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.