Request

获取数据

calss request	meaning
getParameter("name")	获取1个name参数对应的值
getAllParameter("name")	获取所有name对应的值，返回[]String
Enumeration getParameterNames()
Object getAttribute(String key)	返回Map映射中key对应的值
void setAttribute(String key,Object value)
Enumeration getAttributeNames()

获取客户及服务器的机器信息

方法	meaning
String getRemoteAddr	获取客户端的IP地址
String getRemoteHost
String getRemoteUser
String getLocalName
String getLocalAddr
String getLocalPort

response

method	meaning
void setHeader(String key,String value)
vlid addHeader(String key,String value)
Collection getHeaderNames()
String getHeader(String key)
Collection getHeaders(String key)
void setContentType(String type)

Shared var object

application session request

Session	meaning
getId()	return session ID
boolean isNew()	return is a new session
setAttribute(Stirng key,String object)	put key-value in session
ObjectgetAttribute(String name)
Enumeration getAttributeNames()
long getCreationTime()
long getLastAccessTime
setMaxInactive Interval	set session max-time
set invalidate()	clear the session

application
String getInitParameter(String name)	for read web.xml
void log(String msg)
void log(Stirng msg,Throwable th)	print msg in log file