Spring MVC小結(jié)

Spring MVC項(xiàng)目搭建

添加依賴

(省略)

Spring MVC配置類

@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,實(shí)現(xiàn)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注解在類上,表明這個(gè)類為Spring MVC的Controller,并講Web請(qǐng)求映射到注解了@RequestMapping的方法上

  • @RequestMapping
    @RequestMapping是用來(lái)映射Web請(qǐng)求的的方法,可以注解在類上,方法上的@RequestMapping路徑會(huì)繼承類上的路基,并且produces屬性可以設(shè)置請(qǐng)求的媒體類型

  • @ResponseBody
    @ResponseBody可以注解類上也可注解在方法上,支持把返回值放入response體內(nèi),而不是返回一個(gè)頁(yè)面

  • @RequestBody
    @RequestBody注解在參數(shù)前,允許請(qǐng)求的參數(shù)在request體中,而不是直接放在鏈接地址的后面

  • @PathVariable
    @PathVariable用來(lái)接受路勁參數(shù),次注解用在參數(shù)前面,如pathvar/{str},可接受參數(shù)str

  • @RestController
    @RestController是一個(gè)組合注解,是@Controller和@ResponseBody的組合

@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")
    @ResponseBody
    public 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

攔截器配置

  • 攔截器類
  1. 繼承HandlerInterceptorAdapter實(shí)現(xiàn)自定義攔截器
  2. 重寫preHandle方法,請(qǐng)求發(fā)生時(shí)執(zhí)行
  3. 重寫postHandle方法,請(qǐng)求結(jié)束是執(zhí)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("一次請(qǐng)求的時(shí)間為" + handlerTime + "ms");
        request.setAttribute("handlerTime", handlerTime);
    }
}
  • 配置
  1. 配置攔截器的Bean
  2. 重寫addInterceptors(InterceptorRegistry registry)方法,添加攔截器
@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;
    }
    
    //自定義攔截器
    @Bean
    public DemoInterceptor handlerTimeInterceptor(){
        return new DemoInterceptor();
    }

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

@ControllerAdvice

使用@ControllerAdvice注解可以將對(duì)于控制器的全局配置放在一起

  • @ExceptionHandler 用于處理全局處理器中的異常
  • @ModelAttribute 本來(lái)是用于將鍵值對(duì)綁定到Model里,這里用于讓全局的@RequestMapping都能接收到此鍵值對(duì)
//聲明一個(gè)全局通知  此注解包含了 @Component
@ControllerAdvice
public class ExceptionHandlerAdvice {

    //攔截所有的異常 顯示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 都能獲取這個(gè)鍵值對(duì)
    @ModelAttribute
    public void addAttribute(Model mode) {
        mode.addAttribue("msg", "額外信息");
    }
}

文件上傳配置

  • 添加依賴
<!-- 文件上傳 -->
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.2</version>
</dependency>
<!-- 簡(jiǎn)化文件操作 -->
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.4</version>
</dependency>
  • 上傳頁(yè)面
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>文件上傳</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="上傳文件">
    </form>
</div>
</body>
</html>
  • 添加upLoad的ViewController
//集中處理跳轉(zhuǎn)頁(yè)面
@Override
public void addViewControllers(ViewControllerRegistry registry) {
    registry.addViewController("/toUpload").setViewName("/upload");
}
  • 配置MultipartResolver
//配置MultipartResolver,用MultipartFile 接受文件上傳
@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包實(shí)現(xiàn)快讀文件寫入磁盤
            FileUtils.writeByteArrayToFile(new File("e:/upload/" + file.getOriginalFilename()), file.getBytes());
            return "success";
        } catch (IOException e) {
            e.printStackTrace();
            return "fail";
        }
    }
}
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