SpringBoot 拦截器 && 拦截之后返回前台自定义格式

1、加入 阿里的 json jar包

<!--json  jar相关jar包-->

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.9.0</version>
</dependency>

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.9.7</version>
</dependency>

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.7</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.23</version>
</dependency>

本文需要jar依赖 如图 - >

拦截之后返回的效果->

新建 config 包 并新建 InterceptorConfig  配置类 类上面添加 @Configuration 注解 表示是一个配置类

package com.pigs.springbootpigsinterceptor.config;

import com.pigs.springbootpigsinterceptor.interceptor.HomeInterceptor;
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;

/**
 * @author PIGS
 *
 * 拦截 路径
 */
@Configuration
public class InterceptorConfig implements WebMvcConfigurer {

    /**
     * 拦截 类
     */
    @Autowired
    private HomeInterceptor homeInterceptor;

    /**
     * 这个方法用来注册拦截器，写好的拦截器需要通过这里添加注册才能生效
     * @param registry
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {

        /**
         * 表示拦截所有的请求，
         * addPathPatterns("/**");
         * excludePathPatterns("/login", "/register")
         * 表示除了登陆与注册之外，因为登陆注册不需要登陆也可以访问excludePathPatterns("/login", "/register")
         *
         *
         */
        registry.addInterceptor(homeInterceptor).addPathPatterns("/home");

    }

}

新建 一个拦截类

HomeInterceptor 在类上面添加 @Component 注解 交给spring 容器管理 并实现 HandlerInterceptor  类

代码 ->

package com.pigs.springbootpigsinterceptor.interceptor;

import com.alibaba.fastjson.JSON;
import com.pigs.springbootpigsinterceptor.util.ResultUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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;
import java.io.IOException;
import java.io.PrintWriter;

/**
 *
 * 拦截器
 *
 * @author PIGS
 */
@Component
public class HomeInterceptor implements HandlerInterceptor {

    private static final Logger logger = LoggerFactory.getLogger(HomeInterceptor.class);

    /**
     * 判断session 是否有值
     *
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        String userName = (String) request.getSession().getAttribute("userName");
        logger.info("userName={}",userName);

        if (userName==null){
            String result = JSON.toJSONString(ResultUtil.error(101, "你还没有登录哦！"));
            returnJson(response, result);
            return false;
        }

        return true;
    }

    /**
     * 返回客户端数据
     */
    private void returnJson(HttpServletResponse response, String result) throws Exception {
        PrintWriter writer = null;
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html; charset=utf-8");
        try {
            writer = response.getWriter();
            writer.print(result);

        } catch (IOException e) {
        } finally {
            if (writer != null) {
                writer.close();
            }
        }

    }

    /**
     * 处理请求完成后视图渲染之前的处理操作
     *
     * @param httpServletRequest
     * @param httpServletResponse
     * @param o
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object
            o, ModelAndView modelAndView) throws Exception {

    }

    /**
     * 视图渲染之后的操作
     *
     * @param httpServletRequest
     * @param httpServletResponse
     * @param o
     * @param e
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse
            httpServletResponse, Object o, Exception e) throws Exception {

    }

}

自定义返回格式 ResultFormat 类 ->

代码->

package com.pigs.springbootpigsinterceptor.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.stereotype.Component;

/**
 * @author PIGS-猪农·杨
 * @version 1.0
 * @date 2020/2/17 14:41
 * 统一返回格式
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
@Component
public class ResultFormat<T> {
    /**
     * 错误码
     */
    private Integer code;

    /**
     * 提示信息
     */
    private String msg;

    /**
     * 内容
     */
    private T data;

}

ResultUtil返回工具类 ->

代码->

package com.pigs.springbootpigsinterceptor.util;

import com.pigs.springbootpigsinterceptor.entity.ResultFormat;
import org.springframework.beans.factory.annotation.Autowired;

/**
 * @author PIGS-猪农·杨
 * @version 1.0
 * @date 2020/2/17 14:53
 * 统一返回工具类
 */
public class ResultUtil {

    public static ResultFormat success(Object object) {
        ResultFormat result =new ResultFormat();
        result.setCode(200);
        result.setMsg("成功");
        result.setData(object);
        return result;
    }

    public static ResultFormat success() {
        return success(null);
    }

    public static ResultFormat error(Integer code, String msg) {
        ResultFormat result =new ResultFormat();
        result.setCode(code);
        result.setMsg(msg);
        return result;
    }

}

已经托管 码云 
https://gitee.com/pig_farmer_x/springboot/blob/master/springboot-pigs-interceptor.zip