SpringMVC-入门

作者: Dane_404 | 来源:发表于2019-09-25 14:47 被阅读0次

Hello SpringMVC

引用

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
    <scope>provided</scope>
</dependency>

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.1.8.RELEASE</version>
</dependency>

HelloController:写类实现Controller，重写handleRequest

public class HelloController implements Controller {


    @Override
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest,
                                      HttpServletResponse httpServletResponse) throws Exception {


        ModelAndView modelAndView = new ModelAndView();
        //相当于setAttribute
        modelAndView.addObject("name","dane");
        //返回的jsp界面
        modelAndView.setViewName("/index");
        return modelAndView;
    }
}

spring.xml中配置

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean name="/hello" class="com.dane.springmvc.controller.HomeController"/>

</beans>

jsp页面

<%@ page contentType="text/html;charset=utf-8" language="java"
         isELIgnored="false" %>
<html>
<body>
<h2>Hello World! ${name}</h2>
</body>
</html>

编写web.xml

<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:spring.xml</param-value>
    </init-param>
</servlet>

<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

如果jsp放在WEB-INF里，需要在spring.xml中配置，添加了后缀suffix，ModelAndView setViewName就不需要xxx.jsp了，xxx即可：

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean name="/hello" class="com.dane.springmvc.controller.HelloController"/>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsps/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
</beans>

SpringMVC注解形式开发

使用@Controller和 @RequestMapping

@Controller
public class HelloController {

    @RequestMapping("test")
    public ModelAndView test1(){
        ModelAndView modelAndView = new ModelAndView();
        //相当于setAttribute
        modelAndView.addObject("name","dane");
        //返回的jsp界面
        modelAndView.setViewName("index");
        return modelAndView;
    }

}

编写配置文件：

<context:component-scan base-package="com.dane.springmvc.controller"/>
<mvc:annotation-driven/>

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/jsps/"></property>
    <property name="suffix" value=".jsp"></property>
    <property name="order" value="10"></property>
</bean>

@RequestMapping可以用于类上，例如：这样访问路径就是.../test/test1

@Controller
@RequestMapping(value = "/test", method = RequestMethod.GET)
public class HelloController {

    @RequestMapping("/test1")
    public ModelAndView test1(){
        ModelAndView modelAndView = new ModelAndView();
        //相当于setAttribute
        modelAndView.addObject("name","dane");
        //返回的jsp界面
        modelAndView.setViewName("index");
        return modelAndView;
    }

}

@ModelAttribute

@ModelAttribute注解的方法将在这个Controller每次处理请求前被调用，可以用于权限控制等。

@ModelAttribute
public  void isLogin(HttpSession session){
        
}

Controller返回类型

string类型，表示返回某个jsp页面

@Controller
@RequestMapping("/user")
public class UserController {


    @RequestMapping("/tologin")
    public String login() {
        
        return "login";
    }
}

也可以进行重定向和转发处理，重定向：redirect:login，转发：forward:login

json类型

引入jackson

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.9.9.3</version>
</dependency>

使用@ResponseBody

public class JsonResult<T> {

    private int errorCode;

    private  String message;

    private T data;
}

@CrossOrigin  //解决跨越问题
@Controller
@RequestMapping("/user")
public class UserController {

    @Autowired
    UserService userService;

    @RequestMapping(value = "/login",method = RequestMethod.POST)
    @ResponseBody
    public JsonResult login(@RequestBody User user) throws Exception {

        JsonResult jsonResult = userService.login(user);

        return jsonResult;

    }  
}

使用@ExceptionHandler统一处理异常

@RestControllerAdvice
public class ExceptionHandler {

    private static final Logger log = LoggerFactory.getLogger(SSMExceptionHandler.class);

    @ExceptionHandler(BaseException.class)
    public JsonResult unknownException(BaseException e) {

        JsonResult jsonResult=new JsonResult();
        jsonResult.setErrorCode(e.getErrorCode());
        jsonResult.setMessage(e.getMessage());
        return jsonResult;
    }
}

Controller接收请求参数

通过形式参数接收

请求上来的参数要和行参完全相同：

@RequestMapping("/login")
public String login(String account,String password) {

    if("test".equals(account) && "123456".equals(password)){
        return "main";
    }

    return "login";
}

其中，形参可以添加@RequestParam，没有加和有加的区别是：通过@RequestParam接收的请求参数，若参数名错误时，会报404错误，没有使用@RequestParam，则不会报404。

@RequestMapping("/login")
public String login(@RequestParam String account,@RequestParam String password) {

    if("test".equals(account) && "123456".equals(password)){
        return "main";
    }

    return "login";
}

通过bean参数接收

请求上来的参数要和bean的属性名完全相同：

public class User{
    private String account;
    private String password;
}

@RequestMapping("/login")
public String login(User user) {

    if("test".equals(user.account) && "123456".equals(user.password)){
        return "main";
    }

    return "login";
}

通过@PathVariable接收URL中的请求参数

注意必须加method属性

@RequestMapping(value = "/register/{account}/{password}",method = RequestMethod.GET)
public String register(@PathVariable String account, @PathVariable String password) {

    if("test".equals(account) && "123456".equals(password)){
        return "login";
    }

    return "register";
}

拦截器

SpringMVC定义拦截器有两种方式，一种是实现HandlerInterceptor，另一种是实现WebRequestInterceptor。

实现HandlerInterceptor

public class TestInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) 
            throws Exception {
        
        //该方法在Controller的处理请求方法前执行，其返回值表示是否中断后续操作
        //true表示继续向下执行，false表示中断后续操作
        
        return true;
    }


    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response,
                           Object handler, ModelAndView modelAndView) 
            throws Exception {
        
        //该方法在Controller的处理请求方法之后，解析视图之前执行，可以通过此方法对请求域中
        //的模型和视图进行修改
        
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, 
                                Object handler, Exception ex) 
            throws Exception {

        //该方法在Controller的处理请求方法之后，解析视图之后执行
        
    }
}

配置拦截器：

<mvc:interceptors>
    <!--全局拦截器-->
    <bean class="com.dane.springmvc.interceptor.TestInterceptor"/>

    <!--单独配置特定的拦截器-->
    <mvc:interceptor>
        <!--拦截的路径 /**表示所有-->
        <mvc:mapping path="/**"/>
        <!--不拦截的路径 /**表示所有-->
        <mvc:exclude-mapping path="/"/>
        <bean class="com.dane.springmvc.interceptor.TestInterceptor"/>
    </mvc:interceptor>
</mvc:interceptors>

国际化

Java的国际化

在resource下新建xxxx_zh_CN.properties，中文要转成Unicode:

hello=hello
hi=hi,{0}

然后可以这样测试：

//获取系统默认的国家语言环境
Locale locale = Locale.getDefault();

ResourceBundle resourceBundle 
  = ResourceBundle.getBundle("messageResource",locale);

System.out.println(resourceBundle.getString("hello"));

String hi = resourceBundle.getString("hi");
hi = MessageFormat.format(hi,"Dane");
System.out.println(hi);

输出：

hello
hi,Dane

SpringMVC国际化

配置资源路径

<bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
    <property name="basename" value="message.messageResource"/>
</bean>

语言选择

AcceptHeaderLocaleResolver
根据浏览器的Http Header中的accept-language域设定的语言。

<bean id="localResolver" class="org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver">
    <property name="defaultLocale" value="zh_CN"/>
</bean>

SessionLocaleResolver和CookieLocaleResolver
SessionLocaleResolver根据用户每次会话过程中的语言设定。
CookieLocaleResolver根据Cookie判断用户的语言。

<bean id="localResolver" class="org.springframework.web.servlet.i18n.SessionLocaleResolver">
    <property name="defaultLocale" value="zh_CN"/>
</bean>
<!--<bean id="localResolver" class="org.springframework.web.servlet.i18n.CookieLocaleResolver">-->
    <!--<property name="defaultLocale" value="zh_CN"/>-->
<!--</bean>-->
<!--SessionLocaleResolver 和 CookieLocaleResolver 必须配-->
<mvc:interceptors>
   <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor"/>
</mvc:interceptors>

文件上传、下载

上传

引入jar

<dependency>
  <groupId>commons-fileupload</groupId>
  <artifactId>commons-fileupload</artifactId>
  <version>1.4</version>
</dependency>

配置文件

其中，p:uploadTempDir="file:temp"是resources下的temp目录

<bean id="multipartResolver"
  class="org.springframework.web.multipart.commons.CommonsMultipartResolver"
  p:defaultEncoding="UTF-8" p:maxUploadSize="5400000" p:uploadTempDir="file:temp"/>

最后Controller

@CrossOrigin
@Controller
public class FileController {
    
    @RequestMapping(value = "/onefile",method = RequestMethod.POST)
    @ResponseBody
    public JsonResult onefile(UploadFile file, HttpServletRequest request) throws Exception {

        JsonResult jsonResult = new JsonResult();

        String realPath = request.getServletContext().getRealPath("uploadfils");
        String filename = file.getMyFile().getOriginalFilename();
        File targetFile = new File(realPath,filename);
        if (!targetFile.exists()){
            targetFile.mkdirs();
        }

        file.getMyFile().transferTo(targetFile);
        jsonResult.setErrorCode(0);

        return jsonResult;

    }
}

下载

 @RequestMapping(value = "/down",method = RequestMethod.GET)
    public String down(String filename,  HttpServletRequest request,
                       HttpServletResponse response) throws Exception {

        String realPath = request.getServletContext().getRealPath("uploadfils");
        response.setHeader("Content-Type","application/x-msdownload");
        response.setHeader("Content-Disposition","attachment;filename="+filename);

        FileInputStream in = new FileInputStream(realPath + "/" + filename);
        ServletOutputStream out = response.getOutputStream();
        out.flush();
        int read = 0;
        byte[] b = new byte[1024];
        while (in!=null && (read = in.read(b)) != -1){
            out.write(b,0,read);
        }
        out.flush();
        in.close();
        out.close();

        return  null;

    }