登录校验及全局异常处理器

登录校验

会话技术

• 会话:用户打开浏览器,访问web服务器的资源,会话建立,直到有一方断开连接,会话结束.在一次会话中可以包含多次请求和响应
• 会话跟踪:一种维护浏览器状态的方法,服务器需要识别多次请求是否来自于同一浏览器,以便在同一次会话请求间共享数据
• 会话跟踪方案

1. 1. 客户端会话跟踪技术:Cookie
   2. 服务端会话跟踪技术:Session
   3. 令牌技术

JWT令牌(JSON Web Token)

1. 组成

• 第一部分：Heade（头），记录令牌类型，算法签名等。例如：{"alg":"HS256","type":"JWT"}
• 第二部分：Payload（有效载荷），携带一些自定义信息，默认信息等等。例如：{"id":"1","name":"Tom"}
• 第三部分：Signature（签名），防止Token被篡改，确保安全性。将Header , payload , 并加入指定秘钥 , 通过指定签名算法计算而来

2. 生成/解析

 @Testpublic void testGenJWT(){HashMap<String, Object> claims = new HashMap<>();claims.put("id",1);claims.put("name","Tom");String jwt = Jwts.builder().signWith(SignatureAlgorithm.HS256, "comcrn")//签名算法.setClaims(claims)//自定义内容,载荷.setExpiration(new Date(System.currentTimeMillis() + 3600 * 1000))//设置有效期是一个小时.compact();System.out.println(jwt);}@Test//解析public void testParseJwt(){Claims claims= Jwts.parser().setSigningKey("comcrn").parseClaimsJws("eyJhbGciOiJIUzI1NiJ9.eyJuYW1lIjoiVG9tIiwiaWQiOjEsImV4cCI6MTcxNjk5NTA1Nn0.ArBnzJo8SWv1YbJIddsiH8_ZgAX_IapDf0vENI43tfo").getBody();System.out.println(claims);}

过滤器Filter

• 一般完成一些通用的操作 , 比如 : 登录校验 , 统一编码处理 , 敏感字符处理等 .

1. 快速入门

1.1. 定义Filter:定义一个类,实现Filter接口,并重写其所有方法

package com.crn.filter;import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;@WebFilter(urlPatterns = "/*")
public class DemoFilter implements Filter {@Override //初始化方法,只调用一次public void init(FilterConfig filterConfig) throws ServletException {Filter.super.init(filterConfig);}@Override //拦截到请求之后调用,调用多次public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {//放行filterChain.doFilter(servletRequest,servletResponse);}@Override//销毁方法,只调用一次public void destroy() {Filter.super.destroy();}
}

1.2. 配置Filter:Filter配置类上加@WebFilter注解,配置资源拦截的路劲.引导类加上@ServletComponentScan开启支持Servlet组件

package com.crn;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;@ServletComponentScan
@SpringBootApplication
public class SpringbootTliasYbApplication {public static void main(String[] args) {SpringApplication.run(SpringbootTliasYbApplication.class, args);}}

 <dependency><groupId>io.jsonwebtoken</groupId><artifactId>jjwt</artifactId><version>0.9.1</version></dependency>

2. 过滤器链

• 注解配置的Filter,优先级是按照过滤器类名(字符串)的自然排序

3. 登录校验流程

package com.crn.filter;import com.alibaba.fastjson.JSONObject;
import com.crn.pojo.Result;
import com.crn.utils.JwtUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.StringUtils;import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@Slf4j
@WebFilter(urlPatterns = "/*")
public class LoginCheckFilter implements Filter {@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {HttpServletRequest req = (HttpServletRequest) servletRequest;HttpServletResponse resp = (HttpServletResponse) servletResponse;//1.获取请求urlString url = req.getRequestURL().toString();log.info("url:{}", url);//2.判断URL中是否包含login,如果包含,说明是登录操作,放行if(url.contains("login")){log.info("登录操作,放行");filterChain.doFilter(servletRequest, servletResponse);return;}//3.获取请求头中的令牌String jwt = req.getHeader("token");//4.判断令牌是否存在if(!StringUtils.hasLength(jwt)){//令牌不存在,说明用户没有登录,返回错误信息log.info("令牌不存在,请先登录");Result error = Result.error("NOT_LOGIN");//手动转换  对象-->json  ---->阿里巴巴fastJSONString jsonString = JSONObject.toJSONString(error);resp.getWriter().write(jsonString);return ;}//5.解析token,如果解析失败,返回错误结果try {JwtUtils.parseJWT(jwt);} catch (Exception e) { //解析失败e.printStackTrace();log.info("令牌解析失败");Result error = Result.error("NOT_LOGIN");//手动转换  对象-->json  ---->阿里巴巴fastJSONString jsonString = JSONObject.toJSONString(error);resp.getWriter().write(jsonString);return ;}//6.放行log.info("令牌合法,放行");filterChain.doFilter(servletRequest, servletResponse);}
}

拦截器Interceptor

• spring框架提供的,用来动态拦截控制器方法的执行

1. 快速入门

1.1. 定义拦截器,实现HandlerInterceptor接口,并从写其方法

package com.crn.interceptor;import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;@Component
public class LoginCheckInterceptor implements HandlerInterceptor {@Override //目标资源方法运行前运行,返回为true,代表放行;返回值为false,代表拦截public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println("preHandle运行了...");return true;}@Override //目标资源方法运行后运行public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("postHandle运行了...");}@Override  //视图渲染完毕后运行,最后运行public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("afterCompletion运行了...");}
}

1.2. 定义拦截器

package com.crn.config;import com.crn.interceptor.LoginCheckInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
public class WebConfig implements WebMvcConfigurer {@Autowiredprivate LoginCheckInterceptor loginCheckInterceptor;@Override //注册拦截器public void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(loginCheckInterceptor).addPathPatterns("/**");}
}

2. 详解

3. 登录校验流程

package com.crn.interceptor;import com.alibaba.fastjson.JSONObject;
import com.crn.pojo.Result;
import com.crn.utils.JwtUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@Slf4j
@Component
public class LoginCheckInterceptor implements HandlerInterceptor {@Override //目标资源方法运行前运行,返回为true,代表放行;返回值为false,代表拦截public boolean preHandle(HttpServletRequest req, HttpServletResponse resp, Object handler) throws Exception {//1.获取请求urlString url = req.getRequestURL().toString();log.info("url:{}", url);//2.判断URL中是否包含login,如果包含,说明是登录操作,放行if(url.contains("login")){log.info("登录操作,放行");return true;}//3.获取请求头中的令牌String jwt = req.getHeader("token");//4.判断令牌是否存在if(!StringUtils.hasLength(jwt)){//令牌不存在,说明用户没有登录,返回错误信息log.info("令牌不存在,请先登录");Result error = Result.error("NOT_LOGIN");//手动转换  对象-->json  ---->阿里巴巴fastJSONString jsonString = JSONObject.toJSONString(error);resp.getWriter().write(jsonString);return false;}//5.解析token,如果解析失败,返回错误结果try {JwtUtils.parseJWT(jwt);} catch (Exception e) { //解析失败e.printStackTrace();log.info("令牌解析失败");Result error = Result.error("NOT_LOGIN");//手动转换  对象-->json  ---->阿里巴巴fastJSONString jsonString = JSONObject.toJSONString(error);resp.getWriter().write(jsonString);return false;}//6.放行log.info("令牌合法,放行");return true;}@Override //目标资源方法运行后运行public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("postHandle运行了...");}@Override  //视图渲染完毕后运行,最后运行public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("afterCompletion运行了...");}
}

过滤器与拦截器的区别

• 接口规范不同:过滤器需要实现Filter接口,二拦截器需要实现HandleInterceptor接口
• 拦截范围不同:过滤器Filer会拦截所有资源,而Interceptor只会拦截进入Spring环境中的资源

异常处理器

package com.crn.exception;import com.crn.pojo.Result;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;/*** 全局异常处理器*/
@RestControllerAdvice
public class GlobalExceptionHandler {@ExceptionHandler(Exception.class) //捕获所有异常public Result ex(Exception e){e.printStackTrace();return Result.error("对不起,操作失败,请联系管理员");}
}