Java中关于使用COS实现文件上传功能的详解

cos是O'Rrilly公司开发的一款用于HTTP上传文件的OpenSource组件。下面通过本文给大家分享使用COS实现文件上传功能，感兴趣的朋友一起看看吧

cos是O'Rrilly公司开发的一款用于HTTP上传文件的OpenSource组件

需要cos.jar

cos上传文件很简单，比fileupload还简单：但是上传最大我试了试，是800多兆，超过直接崩溃：

java.io.IOException: Posted content length of 1627105576 exceeds limit of 889192448 --->byte，800多M

只需一个servelt即可：

package com.lhy.upload;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Enumeration;
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 com.oreilly.servlet.MultipartRequest;
import com.oreilly.servlet.multipart.FileRenamePolicy;
/**
 * CosServlet 
 * 在Cos中就一个类，
 * MultipartRequest它是request的包装类。
 */
@WebServlet(name="CosServlet",urlPatterns="/CosServlet")
public class CosServlet extends HttpServlet{
 @Override
 protected void doPost(HttpServletRequest req, 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：文件上传
  //声明文件重新命名策略,默认的不行不能重命名，自己实现FileRenamePolicy接口
//  FileRenamePolicy rename = new DefaultFileRenamePolicy();
  MultipartRequest multiReq = new MultipartRequest(req, path, 1024*1024*100, "UTF-8",new MyRename());
  //输出所上传的文件的信息 
  Enumeration fileNames = multiReq.getFileNames(); 
  while(fileNames.hasMoreElements()){ 
    String name = (String)fileNames.nextElement(); 
    File file = multiReq.getFile(name);//得到上传的文件
    if(null != file){ 
      String fileName = multiReq.getFilesystemName(name);  //取得文件名 
      String contentType = multiReq.getContentType(name);//类型
      System.out.println("上传的文件: " +fileName+"， 文件类型: "+contentType); 
    } 
  } 
  //输出所提交的表单中其它文本输入域的值 
  Enumeration formValue = multiReq.getParameterNames(); 
  while(formValue.hasMoreElements()){ 
    String param = (String)formValue.nextElement(); 
    String value = multiReq.getParameter(param); 
    System.out.println(value); 
  } 
  //第三步：如果知道input的name，还可以直接获取信息，
  /*resp.setContentType("text/html;charset=UTf-8");
  PrintWriter out = resp.getWriter();
  out.print("文件名称1:"+multiReq.getOriginalFileName("img1"));
  out.print("<br/>新名称:"+multiReq.getFilesystemName("img1"));
  out.print("<br/>类型1:"+multiReq.getContentType("img1"));
  out.print("<br/>大小1："+multiReq.getFile("img1").length());
  out.print("<br/>说明:"+multiReq.getParameter("desc1"));
  if(multiReq.getContentType("img1").contains("image/")){
   out.print("<img width=&#39;300px&#39; height=&#39;200px&#39; src=&#39;"+req.getContextPath()+"/up/"+multiReq.getFilesystemName("img1")+"&#39;></img>");
  }
 out.print("<hr/>");
 out.print("文件名称2:"+multiReq.getOriginalFileName("img2"));
 out.print("<br/>类型2:"+multiReq.getContentType("img2"));
 out.print("<br/>大小2："+multiReq.getFile("img2").length());
 out.print("<br/>说明2:"+multiReq.getParameter("desc2"));
// 
 out.print("<hr/>");
 out.print("文件名称3:"+multiReq.getOriginalFileName("img3"));
 out.print("<br/>类型3:"+multiReq.getContentType("img3"));
 out.print("<br/>大小3："+multiReq.getFile("img3").length());
 out.print("<br/>说明3:"+multiReq.getParameter("desc3"));*/
 }
}
/**
 * 重命名策略，
 */
class MyRename implements FileRenamePolicy{
 @Override
 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;
 }
}

表单：

<form action="<c:url value=&#39;/CosServlet&#39;/>" method="post"
    enctype="multipart/form-data">
    File1：<input type="file" name="img1"><br /> 说明1：
    <input type="text" name="desc1"><br />
    File2：<input type="file" name="img2"><br/>
    说明2：<input type="text" name="desc2"><br/>
    File3：<input type="file" name="img3"><br/>
    说明3：<input type="text" name="desc3"><br/>
    <input type="submit" />
  </form>

启动上传：

服务端：

总结

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