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利用MultipartFile实现文件上传功能

利用MultipartFile实现文件上传功能

作者: Python编程社区 | 来源:发表于2019-05-20 10:34 被阅读9次

    这篇文章主要为大家详细介绍了利用MultipartFile实现文件上传功能,具有一定的参考价值,感兴趣的小伙伴们可以参考一下

    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.

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