\u7bc7\u6587\u7ae0\uff1a<\/p>\n<ul>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=u0beGHZmYpegPloxMdIYNA%3D%3D.OyOosgNJ%2BhotgkDLihw9yrEKkvmMV4Ngx87C5oaVQeKXIbAQ1uvdZ08zeYPVRrNz\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">Java \u5185\u5b58\u533a\u57df\u8be6\u89e3\uff08\u91cd\u70b9\uff09<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=v1K2GOM%2FE9oxwMRJvK3JzA%3D%3D.%2FMcQ%2BZqA93t5QfrXv70CNL%2B589fk%2FdHxxWeah5HEuhypnUq8TXrFkq2rLtO3gj0YasHD85hvlkk1nyJ55qcAFA%3D%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">JVM \u5783\u573e\u56de\u6536\u8be6\u89e3\uff08\u91cd\u70b9\uff09<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=e4ggeijnOEufxacOool0aA%3D%3D.y8jFvFeno%2BN33udpCavmD%2BmWYjavzbf9Kd8TbD0BVkzKGViq%2BdrFhLGvcmOiNnzIxFOYNT2b92FX%2Bd3h01C9%2Bg%3D%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">\u7c7b\u6587\u4ef6\u7ed3\u6784\u8be6\u89e3<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=bWSvodCAHabWt96mxoTnLw%3D%3D.UbOdGxehI2iCkn0lDPjy6gLB1Ev%2BTDAZTQbvQ2vyNL8UZb5N0rQGeuoBYwdJWW1njdJCrUhg9mgiMbuxgAvtcA%3D%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">\u7c7b\u52a0\u8f7d\u8fc7\u7a0b\u8be6\u89e3<\/a><\/li>\n<li><a href=\"https:\/\/link.segmentfault.com\/?enc=WDnkn426D86K3NpSeE3YBg%3D%3D.go89RiArjmF7ZSPeld2fPoQAXqql2LyiXZseZqtErWxzJh3MnxhxKLjSygxcOdZa\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">\u7c7b\u52a0\u8f7d\u5668\u8be6\u89e3\uff08\u91cd\u70b9\uff09<\/a><\/li>\n<\/ul>\n<h3>10\u3001\u4f60\u77e5\u9053\u54ea\u4e9b Java \u6027\u80fd\u4f18\u5316\u548c\u95ee\u9898\u6392\u67e5\u5de5\u5177\uff1f<\/h3>\n<p>JDK \u81ea\u5e26\u7684\u53ef\u89c6\u5316\u5206\u6790\u5de5\u5177\uff1a<\/p>\n<ul>\n<li><strong>JConsole<\/strong> \uff1a\u57fa\u4e8e JMX \u7684\u53ef\u89c6\u5316\u76d1\u89c6\u3001\u7ba1\u7406\u5de5\u5177\uff0c\u53ef\u4ee5\u7528\u4e8e\u67e5\u770b\u5e94\u7528\u7a0b\u5e8f\u7684\u8fd0\u884c\u6982\u51b5\u3001\u5185\u5b58\u3001\u7ebf\u7a0b\u3001\u7c7b\u3001VM \u6982\u62ec\u3001MBean \u7b49\u4fe1\u606f\u3002<\/li>\n<li><strong>VisualVM<\/strong>\uff1a\u57fa\u4e8e NetBeans \u5e73\u53f0\u5f00\u53d1\uff0c\u5177\u5907\u4e86\u63d2\u4ef6\u6269\u5c55\u529f\u80fd\u7684\u7279\u6027\u3002\u5229\u7528\u5b83\u4e0d\u4ec5\u80fd\u591f\u76d1\u63a7\u670d\u52a1\u7684 CPU\u3001\u5185\u5b58\u3001\u7ebf\u7a0b\u3001\u7c7b\u7b49\u4fe1\u606f\uff0c\u8fd8\u53ef\u4ee5\u6355\u83b7\u6709\u5173 JVM \u8f6f\u4ef6\u5b9e\u4f8b\u7684\u6570\u636e\uff0c\u5e76\u5c06\u8be5\u6570\u636e\u4fdd\u5b58\u5230\u672c\u5730\u7cfb\u7edf\uff0c\u4ee5\u4f9b\u540e\u671f\u67e5\u770b\u6216\u4e0e\u5176\u4ed6\u7528\u6237\u5171\u4eab\u3002\u6839\u636e\u300a\u6df1\u5165\u7406\u89e3 Java \u865a\u62df\u673a\u300b\u4ecb\u7ecd\uff1a\u201cVisualVM \u7684\u6027\u80fd\u5206\u6790\u529f\u80fd\u751a\u81f3\u6bd4\u8d77 JProfiler\u3001YourKit \u7b49\u4e13\u4e1a\u4e14\u6536\u8d39\u7684 Profiling \u5de5\u5177\u90fd\u4e0d\u4f1a\u900a\u8272\u591a\u5c11\uff0c\u800c\u4e14 VisualVM \u8fd8\u6709\u4e00\u4e2a\u5f88\u5927\u7684\u4f18\u70b9\uff1a\u4e0d\u9700\u8981\u88ab\u76d1\u89c6\u7684\u7a0b\u5e8f\u57fa\u4e8e\u7279\u6b8a Agent \u8fd0\u884c\uff0c\u56e0\u6b64\u4ed6\u5bf9\u5e94\u7528\u7a0b\u5e8f\u7684\u5b9e\u9645\u6027\u80fd\u7684\u5f71\u54cd\u5f88\u5c0f\uff0c\u4f7f\u5f97\u4ed6\u53ef\u4ee5\u76f4\u63a5\u5e94\u7528\u5728\u751f\u4ea7\u73af\u5883\u4e2d\u3002\u8fd9\u4e2a\u4f18\u70b9\u662f JProfiler\u3001YourKit \u7b49\u5de5\u5177\u65e0\u6cd5\u4e0e\u4e4b\u5ab2\u7f8e\u7684\u201d\u3002<\/li>\n<\/ul>\n<p>JDK \u81ea\u5e26\u7684\u547d\u4ee4\u884c\u5de5\u5177\uff1a<\/p>\n<ul>\n<li><strong><code>jps<\/code><\/strong> (JVM Process Status\uff09: \u7c7b\u4f3c UNIX \u7684 <code>ps<\/code> \u547d\u4ee4\u3002\u7528\u4e8e\u67e5\u770b\u6240\u6709 Java \u8fdb\u7a0b\u7684\u542f\u52a8\u7c7b\u3001\u4f20\u5165\u53c2\u6570\u548c Java \u865a\u62df\u673a\u53c2\u6570\u7b49\u4fe1\u606f\uff1b<\/li>\n<li><strong><code>jstat<\/code><\/strong> \uff08JVM Statistics Monitoring Tool\uff09: \u7528\u4e8e\u6536\u96c6 HotSpot \u865a\u62df\u673a\u5404\u65b9\u9762\u7684\u8fd0\u884c\u6570\u636e;<\/li>\n<li><strong><code>jinfo<\/code><\/strong> (Configuration Info for Java) : Configuration Info for Java,\u663e\u793a\u865a\u62df\u673a\u914d\u7f6e\u4fe1\u606f;<\/li>\n<li><strong><code>jmap<\/code><\/strong> (Memory Map for Java) : \u751f\u6210\u5806\u8f6c\u50a8\u5feb\u7167;<\/li>\n<li><strong><code>jhat<\/code><\/strong> (JVM Heap Dump Browser) : \u7528\u4e8e\u5206\u6790 heapdump \u6587\u4ef6\uff0c\u5b83\u4f1a\u5efa\u7acb\u4e00\u4e2a HTTP\/HTML \u670d\u52a1\u5668\uff0c\u8ba9\u7528\u6237\u53ef\u4ee5\u5728\u6d4f\u89c8\u5668\u4e0a\u67e5\u770b\u5206\u6790\u7ed3\u679c\u3002JDK9 \u79fb\u9664\u4e86 jhat\uff1b<\/li>\n<li><strong><code>jstack<\/code><\/strong> (Stack Trace for Java) : \u751f\u6210\u865a\u62df\u673a\u5f53\u524d\u65f6\u523b\u7684\u7ebf\u7a0b\u5feb\u7167\uff0c\u7ebf\u7a0b\u5feb\u7167\u5c31\u662f\u5f53\u524d\u865a\u62df\u673a\u5185\u6bcf\u4e00\u6761\u7ebf\u7a0b\u6b63\u5728\u6267\u884c\u7684\u65b9\u6cd5\u5806\u6808\u7684\u96c6\u5408\u3002<\/li>\n<\/ul>\n<p>\u7b2c\u4e09\u65b9\u5de5\u5177\uff1a<\/p>\n<ul>\n<li><strong>MAT<\/strong>\uff1a\u4e00\u6b3e\u529f\u80fd\u5f3a\u5927\u7684 Java \u5806\u5185\u5b58\u5206\u6790\u5668\uff0c\u53ef\u4ee5\u7528\u4e8e\u67e5\u627e\u5185\u5b58\u6cc4\u6f0f\u4ee5\u53ca\u67e5\u770b\u5185\u5b58\u6d88\u8017\u60c5\u51b5\uff0c\u7528\u6237\u53ef\u4ee5\u5229\u7528 VisualVM \u6216\u8005\u662f <code>jmap<\/code> \u547d\u4ee4\u751f\u4ea7\u5806\u6587\u4ef6\uff0c\u7136\u540e\u5bfc\u5165\u5de5\u5177\u4e2d\u8fdb\u884c\u5206\u6790\u3002<\/li>\n<li><strong>GCeasy<\/strong>\uff1a\u4e00\u6b3e\u5728\u7ebf\u7684 GC \u65e5\u5fd7\u5206\u6790\u5668\uff0c\u4f7f\u7528\u8d77\u6765\u975e\u5e38\u65b9\u4fbf\uff0c\u7528\u6237\u53ef\u4ee5\u901a\u8fc7\u5b83\u7684 Web \u7f51\u7ad9\u5bfc\u5165 GC \u65e5\u5fd7\uff0c\u5b9e\u65f6\u8fdb\u884c\u5185\u5b58\u6cc4\u6f0f\u68c0\u6d4b\u3001GC \u6682\u505c\u539f\u56e0\u5206\u6790\u3001JVM \u914d\u7f6e\u5efa\u8bae\u4f18\u5316\u7b49\u529f\u80fd\u3002\u7f51\u7ad9\u5730\u5740\uff1a<a href=\"https:\/\/link.segmentfault.com\/?enc=NbHHVAV9zL5V3ZGV1tRLRw%3D%3D.7i4cSdSDEbUNHyIBKzsVv%2BPpc8ZBf9cDkcInp2t6634%3D\" rel=\"nofollow noopener noreferrer\" target=\"_blank\">https:\/\/gceasy.io\/<\/a> \u3002<\/li>\n<li><strong>GCViewer<\/strong>\uff1a\u4e00\u6b3e\u975e\u5e38\u5f3a\u5927\u7684 GC \u65e5\u5fd7\u53ef\u89c6\u5316\u5206\u6790\u5de5\u5177\uff0c\u529f\u80fd\u5f3a\u5927\u800c\u4e14\u5b8c\u5168\u514d\u8d39\u3002<\/li>\n<li><strong>JProfiler<\/strong>\uff1a\u4e00\u6b3e\u5546\u7528\u7684\u6027\u80fd\u5206\u6790\u5229\u5668\uff0c\u529f\u80fd\u5f3a\u5927\uff0c\u4f46\u9700\u8981\u4ed8\u8d39\u4f7f\u7528\u3002 \u5b83\u63d0\u4f9b\u66f4\u6df1\u5165\u7684\u6027\u80fd\u5206\u6790\u529f\u80fd\uff0c\u4f8b\u5982\u65b9\u6cd5\u8c03\u7528\u5206\u6790\u3001\u5185\u5b58\u5206\u914d\u5206\u6790\u7b49\u3002<\/li>\n<li><strong>Arthas<\/strong>\uff1a\u963f\u91cc\u5f00\u6e90\u7684\u4e00\u6b3e\u7ebf\u4e0a\u76d1\u63a7\u8bca\u65ad\u5de5\u5177\uff0c\u53ef\u4ee5\u67e5\u770b\u5e94\u7528\u8d1f\u8f7d\u3001\u5185\u5b58\u3001gc\u3001\u7ebf\u7a0b\u7b49\u4fe1\u606f\u3002<\/li>\n<\/ul>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000045671548\">https:\/\/segmentfault.com\/a\/1190000045671548<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4f60\u597d\uff0c\u6211\u662f Guide\u3002\u5f88\u4e45\u6ca1\u6709\u5206\u4eab\u51c9\u7ecf\u4e86\uff0c\u4eca\u5929\u6765\u5206\u4eab\u4e00\u4f4d\u897f\u5317\u5de5\u4e1a\u5927\u5b66\u7684\u8bfb\u8005\u9762\u8bd5\u5feb\u624b\uff0c\u4e00\u9762\u5c31\u76f4\u63a5\u79d2\u6302\u7684\u9762\u7ecf\u3002  [&hellip;]<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10020541","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10020541","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10020541"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10020541\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10020541"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10020541"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10020541"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}