Spring MVC系列(四)之session處理[email
介紹
在web開發中,session的重要性不言而喻,與cookie相比,session更加安全,處於伺服器端,開發者經常把一些重要的資訊放在session,方便在多次請求中方便的獲取資訊,Spring MVC 對session的支援也依舊很強大很靈活
Spring MVC對session的支援分為兩種
基於HttpSession的天然支援
基於註解@SessionAttributes的靈活多變的支援
首先我們先一起分析一下基於天生的HttpSession的支援吧
加入使用者登入的時候,我們把使用者資訊記錄到session中
我們先請求http://localhost:8080/spring-mvc/session/test/1/lynccpackage org.study.lyncc.web.controller; import javax.servlet.http.HttpSession; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.servlet.ModelAndView; import org.study.lyncc.web.entity.User; @Controller public class SessionAttributesController { /** * user物件存入session * @param id * @param name * @param session * @return */ @RequestMapping("/session/test/{id}/{name}") public ModelAndView localsessionAttributes(@PathVariable Integer id,@PathVariable String name,HttpSession session){ session.setAttribute("currentUser", new User(id,name)); ModelAndView mav = new ModelAndView("session"); return mav; } /** * 獲取session中的user物件 * @param session * @return */ @RequestMapping("/session/attributes") public ModelAndView sessionAttributesage(HttpSession session){ User u = (User)session.getAttribute("currentUser"); System.out.println(u.getUsername()); ModelAndView mav = new ModelAndView("session"); return mav; } }
然後我們再次請求http://localhost:8080/spring-mvc/session/attributes
會發現我們可以衝session取出我們上次請求存入session的user物件,併成功列印user的名字
基於@SessionAttributes註解實現的對session的管理
SessionAttributes是隻能註解於類或者介面,@SessionAttributes的value代表我們需要把什麼樣的物件放入session,在我們的方法後當我們把物件放入ModelMap這個物件的時候,如果給出的key也會自動放入session的,我們舉例說明
package org.study.lyncc.web.controller; import javax.servlet.http.HttpSession; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.SessionAttributes; import org.springframework.web.servlet.ModelAndView; import org.study.lyncc.web.entity.User; @Controller @SessionAttributes(value="currentUser") public class SessionAttributesController { @RequestMapping("/session/attributes/{id}/{name}") public ModelAndView sessionAttributes(@PathVariable Integer id,@PathVariable String name){ ModelAndView mav = new ModelAndView("session"); mav.addObject("currentUser", new User(id,name)); return mav; } /** * 獲取session中的user物件 * @param session * @return */ @RequestMapping("/session/attributes") public ModelAndView sessionAttributesage(HttpSession session){ User u = (User)session.getAttribute("currentUser"); System.out.println(u.getUsername()); ModelAndView mav = new ModelAndView("session"); return mav; } }
上面程式碼中,我們註解了@SessionAttributes,並且在sessionAttributes方法中,mav.addObject("currentUser", new User(id,name));我們建立一個物件放入ModelAndView中,因為@SessionAttributes的value與addObject的key值相同,所以該User會自動存入session中(上面說是ModelMap物件,其實看原始碼就知道ModelAndView的model就是ModelMap)
好了,我們測試一下,先執行http://localhost:8080/spring-mvc/session/test/1/lyncc
再執行http://localhost:8080/spring-mvc/session/attributes,測試結果
能獲取到值,說明user放入session成功了
我們除了顯性的從HttpSession中獲取物件,我們還可以利用@ModelAttribute與@SessionAttributes相互配合,隱性的獲取到放在session中的值,程式碼如下
package org.study.lyncc.web.controller;
import javax.servlet.http.HttpSession;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.servlet.ModelAndView;
import org.study.lyncc.web.entity.User;
@Controller
@SessionAttributes(value="currentUser")
public class SessionAttributesController {
@RequestMapping("/session/attributes/{id}/{name}")
public ModelAndView sessionAttributes(@PathVariable Integer id,@PathVariable String name){
ModelAndView mav = new ModelAndView("session");
mav.addObject("currentUser", new User(id,name));
return mav;
}
@RequestMapping("/session/attributes/test")
public ModelAndView sessionAttributesage(@ModelAttribute("currentUser") User u){
System.out.println(u.getUsername());
ModelAndView mav = new ModelAndView("session");
return mav;
}
}
這樣依舊能獲取到值,不過要注意
最後我們再看看@SessionAttributes這個註解
package org.springframework.web.bind.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.core.annotation.AliasFor;
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface SessionAttributes {
@AliasFor("names")
String[] value() default {};
@AliasFor("value")
String[] names() default {};
Class<?>[] types() default {};
}
都是陣列型的,也就說可以支援多個物件放入session中,舉例說明
package org.study.lyncc.web.controller;
import java.util.Date;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.servlet.ModelAndView;
import org.study.lyncc.web.entity.User;
@Controller
@SessionAttributes(value={"currentUser","saveTime"},types={User.class,Date.class})
public class SessionAttributesController {
@RequestMapping("/session/attributes/{id}/{name}")
public ModelAndView sessionAttributes(@PathVariable Integer id,@PathVariable String name){
ModelAndView mav = new ModelAndView("session");
mav.addObject("currentUser", new User(id,name));
mav.addObject("saveTime", new Date());
return mav;
}
@RequestMapping("/session/attributes/test")
public ModelAndView sessionAttributesage(@ModelAttribute("currentUser") User u,@ModelAttribute("saveTime") Date d){
System.out.println(u.getUsername());
System.out.println(d);
ModelAndView mav = new ModelAndView("session");
return mav;
}
}
測試結果:
好了,這節END~