SpringMVC小结

Spring MVC项目搭建

添加依赖

(省略)

Spring MVC配置类

@Configuration
@EnableWebMvc
@ComponentScan("com.sjx.springmvc")
public class MyMvcConfig extends WebMvcConfigurerAdapter{
    @Bean
    public InternalResourceViewResolver viewResolver(){
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("/WEB-INF/classes/views/");
        viewResolver.setSuffix(".jsp");
        viewResolver.setViewClass(JstlView.class);
        return viewResolver;
    }
}

Web配置,实现WebApplicationInitializer接口代替web.xml文件

public class WebInitializer implements WebApplicationInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(MyMvcConfig.class);
        ctx.setServletContext(servletContext);

        Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(ctx));
        servlet.addMapping("/");
        servlet.setLoadOnStartup(1);
    }
}

Spring MVC的常用注解

• @controller
  @controller注解在类上,表明这个类为Spring MVC的Controller,并讲Web请求映射到注解了@RequestMapping的方法上

• @RequestMapping
  @RequestMapping是用来映射Web请求的的方法,可以注解在类上,方法上的@RequestMapping路径会继承类上的路基,并且produces属性可以设置请求的媒体类型

• @ResponseBody
  @ResponseBody可以注解类上也可注解在方法上,支持把返回值放入response体内,而不是返回一个页面

• @RequestBody
  @RequestBody注解在参数前,允许请求的参数在request体中,而不是直接放在链接地址的后面

• @PathVariable
  @PathVariable用来接受路劲参数,次注解用在参数前面,如pathvar/{str},可接受参数str

• @RestController
  @RestController是一个组合注解,是@Controller和@ResponseBody的组合

@Controller
@RequestMapping("/anno")
public class DemoAnnoController {

    @RequestMapping(produces = "text/plain;charset=UTF-8")
    public @ResponseBody String index(HttpServletRequest request) {
        return "url" + request.getRequestURI() + "can access";
    }

    // http://localhost:8080/springmvc1/anno/pathvar/sjx@RequestMapping(value = "pathvar/{str}", produces = "text/plain;charset=UTF-8")
    public @ResponseBody String demoPathVar(@PathVariable String str, HttpServletRequest request) {
        return "url" + request.getRequestURI() + " can access str:" + str;
    }

    // http://localhost:8080/springmvc1/anno/requestParam?id=25@RequestMapping(value = "/requestParam", produces = "text/plain;charset=UTF-8")
    public @ResponseBody String passRequestParam(Long id, HttpServletRequest request) {
        return "url" + request.getRequestURI() + " can access id:" + id;
    }

    @RequestMapping(value = "/obj", produces = "application/json;charset=UTF-8")
    @ResponseBodypublic String passObj(DemoObj obj, HttpServletRequest request) {
        return "url" + request.getRequestURI() + " can access, obj id:" + obj.getId() + "  obj name:" + obj.getName();
    }

    @RequestMapping(value = { "/name1", "/name2" }, produces = "text/plain;charset=UTF-8")
    public @ResponseBody String remove(HttpServletRequest request) {
        return "url: " + request.getRequestURL() + " can access";
    }
}

Spring MVC的基本配置

拦截器配置

• 拦截器类
  1. 继承HandlerInterceptorAdapter实现自定义拦截器
  2. 重写preHandle方法,请求发生时执行
  3. 重写postHandle方法,请求结束是执行

public class DemoInterceptor extends HandlerInterceptorAdapter {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        long startTime = System.currentTimeMillis();
        request.setAttribute("startTime", startTime);
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        Long startTime = (Long) request.getAttribute("startTime");
        Long currentTime = System.currentTimeMillis();
        long handlerTime = currentTime - startTime;
        System.out.println("一次请求的时间为" + handlerTime + "ms");
        request.setAttribute("handlerTime", handlerTime);
    }
}

• 配置
  1. 配置拦截器的Bean
  2. 重写addInterceptors(InterceptorRegistry registry)方法,添加拦截器

@Configuration
@EnableWebMvc
@ComponentScan("com.sjx.springmvc")
public class MyMvcConfig extends WebMvcConfigurerAdapter{
    @Bean
    public InternalResourceViewResolver viewResolver(){
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("/WEB-INF/classes/views/");
        viewResolver.setSuffix(".jsp");
        viewResolver.setViewClass(JstlView.class);
        return viewResolver;
    }

    //自定义拦截器
    @Bean
    public DemoInterceptor handlerTimeInterceptor(){
        return new DemoInterceptor();
    }

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

@ControllerAdvice

使用@ControllerAdvice注解可以将对于控制器的全局配置放在一起

• @ExceptionHandler 用于处理全局处理器中的异常
• @ModelAttribute 本来是用于将键值对绑定到Model里,这里用于让全局的@RequestMapping都能接收到此键值对

//声明一个全局通知  此注解包含了
@Component
@ControllerAdvice
public class ExceptionHandlerAdvice {

    //拦截所有的异常 显示error界面@ExceptionHandler(value = Exception.class)
    public ModelAndView exception(Exception exception, WebRequest request) {
        ModelAndView view = new ModelAndView("error");// error界面
        view.addObject("errorMessage", exception.getMessage());
        return view;
    }

    //所有用@RequestMapping注解的方法 都能获取这个键值对
    @ModelAttribute
    public void addAttribute(Model mode) {
        mode.addAttribue("msg", "额外信息");
    }
}

文件上传配置

• 添加依赖

<dependency>
  <groupId>commons-fileuploadgroupId>
  <artifactId>commons-fileuploadartifactId>
  <version>1.2version>
dependency>

<dependency>
  <groupId>commons-iogroupId>
  <artifactId>commons-ioartifactId>
  <version>2.4version>
dependency>

• 上传页面

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%>

<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  <title>文件上传title>
head>
<body>
  <div class="upload">
  <form action="upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file"><br><input type="submit" value="上传文件">
  form>
  div>
body>
html>

• 添加upLoad的ViewController

//集中处理跳转页面
@Override
public void addViewControllers(ViewControllerRegistry registry) {
    registry.addViewController("/toUpload").setViewName("/upload");
}

• 配置MultipartResolver

//配置MultipartResolver,用MultipartFile 接受文件上传
@Bean
public MultipartResolver multipartResolver(){
    CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
    multipartResolver.setMaxUploadSize(1000000);
    return multipartResolver;
}

• 控制器

@Controller
public class UploadController {
    @RequestMapping(value = "upload", method = RequestMethod.POST)
    public @ResponseBody String upload(MultipartFile file) {
        try {
            // 使用 commons-io包实现快读文件写入磁盘
            FileUtils.writeByteArrayToFile(new File("e:/upload/" + file.getOriginalFilename()), file.getBytes());
            return "success";
        } catch (IOException e) {
            e.printStackTrace();
            return "fail";
        }
    }
}