Java实现文件上传的方法

本文实例为大家分享了java实现文件上传的具体代码，具体内容如下

1、java代码：

package com.github.reston.servlet;
 
import java.io.file;
import java.io.fileoutputstream;
import java.io.ioexception;
import java.io.printwriter;
import java.util.iterator;
import java.util.list;
 
import javax.servlet.servletconfig;
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.fileitemfactory;
import org.apache.commons.fileupload.disk.diskfileitemfactory;
import org.apache.commons.fileupload.servlet.servletfileupload;
import org.apache.commons.io.ioutils;
 
@webservlet("/ajaxupload")
public class ajaxupload extends httpservlet{
 @override
 public void init(servletconfig config) throws servletexception{
  // todo auto-generated method stub
  super.init(config);
 }
 
 @override
 protected void service(httpservletrequest request,httpservletresponse response) throws servletexception,ioexception{
  response.setcontenttype("text/html");
  request.setcharacterencoding("utf-8");
  boolean ismultipart=servletfileupload.ismultipartcontent(request);
 
  string basepath=getservletcontext().getrealpath("/upload");
  file basedirectory=new file(basepath);
  string filename="";
  long start=0;
  if(!basedirectory.isdirectory()) basedirectory.mkdirs();
  if(ismultipart){
   try{
    fileitemfactory factory=new diskfileitemfactory();
    servletfileupload upload=new servletfileupload(factory);
    @suppresswarnings("unchecked") list<fileitem> fileitems=upload.parserequest(request);
    for(fileitem i:fileitems){
     if(i.isformfield()){
      string name=i.getfieldname();
      string value=i.getstring();
      if(name.equals("start"))start=long.parselong(i.getstring());
     }
    }
    for(fileitem item:fileitems){
     if(item.isformfield()) continue;
     filename=item.getfieldname();
     if(mkdir(basepath)){
      file fileonserver=createfile(basepath,filename);
      if(fileonserver.length()==0){
       fileoutputstream fos=new fileoutputstream(fileonserver,true);
       ioutils.copy(item.getinputstream(),fos);
      }
      if(start>0){
       fileoutputstream fos=new fileoutputstream(fileonserver,true);
       ioutils.copy(item.getinputstream(),fos);
      }
      printwriter pw=response.getwriter();
      pw.write("{\"length\":\""+fileonserver.length()+"\"}");
      pw.flush();
     }
    }
   }catch(exception e){
   }
  }
 }
 
 private file createfile(string path,string name) throws ioexception{
   
  file tmp=new file(path,name);
  if(!tmp.exists()){
   tmp.createnewfile();
  }
  return tmp;
 }
 
 private boolean mkdir(string path){
  boolean result=true;
  file tmp=new file(path);
  if(!tmp.isdirectory()){
   result=tmp.mkdirs();
  }
  return result;
 }
}

2、java代码：

var ajaxupload = function(e) {
 /**
  * e url method data success error
  */
 var xmlhttprequest;
 if (window.xmlhttprequest) {
  xmlhttprequest = new xmlhttprequest();
  if (xmlhttprequest.overridemimetype) {
   xmlhttprequest.overridemimetype("text/xml");
  }
 } else if (window.activexobject) {
  var activename = [ "msxml2.xmlhttp", "microsoft.xmlhttp" ];
  for (var i = 0; i < activename.length; i++) {
   try {
    xmlhttprequest = new activexobject(activename[i]);
    break;
   } catch (e) {
    return;
   }
  }
 }
 if (xmlhttprequest == undefined || xmlhttprequest == null) {
  alert("xmlhttprequest对象创建失败！！");
  return;
 } else {
  this.xmlhttp = xmlhttprequest;
 }
 
 var file = document.getelementbyid(e.id);
 if (this.xmlhttp != undefined && this.xmlhttp != null) {
  e.method = e.method.touppercase();
  if (e.method != "get" && e.method != "post") {
   alert("http的请求方法必须为get或post!!!");
   return;
  }
  if (e.url == null || e.url == undefined) {
   e.alert("http的请求地址必须设置！");
   return;
  }
 }
 
 this.xmlhttp.onreadystatechange = function() {
  if (this.readystate == 4) {
   if (this.status == 200) {
    var responsetext = this.responsetext;
    var responsexml = this.reponsexml;
    if (e.success == undefined || e.success == null) {
     alert("没有设置处理数据正确返回的方法");
     alert("返回的数据：" + responsetext);
    } else {
     e.success(responsetext, responsexml);
    }
   } else {
    if (e.error == undefined || e.error == null) {
     alert("没有设置处理数据返回失败的处理方法！");
     alert("http的响应码：" + this.status + ",响应码的文本信息：" + this.statustext);
    } else {
     e.error(this.status, this.statustext);
    }
   }
  }
 }
 
// var formhtm="<form id='output' enctype='multipart/form-data' ></form>";
  
 var filename = getfilename(e.id);
 this.xmlhttp.open(e.method, e.url, true);
 var data = new formdata(document.getelementbyid("output"));
 data.append("name", filename);
 data.append("start", e.data.start);
 data.append(filename, document.getelementbyid(e.id).files[0].slice(e.data.start, getfilesize(e.id)));
 this.xmlhttp.send(data);
}
 
function getfilename(id) {
 var path = document.getelementbyid(id).value
 var pos1 = path.lastindexof('/');
 var pos2 = path.lastindexof('\\');
 var pos = math.max(pos1, pos2);
 return path.substring(pos + 1);
}
 
function getfilesize(id) {
 return document.getelementbyid(id).files[0].size;
}

3、html代码：

<!doctype html>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<script type="text/javascript" src="test.js"></script>
 
</head>
<body>
  
 <input type="file" name="upload" id="upload" value="上传"/><span>请选择要上传的文件(小于1g)</span>
 <input type="button" value="上传" onclick="test();"/>
<form id="output" enctype="multipart/form-data" ></form>
 <script>
 
 function test(){
  ajaxupload({
  id : "upload",
  url : "/pcc/reston/ajaxupload",
  method : "post",
  data : {start:0},
  success : function(e) {
   var l=json.parse(e).length;
   ajaxupload({
    id : "upload",
    url : "/pcc/reston/ajaxupload",
    method : "post",
    data : {start:l},
    success : function(e) {
    },
    error : function(e) {
     console.log(e);
    }
   });
  },
  error : function(e) {
   console.log(e);
  }
 });
  
 }
 
 </script>
</body>
 
</html>

以上就是本文的全部内容，希望对大家学习java程序设计有所帮助。