Cookie和Session的获取方法

1、Cookie的简单获取方法（可以获取到所有的cookie）

（1）在参数里还有HttpServletResponse response这些，这些都是内置对象需要就拿不需要就删掉就可以，在这里我们用到的是HttpServletRequest request

（2）lambda表达式方法

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r2")public  String getCookie(HttpServletRequest request)  {Cookie[] cookies=request.getCookies();if(cookies!=null){Arrays.stream(cookies).forEach(x->System.out.println(x.getName()+":"+x.getValue()));return "获取cookie成功";}return "Cookie为空";}
}

（3）for循环方法

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r2")public  String getCookie(HttpServletRequest request)  {Cookie[] cookies=request.getCookies();if(cookies!=null){for (Cookie c:cookies){System.out.println(c.getName()+":"+c.getValue());}return "获取cookie成功";}return "Cookie为空";}
}

2、用spring boot方法获取cookie（获取指定的，获取不到所有的）也可以继续在声明里加其他的cookie

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r2")public  String getCookie(@CookieValue("lala") String lala )  {return "lala:"+lala;}
}

3、获取session（传统方式）

要先运行SetSession在访问GetSession，如果直接get会返回默认值为null

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r1")public  String setSession(HttpServletRequest request )  {HttpSession session=request.getSession();session.setAttribute("username","zhangsan");return "设置session成功";
}@RequestMapping("/r2")public String getSession(HttpServletRequest request){HttpSession session=request.getSession();String username=(String) session.getAttribute("username");return "登录用户："+username;}
}

4、spring boot方法获取session（对代码起到简化效果）声明中的HttpSession是内置对象不需要可以去掉

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r1")public  String setSession(HttpServletRequest request )  {HttpSession session=request.getSession();session.setAttribute("username","zhangsan");return "设置session成功";
}@RequestMapping("/r2")public String getSession(HttpSession session){String username=(String) session.getAttribute("username");return "登录用户："+username;}
}

5、使用注解方式获取session，再次简化代码，运行结果和上面两个一样

（1）这个代码的session不能为空，为空就报错

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r1")public  String setSession(HttpServletRequest request )  {HttpSession session=request.getSession();session.setAttribute("username","zhangsan");return "设置session成功";
}@RequestMapping("/r2")public String getSession(@SessionAttribute("username") String username){return "登录用户："+username;}
}

（2）我们为了为空时候不报错，需要对我们代码进行修改

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r1")public  String setSession(HttpServletRequest request )  {HttpSession session=request.getSession();session.setAttribute("username","zhangsan");return "设置session成功";
}@RequestMapping("/r2")public String getSession(@SessionAttribute(value = "username",required = false) String username){return "登录用户："+username;}
}

这个就是修改过程，加了一个require

6、拓展我们可以用我们的声明获得我们的其他信息，其他参数信息（举例获取User-Agent）获取全部的

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r1")public  String getHeader(HttpServletRequest request )  {String userAgent=request.getHeader("User-Agent");return "User-Agent:"+userAgent;
}
}

postman的User-Agent

浏览器的User-Agent

7、指定获取参数，用注解方法

@RestController
@RequestMapping("/user")
public class user {@RequestMapping("/r1")public  String getHeader(@RequestHeader("User-Agent") String userAgent)  {return "User-Agent:"+userAgent;
}
}