Servlet实现文件上传的三种方法总结

servlet实现文件上传的三种方法总结

1. 通过getinputstream()取得上传文件。

/** 
 * to change this template, choose tools | templates 
 * and open the template in the editor. 
 */ 
package net.individuals.web.servlet; 
 
import java.io.datainputstream; 
import java.io.fileoutputstream; 
import java.io.ioexception; 
import javax.servlet.servletexception; 
import javax.servlet.annotation.webservlet; 
import javax.servlet.http.httpservlet; 
import javax.servlet.http.httpservletrequest; 
import javax.servlet.http.httpservletresponse; 
 
/** 
 * 
 * @author barudisshu 
 */ 
@webservlet(name = "uploadservlet", urlpatterns = {"/uploadservlet"}) 
public class uploadservlet extends httpservlet { 
 
  /** 
   * processes requests for both http 
   * <code>get</code> and 
   * <code>post</code> methods. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  protected void processrequest(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    response.setcontenttype("text/html;charset=utf-8"); 
    //读取请求body 
    byte[] body = readbody(request); 
    //取得所有body内容的字符串表示 
    string textbody = new string(body, "iso-8859-1"); 
    //取得上传的文件名称 
    string filename = getfilename(textbody); 
    //取得文件开始与结束位置 
    position p = getfileposition(request, textbody); 
    //输出至文件 
    writeto(filename, body, p); 
  } 
 
  //构造类 
  class position { 
 
    int begin; 
    int end; 
 
    public position(int begin, int end) { 
      this.begin = begin; 
      this.end = end; 
    } 
  } 
 
  private byte[] readbody(httpservletrequest request) throws ioexception { 
    //获取请求文本字节长度 
    int formdatalength = request.getcontentlength(); 
    //取得servletinputstream输入流对象 
    datainputstream datastream = new datainputstream(request.getinputstream()); 
    byte body[] = new byte[formdatalength]; 
    int totalbytes = 0; 
    while (totalbytes < formdatalength) { 
      int bytes = datastream.read(body, totalbytes, formdatalength); 
      totalbytes += bytes; 
    } 
    return body; 
  } 
 
  private position getfileposition(httpservletrequest request, string textbody) throws ioexception { 
    //取得文件区段边界信息 
    string contenttype = request.getcontenttype(); 
    string boundarytext = contenttype.substring(contenttype.lastindexof("=") + 1, contenttype.length()); 
    //取得实际上传文件的气势与结束位置 
    int pos = textbody.indexof("filename=\""); 
    pos = textbody.indexof("\n", pos) + 1; 
    pos = textbody.indexof("\n", pos) + 1; 
    pos = textbody.indexof("\n", pos) + 1; 
    int boundaryloc = textbody.indexof(boundarytext, pos) - 4; 
    int begin = ((textbody.substring(0, pos)).getbytes("iso-8859-1")).length; 
    int end = ((textbody.substring(0, boundaryloc)).getbytes("iso-8859-1")).length; 
 
    return new position(begin, end); 
  } 
 
  private string getfilename(string requestbody) { 
    string filename = requestbody.substring(requestbody.indexof("filename=\"") + 10); 
    filename = filename.substring(0, filename.indexof("\n")); 
    filename = filename.substring(filename.indexof("\n") + 1, filename.indexof("\"")); 
 
    return filename; 
  } 
 
  private void writeto(string filename, byte[] body, position p) throws ioexception { 
    fileoutputstream fileoutputstream = new fileoutputstream("e:/workspace/" + filename); 
    fileoutputstream.write(body, p.begin, (p.end - p.begin)); 
    fileoutputstream.flush(); 
    fileoutputstream.close(); 
  } 
 
  // <editor-fold defaultstate="collapsed" desc="httpservlet methods. click on the + sign on the left to edit the code."> 
  /** 
   * handles the http 
   * <code>get</code> method. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  @override 
  protected void doget(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    processrequest(request, response); 
  } 
 
  /** 
   * handles the http 
   * <code>post</code> method. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  @override 
  protected void dopost(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    processrequest(request, response); 
  } 
 
  /** 
   * returns a short description of the servlet. 
   * 
   * @return a string containing servlet description 
   */ 
  @override 
  public string getservletinfo() { 
    return "short description"; 
  }// </editor-fold> 
} 

 2. 通过getpart()、getparts()取得上传文件。

    body格式：

post http://www.example.com http/1.1  
content-type:multipart/form-data; boundary=----webkitformboundaryrgkcby7qhfd3trwa  
 
------webkitformboundaryrgkcby7qhfd3trwa  
content-disposition: form-data; name="text"  
 
title  
------webkitformboundaryrgkcby7qhfd3trwa  
content-disposition: form-data; name="file"; filename="chrome.png"  
content-type: image/png  
 
png ... content of chrome.png ...  
------webkitformboundaryrgkcby7qhfd3trwa--  

 

[html] view plain copy
/** 
 * to change this template, choose tools | templates 
 * and open the template in the editor. 
 */ 
package net.individuals.web.servlet; 
 
import java.io.filenotfoundexception; 
import java.io.fileoutputstream; 
import java.io.ioexception; 
import java.io.inputstream; 
import java.io.outputstream; 
import javax.servlet.servletexception; 
import javax.servlet.annotation.multipartconfig; 
import javax.servlet.annotation.webservlet; 
import javax.servlet.http.httpservlet; 
import javax.servlet.http.httpservletrequest; 
import javax.servlet.http.httpservletresponse; 
import javax.servlet.http.part; 
 
/** 
 * 
 * @author barudisshu 
 */ 
@multipartconfig 
@webservlet(name = "uploadservlet", urlpatterns = {"/uploadservlet"}) 
public class uploadservlet extends httpservlet { 
 
  /** 
   * processes requests for both http 
   * <code>get</code> and 
   * <code>post</code> methods. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  protected void processrequest(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    part part = request.getpart("photo"); 
    string filename = getfilename(part); 
    writeto(filename, part); 
  } 
 
  //取得上传文件名 
  private string getfilename(part part) { 
    string header = part.getheader("content-disposition"); 
    string filename = header.substring(header.indexof("filename=\"") + 10, header.lastindexof("\"")); 
 
    return filename; 
  } 
 
  //存储文件 
  private void writeto(string filename, part part) throws ioexception, filenotfoundexception { 
    inputstream in = part.getinputstream(); 
    outputstream out = new fileoutputstream("e:/workspace/" + filename); 
    byte[] buffer = new byte[1024]; 
    int length = -1; 
    while ((length = in.read(buffer)) != -1) { 
      out.write(buffer, 0, length); 
    } 
 
    in.close(); 
    out.close(); 
  } 
 
  // <editor-fold defaultstate="collapsed" desc="httpservlet methods. click on the + sign on the left to edit the code."> 
  /** 
   * handles the http 
   * <code>get</code> method. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  @override 
  protected void doget(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    processrequest(request, response); 
  } 
 
  /** 
   * handles the http 
   * <code>post</code> method. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  @override 
  protected void dopost(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    processrequest(request, response); 
  } 
 
  /** 
   * returns a short description of the servlet. 
   * 
   * @return a string containing servlet description 
   */ 
  @override 
  public string getservletinfo() { 
    return "short description"; 
  } 
} 

3、另一种较为简单的方法：采用part的wirte(string filename)上传，浏览器将产生临时tmp文件

/** 
 * to change this template, choose tools | templates 
 * and open the template in the editor. 
 */ 
package net.individuals.web.servlet; 
 
import java.io.ioexception; 
import java.io.printwriter; 
import javax.servlet.servletexception; 
import javax.servlet.annotation.multipartconfig; 
import javax.servlet.annotation.webservlet; 
import javax.servlet.http.httpservlet; 
import javax.servlet.http.httpservletrequest; 
import javax.servlet.http.httpservletresponse; 
import javax.servlet.http.part; 
 
/** 
 *采用part的wirte(string filename)上传，浏览器将产生临时tmp文件。 
 * @author barudisshu 
 */ 
@multipartconfig(location = "e:/workspace") 
@webservlet(name = "uploadservlet", urlpatterns = {"/uploadservlet"}) 
public class uploadservlet extends httpservlet { 
 
  /** 
   * processes requests for both http 
   * <code>get</code> and 
   * <code>post</code> methods. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  protected void processrequest(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    //处理中文文件名 
    request.setcharacterencoding("utf-8"); 
    part part = request.getpart("photo"); 
    string filename = getfilename(part); 
    //将文件写入location指定的目录 
    part.write(filename); 
  } 
 
  private string getfilename(part part) { 
    string header = part.getheader("content-disposition"); 
    string filename = header.substring(header.indexof("filename=\"") + 10, header.lastindexof("\"")); 
    return filename; 
  } 
 
  // <editor-fold defaultstate="collapsed" desc="httpservlet methods. click on the + sign on the left to edit the code."> 
  /** 
   * handles the http 
   * <code>get</code> method. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  @override 
  protected void doget(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    processrequest(request, response); 
  } 
 
  /** 
   * handles the http 
   * <code>post</code> method. 
   * 
   * @param request servlet request 
   * @param response servlet response 
   * @throws servletexception if a servlet-specific error occurs 
   * @throws ioexception if an i/o error occurs 
   */ 
  @override 
  protected void dopost(httpservletrequest request, httpservletresponse response) 
      throws servletexception, ioexception { 
    processrequest(request, response); 
  } 
 
  /** 
   * returns a short description of the servlet. 
   * 
   * @return a string containing servlet description 
   */ 
  @override 
  public string getservletinfo() { 
    return "short description"; 
  }// </editor-fold> 
} 

以上就是servlet实现文件上传的实例，如有疑问请留言或者到本站社区交流讨论，感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！