利用MultipartFile实现文件上传

利用MultipartFile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;

    /** *//**
     * @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.