文件上传之 MultipartFile

利用MultipartFile（组件）实现文件上传

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;

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;

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;

        }

    }

    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.

原文博客地址：http://blog.csdn.net/hbcui1984/article/details/1498112