JDBC存储和读取二进制数据

以下JSP文件用common-fileupload组件实现文件上传，并将文件以二进制文件的形式存入数据库

<%
if("POST".equalsIgnoreCase(request.getMethod)){//如果是POST表单
      DiskFileUpload diskFileUpload = newDiskFileUpload();
      diskFileUpload.setHeaderEncoding("UTF-8");//设置编码
      //解析上传的数据
      List <FileItem> list =diskFileUpload.parseRequest(request);

      for(FileItem fileItem : list){
             if(!fileItem.isFormField()){  //如果是文件域
                    //文件路径，替换掉特殊字符
                    String filename =fileItem.getName().replace("\\","/");
                    //获取文件名
                    filename =filename.substring(filename.lastIndexOf("/")+1);
                    //获取文件类型
                    String filetype =fileItem.getContentType();
                    //获取文件大小
                    Int filesize =fileItem.getSize();

      Connection conn = null;
      PrepareStatement preStmt = null;

      try{
             conn = DbManager.getConnection();
             preStmt = conn.prepareStatement(
"insert into table_name (filename,filetype,size,content,date) values(?,?,?,?,?)");

             preStmt.setString(1,filename);
             preStmt.setString(2,filetype);
             preStmt.setInt(3,filesize);
             preStmt.setBinaryStream(4,fileItem.getInputStream(),filesize);
             preStmt.setTimestamp(5,newTimestamp(System.currentTimeMills()));
             preStmt.executeUpdate();

      }finally{
             if(preStmt != null)  preStmt.close();
             if(conn != null)  conn.close();

      }

             }
      }

}
%>

读取二进制文件

<%
out.clear();  //清空一切输出
int id=Integer.parseInt(request.getParameter("id")); //获取附件ID

Connection conn= null;
PrepareStatementpreStmt = null;
ResultSet rs =null;

try{
conn =DbManager.getConnection();
preStmt =conn.prepareStatement("select from table_name where id = ?");
preStmt.setInt(1,id);
rs =preStmt.executeQuery();

      if(rs.next()){
      response.reset();  //重置response
      response.setContentType(rs.getString("fileType"));//设置输出的文件类型
      response.setContentLength(ra.getInt("filesize"));//设置输出的文件长度

      InputStream ins = null;
      OutputStream ous = null;
             try{
             ins = rs.getBinaryStream("content");
             ous = response.getOutputStream();
             byte [] b = new byte[1024];
             int len = 0;
                    while((len = ins.read(b)) !=-1){
                           ous.write(b,0,len);
                    }
             }finally{
                    if(ous != null) ous.close();
                    if(ins != null) ins.close();
             }
      }else{
             out.println("没有找到附件："+id);
      }

}finally{
      if(rs! = null)  rs.close();
      if(preStmt != null)  preStmt.close();
      if(conn != null)  conn.close();
}

%>