SpringBoot推荐开发者使用Java配置来搭建框架，SpringBoot中大量的自动化配置都是通过Java代码配置实现的，而不是XML配置，同理，我们自己也可以使用纯Java来搭建一个SSM环境，即在项目中不存在任何XML配置，包括web.xml

环境要求：

Tomact版本必须在7以上

1.在IDEA中创建一个普通的maven项目

在pom.xml加入项目中需要用到的依赖

    4.0.0

    com.xiao.ssm
    SSM-demo
    1.0-SNAPSHOT
    war

    
        8
        8
        2.2
        8888
        UTF-8
    

    

        
        
            org.springframework
            spring-webmvc
            5.2.12.RELEASE
        

        
        
        
            javax.servlet
            javax.servlet-api
            4.0.1
            provided
        

        
            javax.servlet.jsp
            jsp-api
            2.2
        
    

    
        
            
            
                org.apache.tomcat.maven
                tomcat7-maven-plugin
                ${tomcat.version}
                
                    ${webserver.port}
                    /${project.artifactId}
                    ${project.build.sourceEncoding}
                
            
        
    

    
        
            central
            https://maven.aliyun.com/nexus/content/repositories/central
        
    
    
        
            central
            https://maven.aliyun.com/nexus/content/repositories/central
        
    

2.添加Spring配置

创建SpringConfig.java文件

package com.xiao.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;



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

3.添加SpringMVC配置

创建SpringMVCConfig.java文件

package com.xiao.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;


@Configuration
//@ComponentScan(basePackages = "com.xiao",useDefaultFilters = true,
//        excludeFilters = {@ComponentScan.Filter(type = FilterType.ANNOTATION,classes = Controller.class)})
@ComponentScan(basePackages = "com.xiao")
public class SpringMVCConfig extends WebMvcConfigurationSupport {

    
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/js
    @Override
    protected void configureViewResolvers(ViewResolverRegistry registry) {
        registry.jsp("/jsp/",".jsp");
    }
    
    
    @Override
    protected void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/hello3").setViewName("hello");
    }
    
    
    @Override
    protected void configureMessageConverters(List> converters) {
        FastJsonHttpMessageConverter converter=new FastJsonHttpMessageConverter();
        converter.setDefaultCharset(Charset.forName("UTF-8"));
        FastJsonConfig fastJsonConfig=new FastJsonConfig();
        fastJsonConfig.setCharset(Charset.forName("UTF-8"));
        converter.setFastJsonConfig(fastJsonConfig);
        converters.add(converter);
    }
}

4.配置web.xml

创建WebInit.java文件

package com.xiao.config;

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

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


public class WebInit implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        //首先来加载SpringMVC的配置文件
        AnnotationConfigWebApplicationContext ctx=new AnnotationConfigWebApplicationContext();
        ctx.register(SpringMVCConfig.class);

        //添加DispatcherServlet
        ServletRegistration.Dynamic springmvc=servletContext.addServlet("springmvc",new DispatcherServlet(ctx));

        //给DispatcherServlet添加路径映射
        springmvc.addMapping("/");

        //给DispatcherServlet添加启动时机
        springmvc.setLoadonStartup(1);
    }
}

WebInit的作用类似于web.xml，这个类需要实现WebApplicationInitializer接口，并实现其方法，当项目启动时，onStartup方法会被自动执行，我们可以在这里进行项目初始化操作，如：加载SpringMVC容器，添加过滤器，添加Listener，添加Servlet等

注：

由于在onStartup里面只加载了springmvc配置，没有加载spring容器，如果要加载Spring容器

方案一：

修改springmvc配置，在配置的包扫描中也去扫描@Configuration注解

推荐 方案二：

去掉springConfig文件，讲所有的配置都放到springmvc里面

5.测试

5.1创建HelloController类

package com.xiao.control;

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


@RestController
public class HelloController {

    @GetMapping("/hello")
    public String hello(){
        return "hello";
    }
}

运行结果：

5.2创建HelloController2类

package com.xiao.control;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;


@Controller
public class HelloController2 {

    @GetMapping("hello2")
    public String hello2(){
        return "hello";
    }
}

运行结果：

5.3路径映射

6.JSON配置

SpringMVC可以接收json参数，也可以返回json参数，这一切依赖于HttpMessageConverter

HttpMessageConverter可以将一个json字符串转为对象，也可以将一个对象转为json字符串，实际上它的底层还是依赖具体的json库

SpringMVC中默认提供了Jackson和gson的HttpMessageConverter，分别是：

MappingJackson2HttpMessageConverter、GsonHttpMessageConverter

7.总结

1.本项目需要在idea中配置外部的tomact才可运行

2.自己也尝试在pom.xml中配置tomact插件，最后发现不行

3.使用mave插件打包不行，因为他会找web.xml，所以找不到就会打包失败