利用MultipartFile实现文件上传功能

在java中上传文件似乎总有点麻烦，没.net那么简单，记得最开始的时候用smartupload实现文件上传，最近在工作中使用spring的multipartfile实现文件上传，感觉挺简单，在这里和大家分享一下。

一.主要有两个java类,和一般的servlet放在一起即可.

1.fileuploadbean.java

package chb.demo.web;

import org.springframework.web.multipart.multipartfile;

/**
 * @author chb
 *
 */
public class fileuploadbean {

  private multipartfile file;

  public void setfile(multipartfile file) {
    this.file = file;
  }

  public multipartfile getfile() {
    return file;
  }
}

2.fileuploadcontroller.java

package chb.demo.web;

import java.io.fileoutputstream;
import java.io.ioexception;
import java.io.inputstream;

import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;

import org.springframework.validation.bindexception;
import org.springframework.web.multipart.multipartfile;
import org.springframework.web.servlet.modelandview;
import org.springframework.web.servlet.mvc.simpleformcontroller;


/**
 * @author chb
 *
 */
public class fileuploadcontroller extends simpleformcontroller {
    
  protected modelandview onsubmit(
    httpservletrequest request,
    httpservletresponse response,
    object command,
    bindexception errors){
    
    try
    {
      // cast the bean
      fileuploadbean bean = (fileuploadbean) command;

      // let's see if there's content there
      multipartfile file = bean.getfile();
                
      if (file == null) {
        throw new exception("上传失败：文件为�空");  
      }
      if(file.getsize()>10000000)    
      {
        throw new exception("上传失败：文件大小不能超过10m");      
      }
      //得到文件�名
      string filename=file.getoriginalfilename();    
      
      if(file.getsize()>0){        
        try {
          savefilefrominputstream(file.getinputstream(),"d:/",filename);
        } catch (ioexception e) {
          system.out.println(e.getmessage());
          return null;
        }
      }
      else{
        throw new exception("上传失败：上传文件不能为�空");
      }
      // well, let's do nothing with the bean for now and return:
      try {
        return super.onsubmit(request, response, command, errors);
        
      } catch (exception e) {
        system.out.println(e.getmessage());
        return null;
      }
    }
    catch(exception ex)
    {
      system.out.println(ex.getmessage());
      return null;
    }
  }  
  
  /**保存文件
   * @param stream
   * @param path
   * @param filename
   * @throws ioexception
   */
  public void savefilefrominputstream(inputstream stream,string path,string filename) throws ioexception
  {   
    fileoutputstream fs=new fileoutputstream( path + "/"+ filename);
    byte[] buffer =new byte[1024*1024];
    int bytesum = 0;
    int byteread = 0; 
    while ((byteread=stream.read(buffer))!=-1)
    {
      bytesum+=byteread;
      fs.write(buffer,0,byteread);
      fs.flush();
    } 
    fs.close();
    stream.close();   
  }    
}

二.配置文件中如下配置:

1.web.xml,利用spring mvc模式,大家应该都很熟悉了

  <servlet>
    <servlet-name>chb</servlet-name>
    <servlet-class>org.springframework.web.servlet.dispatcherservlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>

  <servlet-mapping>
    <servlet-name>chb</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>

2.chb-servlet.xml,这里要配置映射,并可以设定最大可上传文件的大小

<?xml version="1.0" encoding="utf-8"?>
<!doctype beans public "-//spring//dtd bean//en" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
  <!-- multi-action 用来标识method的变量名定义-->
  <bean id="methodnameresolver" class="org.springframework.web.servlet.mvc.multiaction.parametermethodnameresolver">
    <property name="paramname">
      <value>action</value>
    </property>
    <property name="defaultmethodname">
      <value>index</value>
    </property>
  </bean>
  
  <bean id="multipartresolver" class="org.springframework.web.multipart.commons.commonsmultipartresolver">
    <!-- one of the properties available; the maximum file size in bytes -->
    <property name="maxuploadsize" value="10000000"/>
  </bean>
  

  <bean id="handlermapping" class="org.springframework.web.servlet.handler.simpleurlhandlermapping">
    <property name="mappings">
     <props>
      <prop key="/upload.do">fileuploadcontroller</prop>
     </props>
    </property>
  </bean>
  
  <bean id="fileuploadcontroller" class="chb.demo.web.fileuploadcontroller">
    <property name="commandclass" value="chb.demo.web.fileuploadbean"/>
    <!-- 上传失败时跳转页面 -->
    <property name="formview" value="/user/err.jsp"/>
    <!-- 上传成功时跳转页面 -->
     <property name="successview" value="/user/confirmation.jsp"/>
  </bean>
</beans>

三.设定jsp页面

 <form id="form1" method="post" action="upload.do" enctype="multipart/form-data">        
  <tr>
    <td width="25%" align="right">上传文件：</td>
    <td><input id="file" type="file" name="file" style="width:300px;"></td>
  </tr>
  <tr align="center" valign="middle">
    <td height="60" colspan="2"><input type="submit" id="btnok" value="确认上传"></td>
  </tr>
</form>  

ok,现在就可以上传文件了,挺简单吧?这里我只列出了基本步骤,至于具体的操作(比如中文问题)可能就需要大家自己再完善完善了.

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。