Apache的FileUpload组件实现文件上传
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 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 action="demo1.jsp" method="post" enctype="multipart/form-data">
Your name:<br>
<input size="15"><br>
File:<br>
<input><br><br>
<input value="Commit">
</form>
</body>
</html>demo1.jsp <%@ page 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"
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 action="demo2.jsp" method="post" enctype="multipart/form-data">
File1:<br>
<input><br>
File2:<br>
<input><br><br>
<input value="Commit">
</form>
</body>
</html>demo2.jsp <%@ page 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 action="demo3.jsp" method="post" enctype="multipart/form-data">
File:<br>
<input><br><br>
<input value="Commit">
</form>
</body>
</html>demo3.jsp <%@ page 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 action="fileupload" method="post" enctype="multipart/form-data">
File:<br>
<input><br><br>
<input 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>