首页手记 SpringBoot拦截器

SpringBoot拦截器

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Java SpringBoot

在实际开发中，总存在着这样的场景，比如拦截请求的ip地址，或者在所有的请求都返回相同的数据，如果每一个方法都写出相同数据固然可以实现，但是随着项目的变大，重复的代码会越来越多，所以在这种情况我们可以用拦截器来实现。

最近一直在研究thymeleaf，越发的感觉这个很好用，所以这篇文章也选择结合这个来使用。

新建项目，pom文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.dalaoyang</groupId>
    <artifactId>springboot_interceptor</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springboot_interceptor</name>
    <description>springboot_interceptor</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>net.sourceforge.nekohtml</groupId>
            <artifactId>nekohtml</artifactId>
            <version>1.9.15</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

新建一个拦截器CommonInterceptor，继承HandlerInterceptorAdapter。给大家说一下，在继承HandlerInterceptorAdapter有三个拦截器是经常使用的：
1.preHandle在业务处理器处理请求之前被调用
2.postHandle在业务处理器处理请求执行完成后,生成视图之前执行
3.afterCompletion在DispatcherServlet完全处理完请求后被调用

本文使用的是postHandle，代码如下：

package com.dalaoyang.interceptor;

import org.apache.log4j.Logger;
import org.springframework.stereotype.Component;
import org.springframework.ui.ModelMap;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

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

/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.interceptor
 * @email yangyang@dalaoyang.cn
 * @date 2018/4/27
 */
@Component
public class CommonInterceptor extends HandlerInterceptorAdapter {
    Logger logger = Logger.getLogger(CommonInterceptor.class);

    //preHandle在业务处理器处理请求之前被调用，
    //postHandle在业务处理器处理请求执行完成后,生成视图之前执行
    //afterCompletion在DispatcherServlet完全处理完请求后被调用
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
                           ModelAndView modelAndView) throws Exception {
        logger.info("请求ip："+request.getRemoteAddr());
        logger.info("请求的方法："+request.getMethod());
        ModelMap modelMap = modelAndView.getModelMap();
        modelMap.addAttribute("title","dalaoyang");
    }
}

在启动类继承WebMvcConfigurerAdapter来为项目添加拦截器，代码如下：

package com.dalaoyang;

import com.dalaoyang.interceptor.CommonInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@SpringBootApplication
public class SpringbootInterceptorApplication extends WebMvcConfigurerAdapter {

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

    @Autowired
    CommonInterceptor commonInterceptor;

    // 增加拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(commonInterceptor);
    }
}

IndexController负责跳转，代码如下：

package com.dalaoyang.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaaoyang.controller
 * @email yangyang@dalaoyang.cn
 * @date 2018/4/27
 */

@Controller
public class IndexController {

    @RequestMapping("/")
    public String index(Model model){
        model.addAttribute("content","hi , dalaoyang !");
        return "index";
    }
}

在templates下新建index.html，其中content是controller返回的内容，title是在拦截器中返回的内容，代码如下：

<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">

<!DOCTYPE html>
<head>
    <meta charset="UTF-8">
    <title th:text="${title}"></title>
</head>
<body>
<p th:text="${content}"></p>
</body>
</html>

启动项目，访问 http://localhost:8888/，控制台如下：