Servlet中配合common-fileupload.jar和common-io.jar进行文件上传

common-fileupload.jar和common-io.jar是apache组织下文件上传的开发包，有了这两个jar包，文件上传将变得方便很多。

①上传文件的界面

文件上传. <br>
<form action="FileUpload"  method="post" enctype="multipart/form-data">
userName:<input type="text" name="userName" /><br/>
file1:<input type="file" name="myfile1"/><br/>
file2:<input type="file" name="myfile2"/><br/>
<input type="submit" name="上传">
</form>

②上传处理的servlet，首先需要在web.xml中配置

<servlet>
<servlet-name>FileUpload</servlet-name>
<servlet-class>edu.njcit.upload.FileUpload</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>FileUpload</servlet-name>
<url-pattern>/FileUpload</url-pattern>
</servlet-mapping>

③接下来是处理servlet

package edu.njcit.upload;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.*;
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;

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

public void destroy() {
}

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

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
DiskFileItemFactory factory = new DiskFileItemFactory();
// 得到WEB-ROOT下某个文件夹的实际的，绝对的路径
String path = request.getRealPath("/fileUpload");
// 当文件大于默认的10K时，文件将放到该仓库临时存储
factory.setRepository(new File(path));
// 修改默认的10K为1M大小
factory.setSizeThreshold(1024 * 1024);// 1M
ServletFileUpload upload = new ServletFileUpload(factory);
try {
List<FileItem> list = upload.parseRequest(request);
// 遍历
for (FileItem item : list) {
String name = "";
// 1、当是简单的文本域时
if (item.isFormField()) {
name = item.getFieldName();// userName
// 编码格式转换
name = new String(name.getBytes("gbk"), "UTF-8");
String inputValue = item.getString("UTF-8");
System.out.println(name + "=" + inputValue);
request.setAttribute(name, inputValue);
} else {
// 2、是文件
// 获取文件不带路径的名字，注意opera浏览器会有路径信息
name = item.getFieldName();
name = new String(name.getBytes("gbk"), "UTF-8");
String value = item.getName();
// 解决opera浏览器问题
int start = value.lastIndexOf("\\");
String fileName = value.substring(start + 1);
fileName = new String(fileName.getBytes("gbk"), "UTF-8");
System.out.println("fileName:" + fileName);
request.setAttribute(name, fileName);
// 写文件
item.write(new File(path, fileName));

/**
// 手动写磁盘start
OutputStream out = new FileOutputStream(new File(path, fileName));
InputStream in = item.getInputStream();
byte buffer[] = new byte[1024];
int lenght = 0;
while ((lenght = in.read(buffer)) != -1) {
out.write(buffer, 0, lenght);
}
out.close();
in.close();
// 手动写磁盘end
*/
}
}

} catch (Exception e) {
e.printStackTrace();
}
// /WEB-INF/page/fileUploadResult.jsp去掉WEB-INF前面的/也是可以的
request.getRequestDispatcher("/WEB-INF/page/fileUploadResult.jsp")
.forward(request, response);
}

public void init() throws ServletException {
}

}

④后台写磁盘结束后，将跳转到fileUploadResult.jsp，如下：

上传结果： <br>
userName:${requestScope.userName }
<br/>
file1:${requestScope.myfile1}
<br/>
file2:${requestScope.myfile2}