<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[jiangrou88的博客]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/jiangrou88</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; jiangrou88]]></copyright><item><title><![CDATA[String，list，map判空]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/121072173</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/121072173</guid><author>jiangrou88</author><pubDate>Sun, 31 Oct 2021 23:33:35 +0800</pubDate><description><![CDATA[String判空
StringUtils.isEmpty
str == null || “”.equals(str)
list判空
null == list || list.size() ==0
map判空
map!=null
通过key，拿出value，对String再次判断。

]]></description><category></category></item><item><title><![CDATA[树形子菜单]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/120547533</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/120547533</guid><author>jiangrou88</author><pubDate>Wed, 29 Sep 2021 14:12:24 +0800</pubDate><description><![CDATA[public List&lt;Types&gt; loadTreeList()
    {
        List&lt;Types&gt; resultList = new ArrayList&lt;&gt;();
        List&lt;Types&gt; searchList = typesMapper.findAllVisibleList();

        // 1. 找出根菜单
        searchList.stream()
                .filter(]]></description><category></category></item><item><title><![CDATA[Maven: Using platform encoding (GBK actually) to copy filtered resources, i.e. build is platform dep]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/118012897</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/118012897</guid><author>jiangrou88</author><pubDate>Fri, 18 Jun 2021 07:12:47 +0800</pubDate><description><![CDATA[父工程中pom要加入这段代码。
若子工程中有war包形式，也需要加入这段代码！
具体什么原因也不清楚。
 &lt;properties&gt;
      &lt;project.build.sourceEncoding&gt;UTF8&lt;/project.build.sourceEncoding&gt;
       &lt;/properties&gt;


...]]></description><category></category></item><item><title><![CDATA[mysql的url]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/117599356</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/117599356</guid><author>jiangrou88</author><pubDate>Sat, 05 Jun 2021 16:36:55 +0800</pubDate><description><![CDATA[mysql8
url=“jdbc:mysql://localhost:3306/db1?useUnicode=true&amp;characterEncoding=UTF-8&amp;userSSL=false&amp;serverTimezone=GMT%2B8”
mysql5.7
jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8

]]></description><category></category></item><item><title><![CDATA[idea使用git]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/117573027</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/117573027</guid><author>jiangrou88</author><pubDate>Sat, 05 Jun 2021 16:35:22 +0800</pubDate><description><![CDATA[1安装git
git config --list 查看信息
git config --global user.name "name "
git config --global user.email  “email”
信息保存在C:\Users\hui.gitconfig 文件里面
2idea中找到setting–version ctrol-安装目录cmd–git.exe
3然后关闭项目，在首页get from version control
url ：复制项目链接
directory：找到想要的位置
4id]]></description><category></category></item><item><title><![CDATA[git使用大全]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/117567992</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/117567992</guid><author>jiangrou88</author><pubDate>Fri, 04 Jun 2021 17:31:15 +0800</pubDate><description><![CDATA[安装git
设置用户信息
git config --list 查看信息
git config --global user.name “name”
git config --global user.email  “email”
信息保存在系统用户gitconfig 文件里面
本地仓库与远程仓库的操作
一、本地拉取仓库
1.选择一个合适的文件夹位置
2.右键 git clone 地址（粘贴用右键+paste）
拉取的本地仓库和远程仓库已经建立关联
git remote (会显示origin)
git remot]]></description><category></category></item><item><title><![CDATA[yog mysql 报错2003]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/116347112</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/116347112</guid><author>jiangrou88</author><pubDate>Sun, 02 May 2021 08:40:57 +0800</pubDate><description><![CDATA[未连接mysql
服务里面直接开启

]]></description><category></category></item><item><title><![CDATA[java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleExcept]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/116238659</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/116238659</guid><author>jiangrou88</author><pubDate>Wed, 28 Apr 2021 17:20:32 +0800</pubDate><description><![CDATA[WebServlet("/aaa")
检查加没加斜线

]]></description><category></category></item><item><title><![CDATA[查询监听端口]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/116209977</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/116209977</guid><author>jiangrou88</author><pubDate>Tue, 27 Apr 2021 20:56:26 +0800</pubDate><description><![CDATA[netstat 空-ano

]]></description><category></category></item><item><title><![CDATA[mysql突然连接不上]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/116033748</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/116033748</guid><author>jiangrou88</author><pubDate>Thu, 22 Apr 2021 21:55:49 +0800</pubDate><description><![CDATA[mysql突然连接不上
找到mysql  bin  cmd
然后输入命令’mysqld -nt -remove’ 命令，回车

]]></description><category></category></item><item><title><![CDATA[删除help下的vm]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115997235</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115997235</guid><author>jiangrou88</author><pubDate>Thu, 22 Apr 2021 07:59:57 +0800</pubDate><description><![CDATA[idea又抽风
删除了help下vm配置文件
在c盘的

]]></description><category></category></item><item><title><![CDATA[java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleExcept]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115936580</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115936580</guid><author>jiangrou88</author><pubDate>Wed, 21 Apr 2021 10:06:31 +0800</pubDate><description><![CDATA[解决方法：
更改tomcat配置文件catalina.properties 。
tomcat.util.scan.DefaultJarScanner.jarsToSkip=\ 值后面加"*"。

]]></description><category></category></item><item><title><![CDATA[tomcat中配置项目，项目压缩成war，放入webapps文件夹]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115896654</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115896654</guid><author>jiangrou88</author><pubDate>Tue, 20 Apr 2021 10:43:29 +0800</pubDate><description><![CDATA[1压缩成zip（rar不行）
2然后可以直接修改成war

]]></description><category></category></item><item><title><![CDATA[查询没有学过课程的学生的信息]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115595201</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115595201</guid><author>jiangrou88</author><pubDate>Sun, 11 Apr 2021 12:24:58 +0800</pubDate><description><![CDATA[查询没有学过课程的学生的信息：
1.首先查学过课程的不重复的值，
2.再去和学生表取反。

]]></description><category></category></item><item><title><![CDATA[mysql子查询重命名]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115591416</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115591416</guid><author>jiangrou88</author><pubDate>Sun, 11 Apr 2021 11:03:04 +0800</pubDate><description><![CDATA[SELECT 
	t2.id,t2.name,t3.xuanke,t3.zongfen
FROM 
	student t2,	
	(SELECT
		 t1.`student_id`,
		 COUNT(t1.`course_id`) 	xuanke,
		 SUM(t1.`score`) zongfen
	FROM
		 studentcourse t1,
		 student t2
	WHERE 
		t1.`student_id`=t2.`id`
	GROUP BY 
		t1.`student_id]]></description><category></category></item><item><title><![CDATA[mysql约束]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115588577</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115588577</guid><author>jiangrou88</author><pubDate>Sun, 11 Apr 2021 10:09:39 +0800</pubDate><description><![CDATA[1.AUTO_INCREMENT
删：
alter table表 **modify** 列名 类型 ; 
只能删掉自动增长，主键删不掉

2.primary key
删：
alter table 表 **drop** primary key；
若有自增长，必须先删除自动增张，才能删主键。
有外键的情况下，删不掉。

3.unique
删：
ALTER TABLE student **DROP INDEX** 列名;
必须加index

4.外键
删：
ALTER TABLE 表DROP FOREIGN KE]]></description><category></category></item><item><title><![CDATA[mysql查询语句完整版本]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115585003</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115585003</guid><author>jiangrou88</author><pubDate>Sat, 10 Apr 2021 21:52:59 +0800</pubDate><description><![CDATA[select 字段
from 表
where 条件
group by
having
order by
limit n,n

]]></description><category></category></item><item><title><![CDATA[查询问题]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115584539</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115584539</guid><author>jiangrou88</author><pubDate>Sat, 10 Apr 2021 21:24:25 +0800</pubDate><description><![CDATA[1.使用哪种语言
2.正在做什么事情
3.报错信息

]]></description><category></category></item><item><title><![CDATA[SQLyog使用.操作符不出现提示]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115564239</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115564239</guid><author>jiangrou88</author><pubDate>Sat, 10 Apr 2021 09:45:45 +0800</pubDate><description><![CDATA[1.换注册码。

]]></description><category></category></item><item><title><![CDATA[sqlyog]]></title><link>https://blog.youkuaiyun.com/jiangrou88/article/details/115545160</link><guid>https://blog.youkuaiyun.com/jiangrou88/article/details/115545160</guid><author>jiangrou88</author><pubDate>Fri, 09 Apr 2021 11:59:33 +0800</pubDate><description><![CDATA[mysql 5.5
在mysql中unique约束列可以含有多个null!

]]></description><category></category></item></channel></rss>