java spring boot 拦截器 实现未登录用户不能登录详解编程语言

package com.example.demo212; 
 
import org.springframework.web.servlet.HandlerInterceptor; 
import org.springframework.web.servlet.ModelAndView; 
import cn.hutool.json.JSONObject; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import java.io.PrintWriter; 
 
public class MyInterceptor implements HandlerInterceptor { 
    @Override 
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { 
        if (request.getSession().getAttribute("user") == null) { 
            response.setCharacterEncoding("UTF-8"); 
            response.setContentType("application/json; charset=utf-8"); 
            PrintWriter out = null; 
            try { 
                JSONObject res = new JSONObject(); 
                res.put("success", false); 
                res.put("message", "用户未登录！"); 
                out = response.getWriter(); 
                out.append(res.toString()); 
                return false; 
            } catch (Exception e) { 
                e.printStackTrace(); 
                response.sendError(500); 
                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 { 
 
    } 
}

package com.example.demo212; 
 
import org.springframework.context.annotation.Configuration; 
import org.springframework.web.servlet.config.annotation.InterceptorRegistration; 
import org.springframework.web.servlet.config.annotation.InterceptorRegistry; 
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer; 
 
@Configuration 
public class InterceptorConfig implements WebMvcConfigurer { 
    @Override 
    public void addInterceptors(InterceptorRegistry registry) { 
        // 注册拦截器 
        InterceptorRegistration ir = registry.addInterceptor(new MyInterceptor()); 
        // 添加拦截请求 
        ir.addPathPatterns("/*"); 
        // 添加不拦截的请求 
        ir.excludePathPatterns("/login"); 
 
        // 以上三句代码可以使用下面的代替 
        // registry.addInterceptor(new MyInterceptor()).addPathPatterns("/*").excludePathPatterns("/login"); 
    } 
}

package com.example.demo212; 
 
import org.springframework.boot.SpringApplication; 
import org.springframework.boot.autoconfigure.SpringBootApplication; 
import org.springframework.validation.annotation.Validated; 
import org.springframework.web.bind.annotation.GetMapping; 
import org.springframework.web.bind.annotation.RequestMapping; 
import org.springframework.web.bind.annotation.RestController; 
 
import javax.validation.constraints.*; 
 
 
@SpringBootApplication 
@RestController 
@Validated 
public class Demo212Application { 
 
    public static void main(String[] args) { 
        SpringApplication.run(Demo212Application.class, args); 
    } 
    @RequestMapping("/getUser") 
    public String getUserStr(String name, Integer age) { 
        return "name: " + name + " ,age:" + age; 
    } 
    @GetMapping("/login") 
    public String Login(){ 
        return "login"; 
    } 
 
    @GetMapping("/add") 
    public String add(){ 
        return "add"; 
    } 
}