Sission与aplication 在servlet中用法汇总
application用法：
在Servlet中，取得application有兩種方法：?
1.通過無參初始化方法，直接取得；?
2.通過有參初始化方法，必須使用config對象取得。?
實例：?
1.無參初始化方法：?
Application.java:?
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?? 1. package mgc.servlet.test;???
?? 2.???
?? 3. import java.io.*;???
?? 4. import javax.servlet.*;???
?? 5. import javax.servlet.http.*;???
?? 6.???
?? 7. public class Application extends HttpServlet {???
?? 8.????????
?? 9.???? public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {???
? 10.???????? this.doPost(request,response);???
? 11.???? }???
? 12.????????
? 13.???? public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {???
? 14.???????? //取得Application對象???
? 15.???????? ServletContext application=this.getServletContext();???
? 16.???????? //設置Application屬性???
? 17.???????? application.setAttribute("name", "Magci");???
? 18.???????? //跳轉到接收頁面???
? 19.???????? response.sendRedirect("application.jsp");???
? 20.???? }???
? 21. }??
package mgc.servlet.test;?
import java.io.*;?
import javax.servlet.*;?
import javax.servlet.http.*;?
public class Application extends HttpServlet {?
????
??? public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {?
??????? this.doPost(request,response);?
??? }?
????
??? public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {?
??????? //取得Application對象?
??????? ServletContext application=this.getServletContext();?
??????? //設置Application屬性?
??????? application.setAttribute("name", "Magci");?
??????? //跳轉到接收頁面?
??????? response.sendRedirect("application.jsp");?
??? }?
}?
web.xml:?
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?? 1.?? <servlet>??
?? 2.???? <servlet-name>Application</servlet-name>??
?? 3.???? <servlet-class>mgc.servlet.test.Application</servlet-class>??
?? 4.?? </servlet>??
?? 5.???
?? 6.?? <servlet-mapping>??
?? 7.???? <servlet-name>Application</servlet-name>??
?? 8.???? <url-pattern>/servlet/application</url-pattern>??
?? 9.?? </servlet-mapping>??
? <servlet>?
??? <servlet-name>Application</servlet-name>?
??? <servlet-class>mgc.servlet.test.Application</servlet-class>?
? </servlet>?
? <servlet-mapping>?
??? <servlet-name>Application</servlet-name>?
??? <url-pattern>/servlet/application</url-pattern>?
? </servlet-mapping>?
application.jsp:?
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?? 1. <%@page contentType="text/html;charset=GB2312" %>??
?? 2. <html>??
?? 3.?? <head>??
?? 4.???? <title>application</title>??
?? 5.?? </head>??
?? 6.??????
?? 7.?? <body>??
?? 8.?????? <h1><%=getServletContext().getAttribute("name") %></h1>??
?? 9.?? </body>??
? 10. </html>??
<%@page contentType="text/html;charset=GB2312" %>?
<html>?
? <head>?
??? <title>application</title>?
? </head>?
??
? <body>?
????? <h1><%=getServletContext().getAttribute("name") %></h1>?
? </body>?
</html>?
2.有參初始化方法:?
Config.java:?
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?? 1. package mgc.servlet.test;???
?? 2.???
?? 3. import java.io.*;???
?? 4. import javax.servlet.*;???
?? 5. import javax.servlet.http.*;???
?? 6.???
?? 7. public class Config extends HttpServlet {???
?? 8.????????
?? 9.???? private ServletConfig conf=null;???
? 10.????????
? 11.???? public void init(ServletConfig conf) throws ServletException {???
? 12.???????? //實例化config對象???
? 13.???????? this.conf=conf;???
? 14.???? }???
? 15.????????
? 16.???? public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {???
? 17.???????? this.doPost(request,response);???
? 18.???? }???
? 19.????????
? 20.???? public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {???
? 21.???????? //通過config對象取得Application對象???
? 22.???????? ServletContext application=this.conf.getServletContext();???
? 23.???????? //設置Application屬性???
? 24.???????? application.setAttribute("name", "Magci");???
? 25.???????? //跳轉到接收頁面???
? 26.???????? response.sendRedirect("config.jsp");???
? 27.???? }???
? 28. }??
package mgc.servlet.test;?
import java.io.*;?
import javax.servlet.*;?
import javax.servlet.http.*;?
public class Config extends HttpServlet {?
????
??? private ServletConfig conf=null;?
????
??? public void init(ServletConfig conf) throws ServletException {?
??????? //實例化config對象?
??????? this.conf=conf;?
??? }?
????
??? public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {?
??????? this.doPost(request,response);?
??? }?
????
??? public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {?
??????? //通過config對象取得Application對象?
??????? ServletContext application=this.conf.getServletContext();?
??????? //設置Application屬性?
??????? application.setAttribute("name", "Magci");?
??????? //跳轉到接收頁面?
??????? response.sendRedirect("config.jsp");?
??? }?
}?
web.xml:?
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?? 1.?? <servlet>??
?? 2.???? <servlet-name>Config</servlet-name>??
?? 3.???? <servlet-class>mgc.servlet.test.Config</servlet-class>??
?? 4.?? </servlet>??
? <servlet>?
??? <servlet-name>Config</servlet-name>?
??? <servlet-class>mgc.servlet.test.Config</servlet-class>?
? </servlet>?
config.jsp:?
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?? 1. <%@page contentType="text/html;charset=GB2312" %>??
?? 2. <html>??
?? 3.?? <head>??
?? 4.???? <title>config</title>??
?? 5.?? </head>??
?? 6.??????
?? 7.?? <body>??
?? 8.?????? <h1><%=getServletContext().getAttribute("name") %></h1>??
?? 9.?? </body>??
? 10. </html>?
?
Sission用法：
眾所周知，在JSP頁面上可直接通過session.setAttribute(name,object)設置session,可如果想在servlet使用session 的話，就和在JSP有點區別了。在servlet中通過HttpSession session=request.getSession(boolean create);得到一個session對象（準確來說，得到的應該是一個HttpSession 對象），然后，就可以像在JSP頁面中直接使用它了。
參數Boolean create說明:如果當前請求不屬于任何會話，而且create參數為true，則創建一個會話，否則返回null.當然如果為false的時候，那就和不帶參數的HttpSession session=request.getSession();等價了。
其實，jsp中的session和servlet中的HttpSession其實根本沒有區別，JSP頁面在編譯時會通過Jsp ? container將session對象變換為javax.servlet.http.HttpSession對象。
捎帶介紹下HttpSession的方法吧。
public void setAttribute(String name,Object value)
將value對象以name名稱綁定到會話
public object getAttribute(String name)
取得name的屬性值，如果屬性不存在則返回null
public void removeAttribute(String name)
從會話中刪除name屬性，如果不存在不會執行，也不會拋處錯誤.
public Enumeration getAttributeNames()
返回和會話有關的枚舉值
public void invalidate()
使會話失效，同時刪除屬性對象
public Boolean isNew()
用于檢測當前客戶是否為新的會話
public long getCreationTime()
返回會話創建時間
public long getLastAccessedTime()
返回在會話時間內web容器接收到客戶最后發出的請求的時間
public int getMaxInactiveInterval()
返回在會話期間內客戶請求的最長時間.秒
public void setMasInactiveInterval(int seconds)
允許客戶客戶請求的最長時間
ServletContext getServletContext()
返回當前會話的上下文環境，ServletContext對象可以使Servlet與web容器進行通信
public String getId()
返回會話期間的識別號
?
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