FRAMEWORK/SPRING

Spring MVC download files(02)

적외선 2014. 12. 2. 14:49

The file to be downloaded in this application is SpringProject.zip file which resides in the downloads directory which is relative to the application’s directory.

1. Code of download page

Create index.jsp file under WebContent directory with the following HTML code:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Download Page</title>
</head>
<body>
    <center>
        <h2><a href="/download.do">Click here to download file</a></h2>
    </center>
</body>
</html>

This page simply shows a link “Click here to download file” with URL points to the relative path: download.do. We’ll configure Spring controller class to handle this URL.

2. Code of Spring controller class

Create FileDownloadController.java file under the source package net.codejava.spring with the following code:

package net.codejava.spring;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
 
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
 
@Controller
@RequestMapping("/download.do")
public class FileDownloadController {
     
    /**
     * Size of a byte buffer to read/write file
     */
    private static final int BUFFER_SIZE = 4096;
             
    /**
     * Path of the file to be downloaded, relative to application's directory
     */
    private String filePath = "/downloads/SpringProject.zip";
     
    /**
     * Method for handling file download request from client
     */
    @RequestMapping(method = RequestMethod.GET)
    public void doDownload(HttpServletRequest request,
            HttpServletResponse response) throws IOException {
 
        // get absolute path of the application
        ServletContext context = request.getServletContext();
        String appPath = context.getRealPath("");
        System.out.println("appPath = " + appPath);
 
        // construct the complete absolute path of the file
        String fullPath = appPath + filePath;      
        File downloadFile = new File(fullPath);
        FileInputStream inputStream = new FileInputStream(downloadFile);
         
        // get MIME type of the file
        String mimeType = context.getMimeType(fullPath);
        if (mimeType == null) {
            // set to binary type if MIME mapping not found
            mimeType = "application/octet-stream";
        }
        System.out.println("MIME type: " + mimeType);
 
        // set content attributes for the response
        response.setContentType(mimeType);
        response.setContentLength((int) downloadFile.length());
 
        // set headers for the response
        String headerKey = "Content-Disposition";
        String headerValue = String.format("attachment; filename=\"%s\"",
                downloadFile.getName());
        response.setHeader(headerKey, headerValue);
 
        // get output stream of the response
        OutputStream outStream = response.getOutputStream();
 
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = -1;
 
        // write bytes read from the input stream into the output stream
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outStream.write(buffer, 0, bytesRead);
        }
 
        inputStream.close();
        outStream.close();
 
    }
}

This is a typical Spring controller class which is annotated by Spring MVC annotation types. The method doDownload() will receive requests from the client, read the file on server and send it to the client for downloading. Note that, unlike traditional Spring controller’s methods, the method doDownload()does not return a view name, because our purpose is to send a file to the client. The method exits as soon as the file is completely transferred to the client.

3. Code of Spring configuration file

Create spring-mvc.xml file under WebContent\WEB-INF directory with the following content:

<?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:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">
 
    <context:component-scan base-package="net.codejava.spring" />
 
    <!-- your beans declaration goes here -->
</beans>

This is a deadly simple Spring configuration file which tells the framework to scan the package net.codejava.spring for annotated types (element <context:component-scan />). Of course your application will have some bean definitions, but for the purpose of this application, such configuration is enough to work.

4. Code of web.xml

The Spring dispatcher servlet is configured to handle requests in the web.xml file as follows:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
        http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">
    <display-name>FileDownloadSpringMVC</display-name>
    <servlet>
        <servlet-name>SpringController</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring-mvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
 
    <servlet-mapping>
        <servlet-name>SpringController</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>
</web-app>

5. Required jar files

Add the following jar files into the WebContent\WEB-INF\lib directory:

1. commons-logging-1.1.1.jar
2. spring-beans-3.2.1.RELEASE.jar
3. spring-context-3.2.1.RELEASE.jar
4. spring-core-3.2.1.RELEASE.jar
5. spring-expression-3.2.1.RELEASE.jar
6. spring-web-3.2.1.RELEASE.jar
7. spring-webmvc-3.2.1.RELEASE.jar

The Commons Logging jar files can be downloaded from Apache Commons Logging, other jar files come from Spring framework 3.2.1 RELEASE download.

출처 - http://www.codejava.net/frameworks/spring/spring-mvc-sample-application-for-downloading-files

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