解决jspsmartupload上传文件时大小受限制问题

最新推荐文章于 2023-07-29 15:19:10 发布

iteye_4515

最新推荐文章于 2023-07-29 15:19:10 发布

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文章标签： java web.xml

本文介绍了一个使用FileUpload组件实现的大文件上传解决方案。该方案详细展示了如何通过Java Servlet处理大文件的上传过程，包括限制文件大小、指定允许上传的文件类型等。

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用的fileupload组件实现的大文件上传，现在分享一下。
1.FileUploadServlet.java文件，实现上传处理
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.DecimalFormat;
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.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class FileUploadServlet extends HttpServlet
{
private static final long serialVersionUID = 1L;

public FileUploadServlet()
{
super();
}

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

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

final long MAX_SIZE = 2048 * 1024 * 1024;// 设置上传文件最大值为2G，可以改为更大
// 允许上传的文件格式的列表
final String[] allowedExt = new String[]
{ "exe","jpg","DT" };
response.setContentType("text/html");
// 设置字符编码为UTF-8, 统一编码，处理出现乱码问题
response.setCharacterEncoding("UTF-8");

// 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload
DiskFileItemFactory dfif = new DiskFileItemFactory();

// 用以上工厂实例化上传组件
ServletFileUpload sfu = new ServletFileUpload(dfif);
// 设置最大上传大小
sfu.setSizeMax(MAX_SIZE);

PrintWriter out = response.getWriter();
// 从request得到所有上传域的列表
List fileList = null;
try
{
fileList = sfu.parseRequest(request);
} catch (FileUploadException e)
{// 处理文件尺寸过大异常
if (e instanceof SizeLimitExceededException)
{
out.println("文件尺寸超过规定大小:" + MAX_SIZE + "字节 <p />");
out.println(" <a href=/"FileUpload.html/" target=/"_top/">返回 </a>");
return;
}
e.printStackTrace();
}
// 没有文件上传
if (fileList == null || fileList.size() == 0)
{
out.println("请选择上传文件 <p />");
out.println(" <a href=/"FileUpload.html/" target=/"_top/">返回 </a>");
return;
}
//文件大小取两位小数
DecimalFormat digit=new DecimalFormat("0.00");
// 得到所有上传的文件
Iterator fileItr = fileList.iterator();
// 循环处理所有文件
while (fileItr.hasNext())
{
FileItem fileItem = null;
String path = null;
double size = 0;
// 得到当前文件
fileItem = (FileItem) fileItr.next();
// 忽略简单form字段而不是上传域的文件域( <input type="text" />等)
if (fileItem == null || fileItem.isFormField())
{
continue;
}

// 得到文件的大小，K为单位并保留两位小数
size = (double)fileItem.getSize()/1024;
if ("".equals(path) || size == 0)
{
out.println(" <html> <head> <title>上传处理界面 </title> </head>");
out.println("请选择上传文件 <p />");
out.println(" <a href=/"FileUpload.html/" target=/"_top/">返回 </a>");
out.println(" </html>");
return;
}
// 得到文件的完整路径
path = fileItem.getName();

// 得到去除路径的文件名
String t_name = path.substring(path.lastIndexOf("//") + 1);
// 得到文件的扩展名(无扩展名时将得到全名)
String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
// 拒绝接受规定文件格式之外的文件类型
int allowFlag = 0;
int allowedExtCount = allowedExt.length;
for (; allowFlag < allowedExtCount; allowFlag++)
{
if (allowedExt[allowFlag].equals(t_ext))
break;
}
if (allowFlag == allowedExtCount)
{
out.println(" <html> <head> <title>上传处理界面 </title> </head>");
out.println("请上传以下类型的文件 <p />");
for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)
out.println("*." + allowedExt[allowFlag]
+ "   ");
out.println(" <p /> <a href=/"FileUpload.html/" target=/"_top/">返回 </a>");
out.println(" </html>");
return;
}
try
{
// 保存文件到服务器根目录下
fileItem.write(new File("//"+t_name));
System.out.println(t_name);
out.println(" <html> <head> <title>上传处理界面 </title> </head>");
out.println("文件名称为：" + path + " <br>");
out.println("文件上传成功，已保存为: " + t_name
+ " <br>"+" 文件大小: " + digit.format(size) + "K <p />");
out.println(" <a href=/"FileUpload.html/" target=/"_top/">继续上传 </a>");
out.println(" </html>");
} catch (Exception e)
{
e.printStackTrace();
}
}
}
}
2.FileUpload.html文件，实现上传页面。
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>文件上传 </title>
</head>
<body>
<form action="FileUploadServlet" method="post"
enctype="multipart/form-data">
<input type="file" size="30"
name="file01" /> <br>
<pre> <input name="submit" type="submit" value="上传"> <input name="reset" type="reset" value="重置">
</pre>
</form>
</body>
</html>

3.配置web.xml文件中的的servlet和过滤器，过滤器解决上传文件名为中文时出现乱码。
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
<display-name>FileUploadServlet </display-name>
<servlet-name>FileUploadServlet </servlet-name>
<servlet-class>FileUploadServlet </servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>FileUploadServlet </servlet-name>
<url-pattern>/FileUploadServlet </url-pattern>
</servlet-mapping>

<filter>
<filter-name>setCharacterEncoding </filter-name>
<filter-class>com.xulu.EncodingChange </filter-class>
<init-param>
<param-name>ignore </param-name>
<param-value>true </param-value>
</init-param>

<init-param>
<param-name>encoding </param-name>
<param-value>UTF-8 </param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>setCharacterEncoding </filter-name>
<url-pattern>/* </url-pattern>
</filter-mapping>
<welcome-file-list>
<welcome-file>index.jsp </welcome-file>
</welcome-file-list>
<login-config>
<auth-method>BASIC </auth-method>
</login-config>
</web-app>
4.过滤器文件EncodingChange.java和setCharacterEncoding.java分别如下，并且在根目录下的WEB-INF/classes/com/xulu文件夹中放入他它们编译生成的.class文件
package com.xulu;

import java.io.IOException;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class EncodingChange implements Filter
{
protected String encoding = null;
protected FilterConfig filterconfig = null;
protected boolean ignore = true;

public void destroy()
{
this.encoding = null;
this.filterconfig = null;
}

public void doFilter(ServletRequest requests, ServletResponse responses,
FilterChain chain) throws IOException, ServletException
{
// TODO Auto-generated method stub
HttpServletRequest request = (HttpServletRequest) requests;
HttpServletResponse response = (HttpServletResponse) responses;
if (ignore || request.getCharacterEncoding() == null)
{
String encoding = selectEncoding(request);
if (encoding != null)
{
request.setCharacterEncoding(encoding);
request.getSession().getAttribute("Login_Student");
request.getSession().getAttribute("Login_Teacher");
request.getSession().getAttribute("Login_Admin");
}
}
chain.doFilter(request, response);
}

public void init(FilterConfig filterconfig) throws ServletException
{
// TODO Auto-generated method stub
this.filterconfig = filterconfig;
this.encoding = filterconfig.getInitParameter("encoding");
String value = filterconfig.getInitParameter("ignore");
if (value == null)
{
this.ignore = true;
} else if (value.equalsIgnoreCase("true"))
{
this.ignore = true;
} else if (value.equalsIgnoreCase("yes"))
{
this.ignore = true;
} else
{
this.ignore = false;
}
}

public String selectEncoding(ServletRequest request)
{
return this.encoding;
}
}
和
package com.xulu;

import java.io.IOException;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class setCharacterEncoding implements Filter{
protected String encoding=null;
protected FilterConfig filterconfig=null;
protected boolean ignore=true;

public void destroy() {
this.encoding=null;
this.filterconfig=null;
}

public void doFilter(ServletRequest requests, ServletResponse responses,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
HttpServletRequest request=(HttpServletRequest)requests;
HttpServletResponse response=(HttpServletResponse)responses;
if(ignore||request.getCharacterEncoding()==null){
String encoding=selectEncoding(request);
if(encoding!=null){
request.setCharacterEncoding(encoding);
request.getSession().getAttribute("Login_Student");
request.getSession().getAttribute("Login_Teacher");
request.getSession().getAttribute("Login_Admin");
}
}
chain.doFilter(request, response);
}

public void init(FilterConfig filterconfig) throws ServletException {
// TODO Auto-generated method stub
this.filterconfig = filterconfig;
this.encoding = filterconfig.getInitParameter("encoding");
String value = filterconfig.getInitParameter("ignore");
if (value == null) {
this.ignore = true;
} else if (value.equalsIgnoreCase("true")) {
this.ignore = true;
} else if (value.equalsIgnoreCase("yes")) {
this.ignore = true;
} else {
this.ignore = false;
}
}
public String selectEncoding(ServletRequest request){
return this.encoding;
}
}

5.在浏览器中就可以实现页面的上传了，访问http://localhost:8080/**/FileUpload.html就可以了。其中**为自己命名的web文件夹，如DoUpload，上面的文件都在该目录里，且DoUpload文件夹放在Tomcat的webapp文件夹下。
补充：在上述所有步骤之前需引入三个.jar文件，分别为commons-fileupload-1.2.1.jar，commons-io-1.4.jar和servlet-api.jar网上可以下载到