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我们。