java实现文件的上传与下载

（一）文件的上传：在这一部分，我要将execl文件的内容上传到数据库中，完成这一功能。需要分为两步：

1：将文件上传到tomcat下

文件格式如下：

2：读取execl表中的内容到数据库中

首先：下载jar包：

commons-fileupload-1.3.2.jar
commons-io-2.5.jar

前台html和js:

   <input type="hidden" readonly name="src" id="fsrc" value="0" size="60"/>
      <input type='text' readonly name='textfield' id='textfield' class='txt'  style="height:30px;width:30%;"/>
      <input type='button' class='btn' onClick="findFile()" value='浏览...' style="height:30px;background-color:#ff9900;outline:none;border:none;width:10%;" />
      <input type="file" name="file" class="file" id="file" size="28"  style="display:none;" onchange="document.getElementById('textfield').value=this.value" />
      <input type="button" class="btn2" value="上传" onclick="upload()"/>
      <a  class="btn btn-success"  href="lmxx.do?downLoad&fileName='栏目列表.xls'">下载</a>

 function upload(){

     var file="file";
     var picElement=document.getElementById(file).value;

     var picFormat=picElement.substring(picElement.lastIndexOf('.')+1,picElement.length);
     if(picFormat!="xls"&&picFormat!="xlsx"){
         alert("请选择 excel 2003 (*.xls) 格式的文件!");
         return;
     }

     $.ajaxFileUpload({
              url:"lmxx.do?upLoadExcel",
            secureuri: false,
            fileElementId:file,
            dataType: 'JSON',
            success:function(data){
                   data=decodeURIComponent(data);//解码
                   var arr=JSON.parse(data);//JSON.parse() 方法解析一个JSON字符串
                 $("#fsrc").val(arr.rPath);
                 $.post(
                         "lmxx.do?excelToDb&src="+$("#fsrc").val(),
                         function(data){
                             //data=decodeURIComponent(data);
                             //var arr=JSON.parse(data);
                             if(data==1){
                             alert("上传成功！");
                             }else{
                             alert("上传失败！");
                             }

                         }
                     );
         },
         error: function (){
                alert("上传失败!当前时间为:"+new Date().toLocaleTimeString());

        }
     });
 };

 function findFile(){
     document.getElementById("file").click();
 }

后台操作方法：

 @RequestMapping(params="upLoadExcel")
     @ResponseBody
     public String addFilemsgPic(MultipartFile file,HttpServletRequest request) throws Exception{
         String path="/uploadExcelFiles";
         path=request.getSession().getServletContext().getRealPath(path);//当前运行文件在服务器上的绝对路径
         System.out.println(path);
         //创建文件
         File dir=new File(path);
         if(!dir.exists()){
             dir.mkdirs();
         }
         String uuid=UUID.randomUUID().toString();
         //返回原来在客户端的文件系统的文件名
         String fileName=file.getOriginalFilename();
         //uuid+后缀名
         String img=uuid+fileName.substring(fileName.lastIndexOf("."));//lastIndexOf报告指定 Unicode 字符在此实例中的最后一个匹配项的索引位置（即为后缀）。String.Substring (Int32)从此实例检索子字符串
         FileOutputStream imgOut=new FileOutputStream(new File(dir,img));//根据 dir 抽象路径名和 img 路径名字符串创建一个新 File 实例。
         imgOut.write(file.getBytes());//返回一个字节数组文件的内容
         imgOut.close();
         Map<String, String> map=new HashMap<String, String>();

         map.put("picPath",img);//8b4aff41-420c-419a-b0ab-c18ca36198c6.xls
         map.put("picName",fileName);//lanmu.xls
         String rpath = path+"\\"+img;

         map.put("rPath",rpath);
         JSONObject jsonObject = JSONObject.fromObject(map);//将json字符串转换为json对象
         String r=jsonObject.toString();
         String s=URLEncoder.encode(r, "utf-8");//加密
         return s;
     }

     @RequestMapping(params="excelToDb")
     @ResponseBody
     public int excelToDB(String src){

         String newSrc = src.replace(" ", "+");
         List<Lanmu> lmList=ReadeExcel.taPCL(newSrc);
         int flag=ConnOrcl.connToTable(lmList);
         if(flag==1)
             return 1;
         else
             return 2;
     }

ReadeExcel

 public class ReadeExcel {
     public static List<Lanmu> taPCL(String file)
     {
         List<Lanmu> LTPC = new ArrayList<Lanmu>();
         try
         {
             //选取excel文件
             Workbook rwb=Workbook.getWorkbook(new File(file));//获得工作薄（Workbook）
             //选取excel文件中的第一个工作薄
             Sheet sheet = rwb.getSheet(0);
             //得到excel表行数
             int RowNum = sheet.getRows();
             for(int i=1;i<RowNum;i++)
             {
                 //获得excel表中第1列第i行单元格
                 Cell cell0 = sheet.getCell(0, i);
                 //获得excel表中第2列第i行单元格
                 Cell cell1 = sheet.getCell(1, i);
                 //获得cell0单元格内容
                 String name = cell0.getContents();
                 //获得cell1单元格内容
                 String state = cell1.getContents();
                 Lanmu lanmu = new Lanmu();
                 lanmu.setName(name);
                 lanmu.setState(state);
                 LTPC.add(lanmu);
             }
         }
         catch(Exception e)
         {
             e.printStackTrace();
         }
         return LTPC;
     }
 }

ConnOrcl

 public class ConnOrcl {

         private static Connection conn;
         private static Statement stat;
         private static String driver = "oracle.jdbc.driver.OracleDriver";
         private static int SUCCESS=1;
         private static int FILE=2;
         public static int connToTable(List<Lanmu> lanmus)
         {
             try
             {
                 //数据库连接
                 Class.forName(driver);
                 conn = java.sql.DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:orcl", "GKBMFZXT", "GKBMFZXT");
                 stat = conn.createStatement();
                  int flag=0;
                 //遍历list，插入数据库
                 for(Lanmu lanmu : lanmus)
                 {
                     StringBuffer sql = new StringBuffer();
                     //构造sql语句
                     sql.append("insert into lanmu_table (id,name,state) values ('");
                     String id=UUID.randomUUID().toString().replace("-","");
                     String name = lanmu.getName();
                     String state = lanmu.getState();
                     sql.append(id).append("','");
                     sql.append(name).append("','");
                     sql.append(state).append("')");
                     //执行sql语句
                     stat.execute(sql.toString());
                     flag++;
                 }

                 if(flag==lanmus.size()){
                     return SUCCESS;
                 }
             }
             catch(ClassNotFoundException e)
             {
                 e.printStackTrace();
             }
             catch(SQLException e)
             {
                 e.printStackTrace();
             }
             finally
             {
                 if(null != stat)
                 {
                     try
                     {
                         stat.close();
                     }
                     catch (SQLException e)
                     {
                         e.printStackTrace();
                     }
                 }
                 if(null != conn)
                 {
                     try
                     {
                         conn.close();
                     }
                     catch (SQLException e)
                     {
                         e.printStackTrace();
                     }
                 }
             }
             return FILE;
         }  

 }

（二）文件的下载

 @RequestMapping(params="downLoad")
     public String downLoad(HttpServletRequest request,HttpServletResponse response)throws Exception{

         String fileName=request.getParameter("fileName");
         File f=new File("C:\\Users\\ztl\\Desktop\\lanmu.xls");

         BufferedInputStream buffer=null;
         OutputStream out=null;
     try{
         if(!f.exists()){

             response.sendError(404,"File not find!");
             return "File not find!";

         }
         buffer = new BufferedInputStream(new FileInputStream(f));
         byte[] buf = new byte[1024];
         int len=0;
         response.reset();
         response.setContentType("application/vnd.ms-excel");
         response.setHeader("Content-Disposition","attachment;filename="+fileName);
         out = response.getOutputStream();
         while((len = buffer.read(buf))>0){
             out.write(buf,0,len);
         }
         out.flush();
         response.flushBuffer();

     }catch(Throwable e){
         e.printStackTrace();
     }finally{

         if(out!=null){
             out.close();
         }
     }

     return "view/luntan/lanmu_list";

     }