<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[longyi_java的专栏]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/longyi_java</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; longyi_java]]></copyright><item><title><![CDATA[003、JVM 类的生命周期和类加载机制]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/103133957</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/103133957</guid><author>longyi_java</author><pubDate>Mon, 18 Nov 2019 23:17:09 +0800</pubDate><description><![CDATA[003、面试官对于 JVM 类加载机制的猛烈炮火，你能顶住吗？


]]></description><category></category></item><item><title><![CDATA[002、Java代码到底是如何运行起来的]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/103101074</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/103101074</guid><author>longyi_java</author><pubDate>Sat, 16 Nov 2019 17:44:21 +0800</pubDate><description><![CDATA[002、一探究竟：我们写的Java代码到底是如何运行起来的？


]]></description><category></category></item><item><title><![CDATA[001、开篇词：JVM 优化实战]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/103097890</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/103097890</guid><author>longyi_java</author><pubDate>Sat, 16 Nov 2019 13:54:29 +0800</pubDate><description><![CDATA[001、开篇词：JVM 优化实战，广大 Java 工程师心中永远的痛！
1、怎么统计FullGC的次
2、OOM内存溢出的模块？怎么模拟？
3、OO内存溢出定位步骤？
4、内存模型是怎么样的？
5、内存结构是怎么样的？
6、垃圾算法有那些？
7、类加载
8、垃圾回收
9、JVM参数优化

...]]></description><category></category></item><item><title><![CDATA[HashMap面试题1]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/101606814</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/101606814</guid><author>longyi_java</author><pubDate>Sat, 28 Sep 2019 12:26:10 +0800</pubDate><description><![CDATA[HashMap面试题
转自：http://www.mayikt.com/
1、HashMap和HashTable的区别？
&lt;1&gt;、HashTable是线程安全的，不允许key为空，因为put方法上加上了synchronized,在方法体中，有代码判断如果key为空，则抛出异常；
&lt;2&gt;、HashMap线程是不安全的，允许key为空；
2、HashMap的key可以为空，这个...]]></description><category></category></item><item><title><![CDATA[3、emqx_auth_mysql批量定义ACL鉴权]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/100171144</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/100171144</guid><author>longyi_java</author><pubDate>Sat, 31 Aug 2019 11:53:23 +0800</pubDate><description><![CDATA[emqx_auth_mysql批量定义ACL鉴权


参考 https://blog.youkuaiyun.com/u011142688/article/details/79852325


参考 https://blog.youkuaiyun.com/u011142688/article/details/79852306


参考 https://www.jianshu.com/p/65935a753eab


在初始...]]></description><category></category></item><item><title><![CDATA[2、emqx_auth_mysql数据库配置]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/100171142</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/100171142</guid><author>longyi_java</author><pubDate>Sat, 31 Aug 2019 11:52:51 +0800</pubDate><description><![CDATA[1、创建表
1.1 用户表
SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for mqtt_user
-- ----------------------------
DROP TABLE IF EXISTS `mqtt_user`;
CREATE TABLE `mqtt_user` (
 ...]]></description><category></category></item><item><title><![CDATA[1、emqx_auth_mysql配置]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/100133732</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/100133732</guid><author>longyi_java</author><pubDate>Thu, 29 Aug 2019 11:02:39 +0800</pubDate><description><![CDATA[emqx_auth_mysql配置1、在页面配置1.1、进入插件页面，找到emqx_auth_mysql1.2、点击“配置”，进入配置页面1.3、第一次配置时，缺少用户名和密码的配置，选择“高级配置”2、主要输入框说明2.1 auth.mysql.password_hash2.2 auth.mysql.super_query2.3 auth.mysql.auth_query2.4  auth.my...]]></description><category></category></item><item><title><![CDATA[使用IntelliJ IDEA 配置Maven（入门）]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/54587603</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/54587603</guid><author>longyi_java</author><pubDate>Tue, 17 Jan 2017 21:39:37 +0800</pubDate><description><![CDATA[转自：http://blog.youkuaiyun.com/qq_32588349/article/details/51461182




1. 下载Maven 
官方地址：http://maven.apache.org/download.cgi



解压并新建一个本地仓库文件夹



2.配置本地仓库路径 
 


3.配置maven环境变量

 
 
 
]]></description><category></category></item><item><title><![CDATA[Intellij Idea环境下Spark源码阅读环境]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/52715482</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/52715482</guid><author>longyi_java</author><pubDate>Sat, 01 Oct 2016 04:43:08 +0800</pubDate><description><![CDATA[转自：http://m.blog.youkuaiyun.com/article/details?id=51036300










1. 在windows下搭建﻿﻿

Spark源码阅读环境的准备


Spark源码是有Scala语言写成的，目前，IDEA对Scala的支持要比eclipse要好，大多数人会选在在IDEA上完成Spark平台应用的开发。因此，Spark源]]></description><category></category></item><item><title><![CDATA[spark  DataFrame 使用Java读取mysql和写入mysql的例子]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/52433871</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/52433871</guid><author>longyi_java</author><pubDate>Sun, 04 Sep 2016 18:28:19 +0800</pubDate><description><![CDATA[package com.hjh.demo.mysql;


import java.util.Properties;


import org.apache.log4j.Logger;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaSparkContext;
import org.a]]></description><category></category></item><item><title><![CDATA[FilenameFilter文件名称过滤器]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/41039617</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/41039617</guid><author>longyi_java</author><pubDate>Wed, 12 Nov 2014 10:19:19 +0800</pubDate><description><![CDATA[FilenameFilter文件名称过滤器使用方式]]></description><category></category></item><item><title><![CDATA[配置(rsa验证方式的)ssh免密码连入]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/40856941</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/40856941</guid><author>longyi_java</author><pubDate>Thu, 06 Nov 2014 10:25:59 +0800</pubDate><description><![CDATA[$ssh-keygen -t rsa

$cat id_rsa.pub   >> authorized_keys

$chmod  755 authorized_keys]]></description><category></category></item><item><title><![CDATA[在ubuntu上添加用户]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/40856867</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/40856867</guid><author>longyi_java</author><pubDate>Thu, 06 Nov 2014 10:24:35 +0800</pubDate><description><![CDATA[#1、添加用户组
 $sudo groupadd hadoop
#2、添加用户
 $sudo  adduser huangjh
#3、把用户添加到用户组，并且在home目录下床架用户目录
 $sudo   usermod -G hadoop huangjh
#4、给用户设置密码
 $passwd  huangjh
#5、当在终端执行sudo命令时，系统提示“huangjh is n]]></description><category></category></item><item><title><![CDATA[Hadoop集群配置文件分发工具config-dispatcher.sh .]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/39452211</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/39452211</guid><author>longyi_java</author><pubDate>Sun, 21 Sep 2014 15:37:43 +0800</pubDate><description><![CDATA[转自：http://blog.youkuaiyun.com/rzhzhz/article/details/7056775]]></description><category></category></item><item><title><![CDATA[Hadoop集群启动一直处于safemode]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/39452077</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/39452077</guid><author>longyi_java</author><pubDate>Sun, 21 Sep 2014 15:35:13 +0800</pubDate><description><![CDATA[转自：
 
Hadoop集群启动的时候一切正常，但一直处于safemode，只能读不能写，这种时候应该查看namenode的logs，当然这可能会出现不同的情况... 下面仅介绍一种错误处理方案，希望能抛砖引玉，能对大家有所启发。
以下是日志提示（此地只摘抄了重要部分）
 


org.apache.hadoop.hdfs.server.namenode.SafeModeExcept]]></description><category></category></item><item><title><![CDATA[hadoop错误Name node is in safe mode的解决方法]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/39444353</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/39444353</guid><author>longyi_java</author><pubDate>Sun, 21 Sep 2014 03:40:48 +0800</pubDate><description><![CDATA[错误Name node is in safe mode的解决方法

转自：http://blog.youkuaiyun.com/xw13106209/article/details/6866072]]></description><category></category></item><item><title><![CDATA[ubuntu防火墙关闭命令]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/39444315</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/39444315</guid><author>longyi_java</author><pubDate>Sun, 21 Sep 2014 03:36:48 +0800</pubDate><description><![CDATA[ubuntu防火墙关闭命令
 
ubuntu防火墙关闭命令
 
1、关闭ubuntu的防火墙
 
     ufw disable 
     
2、卸载了iptables 
 
      apt-get remove iptables 
 
3、关闭ubuntu中的防火墙的其余命令 
 
     iptables -P INPUT ACCEPT 
     ip]]></description><category></category></item><item><title><![CDATA[Linux增加用户组、用户和修改目录的所属用户]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/39293839</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/39293839</guid><author>longyi_java</author><pubDate>Mon, 15 Sep 2014 15:54:25 +0800</pubDate><description><![CDATA[#创建 hadoop
用户
/usr/sbin/groupadd hadoop
 
#分配 hadoop
到 hadoop 组中
/usr/sbin/useradd hadoop -g hadoop
 
#创建 hadoop
代码目录结构
mkdir -p /opt/modules/hadoop/
 
#创建 hadoop
数据目录结构
mkdir -p /opt/da]]></description><category></category></item><item><title><![CDATA[快速了解Hadoop架构]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/38013297</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/38013297</guid><author>longyi_java</author><pubDate>Mon, 21 Jul 2014 11:15:07 +0800</pubDate><description><![CDATA[Hadoop是一个能够对大量数据进行分布式处理的软件框架, Hadoop实现了一个分布式文件系统（Hadoop Distributed File System），简称HDFS。hadoop的集群是基于master/slave模式]]></description><category></category></item><item><title><![CDATA[VirtualBox下安装ubuntu出现单个文件超出了4G的提示]]></title><link>https://blog.youkuaiyun.com/longyi_java/article/details/37834235</link><guid>https://blog.youkuaiyun.com/longyi_java/article/details/37834235</guid><author>longyi_java</author><pubDate>Tue, 15 Jul 2014 22:53:32 +0800</pubDate><description><![CDATA[在window xp下安装VirtualBox，然后在VirtualBox下安装ubuntu，安装好后出现了单个文件超出了4G的提示，并且没有空间再安装其他程序；
原因是存放虚拟机文件所在的磁盘是FAT32格式，最大支持单个文件不能超过4G，需要那个磁盘转换成NTFS格式；
1、执行cmd进入Dos；
2、把磁盘(比如E盘)转换为NTFS
   convert e: /FS:NTFS]]></description><category></category></item></channel></rss>