文件上传总结

    这两天想分析一下文件上传的源码，先写一下FileUpload的最基本的使用方法。 主要是给自己做一个总结，高手就不要看了，过两天我会分析FileUpload的源码。

import java.io.IOException;
import java.io.PrintWriter;
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.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * Servlet implementation class UploadServlet
 */
public class UploadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public UploadServlet() {
		super();
	}

	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		process(request, response);
	}

	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		process(request, response);
	}

	@SuppressWarnings("unchecked")
	protected void process(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		response.setContentType("text/html;charset=UTF-8;");
		boolean isMutilpart = ServletFileUpload.isMultipartContent(request);
		if (!isMutilpart) {
			throw new IllegalArgumentException("只能为: multipart/form-data 类型");
		}

		DiskFileItemFactory factory = new DiskFileItemFactory();

		ServletFileUpload fileUpload = new ServletFileUpload(factory);

		fileUpload.setFileSizeMax(1024 * 1024 * 200);
		fileUpload.setHeaderEncoding("UTF-8");

		List<FileItem> fileItems = null;
		try {
			fileItems = fileUpload.parseRequest(request);
		} catch (FileUploadException e) {
			e.printStackTrace();
		}

		StringBuffer buffer = new StringBuffer();

		Iterator<FileItem> iter = fileItems.iterator();
		while (iter.hasNext()) {
			FileItem fileItem = iter.next();
			if (fileItem.isFormField()) {
				processFormField(fileItem, buffer);
			} else {
				processFileField(fileItem, buffer);
			}
		}

		PrintWriter writer = response.getWriter();
		writer.write(buffer.toString());
		writer.flush();
		writer.close();

	}

	private void processFormField(FileItem fileItem, StringBuffer buffer) {
		String name = fileItem.getFieldName();
		String value = fileItem.getString();
		String output = "Name:" + name + " Value: " + value;
		buffer.append(output + "</br>");
		System.out.println(output);
	}

	private void processFileField(FileItem fileItem, StringBuffer buffer) {
		String fieldName = fileItem.getFieldName();
		String fileName = fileItem.getName();
		String contentType = fileItem.getContentType();
		long size = fileItem.getSize();

		boolean isInMemory = fileItem.isInMemory();
		String output = "Name:" + fileName + " Fielname: " + fieldName
				+ " ContentType: " + contentType + " size " + size
				+ " InMemory: " + isInMemory + "";

		buffer.append(output + "</br>");

		System.out.println(output);
	}

}

<?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_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>fileupload</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>UploadServlet</display-name>
    <servlet-name>UploadServlet</servlet-name>
    <servlet-class>UploadServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>UploadServlet</servlet-name>
    <url-pattern>/servlet/uploadServlet</url-pattern>
  </servlet-mapping>
</web-app>