Jsp利用组件上传文件1首先创建一个HTML页面。注意，凡是要上载文件的表单都必须设置enctype属性，且属性的值
Jsp利用组件上传文件
1>首先创建一个HTML页面。注意，凡是要上载文件的表单都必须设置enctype属性，且属性的值必须是multipart/form-data，同时请求方法必须是POST.
<form name="myform" action="fileuploaddemo.jsp"??method="post" enctype="multipart/form-data">
?
2>commons-fileupload-1.1.jar和commons-io-1.1.jar?两个包都要引入，
因为在parseRequest(request)的类有关继承于DiskFileItem类。
3>示例
1．示例1。????DiskFileUpload类会对mulipart类的表单中的所有字段进行处理，不只是file字段。getName（）得到文件名，getString（）得到表单数据内容，isFormField（）可判断是否为普通的表单项。
demo1.html<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>File upload</title>
</head>
<body>
//必须是multipart的表单数据。
<form name="myform" action="demo1.jsp" method="post" enctype="multipart/form-data">
???Your name:<br>
???<input type="text" name="name" size="15"><br>
???File:<br>
???<input type="file" name="myfile"><br><br>
???<input type="submit" name="submit" value="Commit">
</form>
</body>
</html>
demo1.jsp<%@ page language="java" contentType="text/html; charset=GB18030"
?????pageEncoding="GB18030"%>
<%@ page import="org.apache.commons.fileupload.*"%>
<%@ page import="java.util.*"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<%
???boolean isMultipart=FileUpload.isMultipartContent(request);//检查输入请求是否为multipart表单数据。
???if(isMultipart==true){
??????DiskFileUpload upload=new DiskFileUpload();//为该请求创建一个DiskFileUpload对象，通过它来解析请求。执行解析后，所有的表单项目都保存在一个List中。
??????List items=upload.parseRequest(request);
??????Iterator itr=items.iterator();
??????while(itr.hasNext()){
????????????FileItem item=(FileItem)itr.next();
???????????//检查当前项目是普通表单项目还是上传文件。
????????????if(item.isFormField()){//如果是普通表单项目，显示表单内容。
?????????????????String fieldName=item.getFieldName();
?????????????????if(fieldName.equals("name")) //对应demo1.html中type="text" name="name"
?????????????????out.println("the field name is"+ item.getString());//显示表单内容。
?????????????????out.println("<br>");
?????????????}
?????????????else{//如果是上传文件，显示文件名。
???????????????out.println("the upload fielname is"+item.getName());
??????????????out.println("<br>");
????????????}
?????}
}
else{
????out.println("the enctype must be multipart/form-data");
}
%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>File upload</title>
</head>
<body>
</body>
</html>
2．示例2。????上传两个文件到指定的目录。
demo2.html<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>File upload</title>
</head>
<body>
<form name="myform" action="demo2.jsp" method="post" enctype="multipart/form-data">
???File1:<br>
???<input type="file" name="myfile1"><br>
???File2:<br>
???<input type="file" name="myfile2"><br><br>
???<input type="submit" name="submit" value="Commit">
</form>
</body>
</html>
demo2.jsp<%@ page language="java" contentType="text/html; charset=GB18030"
?????pageEncoding="GB18030"%>
<%@ page import="org.apache.commons.fileupload.*"%>
<%@ page import="java.util.*"%>
<%@ page import="java.io.*"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<%String uploadPath="D:\\Dvp\\workspace4Lomboz\\Test4Jsp\\uploadfiles";
??????boolean isMultipart=FileUpload.isMultipartContent(request);
??????if(isMultipart==true){
???????????try{
????????????????DiskFileUpload upload=new DiskFileUpload();
????????????????List items=upload.parseRequest(request);//得到所有的文件
????????????????Iterator itr=items.iterator();
????????????????while(itr.hasNext()){//依次处理每个文件
?????????????????????FileItem item=(FileItem)itr.next();
?????????????????????String fileName=item.getName();//获得文件名，包括路径
?????????????????????if(fileName!=null){
?????????????????????????File fullFile=new File(item.getName());
?????????????????????????File savedFile=new File(uploadPath,fullFile.getName());
?????????????????????????item.write(savedFile);
??????????????????????}
????????????????}
???????????????out.println("upload succeed");
?????????}
?????????catch(Exception e){
?????????????e.printStackTrace();
??????????}
???}
???else{
?????????out.println("the enctype must be multipart/form-data");
???}
%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>File upload</title>
</head>
<body>
</body>
</html>
3．示例3。????上传一个文件到指定的目录，并限定文件大小。
demo3.html<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>File upload</title>
</head>
<body>
<form name="myform" action="demo3.jsp" method="post" enctype="multipart/form-data">
???File:<br>
???<input type="file" name="myfile"><br><br>
???<input type="submit" name="submit" value="Commit">
</form>
</body>
</html>
demo3.jsp<%@ page language="java" contentType="text/html; charset=GB18030"
?????pageEncoding="GB18030"%>
<%@ page import="org.apache.commons.fileupload.*"%>
<%@ page import="java.util.*"%>
<%@ page import="java.io.*"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<%File uploadPath=new File("D:\\upload");//上传文件目录
???????if(!uploadPath.exists()){
????????????uploadPath.mkdirs();
????????}
????????String tempPath="d:\\upload\\temp\"; // 临时文件目录
????????File tempPathFile=new File("d:\\upload\\temp");
????????if(!tempPathFile.exists()){
????????????tempPathFile.mkdirs();
???????}
???????try{
???????????DiskFileUpload fu=new DiskFileUpload();
???????????fu.setSizeMax(4194304); // 设置最大文件尺寸，这里是4MB
???????????fu.setSizeThreshold(4096); // 设置缓冲区大小，这里是4kb
???????????fu.setRepositoryPath(tempPath);//设置缓冲区目录
???????????List fileItems=fu.parseRequest(request);
???????????Iterator i=fileItems.iterator();
???????????while(i.hasNext()){
??????????????FileItem fi=(FileItem)i.next();
??????????????String fileName=fi.getName();
??????????????if(fileName!=null){
???????????????????File fullFile=new File(fi.getName());
???????????????????File savedFile=new File(uploadPath,fullFile.getName());
???????????????????fi.write(savedFile);
??????????????}
?????????}
?????????out.println("upload succeed");
?????}
?????catch(Exception e){
?????????e.printStackTrace();
?????}
%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>File upload</title>
</head>
<body>
</body>
</html>
4．示例4。????利用Servlet来实现文件上传。
Upload.javapackage com.zj.sample;import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import org.apache.commons.fileupload.*;public class Upload extends HttpServlet {
????private String uploadPath="D:\\upload\"; // 上传文件的目录
????private String tempPath= "d:\\upload\\temp\"; // 临时文件目录
????public void doPost(HttpServletRequest request, HttpServletResponse response)
??????throws IOException, ServletException {
???????try {
????????????DiskFileUpload fu = new DiskFileUpload();
????????????fu.setSizeMax(4194304);
????????????fu.setSizeThreshold(4096);
????????????fu.setRepositoryPath(tempPath);
????????????List fileItems = fu.parseRequest(request);
????????????Iterator i = fileItems.iterator();
????????????while (i.hasNext()) {
?????????????????FileItem fi=(FileItem)i.next();
?????????????????String fileName=fi.getName();
?????????????????if(fileName!=null){
??????????????????????File fullFile=new File(fi.getName());
??????????????????????File savedFile=new File(uploadPath,fullFile.getName());
??????????????????????fi.write(savedFile);
?????????????????}
????????????}
????????????System.out.println("upload succeed");
????????}
????????catch (Exception e) {
?????????????// 可以跳转出错页面
?????????????e.printStackTrace();
????????}
???}public void init() throws ServletException {
???????File uploadPath = new File("D:\\upload");
???????if (!uploadPath.exists()) {
????????????uploadPath.mkdirs();
???????}
???????File tempPathFile = new File("d:\\upload\\temp");
???????if (!tempPathFile.exists()) {
???????????tempPathFile.mkdirs();
???????}
????}
}
demo4.html<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>File upload</title>
</head>
<body>
// action="fileupload"对应web.xml中<servlet-mapping>中<url-pattern>的设置。
<form name="myform" action="fileupload" method="post" enctype="multipart/form-data">
???File:<br>
???<input type="file" name="myfile"><br><br>
???<input type="submit" name="submit" value="Commit">
</form>
</body>
</html>
web.xml????<servlet>
???????<servlet-name>Upload</servlet-name>
???????<servlet-class>com.zj.sample.Upload</servlet-class>
?????</servlet>????<servlet-mapping>
??????<servlet-name>Upload</servlet-name>
??????<url-pattern>/fileupload</url-pattern>
