JavaWeb 文件上传和下载
实现文件上传
1.创建项目，导入JAR包
在Eclipse中创建一个名称为chapter12的Web项目，在项目的WEB-INF/ib目录下导入JAR包commons-fileupload-1.3.1.jar和commons-io-2.4.jar,并发布到类路径下。
2.创建上传页面
创建一个form.jsp的文件做界面:
1 | <%@ page language="java" contentType="text/html; charset=UTF-8" |
3.创建Servlet
在自己创建的包下新建一个
UploadServlet的Servlet文件
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83package chapter15.fileupload;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.List;
import java.util.UUID;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
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 UploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
response.setContentType("text/html;charset=utf-8");
DiskFileItemFactory factory = new DiskFileItemFactory();
File f = new File("D:\\TempFolder");
if (!f.exists()) {
f.mkdirs();
}
factory.setRepository(f);
ServletFileUpload fileUpload = new ServletFileUpload(factory);
fileUpload.setHeaderEncoding("utf-8");
List<FileItem> fileitems = fileUpload.parseRequest(request);
PrintWriter writer = response.getWriter();
for(FileItem fileitem : fileitems) {
if (fileitem.isFormField()) {
String name = fileitem.getFieldName();
if(name.equals("name")) {
if(!fileitem.getString().equals("")) {
String value = fileitem.getString("utf-8");
writer.print("上传者："+ value + "<br />");
}
}
}else {
String filename = fileitem.getName();
if(filename != null && !filename.equals("")) {
writer.print("上传的文件名称是：" + filename + "<br />");
filename = filename.substring(filename.lastIndexOf("\\") + 1);
filename = UUID.randomUUID().toString() + "_" + filename;
String webPath = "/upload/";
String filepath = getServletContext().getRealPath(webPath + filename);
File file = new File(filepath);
file.getParentFile().mkdirs();
file.createNewFile();
InputStream in = fileitem.getInputStream();
FileOutputStream out = new FileOutputStream(file);
byte[] buffer = new byte[1024];
int len;
while((len = in.read(buffer)) > 0)
out.write(buffer, 0 , len);
in.close();
out.close();
fileitem.delete();
writer.print("上传文件成功！<br />");
}
}
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
1.创建下载页面
在WebContent目录下创建下载页面download.jsp,代码如下:
1 | <%@ page language="java" contentType="text/html; charset=UTF-8" |
2.创建 Servlet
创建DownloadServlet类实现代码如下:
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41package chapter15.fileupload;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DownloadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html;charset=utf-8");
String filename = request.getParameter("filename");
String folder = "/download/";
response.addHeader("Content-type", "application/octet-stream");
response.addHeader("Content-Disposition", "attachment;filename"+filename);
InputStream in = getServletContext().getResourceAsStream(folder+filename);
OutputStream out =response.getOutputStream();
byte[] buffer = new byte[1024];
int len;
while ((len = in.read(buffer))!= -1) {
out.write(buffer,0,len);
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
3.创建下载目录及文件
在WebContent目录下创建一个名称为download的文件夹(Folder),在该文件夹中放置一个名称为”1.jpg”的图片文件:
