SpringMVC的拦截器实现方式

拦截器是什么

拦截器是什么就不多说了吧，可以自行百度。今天简单用springboot 来做一个登录功能，使用拦截器来过滤一下。

环境配置- pom.xml

	<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.0.RELEASE</version>
    </parent>

    <groupId>org.example</groupId>
    <artifactId>demo02</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependency>

环境配置- application.yml

也没有什么配置，但是习惯就配一下端口

server:
  port: 8888

环境配置- 主启动类

@SpringBootApplication(scanBasePackages = "com.dev")
// 你的bean、controller这些要被spring扫到的，都要放在这个包（”com.dev“）下面 
public class MainTest {
   

    public static void main(String[] args) {
   
        SpringApplication.run(MainTest.class,args);
    }

}

环境配好，开始编码

编写LoginController

@RestController
public class LoginController {
   


    @RequestMapping("/login")
    public String login(String userName, String password) {
   

        if("root".equals(userName) && "123".equals(password)) {
   
            return "你好,root";
        } else {
   
            return "login fail";
        }
        
    }

}

简单测试一下

测试ok

编写拦截器（实现HandlerInterceptor接口）

@Component
public class MyInterceptor implements HandlerInterceptor {
   

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
   
        String userName = request.getParameter("userName");
        /** * 响应编码格式，解决乱码 */
        response.setContentType("text/html;charset=utf-8");
        if (userName == null) {
   
            response.getWriter().println("用户名为空！");
            return false;
        }
        if (userName.contains(".")) {
   
            response.getWriter().println("用户名包含非法字符！");
            return false;
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
   

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
   

    }
}

配置拦截器

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
   

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
   
        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/login");//可以编写多个路径
       // registry.addInterceptor(new MyInterceptor()).addPathPatterns("/login","/login/")
       //也可以添加忽略路径
       //registry.addInterceptor(new MyInterceptor()).addPathPatterns("/login","/login/").excludePathPatterns("/logout")
    }
}

测试拦截器（实现HandlerInterceptor接口）

用户名包含逗号 “.”

没有用户名

拦截器生效！

编写拦截器（实现Filter接口, 老方法）

@Component
@WebFilter(urlPatterns = "/**")
public class MyFilter implements Filter {
   

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
   
        String userName = request.getParameter("userName");
        /** * 响应编码格式，解决乱码 */
        response.setContentType("text/html;charset=utf-8");
        if (userName == null) {
   
            response.getWriter().println("用户名为空！");
            return;
        }
        if (userName.contains(".")) {
   
            response.getWriter().println("用户名包含非法字符！");
            return;
        }
        chain.doFilter(request,response);
    }

}