步骤
- 获取session对象
- 通过setAttribute写入session
- 获取session的值
- session销毁(手动销毁和自动销毁)
设置session
package com.demo;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;
public class SetSessionDemo extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 设置字符集
req.setCharacterEncoding("utf-8");
resp.setContentType("text/html; charset=utf-8");
PrintWriter writer = resp.getWriter();
// 得到Session对象
HttpSession session = req.getSession();
// 写入session
session.setAttribute("GoodsDetail", "商品详情");
// 获取session id
String id = session.getId();
// 判断session否新建
if (session.isNew()) {
writer.write("session 创建成功, session id为: " + id);
} else {
writer.write("session已经在服务器中存在了, ID: " + id);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
super.doPost(req, resp);
}
}
获取session中的值
package com.demo;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class GetSessionDemo extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 设置字符集
req.setCharacterEncoding("utf-8");
resp.setContentType("text/html; charset=utf-8");
// 得到Session
HttpSession session = req.getSession();
String goodsDetail = (String) session.getAttribute("GoodsDetail");
resp.getWriter().write(goodsDetail);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
super.doPost(req, resp);
}
}
session销毁
手动
package com.demo;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class DelSessionDemo extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
HttpSession session = req.getSession();
session.removeAttribute("GoodsDetail");
session.invalidate();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
super.doPost(req, resp);
}
}
自动过期销毁
<session-config>
<!-- 设置session默认的失效时间, 以分钟为单位 -->
<session-timeout>1</session-timeout>
</session-config>
web.xml
<servlet>
<servlet-name>setSessionDemo</servlet-name>
<servlet-class>com.demo.SetSessionDemo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>setSessionDemo</servlet-name>
<url-pattern>/set/session/demo</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>getSessionDemo</servlet-name>
<servlet-class>com.demo.GetSessionDemo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>getSessionDemo</servlet-name>
<url-pattern>/get/session/demo</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>delSessionDemo</servlet-name>
<servlet-class>com.demo.DelSessionDemo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>delSessionDemo</servlet-name>
<url-pattern>/del/session/demo</url-pattern>
</servlet-mapping>