SpringMVC之全注解方式进行web开发

在我们之前进行web开发的时候，通常都会有一个web.xml存在，我们会在web.xml里面配置Servlet、Filter等一些web开发相关的东西。但是由于Servlet3.0的规范和Spring3.1功能的增强，现在我们在进行web开发的时候可以不用再使用web.xml了，转而全部使用java注解就可以了。下面是一个例子：

首先我们先创建一个StrartWebApplicationInitializer类，这个类继承AbstractAnnotationConfigDispatcherServletInitializer这个类，代码如下：

package com.zkn.springmvc.annotationanalysis;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

import javax.servlet.ServletContext;

/**
 * Create By ZKN
 *
 * @date 2017/10/28
 * @time 上午9:53
 */
public class StrartWebApplicationInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
    /**
     * SpringContext中相关的bean
     *
     * @return
     */
    @Override
    protected Class[] getRootConfigClasses() {
        return new Class[]{SpringRootConfig.class};
    }

    /**
     * DispatcherServlet中上下文相关的Bean
     *
     * @return
     */
    @Override
    protected Class[] getServletConfigClasses() {
        return new Class[]{WebMvcConfig.class};
    }

    /**
     * Servlet请求映射路径
     *
     * @return
     */
    @Override
    protected String[] getServletMappings() {
        return new String[]{
                "/"
        };
    }

    @Override
    public void registerDispatcherServlet(ServletContext servletContext) {
        //配置profile，激活不同的环境
        servletContext.setInitParameter("spring.profiles.active", "jsp");
        super.registerDispatcherServlet(servletContext);
    }
}

这里需要注意一下，getRootConfigClasses这个方法返回的类对应的是Spring上下文相关的一些配置，getServletConfigClasses这个方法返回的类是SpringMVC相关的一些类的配置。我们看一下SpringRootConfig和WebMvcConfig这两个类中的配置项：

package com.zkn.springmvc.annotationanalysis;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

/**
 * Create By ZKN
 *
 * @date 2017/10/28
 * @time 上午9:55
 */
@Configuration
@ComponentScan(basePackages = "com.zkn.springmvc.annotationanalysis.service")
public class SpringRootConfig {

}

package com.zkn.springmvc.annotationanalysis;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.http.MediaType;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.context.ServletContextAware;
import org.springframework.web.servlet.HandlerAdapter;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.spring4.SpringTemplateEngine;
import org.thymeleaf.spring4.view.ThymeleafViewResolver;
import org.thymeleaf.templatemode.TemplateMode;
import org.thymeleaf.templateresolver.ITemplateResolver;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;

import javax.servlet.ServletContext;
import java.util.Arrays;

/**
 * Create By ZKN
 *
 * @date 2017/10/28
 * @time 上午10:04
 */
@EnableWebMvc
@Configuration
@ComponentScan(basePackages = "com.zkn.springmvc.annotationanalysis.controller")
public class WebMvcConfig extends WebMvcConfigurerAdapter implements ServletContextAware {

    private ServletContext servletContext;

    @Bean
    @Profile("jsp")
    public ViewResolver jspViewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("WEB-INF/resources/jsp/");
        viewResolver.setSuffix(".jsp");
        viewResolver.setViewClass(JstlView.class);
        viewResolver.setExposePathVariables(true);
        return viewResolver;
    }

    /**
     * 视图解析器
     *
     * @return
     */
    @Bean
    @Profile(value = "thymeleaf")
    public ViewResolver viewResolver() {
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setTemplateEngine(templateEngine());
        return viewResolver;
    }

    /**
     * 模版引擎
     *
     * @return
     */
    @Bean
    @Profile("thymeleaf")
    public TemplateEngine templateEngine() {
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(templateResolver());
        return templateEngine;
    }

    /**
     * 模版引擎解析器
     *
     * @return
     */
    @Bean
    @Profile("thymeleaf")
    public ITemplateResolver templateResolver() {
        ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver(servletContext);
        templateResolver.setPrefix("WEB-INF/resources/thymeleaf/");
        templateResolver.setSuffix(".html");
        templateResolver.setTemplateMode(TemplateMode.HTML);
        return templateResolver;
    }

    @Override
    public void setServletContext(ServletContext servletContext) {
        this.servletContext = servletContext;
    }

    /**
     * 配置静态资源
     *
     * @param configurer
     */
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    /**
     * 处理静态资源
     * @param registry
     */
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/js/**").addResourceLocations("/WEB-INF/resources/js/");
        registry.addResourceHandler("/img/**").addResourceLocations("/WEB-INF/resources/img/");
        super.addResourceHandlers(registry);
    }

    @Bean
    public HandlerAdapter requestMappingHandlerAdapter(){
        RequestMappingHandlerAdapter handlerAdapter = new RequestMappingHandlerAdapter();
        StringHttpMessageConverter messageConverter = new StringHttpMessageConverter();
        messageConverter.setSupportedMediaTypes(Arrays.asList(MediaType.valueOf("text/html;charset=UTF-8")));
        handlerAdapter.getMessageConverters().add(messageConverter);
        handlerAdapter.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
        return handlerAdapter;
    }

}

下面我们写个Controller来测试一下：

package com.zkn.springmvc.annotationanalysis.controller;

import com.zkn.springmvc.annotationanalysis.result.DataResult;
import com.zkn.springmvc.annotationanalysis.vo.PersonInfoVO;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Create By ZKN
 *
 * @date 2017/10/28
 * @time 下午3:00
 */
@RestController
@RequestMapping("rest")
public class RestfulController {
    /**
     * 返回一个字符串
     *
     * @return
     */
    @GetMapping("resultString")
    public String resultString() {
        return "我是一个字符串！";
    }

    /**
     * 返回一个json数据
     *
     * @return
     */
    @GetMapping("resultJson")
    public DataResult resultJson() {
        DataResult dataResult = new DataResult<>();
        PersonInfoVO personInfoVO = new PersonInfoVO();
        personInfoVO.setUserName("我是张三");
        personInfoVO.setPassWord("woshizhangsan");
        dataResult.setData(personInfoVO);
        dataResult.setSuccess(true);
        return dataResult;
    }
}

当我们发送的请求为：http://localhost:8082/rest/resultString时，结果如下：

当我们发送的请求为：http://localhost:8082/rest/resultJson时，结果如下：

在上面的demo中我们使用了两种视图技术，一种是JSP，一种是Thymeleaf，通过激活不同的profile来切换不同的环境。完整代码请点击这里：

https://github.com/zhangconan/JavaWeb/tree/master/springmvc-annotation-analysis

是不是感觉有点神奇呢？不需要web.xml只需要这样配置一下我们就可以进行web开发了。我会在近期的文章中简单的说明一下我们为什么可以这样去做，敬请期待。