纯jsp servlet 实现 upload file功能-优快云博客

本篇主要是简单的实现jsp servlet 的上传文件的功能，基于servlet 2.5。
[b]jar依赖：[/b]
commons-fileupload/commons-io/servlet-api（commons-fileupload 自动依赖common-io）
pom.xml文件的内容如下：


<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.luchenghao.demo</groupId>
	<artifactId>gridconfig</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<org.springframework.version>4.1.5.RELEASE</org.springframework.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>servlet-api</artifactId>
			<version>2.5</version>
		</dependency>

		<dependency>
			<groupId>commons-fileupload</groupId>
			<artifactId>commons-fileupload</artifactId>
			<version>1.3</version>
		</dependency>

	</dependencies>
</project>

[b]form 表单的内容[/b]：
要点： method必须是post方法，get是不支持文件上传的。
enctype 属性值为：multipart/form-data。
action 的名字可以取了humanable的值就好了。
input的type要设为file，以支持文件类型。
代码如下：


<!DOCTYPE title 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>File Uploading Form</title>
	</head>
	<h3>File Upload:</h3>
	Select a file to upload: <br/>
	<form action="UploadServlet" method="post" enctype="multipart/form-data">
		<input type="file" name="file" size="50" />
		<br />
		<input type="Submit" value="Upload"/>
	</form>
</html>

为了能把上传的文件保存起来，我们配置一个保存的路径c:\temp\data，这个路径必须是真是存在，如果不存在就手动去创建该目录（in web.xml）如下：


<context-param> 
		<description>Location to store uploaded file</description> 
		<param-name>file-upload</param-name> 
		<param-value>
         c:\temp\data\
		</param-value> 
	</context-param>

[b]整个web.xml如下[/b]：


<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">
	<context-param> 
		<description>Location to store uploaded file</description> 
		<param-name>file-upload</param-name> 
		<param-value>
         c:\temp\data\
		</param-value> 
	</context-param>

	<servlet>
		<servlet-name>upload</servlet-name>
		<servlet-class>com.statestreetgx.fcm.core.controller.UploadController</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>upload</servlet-name>
		<url-pattern>/UploadServlet</url-pattern>
	</servlet-mapping>
</web-app>

后台的servlet代码如下：


package com.statestreetgx.fcm.core.controller;

import java.io.File;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * 
 * @author a574539
 */
public class UploadController extends HttpServlet {

    /**
     * serialVersionUID
     */
    private static final long serialVersionUID = -3218211616591116540L;
    private boolean isMultipart;
    private String filePath;
    private int maxFileSize = 50 * 1024;
    private int maxMemSize = 4 * 1024;
    private File file;

    public void init() {
        // Get the file location where it would be stored.
        filePath = getServletContext().getInitParameter("file-upload");
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, java.io.IOException {
        // Check that we have a file upload request
        isMultipart = ServletFileUpload.isMultipartContent(request);
        response.setContentType("text/html");
        java.io.PrintWriter out = response.getWriter();
        if (!isMultipart) {
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet upload</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<p>No file uploaded</p>");
            out.println("</body>");
            out.println("</html>");
            return;
        }
        DiskFileItemFactory factory = new DiskFileItemFactory();
        // maximum size that will be stored in memory
        factory.setSizeThreshold(maxMemSize);
        // Location to save data that is larger than maxMemSize.
        factory.setRepository(new File("c:\\temp"));

        // Create a new file upload handler
        ServletFileUpload upload = new ServletFileUpload(factory);
        // maximum file size to be uploaded.
        upload.setSizeMax(maxFileSize);

        try {
            // Parse the request to get file items.
            List fileItems = upload.parseRequest(request);

            // Process the uploaded file items
            Iterator i = fileItems.iterator();

            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet upload</title>");
            out.println("</head>");
            out.println("<body>");
            while (i.hasNext()) {
                FileItem fi = (FileItem) i.next();
                if (!fi.isFormField()) {
                    // Get the uploaded file parameters
                    String fieldName = fi.getFieldName();
                    String fileName = fi.getName();
                    String contentType = fi.getContentType();
                    boolean isInMemory = fi.isInMemory();
                    long sizeInBytes = fi.getSize();
                    // Write the file
                    if (fileName.lastIndexOf("\\") >= 0) {
                        file = new File(filePath + fileName.substring(fileName.lastIndexOf("\\")));
                    } else {
                        file = new File(filePath + fileName.substring(fileName.lastIndexOf("\\") + 1));
                    }
                    fi.write(file);
                    out.println("Uploaded Filename: " + fileName + "<br>");
                }
            }
            out.println("</body>");
            out.println("</html>");
        } catch (Exception ex) {
            System.out.println(ex);
        }
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, java.io.IOException {

        throw new ServletException("GET method used with " + getClass().getName() + ": POST method required.");
    }

//    @RequestMapping(value = "upload")
//    @ResponseBody
//    public void upload() {
//        System.out.println("hello");
//    }
}