一 限制上传大小
1：限制总文件的大小 。 如 上传10文件，设置最多总上传大小为100M。
void
|
setSizeMax(long sizeMax) Sets the maximum allowed size of a complete request, as opposed to setFileSizeMax(long).
|
2：设置第每一个文件的大小 ，如果设置每 一个文件大小10M。
void
|
setFileSizeMax(long fileSizeMax) Sets the maximum allowed size of a single uploaded file, as opposed to getSizeMax().
|
二 用COS实现文件上传
package cn.hx;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.UUID;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.oreilly.servlet.MultipartRequest;
import com.oreilly.servlet.multipart.DefaultFileRenamePolicy;
import com.oreilly.servlet.multipart.FileRenamePolicy;
/**
* 在Cos中就一个类，
* MultipartRequest它是request的包装类。
*/
public class CosServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse resp)
throws ServletException, IOException {
//第一步：声明文件的保存目录
String path = getServletContext().getRealPath("/up");
//第二步：文件传
//声明文件重新取名的策略
FileRenamePolicy rename = new DefaultFileRenamePolicy();
MultipartRequest req =
new MultipartRequest(request,path,1024*1024*100,"UTF-8",new MyRename());
// //第三步：显示信息，
resp.setContentType("text/html;charset=UTf-8");
PrintWriter out = resp.getWriter();
out.print("文件名称1:"+req.getOriginalFileName("img1"));
out.print("<br/>新名称:"+req.getFilesystemName("img1"));
out.print("<br/>类型1:"+req.getContentType("img1"));
out.print("<br/>大小1："+req.getFile("img1").length());
out.print("<br/>说明:"+req.getParameter("desc1"));
if(req.getContentType("img1").contains("image/")){
out.print("<img src=‘"+request.getContextPath()+"/up/"+req.getFilesystemName("img1")+"‘></img>");
}
}
}
class MyRename implements FileRenamePolicy{
public File rename(File file) {
String fileName = file.getName();
String extName = fileName.substring(fileName.lastIndexOf("."));
String uuid = UUID.randomUUID().toString().replace("-","");
String newName = uuid+extName;//abc.jpg
file = new File(file.getParent(),newName);
return file;
}
}
三 下载
即可是get也可以是post。
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
req.setCharacterEncoding("UTF-8");
String name = req.getParameter("name");
//第一步：设置响应的类型
resp.setContentType("application/force-download");
//第二读取文件
String path = getServletContext().getRealPath("/up/"+name);
InputStream in = new FileInputStream(path);
//设置响应头
//对文件名进行url编码
name = URLEncoder.encode(name, "UTF-8");
resp.setHeader("Content-Disposition","attachment;filename="+name);
resp.setContentLength(in.available());
//第三步：开始文件copy
OutputStream out = resp.getOutputStream();
byte[] b = new byte[1024];
int len = 0;
while((len=in.read(b))!=-1){
out.write(b,0,len);
}
out.close();
in.close();
}