Using servlet to download the file from Oracle Instance

As part of the project I am working on , I had to find a way to download the file from OA. I will demostrate here a way to do it on R12 instance

First of all we need to write a servlet.

Here is the code:

 

import java.io.*; 

import javax.servlet.*; 
import javax.servlet.http.*; 

public class DownloadFile extends HttpServlet 
{ 

//I assumed that OA is running on Unix under Korn shell and .profile file used to source the instance  


private String doCommand(String cmd) throws IOException, InterruptedException
{
 int exitCode = 0;
    int c;
    BufferedReader b;
    String [] params = new String[]{"/bin/ksh", "-c", ". profile 1> /dev/null;set -e;" + cmd};
    Process subProc = Runtime.getRuntime().exec(params);
    StringBuffer sb = new StringBuffer(); 

      b = new BufferedReader(new InputStreamReader(subProc.getInputStream())); 

      c = b.read();
 
      while (c != -1) 
      {
       sb.append((char)c);
       c = b.read();
      } 

      b.close();
      
     exitCode = subProc.waitFor();
   if (exitCode != 0)
        {
        sb = new StringBuffer();
              b = new BufferedReader(new InputStreamReader(subProc.getErrorStream()));
              c = b.read();
             while (c != -1)
              {
              sb.append((char)c);
                 c = b.read();
              }//end while
             System.out.println("Output from 'doCommand' "+ sb.toString());
             return sb.toString(); 
        }
   else
   {
   
    System.out.println("Output from 'doCommand' "+ sb.toString());
    return sb.toString();
   }
}
 
public void doGet(HttpServletRequest request, HttpServletResponse response)    throws IOException, ServletException 
{     PrintWriter requestOutput = null;
      String resolvedFile =null;
    try  
    {   
       String file = request.getParameter("fileName");
       resolvedFile = doCommand("echo "+file).trim();
       File documentFile = new File(resolvedFile);
    FileInputStream fin = new FileInputStream(documentFile);
    if (resolvedFile.indexOf('/')!=-1)
      resolvedFile =  resolvedFile.substring(resolvedFile.lastIndexOf('/')+1)  ;
    response.setHeader("Content-disposition", "attachment; filename=" + resolvedFile);
    response.setContentType("application/octet-stream");
    response.setContentLength((int)documentFile.length());
    requestOutput = response.getWriter();
    int c;
    c = fin.read();
    while (c != -1) {
       requestOutput.write(c);
       c = fin.read();
       
   
   }
   fin.close();
 } 
 catch (Exception e) 
 {    if (requestOutput == null) 
    {     
       response.setContentType("text/html");     
       requestOutput = response.getWriter();    
 }    
   requestOutput.write("Error trying to get file : ");                       
   requestOutput.write(e.toString());    
   requestOutput.write("");   
 }   
   requestOutput.close();  
 } 
 public void doPost(HttpServletRequest request, HttpServletResponse response)    throws IOException, ServletException 
 {   
 doGet(request, response);  
 }
}  

Compile the file. Put it under $OA_JAVA on Application Node

Now we need to add servlet definition to OA web service configuration file. It is usually located under  $ORA_CONFIG_HOME/10.1.3/j2ee/oacore/application-deployments/oacore/html/orion-web.xml

Add the following to the servlet section

<servlet>
    <servlet-name>DownloadFile</servlet-name>
    <display-name>DownloadFile</display-name>
    <servlet-class>DownloadFile</servlet-class>
 </servlet> 
   <servlet-mapping>
      <servlet-name>DownloadFile</servlet-name>
      <url-pattern>/DownloadFile</url-pattern>
   </servlet-mapping> 

Save the file and restart OC4J service.

Now you can download any file located on the Application node simply by running http://<instance url>:<instance port>/OA_HTML/DownloadFile?fileName=/path_to_your_file. You can also use instance variables inside  the path, like http://<instance url>:<instance port>/OA_HTML/DownloadFile?fileName=$APPL_TOP/admin/myFile.txt