Java写一个简单的拦截器

1.需要些logininterceptor和webconfig两个类

import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

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

public class LoginInterceptor extends HandlerInterceptorAdapter {
    // 1. 继承HandlerInterceptorAdapter类
    // 2. 重写preHandle方法
    // 3. 指定拦截器使用的位置

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        // 当session中没有user对象时 则重定向 到 登录页面
        if (request.getSession().getAttribute("user") == null) {
            // 重定向
            response.sendRedirect("/login/init_login");
            return false;
        }
        return true;
    }

}

webconfigure类

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor((HandlerInterceptor) new LoginInterceptor())
                .addPathPatterns("/admin/**")
                .excludePathPatterns("/page-register")
                .excludePathPatterns("/login");
    }
}

在这个类中可以设定你允许的路径