文件上传之Apache commons fileupload使用

梦里梦外; 2022-09-24 14:17 203阅读 0赞

http://www.cnblogs.com/xing901022/p/3855613.html

文件上传的方法主要目前有两个常用的，一个是SmartUpload，一个是Apache的Commons fileupload.

我们这里主要介绍下第二个的用法，首先要上传文件，注意几个问题：

**1 form表单内，要添加空间<input type="file" name="myfile">**

**　　2 form表单的内容格式要定义成multipart/form-data格式**

**　　3 需要类库：1 commons-io.jar 2commons-fileupload-1.3.1.jar**

接下来我们看下他的用法。

**首先阅读Apache commons fileupload的官方文档可以发现下面几个常用的函数：**

**1 创建文件解析对象**

DiskFileUpload diskFileUpload = new DiskFileUpload();

**2 进行文件解析后放在List中，因为这个类库支持多个文件上传，因此把结果会存在List中。**

List<FileItem> list = diskFileUpload.parseRequest(request);

3 获取上传文件，进行分析（不是必须）

File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));

**4 创建新对象，进行流拷贝**

![复制代码][copycode.gif]

file1 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());
                            file1.getParentFile().mkdirs();
                            file1.createNewFile();
                            
                            InputStream ins = fileItem.getInputStream();
                            OutputStream ous = new FileOutputStream(file1);
                            
                            try{
                                byte[] buffer = new byte[1024];
                                int len = 0;
                                while((len = ins.read(buffer)) > -1)
                                    ous.write(buffer,0,len);
                                out.println("以保存文件"+file1.getAbsolutePath()+"<br/>");
                            }finally{
                                ous.close();
                                ins.close();
                            }

![复制代码][copycode.gif]

这样我们就完成了文件的上传。

## fileUpload.html ##

![复制代码][copycode.gif]

<form action="servlet/UploadServlet" method="post" enctype="multipart/form-data">
            <div align="center">
                <fieldset style="width:80%">
                    <legend>上传文件</legend><br/>
                        <div align="left">上传文件1</div>
                        <div align="left">
                            <input type="file" name="file1"/>
                        </div>
                        <div align="left">上传文件2</div>
                        <div align="left">
                            <input type="file" name="file2"/>
                        </div>
                        <div>
                            <div align='left'>上传文件说明1</div>
                            <div align='left'><input type="text" name="description1"/></div>
                        </div>
                        <div>
                            <div align='left'>上传文件说明2</div>
                            <div align='left'><input type="text" name="description2"/></div>
                        </div>
                        <div>
                            <div align='left'>
                                <input type='submit' value="上传文件"/>
                            </div>
                        </div>
                </fieldset>
            </div>
        </form>

![复制代码][copycode.gif]

## web.xml ##

![复制代码][copycode.gif]

<servlet>
        <servlet-name>UploadServlet</servlet-name>
        <servlet-class>com.test.hello.UploadServlet</servlet-class>
      </servlet>
    <servlet-mapping>
        <servlet-name>UploadServlet</servlet-name>
        <url-pattern>/servlet/UploadServlet</url-pattern>
      </servlet-mapping>

![复制代码][copycode.gif]

## UploadServlet.java ##

![ExpandedBlockStart.gif][]

![复制代码][copycode.gif]

package com.test.hello;
    
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.io.PrintWriter;
    import java.util.List;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.apache.commons.fileupload.DiskFileUpload;
    import org.apache.commons.fileupload.FileItem;
    import org.apache.commons.fileupload.FileUploadException;
    
    public class UploadServlet extends HttpServlet {
    
        /**
         * Constructor of the object.
         */
        public UploadServlet() {
            super();
        }
    
        /**
         * Destruction of the servlet. <br>
         */
        public void destroy() {
            super.destroy(); // Just puts "destroy" string in log
            // Put your code here
        }
    
        /**
         * The doGet method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to get.
         * 
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
    
            response.setCharacterEncoding("UTF-8");
            response.getWriter().println("请以POST方式上传文件");
        }
    
        /**
         * The doPost method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to post.
         * 
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        @SuppressWarnings({ "unchecked", "deprecation" })
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            File file1 = null,file2=null;
            String description1 = null,description2 = null;
            response.setCharacterEncoding("UTF-8");
            request.setCharacterEncoding("UTF-8");
            response.setContentType("text/html");
            PrintWriter out = response.getWriter();
            
            DiskFileUpload diskFileUpload = new DiskFileUpload();
            try{
                List<FileItem> list = diskFileUpload.parseRequest(request);
                
                out.println("遍历所有的FileItem...<br/>");
                for(FileItem fileItem : list){
                    if(fileItem.isFormField()){
                        if("description1".equals(fileItem.getFieldName())){
                            out.println("遍历到description1 ... <br/>");
                            description1 = new String(fileItem.getString().getBytes(),"UTF-8");
                        }
                        if("description2".equals(fileItem.getFieldName())){
                            out.println("遍历到description2 ... <br/>");
                            description2 = new String(fileItem.getString().getBytes(),"UTF-8");
                        }
                    }else{
                        if("file1".equals(fileItem.getFieldName())){
                            File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));
                            out.println("遍历到file1...<br/>");
                            out.println("客户端文件位置："+remoteFile.getAbsolutePath()+"<br/>");
                            
                            file1 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());
                            file1.getParentFile().mkdirs();
                            file1.createNewFile();
                            
                            InputStream ins = fileItem.getInputStream();
                            OutputStream ous = new FileOutputStream(file1);
                            
                            try{
                                byte[] buffer = new byte[1024];
                                int len = 0;
                                while((len = ins.read(buffer)) > -1)
                                    ous.write(buffer,0,len);
                                out.println("以保存文件"+file1.getAbsolutePath()+"<br/>");
                            }finally{
                                ous.close();
                                ins.close();
                            }
                        }
                        if("file2".equals(fileItem.getFieldName())){
                            File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));
                            out.println("遍历到file2...<br/>");
                            out.println("客户端文件位置："+remoteFile.getAbsolutePath()+"<br/>");
                            
                            file2 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());
                            file2.getParentFile().mkdirs();
                            file2.createNewFile();
                            
                            InputStream ins = fileItem.getInputStream();
                            OutputStream ous = new FileOutputStream(file2);
                            
                            try{
                                byte[] buffer = new byte[1024];
                                int len = 0;
                                while((len = ins.read(buffer)) > -1)
                                    ous.write(buffer,0,len);
                                out.println("以保存文件"+file2.getAbsolutePath()+"<br/>");
                            }finally{
                                ous.close();
                                ins.close();
                            }
                        }
                    }
                    out.println("Request 解析完毕<br/><br/>");
                }
            }catch(FileUploadException e){}
            
            out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
            out.println("<HTML>");
            out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
            out.println("  <BODY>");
            
            if(file1 != null){
                out.println("<div>");
                out.println(" <div align='left'>file1;</div>");
                out.println(" <div align='left'><a href='"+request.getContextPath()+"/attachment/"+
                        file1.getName()+"'target=_blank>"+file1.getName()+"</a>");
                out.println("</div>");
                out.println("</div>");
            }
            if(file2 != null){
                out.println("<div>");
                out.println(" <div align='left'>file2;</div>");
                out.println(" <div align='left'><a href='"+request.getContextPath()+"/attachment/"+
                        file2.getName()+"'target=_blank>"+file2.getName()+"</a>");
                out.println("</div>");
                out.println("</div>");
            }
            out.println("<div>");
            out.println(" <div align='left'>description1:</div>");
            out.println(" <div align='left'>");
            out.println(description1);
            out.println("</div>");
            out.println("</div>");
            
            out.println("<div>");
            out.println(" <div align='left'>description2:</div>");
            out.println(" <div align='left'>");
            out.println(description2);
            out.println("</div>");
            out.println("</div>");
            
            out.println("  </BODY>");
            out.println("</HTML>");
            out.flush();
            out.close();
        }
    
        /**
         * Initialization of the servlet. <br>
         *
         * @throws ServletException if an error occurs
         */
        public void init() throws ServletException {
            // Put your code here
        }
    
    }

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## 运行示例 ##

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[copycode.gif]: /images/20220719/e5caaa63f14c44d399a12a51b619ddaa.png
[ExpandedBlockStart.gif]: /images/20220719/da327df85bab481b9823349f4f3fd575.png
[192309208184308.png]: /images/20220719/ccc4736795da45829f10967823d01aa8.png
[192309292095643.png]: /images/20220719/72a9c04cb06b412d9066064cc9a0dae0.png