SpringBoot_Chapter0 | Eloise's Paradise
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SpringBoot_Chapter0

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Symbols count in article: 10k Reading time ≈ 9 mins.

本节主要介绍传统SSM项目环境构建过程, 然后引入SpringBoot项目构建过程进行对比分析.

SpringBoot基础介绍

XML-Spring项目构建

新建maven项目,

pom文件添加packaging标签,表示项目最终打包成war包

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<packaging>war</packaging>

项目目录结构组织

在项目目录结构中添加webapp目录及其里面的web.xml文件

创建SSM项目

pom中引入webmvc相关依赖

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<dependencies>
     <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-webmvc</artifactId>
         <version>5.1.6.RELEASE</version>
     </dependency>
 </dependencies>

配置spring和MVC的配置文件:

applicationContext.xml : 

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
  
    <!-- 包扫描 spring容器扫描除了Controller以外的其他类, Controller交给MVC扫描处理 -->
    <context:component-scan base-package="com.lee" use-default-filters="true">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>  
  
</beans>

spring-MVC.xml :

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!-- include 标签来表明只扫描Controller-->
    <context:component-scan base-package="com.lee">
        <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>
    <mvc:annotation-driven/>
</beans>

配置web.xml

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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">


    <!-- spring 配置-->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <!-- spring-MVC 配置-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-MVC.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
   
 
</web-app>

创建Controller

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package com.lee.controller;

import com.lee.service.HiService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HiController {

    @Autowired
    HiService hiService;
    @GetMapping(value = "/hi",produces = "text/html;charset=utf-8")
    public String hi(){
        return hiService.sayHi();
    }
}

@GetMapping(value = “/hi”,produces = “text/html;charset=utf-8”) 中的produces是为了解决前端乱码问题.

创建Service

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package com.lee.service;

import org.springframework.stereotype.Service;

import javax.xml.ws.ServiceMode;

@Service
public class HiService {
    public String sayHi() {
        return "Hi Spring,久仰!";
    }
}

至此, 整个项目的目录结构:

目录结构

配置本地Tomcat

配置本地tomcat

测试结果

配置本地tomcat

Annotation-Spring项目构建

新建maven项目

并添加package和webMVC依赖 (和XML方式构建spring项目一致)

新建Spring配置类

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@Configuration
@ComponentScan(basePackages = {"com.lee"}
                ,useDefaultFilters = true,
                excludeFilters = {@ComponentScan.Filter(type = FilterType.ANNOTATION,classes = {Controller.class})})
public class ApplicationContextConfig {

}

新建MVC配置类

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@Configuration
@ComponentScan(basePackages = {"com.lee"}
        ,useDefaultFilters = false,
        includeFilters  = {@ComponentScan.Filter(type = FilterType.ANNOTATION,classes = {Controller.class})})
public class MvcConfig {
}

新建初始化配置加载类WebInit

该类功能等效于XML配置中的web.xml, 用来加载spring和mvc的配置类

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package com.lee.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;


public class WebInit implements WebApplicationInitializer {
    @Override
    public void onStartup(javax.servlet.ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
        context.setServletContext(servletContext);
        context.register(MvcConfig.class);
        ServletRegistration.Dynamic springMVC = servletContext.addServlet("springMVC", new DispatcherServlet(context));
        springMVC.addMapping("/");
        springMVC.setLoadOnStartup(1);

    }
}

注意, 该类需要实现WebApplicationInitializer, 需要servlet相关支持, 所以要在pom中添加servlet的依赖, 最终pom.xml:

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<?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.lee</groupId>
    <artifactId>annotationSSM</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.16.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>

</project>

创建controller类并配置

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package com.lee.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HiController {

    @GetMapping(value = "/hi",produces = "text/html;charset=utf-8")
    public String hi(){
        return "注解构建Spring成功!";
    }

}

本地tomcat

启动项目进行测试结果如下:

配置本地tomcat

注解方式构建的补充

上面已经用最简单的方式进行了注解方式构建spring项目, 但是, 如果要一些其他的附加功能又该如何整合呢? 下面对几种常见功能进行了简要介绍, 更具体的细节会在后续章节进行详细展开.

静态资源访问

让MvcConfig类继承WebMvcConfigurationSupport, 重写addResourceHandlers方法,如下:

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@Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");
        super.addResourceHandlers(registry);
    }

然后在resources目录下创建静态资源

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Hello</title>
</head>
<body>
    <h1>你好, 静态资源 !</h1>
</body>
</html>

重启应用访问, 测试结果如下:

配置本地tomcat

拦截器

新建一个类MyInterceptor实现HandlerInterceptor

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package com.lee.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

public class MyInterceptor implements HandlerInterceptor{
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("pre");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("post");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("after");
    }
}

然后在MvcConfig类中注册该拦截器

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@Override
    protected void addInterceptors(InterceptorRegistry registry) {
        MyInterceptor myInterceptor = new MyInterceptor();
        registry.addInterceptor(myInterceptor).addPathPatterns("/**");
        super.addInterceptors(registry);
    }

在controller中添加一个方法进行测试:

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@GetMapping(value = "/interceptor",produces = "text/html;charset=utf-8")
    public String interceptor(){
        return "Anthing";
    }

前端测试访问后发现控制台输出结果如下 :

后台输出

Json数据访问

添加FastJson依赖

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<groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.2.49</version>
</dependency>

添加controller方法进行测试:

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@GetMapping(value = "/json",produces = "text/html;charset=utf-8")
    public List<String> json(){
        ArrayList<String> strings = new ArrayList<>();
        for (int i=0;i<10;i++){
            strings.add("www.eloise ".concat(String.valueOf(i)).concat(".com"));
        }
        return strings;
    }

在MvcConfig类中重写方法配置JSON:

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@Override
protected void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
    FastJsonConfig config=new FastJsonConfig();
    config.setCharset(Charset.defaultCharset());
    config.setDateFormat(new SimpleDateFormat("yyyy-MM-dd").format(new Date()));
    fastJsonHttpMessageConverter.setFastJsonConfig(config);
    converters.add(fastJsonHttpMessageConverter);
    super.configureMessageConverters(converters);
}

config相关的配置不是必须的, 这里仅仅只是列出来做展示而已.

测试结果如下:

JSON格式结果

更多整合教程请继续浏览springboot系列博客 .

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