<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[Jadan-Z的博客]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/JoneZ</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; JoneZ]]></copyright><item><title><![CDATA[JDK1.8 新特性之Stream的练习题]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/105152916</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/105152916</guid><author>JoneZ</author><pubDate>Fri, 27 Mar 2020 23:14:12 +0800</pubDate><description><![CDATA[练习题：


// 1. 找出2011年发生的所有交易,并按交易额排序(从低到高)
// 2. 交易员都在哪些不同的城市工作过
// 3. 查找所有来自剑桥的交易员,并按姓名排序
// 4. 返回所有交易员的姓名字符串,按字母顺序排序
// 5. 有没有交易员是在米兰工作的?
// 6. 所有交易中,最高的交易额是多少
// 7. 找到交易额最小的交易
public class StreamTes...]]></description><category></category></item><item><title><![CDATA[JDK1.8 新特性之Stream的常用方法2]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/105152809</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/105152809</guid><author>JoneZ</author><pubDate>Fri, 27 Mar 2020 23:07:34 +0800</pubDate><description><![CDATA[终止操作常用方法：

 查找与匹配

 allMatch --- 检查是否匹配所有元素

 anyMatch --- 检查是否至少匹配一个元素

 noneMatch --- 检查是否没有匹配所有元素

 findFirst --- 返回第一个元素

 findAny --- 返回当前流中的任意元素

 c...]]></description><category></category></item><item><title><![CDATA[JDK1.8 新特性之Stream的常用方法1]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/105152179</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/105152179</guid><author>JoneZ</author><pubDate>Fri, 27 Mar 2020 22:35:13 +0800</pubDate><description><![CDATA[Stream的三个操作步骤：

 1. 创建Stream: 一个数据源（如：集合、 数组），获取一个流

 2. 中及操作： 一个中间操作链，对数据源的数据进行处理

 3. 终止操作（终端操作）：一旦执行终止操作，就执行中间操作链，并产生结果。之后，不会再被使用。



创建Stream的常见方式： 详情查看 demo1



中间操作的常用方法：

 filt...]]></description><category></category></item><item><title><![CDATA[JDK1.8 新特性之Optional的常用方法]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/105059992</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/105059992</guid><author>JoneZ</author><pubDate>Mon, 23 Mar 2020 22:43:10 +0800</pubDate><description><![CDATA[基础类（员工类）：


import java.util.Objects;

// 员工信息
public class Employee {
    private String name; // 姓名
    private Integer age; // 年龄
    private Double salary; // 工资
    private Status status; // 状态

...]]></description><category></category></item><item><title><![CDATA[MySQL中的SQL的常见优化策略]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/91524757</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/91524757</guid><author>JoneZ</author><pubDate>Wed, 12 Jun 2019 14:43:35 +0800</pubDate><description><![CDATA[1 避免全表扫描

 对查询进行优化，应尽量避免全表扫描，首先应考虑在where及order by涉及的列上建立索引。



2 避免判断null值

 应尽量避免在where子句中对字段进行null值判断，否则将导致引擎放弃使用索引而进行全表扫描，如：

 select id from t where num is null

 可以在num上设置默认值0，确保表中nu...]]></description><category></category></item><item><title><![CDATA[MySQL中的索引优化]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/91524074</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/91524074</guid><author>JoneZ</author><pubDate>Wed, 12 Jun 2019 14:41:50 +0800</pubDate><description><![CDATA[1 索引不会包含有NULL值的列

   只要列中包含有NULL值都将不会被包含在索引中，组合索引中只要有一列含有NULL值，那么这一列对于此组合索引就是无效的。所以我们在数据库设计时不要让字段的默认值为NULL。create table table_name(c1 varchar(32) default ’0’)

2 使用短索引

   对串列进行索引，如果可能应该指定一个前缀...]]></description><category></category></item><item><title><![CDATA[update left join 多表关联更新]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/90714310</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/90714310</guid><author>JoneZ</author><pubDate>Fri, 31 May 2019 12:59:35 +0800</pubDate><description><![CDATA[update table1 as t1
LEFT JOIN table2 as t2 ON t1.tasksub_id = t2.id
set receive_state = 1
where t1.id = 1
]]></description><category></category></item><item><title><![CDATA[单例模式]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/86419377</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/86419377</guid><author>JoneZ</author><pubDate>Sun, 13 Jan 2019 15:09:31 +0800</pubDate><description><![CDATA[- 核心作用：保证一个类只有一个实例，并且提供一个访问该实例的全局访问点

 

## 优点

- 由于单例模式只生成一个实例，减少了系统性能开销，当一个对象的产生需要比较多的资源时，如读取配置、产生其他依赖对象时，则可以通过在应用启动时直接产生一个单例对象，然后永久驻留内存的方式来解决

- 单例模式可以在系统设置全局的访问点，优化环共享资源访问，例如可以设计一个单例类，负责所有数据表的映射处理...]]></description><category></category></item><item><title><![CDATA[@RequestBody 传数组的两种方式]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/86135738</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/86135738</guid><author>JoneZ</author><pubDate>Wed, 09 Jan 2019 10:38:43 +0800</pubDate><description><![CDATA[1、@RequestBody List&amp;lt;MarketFullReduce&amp;gt; marketFullReduce

2、@RequestBody MarketFullReduce[] marketFullReduce]]></description><category></category></item><item><title><![CDATA[mysql 查询下一个自增的id值]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/85928296</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/85928296</guid><author>JoneZ</author><pubDate>Sun, 06 Jan 2019 14:43:35 +0800</pubDate><description><![CDATA[-- 查询自增id的下一个值
SELECT
    AUTO_INCREMENT
FROM
    INFORMATION_SCHEMA. TABLES
WHERE
    TABLE_NAME = '{table name}' limit 1,1
 ]]></description><category></category></item><item><title><![CDATA[@Transactional注解回滚问题]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/83144337</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/83144337</guid><author>JoneZ</author><pubDate>Thu, 18 Oct 2018 11:49:17 +0800</pubDate><description><![CDATA[@Transactional(rollbackFor=Exception.class) 这个的意思是指定回滚的异常，我直接就指定了Exception。也就是只要是Exception或者是Exception的子类，那么在此方法中，都会进行回滚。当然，还有notRollbackFor，这个是指定异常不回滚。
原文：https://blog.youkuaiyun.com/singgel/article/detail...]]></description><category></category></item><item><title><![CDATA[mybatis 一次执行多条SQL]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/82873552</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/82873552</guid><author>JoneZ</author><pubDate>Thu, 27 Sep 2018 21:16:48 +0800</pubDate><description><![CDATA[怎么开启呢？在拼装mysql链接的url时，为其加上allowMultiQueries参数，设置为true，如下：

jdbc.jdbcUrl=jdbc:mysql://127.0.0.1:3306/database?useUnicode=true&amp;amp;characterEncoding=utf8&amp;amp;allowMultiQueries=true

原文出处：https://blog.cs...]]></description><category></category></item><item><title><![CDATA[Java日历格式]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/82717297</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/82717297</guid><author>JoneZ</author><pubDate>Sat, 15 Sep 2018 20:12:45 +0800</pubDate><description><![CDATA[Json格式：



实现代码：


@GetMapping(value=&quot;/teacher/week&quot;)
    public Map standardweek(HttpServletRequest request,
                              HttpServletResponse response) throws ParseException {
      ...]]></description><category></category></item><item><title><![CDATA[Json与List之间的相互转换]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/82699446</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/82699446</guid><author>JoneZ</author><pubDate>Fri, 14 Sep 2018 11:00:37 +0800</pubDate><description><![CDATA[谷歌的Gson.jar:


//list转换为json
Gson gson = new Gson();  
List&amp;lt;Person&amp;gt; persons = new ArrayList&amp;lt;Person&amp;gt;();  
String str = gson.toJson(persons); 


//json转换为list
Gson gson = new Gson();  
List&amp;...]]></description><category></category></item><item><title><![CDATA[关于给springboot添加定时器的两种方式]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/82458554</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/82458554</guid><author>JoneZ</author><pubDate>Thu, 06 Sep 2018 11:32:22 +0800</pubDate><description><![CDATA[原文地址：https://blog.youkuaiyun.com/huxu981598436/article/details/79252969]]></description><category></category></item><item><title><![CDATA[Linux下运行jar包的方法]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/82423308</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/82423308</guid><author>JoneZ</author><pubDate>Wed, 05 Sep 2018 14:23:28 +0800</pubDate><description><![CDATA[原文地址：https://blog.youkuaiyun.com/qq229596421/article/details/52230948]]></description><category></category></item><item><title><![CDATA[使用SSH的scp命令传输文件到远程服务器]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/82423052</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/82423052</guid><author>JoneZ</author><pubDate>Wed, 05 Sep 2018 14:10:14 +0800</pubDate><description><![CDATA[原文地址：https://blog.youkuaiyun.com/m0_37138008/article/details/78283347]]></description><category></category></item><item><title><![CDATA[Required request body is missing错误]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/81938634</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/81938634</guid><author>JoneZ</author><pubDate>Wed, 22 Aug 2018 09:55:56 +0800</pubDate><description><![CDATA[原文地址：

https://blog.youkuaiyun.com/zyxwvuuvwxyz/article/details/80500146]]></description><category></category></item><item><title><![CDATA[ISO8601时间格式之间的转换]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/81915121</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/81915121</guid><author>JoneZ</author><pubDate>Tue, 21 Aug 2018 21:42:30 +0800</pubDate><description><![CDATA[
@Test
public void ad() throws ParseException {
    TimeZone tz = TimeZone.getTimeZone(&quot;UTC&quot;);
    DateFormat df = new SimpleDateFormat(&quot;yyyy-MM-dd'T'HH:mm:ss.SSS'Z'&quot;);
    df.setTimeZone(tz);
    Sys...]]></description><category></category></item><item><title><![CDATA[（Mybatis）逆向工程]]></title><link>https://blog.youkuaiyun.com/JoneZ/article/details/81089460</link><guid>https://blog.youkuaiyun.com/JoneZ/article/details/81089460</guid><author>JoneZ</author><pubDate>Tue, 17 Jul 2018 22:34:49 +0800</pubDate><description><![CDATA[Mybatis逆向工程：

       作用：mybatis 官方提供逆向工程，可以使用它通过数据库中表来自动生成 Mapper 接口和映射文件（单表的增删改查）和pojo类。

        导入的jar包有：

         

       user.sql：


/*
 Navicat Premium Data Transfer
 Source Server         : l...]]></description><category></category></item></channel></rss>