springmvc(三)

Spring MVC上传

　　Spring MVC为文件上传提供了直接的支持，这种支持是用即插即用的MultipartResolver实现的。SpringMVC使用Apache Commons FileUpload技术实现了一个MultipartResolver实现类：CommonsMultipartResolver。因此，Spring MVC的文件上传还需要依赖于Apache Commons FileUpload的组件。

步骤：
（1） 在mvc配置文件中加入org.springframework.web.multipart.commons.CommonsMultipartResolver
（2） 上传文件会被转成MultipartFile对象。
（3） 调用对象的transferTo方法将文件写出(方式一：标量接收；方式二：对象接收)

Spring MVC下载

　　文件下载，直接在页面给出一个超链接，该链接href的属性等于要下载文件的文件名，就可以实现文件下载了。但是如果该文件的文件名为中文文件名，在某些早期的浏览器上就会导致下载失败，如果使用最新的Firefox、Opera、Chrome、Safari都可以正常下载文件名为中文的文件了。
Spring MVC提供了一个ResponseEntity类型，可以很方便的定义返回的HttpHeaders和HttpStatus。

注意：
springmvc将http的头信息，状态码等都封装成了对象。
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;

下载的方法是：
ResponseEntity(T body, MultiValueMap<String,String> headers, HttpStatus statusCode)

创建web工程，导包

配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>文件上传下载</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <!-- 设置springmvc前端控制器 -->
  <servlet>
          <servlet-name>springmvc</servlet-name>
          <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <!-- 指定路径解析配置文件 -->
  <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>/WEB-INF/springmvc-config.xml</param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
  </servlet>
  
  <!-- 映射拦截 -->
  <servlet-mapping>
          <servlet-name>springmvc</servlet-name>
          <url-pattern>*.jspx</url-pattern>
  </servlet-mapping>
  
  <!-- 过滤器,过滤所有的请求设置字符编码 -->
  <filter>
          <filter-name>characterEncodingFilter</filter-name>
          <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
          <init-param>
              <param-name>encoding</param-name>
              <param-value>UTF-8</param-value>
          </init-param>
  </filter>
  <filter-mapping>
          <filter-name>characterEncodingFilter</filter-name>
          <url-pattern>/*</url-pattern>
  </filter-mapping> 
</web-app>

配置springmvc-config.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd     
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.2.xsd">
        
    <!-- spring可以自动去扫描base-pack下面的包或者子包下面的java文件，
        如果扫描到有Spring的相关注解的类，则把这些类注册为Spring的bean -->
    <context:component-scan base-package="org.fkit.controller"/>
    
    <mvc:annotation-driven/>
    
    <mvc:default-servlet-handler/>
    
    <!-- 视图解析器  -->
     <bean id="viewResolver"
          class="org.springframework.web.servlet.view.InternalResourceViewResolver"> 
        <!-- 前缀 -->
        <property name="prefix">
            <value>/WEB-INF/content/</value>
        </property>
        <!-- 后缀 -->
        <property name="suffix">
            <value>.jsp</value>
        </property>
    </bean>
    
   <bean id="multipartResolver"  
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">  
        <!-- 上传文件大小上限，单位为字节（10MB） -->
        <property name="maxUploadSize">  
            <value>10485760</value>  
        </property>  
        <!-- 请求的编码格式，必须和jSP的pageEncoding属性一致，以便正确读取表单的内容，默认为ISO-8859-1 -->
        <property name="defaultEncoding">
            <value>UTF-8</value>
        </property>
    </bean>
    
</beans>

index.jsp页面

<%@ 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>登录页面</title>
</head>
<body>

<a href="uploadForm.jspx">文件上传测试</a><br><br>
<a href="registerForm.jspx">用户注册</a><br><br>

</body>
</html>

在org.fkit.controller包下创建

package org.fkit.controller;

import java.io.File;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.io.FileUtils;
import org.fkit.domain.User;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.multipart.MultipartFile;

@Controller//声明该类为控制器
public class FileUploadController {
    
    @RequestMapping(value="/uploadForm.jspx")//映射对应index.jsp的请求
    public String loginForm(){
        //返回uploadForm.jsp页面，前缀和后缀在springmvc-config.xml中配置
        return "uploadForm";
    }
    
    //方式二,使用上传文件封装到对象中
    @RequestMapping(value="/registerForm.jspx")
    public String registerForm(){
        return "registerForm";
    }
    
    //上传文件会自动绑定到MultipartFile中
    @RequestMapping(value="/upload.jspx",method=RequestMethod.POST)
    public String upload(HttpServletRequest request,
            String description,
            MultipartFile file) throws Exception{
        System.out.println(description);
        
        //如果文件不为空，写入上传路径
        if(!file.isEmpty()){
            //上传文件路径
            String path = request.getServletContext().getRealPath("/images");
            System.out.println(path);
            //上传文件名
            String filename = file.getOriginalFilename();
            //将上传文件保存到一个目标文件当中 File.separator表示“/” 反斜杠
            file.transferTo(new File(path+File.separator+filename));
            return "success";
        }else{
            return "error";
        }
    }
    
    //方式二，使用对象接收
    @RequestMapping(value="/register.jspx")
    public String register(HttpServletRequest request,
            User user,
            Model model)throws Exception{
        System.out.println(user.getUsername());
        //如果文件不为空，写入上传路径
        if(!user.getImage().isEmpty()){
            
            String path = request.getServletContext().getRealPath("/images");
            System.out.println(path);
            //上传文件名
            String filename = user.getImage().getOriginalFilename();
            //将上传文件保存到一个目标文件当中
            user.getImage().transferTo(new File(path+File.separator+filename));
            //将用户添加到model
            model.addAttribute("user", user);
            return "userInfo";//文件下载
        }else{
        return "error";
        }
    }
    

Spring Mvc下载
    //<a href="download.jspx?filename=  ">
    @RequestMapping(value="/download.jspx")
    public ResponseEntity<byte[]> download(
            HttpServletRequest request,
            String filename,
            Model model)throws Exception{
        //下载文件路径
        String path = request.getServletContext().getRealPath("/images");
        File file = new File(path+File.separator+filename);
        //下载显示的文件名，解决中文名乱码问题
        String downloadFileName = new String(filename.getBytes("UTF-8"),"iso-8859-1");
        //spring中封装的http头信息对象
        HttpHeaders headers = new HttpHeaders();
        //通知浏览器以attachment(附件下载方式)打开图片
        headers.setContentDispositionFormData("attachment", downloadFileName);
         
        /**
         * response.setContentType("application/octet-stream");   二进制流
          * */
        // application/octet-stream ： 二进制流数据（最常见的文件下载）。
        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        //读取下载文件返回二进制对象
        byte[] body = FileUtils.readFileToByteArray(file);
        
        // 201 HttpStatus.CREATED 请求成功并且服务器创建了新的资源。
        HttpStatus statusCode = HttpStatus.CREATED;
        
        /**
         * new ResponseEntity<byte[]>(下载的字节文件，http头信息，http状态码)
         * */
        return new ResponseEntity<byte[]>(body, headers, statusCode);  
    }
    
}

对应content文件下的页面信息

success.jsp页面

<%@ 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>测试文件上传</title>
</head>
<body>
上传文件成功!
</body>
</html>

error.jsp页面

<%@ 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>测试文件上传</title>
</head>
<body>
上传文件失败!
</body>
</html>

registerForm.jsp页面

<%@ 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>用户注册</title>
</head>
<body>
    <h2>用户注册</h2>
    <form action="register.jspx" enctype="multipart/form-data" method="post">
        <table>
            <tr>
                <td>用户名:</td>
                <td><input type="text" name="username"></td>
            </tr>
            <tr>
                <td>请上传头像:</td>
                <td><input type="file" name="image"></td>
            </tr>
            <tr>
                <td><input type="submit" value="注册"></td>
            </tr>
        </table>
    </form>
</body>
</html>

uploadForm.jsp页面

<%@ 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>文件上传</title>
</head>
<body>
    <h2>文件上传</h2>
    <form action="upload.jspx" enctype="multipart/form-data" method="post">
        <table>
            <tr>
                <td>文件描述:</td>
                <td><input type="text" name="description"></td>
            </tr>
            <tr>
                <td>请选择文件:</td>
                <td><input type="file" name="file"></td>
            </tr>
            <tr>
                <td><input type="submit" value="上传"></td>
            </tr>
        </table>
    </form>
</body>
</html>

userInfo.jsp下载页面

<%@ 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>文件下载</title>
</head>
<body>
<h3>文件下载</h3>
<a href="download.jspx?filename=${requestScope.user.image.originalFilename}">
${requestScope.user.image.originalFilename }
</a>
</body>
</html>