jar依赖：
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>
form 表单的内容：
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>
整个web.xml如下：
<?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");
// }
}
参考链接： http://www.tutorialspoint.com/servlets/servlets-file-uploading.htm
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