<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[qingfeng_ych的博客]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/qingfeng_ych</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; qingfeng_ych]]></copyright><item><title><![CDATA[js 文件下载请求两种方式]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/104532932</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/104532932</guid><author>qingfeng_ych</author><pubDate>Thu, 27 Feb 2020 11:48:59 +0800</pubDate><description><![CDATA[1.创建form表单提交
 jQuery('&lt;form action="' url " method="post"&gt;' +
            '&lt;input type="text" name="attachment" value="' + attachment + '"/&gt;&lt;/form&gt;')
            .appendTo('body').su...]]></description><category></category></item><item><title><![CDATA[java web文件上传下载]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/94591474</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/94591474</guid><author>qingfeng_ych</author><pubDate>Wed, 03 Jul 2019 22:45:24 +0800</pubDate><description><![CDATA[1.ajax不能用于文件下载，会将返回的数据保存到内存中，而不是以下载文件形式。
2.js不能控制form自动多次提交，因为前一次submit后请求没结束，再次submit会覆盖前一次的submit，导致只会有最后一次submit
3.文件下载时，一次只能下载一个文件，即一次请求，response只能返回一个文件，但可以将下载的多个文件打包下载。
4.SpringBoot 相对路径 写入文件时找不...]]></description><category></category></item><item><title><![CDATA[spring xml文件加载问题：classpath与classpath*区别]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/90481130</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/90481130</guid><author>qingfeng_ych</author><pubDate>Thu, 23 May 2019 15:22:16 +0800</pubDate><description><![CDATA[&lt;context-param&gt;
		&lt;param-name&gt;contextConfigLocation&lt;/param-name&gt;
		&lt;param-value&gt;classpath*:spring-*.xml&lt;/param-value&gt;
	&lt;/context-param&gt;

&lt;param-value&gt;classpat...]]></description><category></category></item><item><title><![CDATA[pom.xml出现 web.xml is missing and <failOnMissingWebXml> is set to true 错误]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89383900</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89383900</guid><author>qingfeng_ych</author><pubDate>Thu, 18 Apr 2019 17:32:46 +0800</pubDate><description><![CDATA[该错误主要是项目中缺少web.xml文件导致的。
两种解决方案。
一
右键项目-&gt;Java EE Tools-&gt;Generate Deployment Descriptor Stub


二
右键项目-&gt;Properties
去掉箭头处勾选，点击apply。
再次选中后会出现下图中2，点击出现弹框，按下图数字修改后即可。


...]]></description><category></category></item><item><title><![CDATA[Maven不能将xml文件打包问题]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045992</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045992</guid><author>qingfeng_ych</author><pubDate>Fri, 05 Apr 2019 18:11:54 +0800</pubDate><description><![CDATA[maven默认打包 src/main/java 下 .java文件
1.将xml文件放入 src/main/resources 中
2.pom.xml 添加如下内容：
&lt;resources&gt;
    &lt;resource&gt;
       &lt;directory&gt; src/main/java &lt;/directory&gt;
      &lt;includes&...]]></description><category></category></item><item><title><![CDATA[eclipse打包项目]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045886</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045886</guid><author>qingfeng_ych</author><pubDate>Fri, 05 Apr 2019 18:02:01 +0800</pubDate><description><![CDATA[1.remove eclipse中 service 下项目
2.clean service
3.war包放入tomcat下 webapps 下

]]></description><category></category></item><item><title><![CDATA[out与err输出区别]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045847</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045847</guid><author>qingfeng_ych</author><pubDate>Fri, 05 Apr 2019 17:58:37 +0800</pubDate><description><![CDATA[system.out.println 与 system.err.println
1.out能重定向到别的输出流，屏幕不显示
err只能在屏幕上打印，重定向也一样
例：
System.setOut(new PrintStream (new FileOutputStream ( new File  ("C:/test.txt"))));
System.setErr();


2.out要缓冲，优先级低...]]></description><category></category></item><item><title><![CDATA[mybaties 批量插入]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045680</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045680</guid><author>qingfeng_ych</author><pubDate>Fri, 05 Apr 2019 17:45:20 +0800</pubDate><description><![CDATA[oracle:
insert into talbe (........) select sequence.nextval id , T.* from
  ( 
      &lt;foreach collection = "List" item = "item" separator = "union all"&gt;
             select #{item} from dual
  ...]]></description><category></category></item><item><title><![CDATA[js 函数表达式与函数声明]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045266</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89045266</guid><author>qingfeng_ych</author><pubDate>Fri, 05 Apr 2019 17:11:55 +0800</pubDate><description><![CDATA[1.函数表达式
 var a=function()

例：
a(1)  //error  ,undefined

var a = function(index){
         alert(index)
}

a(2)  //success



2.函数声明
function a ()


例：
b (1)  //success

function b(index){
    alert(i...]]></description><category></category></item><item><title><![CDATA[springMVC传数组]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89035964</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89035964</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 21:41:29 +0800</pubDate><description><![CDATA[1
 ajax： 
  temp=["asd","zxc"]
  data:{temp:temp}  
 
controller:
   public ~~~~~(@RequestParam(value="temp[]") string[] temp)


2
ajax:
  data : {temp:temp}
  traditional : true  //防止jQuery序列化数组
    ...]]></description><category></category></item><item><title><![CDATA[springMVC  ajax传对象数组]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89035707</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89035707</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 21:19:01 +0800</pubDate><description><![CDATA[ajax:
contentType:"application/json"
data:JSON.stringify(arr)
dataType:"json"



controller:
     1.bean:
     
          public ~~~~~~(@RequestBody List&lt;bean&gt; arr)
          (@RequestBody 类名[] ...]]></description><category></category></item><item><title><![CDATA[mybatis参数为0 判断非空不通过]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89034630</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89034630</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 20:08:02 +0800</pubDate><description><![CDATA[改：
&lt;if test = " id!=null and id != '' or id ==0 "&gt;
    			t.id = #{id}
    &lt;/if&gt;

注：int，bigdecimal 数值类
mybatis查询结果某字段为null，则不注入entity，可通过get方法设置返回值。

...]]></description><category></category></item><item><title><![CDATA[oracle导出导入某用户所有数据（表、视图、存储过程....）]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89034057</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89034057</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 19:35:32 +0800</pubDate><description><![CDATA[cmd下：
导出： exp 用户名/密码@数据库 owner = 用户名 file=文件保存路径;
例：exp shaoge/123@orcl owner=shaoge file=F:\abc.dmp tables=(t1,t2)  tables可省
导入：imp 用户名/密码@数据库 fromuser = 用户名 touser = 用户名 file = 文件路径 ignore = y
fromu...]]></description><category></category></item><item><title><![CDATA[oracle表空间扩容]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89031537</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89031537</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 17:57:52 +0800</pubDate><description><![CDATA[smalfile tablespace: alter database datafile 文件名  resize  大小;
bigfile tablespace:   alter tablespace 文件名 resize 大小;
判断smalfile  or  bigfile:
select bigfile from dba_tablespaces where tablespace_name=‘...]]></description><category></category></item><item><title><![CDATA[oracle函数]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89031307</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89031307</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 17:52:58 +0800</pubDate><description><![CDATA[1.将字段中字符替换
translate(string(字段),from_str(要替换的字符),to_str(换成字符));
2.查找子串位置
instr(sourceString,destString,start,appearPosition)
instr（‘源字符串’ , ‘目标字符串’ ,‘开始位置’,‘第几次出现’）
开始位置为负数，向左移
start,appearPosition默认为...]]></description><category></category></item><item><title><![CDATA[查询大量数据表的总记录数]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89030419</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89030419</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 17:34:29 +0800</pubDate><description><![CDATA[1.普通
select count(*) from table;
几千万条数据好几分钟
2.快速查询表的总记录数
select table_name,t.num_rows,t.last_analyzed from tabs t;
！！！查出数据库中此用户所有表中的记录数
比较：
1是查用户表，2是查系统表
！！！2查询结果不是非常准确，tables表中存在一个字段last_analyzed（最后分...]]></description><category></category></item><item><title><![CDATA[oracle中connect by prior 算法]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89029061</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89029061</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 17:09:28 +0800</pubDate><description><![CDATA[（递归–&gt;中序遍历）
1.oracle中 start … connect by prior 子句用法。 connect by 是结构化查询中用到的：
select…from table
start with 条件1
connect by 条件2
where 条件3;
条件1：根节点限定语句
条件2：连接条件，prior表示上一条记录
例：connect by prior org_id=par...]]></description><category></category></item><item><title><![CDATA[servlet将内容返回请求和写到页面]]></title><link>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89028634</link><guid>https://blog.youkuaiyun.com/qingfeng_ych/article/details/89028634</guid><author>qingfeng_ych</author><pubDate>Thu, 04 Apr 2019 16:55:06 +0800</pubDate><description><![CDATA[1.将内容写到页面上
response.write();
2.将内容返回给请求
printwriter writer = response.getWriter();
writer.writer();
writer.flush();

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