实训中~~

理解Object...:
Object...objects这种参数定义是在不确定方法参数的情况下的一种多态表现形式。即这个方法可以传递多个参数，这个参数的个数是不确定的。这样你在方法体中需要相应的做些处理。因为Object是基类，所以使用Object.

ajax：异步请求
$.post("test.php",{name:"john",time:"2017.9.11"},);

向页面 test.php 发送数据，并输出结果（HTML 或 XML，取决于所返回的内容）：
$.post("test.php", { name: "John", time: "2pm" },
          function(data){
          alert("Data Loaded: " + data);
          });
 
web.xml里面配置:
<init-param>
<param-name></param-name>
<param-value></param-value>
</init-param>

获取：
ServletConfig config=this.getServletConfig();
String sheng=config.getInitParameter("sheng");
System.out.println(sheng);


HttpServletRequest 一次请求
HttpSession 一次对话
Applictaion 整个服务器有效

ServletContext application=this.getServletContext();//application 初始化

String realPath = application.getRealPath("/aa");//获取真实物理路径

Set<String> set = application.getResourcePaths(path);//获取指定文件夹下的所有文件

foreach: items var varStaus(index,count)

<c:choose>
<c:when test="${index.count==1}">
<a href="http://www.baidu.com"><img src="${img}" width="100px"
height="100px" /></a>
</c:when>
<c:when test="${index.count==11}">
<a href="http://www.xxxx"><img src="${img}" width="100px"
height="100px" /> </a>
</c:when>
<c:otherwise>
<img src="${img}" width="100px" height="100px" />
</c:otherwise>
</c:choose>
<c:if test="${index.count%5==0}">
<br />
</c:if>
</c:forEach>

filter 过滤器

init() 服务器启动时就被初始化
doFilter()  
destroy()

Filter中的request,response和servlet中的reuqest和response不一样。一个是父类，一个是子类

HttpServletRequest request2 = (HttpServletRequest) request;
HttpServletResponse response2 = (HttpServletResponse) response;
request2.setCharacterEncoding(encode);
request2.setAttribute("filterParam", "test");
chain.doFilter(request2, response2);


filter在servlet前执行！

更改密码，提示： mysqladmin: Can't turn off logging; error: 'Access denied; you need the SUPER privilege for this operation'" ：

解决方案： 
1.修改MySQL的登录设置：
# vi /etc/my.cnf
在[mysqld]的段中加上一句：skip-grant-tables
例如：
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
skip-name-resolve
skip-grant-tables
保存并且退出vi。 
 
重新启动mysqld
# /etc/init.d/mysqld restart
Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]


登录并修改MySQL的root密码
# /usr/bin/mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3 to server version: 3.23.56


Type 'help;' or '\h' for help. Type '\c' to clear the buffer.


mysql> USE mysql ;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A


Database changed
mysql> UPDATE user SET Password = password ( 'new-password' ) WHERE User = 'root' ;
Query OK, 0 rows affected (0.00 sec)
Rows matched: 2 Changed: 0 Warnings: 0


mysql> flush privileges ;
Query OK, 0 rows affected (0.01 sec)


mysql> quit
Bye


2．将MySQL的登录设置修改回来
# vi /etc/my.cnf
将刚才在[mysqld]的段中加上的skip-grant-tables删除
保存并且退出vi。


3．重新启动mysqld
# /etc/init.d/mysqld restart
Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]


centos 重启mysql mariadb版本:
service mariadb restart