❤️SpringMVC成神之路之十五、全注解的方式 & 原理解析

package com.javacode2018.springmvc.chat12.config;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
import javax.servlet.Filter;
/**
 * ①：1、创建Mvc初始化类，需要继承AbstractAnnotationConfigDispatcherServletInitializer类
 */
public class MvcInit extends AbstractAnnotationConfigDispatcherServletInitializer {
    /**
     * springmvc容器的父容器spring配置类
     * 实际工作中我们的项目比较复杂，可以将controller层放在springmvc容器中
     * 其他层，如service层、dao层放在父容器了，bean管理起来更清晰一些
     * 也可以没有父容器，将所有bean都放在springmvc容器中
     *
     * @return
     */
    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[0];
    }
    /**
     * ②：2、设置springmvc容器的spring配置类
     *
     * @return
     */
    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{MvcConfig.class};
    }
    /**
     * ③：3、配置DispatcherServlet的url-pattern
     *
     * @return
     */
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }
    /**
     * ④：4、注册拦截器
     *
     * @return
     */
    @Override
    protected Filter[] getServletFilters() {
        //添加拦截器，解决乱码问题
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setEncoding("UTF-8");
        characterEncodingFilter.setForceRequestEncoding(true);
        characterEncodingFilter.setForceResponseEncoding(true);
        return new Filter[]{characterEncodingFilter};
    }
}

package com.javacode2018.springmvc.chat12.config;
import com.javacode2018.springmvc.chat12.interceptor.MyInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.config.annotation.*;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
/**
 * 1.开启springmvc注解配置
 * 2、配置视图解析器
 * 3、配置截器
 * 4、配置静态资源访问
 * 5、配置文件上传解析器
 * 6、配置全局异常处理器
 */
@Configuration
@ComponentScan("com.javacode2018.springmvc.chat12")
@EnableWebMvc //1：使用EnableWebMvc开启springmvc注解方式配置
public class MvcConfig implements WebMvcConfigurer {
    /**
     * ②：2、添加视图解析器（可以添加多个）
     *
     * @param registry
     */
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/view/");
        resolver.setSuffix(".jsp");
        resolver.setOrder(Ordered.LOWEST_PRECEDENCE);
        registry.viewResolver(resolver);
    }
    @Autowired
    private MyInterceptor myInterceptor;
    /**
     * ③：3、添加拦截器（可以添加多个）
     *
     * @param registry
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(this.myInterceptor).addPathPatterns("/**");
    }
    /**
     * ④：4、配置静态资源访问处理器
     *
     * @param registry
     */
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("/static/");
    }
    /**
     * ⑤：5、配置文件上传解析器
     *
     * @return
     */
    @Bean
    public CommonsMultipartResolver multipartResolver() {
        CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver();
        //maxUploadSizePerFile:单个文件大小限制（byte）
        //maxUploadSize：整个请求大小限制（byte）
        commonsMultipartResolver.setMaxUploadSizePerFile(10 * 1024 * 1024);
        commonsMultipartResolver.setMaxUploadSize(100 * 1024 * 1024);
        return commonsMultipartResolver;
    }
}

package com.javacode2018.springmvc.chat12.interceptor;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@Component
public class MyInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("这是MyInterceptor拦截器");
        return true;
    }
}

package com.javacode2018.springmvc.chat12.config;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.ModelAndView;
/**
 * 异常处理
 */
@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler
    public ModelAndView doException(Exception e) {
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.setViewName("error");
        modelAndView.addObject("ex", e);
        return modelAndView;
    }
}

@Controller
public class IndexController {
    /**
     * 首页
     *
     * @return
     */
    @RequestMapping("/")
    public String index() {
        return "index";
    }
    /**
     * 测试异常情况
     *
     * @return
     */
    @RequestMapping("/testError")
    public String testError() {
        System.out.println(10 / 0);
        return "success";
    }
}

public interface ServletContainerInitializer {
    public void onStartup(Set<Class<?>> c, ServletContext ctx)
        throws ServletException; 
}

Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface HandlesTypes {
    Class<?>[] value();
}

@HandlesTypes(WebApplicationInitializer.class)
public class SpringServletContainerInitializer implements ServletContainerInitializer