JAVA SSM拦截器是啥？

Posted 2023-05-05

struts2有拦截器,可以实现进入action之前进行拦截 参考技术A 【SSM】拦截器的原理、实现
拦截器执行原理（流程）：
1、拦截请求的url；
2、从cookie中获取token；
3、如果没有token，则直接拦截，打回登录页面；
4、获取到token，调用sso（单点登录）系统的服务查询用户信息，返回session（用户信息）；
5、对获取到的session进行处理。如果session已经过期，直接打回系统登录页面；如果session有效，则直 接放行，达到用户的请求页面

Java基于ssm框架的restful应用开发

Java基于ssm框架的restful应用开发

好几年都没写过java的应用了，这里记录下使用java ssm框架、jwt如何进行rest应用开发，文中会涉及到全局异常拦截处理、jwt校验、token拦截器等内容。

1、jwt工具类

直接贴代码了，主要包括jwt的sign、verify、decode三个方法，具体实现如下：

package com.isoft.util;

import java.util.Date;

import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.interfaces.DecodedJWT;

public class JwtUtil {

    private static final String SECRET = "xxxxx";
    private static final String USERID = "userId";
    private static final String ISSUER = "xxxx.com";

    // 过期时间7天
    private static final long EXPIRE_TIME = 7 * 24 * 60 * 60 * 1000;

    // jwt sign
    public static String sign(Integer userId) {
        try {
            Date date = new Date(System.currentTimeMillis() + EXPIRE_TIME);
            Algorithm algorithmHS = Algorithm.HMAC256(SECRET);
            return JWT.create().withClaim(USERID, userId).withExpiresAt(date).withIssuer(ISSUER).sign(algorithmHS);
        } catch (Exception e) {
            return null;
        }
    }

    // jwt verify
    public static boolean verify(String token, Integer userId) {
        try {
            Algorithm algorithmHS = Algorithm.HMAC256(SECRET);
            JWTVerifier verifier = JWT.require(algorithmHS).withClaim(USERID, userId).withIssuer(ISSUER).build();
            verifier.verify(token);
            return true;
        } catch (Exception e) {
            System.out.println(e);
            return false;
        }
    }

    // 返回token中的用户名
    public static Integer getUserId(String token) {
        try {
            DecodedJWT jwt = JWT.decode(token);
            return jwt.getClaim(USERID).asInt();
        } catch (Exception e) {
            return null;
        }
    }
}

2、全局异常处理类

ssm中进行rest全局异常拦截处理主要用到RestControllerAdvice型注解类，直接贴代码：

package com.isoft.exception;

import org.springframework.http.HttpStatus;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.web.HttpRequestMethodNotSupportedException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;

import com.isoft.po.Response;

@RestControllerAdvice
public class ExceptionAdvice {

    /**
     * 400 - Bad Request
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(HttpMessageNotReadableException.class)
    public Response handleHttpMessageNotReadableException(HttpMessageNotReadableException e) {
        return new Response().failure("could not read json");
    }

    /**
     * 405 - Method Not Allowed
     * 
     * @param e
     * @return
     */
    @ResponseStatus(HttpStatus.METHOD_NOT_ALLOWED)
    @ExceptionHandler(HttpRequestMethodNotSupportedException.class)
    public Response handleHttpRequestMethodNotSupportedException(HttpRequestMethodNotSupportedException e) {
        return new Response().failure("request method not supported");
    }

    /**
     * 500 - Internal Server Error
     * 
     * @param e
     * @return
     */
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    @ExceptionHandler(Exception.class)
    public Response handleException(Exception e) {
        System.err.println(e);
        return new Response().failure(e.getMessage());
    }
    
}

这里主要拦截了405、400、500的n行yi‘chang异常情况，可根据具体情况拓展。

3、自定义Response返回类

我们自定义的Response返回类格式如下：

{
    "meta": {
        "success": true,
        "message": "ok"
    },
    data: Array or Object
}

代码如下：

package com.isoft.po;

public class Response {

    private static final String OK = "ok";
    private static final String ERROR = "error";

    private Meta meta;
    private Object data;

    public Response success() {
        this.meta = new Meta(true, OK);
        return this;
    }

    public Response success(Object data) {
        this.meta = new Meta(true, OK);
        this.data = data;
        return this;
    }
    
    public Response success(Object data, String msg){
        this.meta = new Meta(true, msg);
        this.data = data;
        return this;
    }
    
    public Response failure() {
        this.meta = new Meta(false, ERROR);
        return this;
    }

    public Response failure(String message) {
        this.meta = new Meta(false, message);
        return this;
    }

    public Meta getMeta() {
        return meta;
    }

    public Object getData() {
        return data;
    }

    public class Meta {

        private boolean success;
        private String message;

        public Meta(boolean success) {
            this.success = success;
        }

        public Meta(boolean success, String message) {
            this.success = success;
            this.message = message;
        }

        public boolean isSuccess() {
            return success;
        }

        public String getMessage() {
            return message;
        }
    }
}

4、jwt的token拦截器Interceptor

spring mvc的Interceptor实现类一般是继承HandlerInterceptor接口并重写preHandle、postHandle、afterCompletion的方法来实现的，这里我们直接进行token的verify返回即可，具体代码如下：

package com.isoft.interceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.http.HttpStatus;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import com.isoft.util.JwtUtil;
import com.isoft.util.StringUtil;

/**
 * jwt token拦截
 * @author sd
 *
 */
public class TokenInterceptor implements HandlerInterceptor{

    @Override
    public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
            throws Exception {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
            throws Exception {
        // TODO Auto-generated method stub
        
    }

    @Override
    public boolean preHandle(HttpServletRequest req, HttpServletResponse res, Object handler) throws Exception {
        String token = req.getHeader("Authorization");
        if (StringUtil.isEmpty(token)) {
            return false;
        }
        token = token.replace("Bearer ", "");
        boolean isPass = JwtUtil.verify(token, JwtUtil.getUserId(token));
        if (isPass) {
            return true;
        }
        res.setStatus(401);
        return false;
    }
    
}

写完这些还不行，需要将拦截器注册到spring-mvc的config中：

<!-- mvc拦截器 -->
<mvc:interceptors>
    <mvc:interceptor>
        <mvc:mapping path="/**"/>
        <mvc:exclude-mapping path="/users/login"/>
        <bean class="com.isoft.interceptor.TokenInterceptor"></bean>
    </mvc:interceptor>
</mvc:interceptors>

这里使用mvc:exclude-mapping可以直接排除某个接口的拦截，比较方便。

5、mysql插入中文乱码解决

使用ssm框架mybatis进行数据插入时，发现插入中文进去后数据有乱码情况，除了设置数据库编码之外还解决不了问题的话，不妨看下mybatis的链接编码设置，如果是db.properties的话，使用如下设置：

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://ip:port/dbname?useUnicode=true&characterEncoding=utf-8
jdbc.username=username
jdbc.password=password

6、一个简单的rest controller实例

package com.isoft.web.controller;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletResponse;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestController;

import com.isoft.po.PageBean;
import com.isoft.po.Response;
import com.isoft.po.User;
import com.isoft.service.UserService;
import com.isoft.util.JwtUtil;
import com.isoft.util.StringUtil;

/**
 * 用户控制器类
 */

@RequestMapping("/users")
@RestController
public class UserController {

    @Resource
    private UserService userService;

    /**
     * 用户注册
     * 
     * @param user
     * @param res
     * @return
     * @throws Exception
     */
    @RequestMapping(value = "/", method = RequestMethod.POST)
    @ResponseStatus(value = HttpStatus.CREATED)
    public Response save(@RequestBody User user, HttpServletResponse res) throws Exception {
        userService.add(user);
        return new Response().success(user);
    }

    /**
     * 用户登录
     * 
     * @param user
     * @param res
     * @return
     * @throws Exception
     */
    @RequestMapping(value = "login", method = RequestMethod.POST)
    @ResponseStatus(value = HttpStatus.OK)
    public Response login(@RequestBody User user, HttpServletResponse res) throws Exception {
        System.out.println(user);
        User u = userService.login(user);
        if (u != null) {
            String token = JwtUtil.sign(u.getId());
            u.setToken(token);
            u.setHashedPassword("");
            return new Response().success(u, "login success");
        }
        return new Response().failure("username or password wrong");
    }

    /**
     * 用户查询带分页
     * 
     * @param user
     * @param res
     * @return
     * @throws Exception
     */
    @RequestMapping(value = "/", method = RequestMethod.GET)
    @ResponseStatus(value = HttpStatus.OK)
    public Response list(@RequestParam(value = "page", required = false, defaultValue = "1") String page,
            @RequestParam(value = "rows", required = false, defaultValue = "10") String rows, User s_user, HttpServletResponse res)
            throws Exception {
        System.out.println(s_user);
        PageBean pageBean = new PageBean(Integer.parseInt(page), Integer.parseInt(rows));
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("userName", StringUtil.formatLike(s_user.getUserName()));
        map.put("email", s_user.getemail());
        map.put("start", pageBean.getStart());
        map.put("size", pageBean.getPageSize());
        List<User> userList = userService.find(map);
        return new Response().success(userList);
    }
    
    /**
     * 用户更新
     * 
     * @param user
     * @param res
     * @return
     * @throws Exception
     */
    @RequestMapping(value = "/{id}", method = RequestMethod.PUT)
    @ResponseStatus(value = HttpStatus.OK)
    public Response update(@PathVariable Integer id, @RequestBody User user, HttpServletResponse res) throws Exception {
        user.setId(id);
        System.out.println(user);
        Integer count = userService.update(user);
        if (count != 0) {
            return new Response().success();
        }
        return new Response().failure();
    }
    
    /**
     * 用户删除，支持批量
     * @param id
     * @param user
     * @param res
     * @return
     * @throws Exception
     */
    @RequestMapping(value = "/{ids}", method = RequestMethod.DELETE)
    @ResponseStatus(value = HttpStatus.OK)
    public Response delete(@PathVariable String ids, HttpServletResponse res) throws Exception {
        String[] idsStrings = ids.split(",");
        for (String id : idsStrings) {
            userService.delete(Integer.parseInt(id));
        }
        return new Response().success();
    }
    
    /**
     * 用户详情
     * @param id
     * @param user
     * @param res
     * @return
     * @throws Exception
     */
    @RequestMapping(value = "/{id}", method = RequestMethod.GET)
    @ResponseStatus(value = HttpStatus.OK)
    public Response getUser(@PathVariable Integer id, HttpServletResponse res) throws Exception {
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("id", id);
        List<User> users = userService.find(map);
        return new Response().success(users);
    }
}