关于文件上传的例子

最新推荐文章于 2021-10-12 16:40:05 发布

最新推荐文章于 2021-10-12 16:40:05 发布 · 177 阅读

文章标签：

#Servlet #Apache #JSP #thread

Java 专栏收录该内容

0 篇文章

订阅专栏

本文介绍如何使用FileUpload组件实现文件上传功能，涵盖前端页面设计与后端处理流程。通过一个简单的示例，演示了普通文本与文件上传的同时提交，并详细展示了FileUploadServlet的Java代码实现。

本文使用FileUpload组件实现文件上传,前台页面包括有普通文本和文件上传同时进行提交,后台利用了一个servlet进行处理,处理后,将状态返回到页面的一个Iframe里面.功能比较简单,只是实现了一个上传,在异常处理等方面考虑的可能不周全,希望大家指正.

FileUploadServlet.java代码:

java 代码

package tbg.upload;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
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.DiskFileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class FileUploadServlet extends HttpServlet {
/**
* 保存版本信息
*/
private static final long serialVersionUID = 1L;
// 默认文件上传保存路径
public static final String UPLOAD_DIR = "/upload";
// 默认字符集
private static final String DEFAULT_ENCODING = "GBK";
// 内存数据大小限制
private int sizeThreshold = 256 * 1024;
// request地最大值
private long sizeMax = 256 * 1024 * 1024;
// 单个上传文件大小限制
private long singleSizeMax = 100 * 256 * 1024;
// 文件临时存放路径
private String tempDirectory = null;
// 存放上传文件名的List
ArrayList fileUploadList = new ArrayList();
// 文件上传状态
private String status = "";
/**
* Constructor of the object.
*/
public FileUploadServlet() {
super();
}
/**
* Destruction of the servlet.
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet.
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
/**
* The doPost method of the servlet.
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html; charset=gb2312");
PrintWriter out = null;
boolean isMultiPart = ServletFileUpload.isMultipartContent(request);
if (isMultiPart) {
processFileUpload(request, response);
}
out = response.getWriter();
out.write(status);
out.print("
");
for (int i = 0; i < fileUploadList.size(); i++) {
out.write((String) fileUploadList.get(i));
out.print("
");
}
out.flush();
out.close();
fileUploadList.clear();
}
/**
* Initialization of the servlet.
*
* @throws ServletException if an error occure
*/
public void init() throws ServletException {
// Put your code here
}
/**
* 处理文件上传
*/
private void processFileUpload (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
DiskFileItemFactory factory = new DiskFileItemFactory();
// 设置内容缓冲区,超过后写入临时文件
factory.setSizeThreshold(sizeThreshold);
// 得到文件临时存放地位置
if (tempDirectory == null) {
tempDirectory = request.getSession().getServletContext().getRealPath("/upload/temp");
}
// 设置文件临时存放位置
factory.setRepository(new File(tempDirectory));
// 设置单个文件地最大上传值
ServletFileUpload upload = new ServletFileUpload(factory);
// 设置字符集
upload.setHeaderEncoding(request.getCharacterEncoding());
// 设置单个文件上传地最大值
upload.setFileSizeMax(singleSizeMax);
// 设置request地最大值
upload.setSizeMax(sizeMax);
try {
List items = upload.parseRequest(request);
// 处理文件上传
for (int i = 0; i < items.size(); i++) {
FileItem item = (FileItem) items.get(i);
// 保存文件
if (!item.isFormField() && item.getName().length() > 0) {
// 取得文件地名字
String fileName = takeFileName(item.getName());
// 取得文件上传路径
String fileRealPath =
request.getSession().getServletContext().getRealPath(UPLOAD_DIR) + File.separator + fileName;
File uploadFile = new File(fileRealPath);
item.write(uploadFile);
// 更新文件上传列表
fileUploadList.add(fileName);
status = "上传成功";
Thread.sleep(500);
} else {
String encoding = "";
String formFieldName = "";
// 设置字符集
if (item instanceof DiskFileItem) {
encoding = ((DiskFileItem) item).getCharSet();
} else {
encoding = request.getCharacterEncoding();
}
// 取得控件对应的值
if (encoding != null) {
formFieldName = item.getString(encoding);
} else {
formFieldName = item.getString(DEFAULT_ENCODING);
}
fileUploadList.add(formFieldName);
}
}
} catch (FileUploadException e) {
uploadExceptionHandle(request, "文件上传错误:" + e.getMessage());
} catch (Exception e) {
uploadExceptionHandle(request, "保存文件时错误:" + e.getMessage());
}
}
/**
* 从文件路径中取出文件名
*/
private String takeFileName (String filePath) {
int pos = filePath.lastIndexOf(File.separator);
if (pos > 0) {
return filePath.substring(pos + 1);
} else {
return filePath;
}
}
/**
* 上传失败处理
*/
private void uploadExceptionHandle (HttpServletRequest request, String errMes) {
deleteUploadFile(request);
status = errMes;
}
/**
* 删除已上传文件
*/
private void deleteUploadFile (HttpServletRequest request) {
for (int i = 0; i < fileUploadList.size(); i++) {
String fileRealPath =
request.getSession().getServletContext().getRealPath(UPLOAD_DIR)
+ File.separator + fileUploadList.get(i);
File uploadFile = new File(fileRealPath);
uploadFile.delete();
}
fileUploadList.clear();
status = "文件已经被删除";
}
}