Copying files

[Scarlet Sphere]

Hi,

I am trying to export selected file from /home/user/ejbca/p12/pem folder to /home/user/Desktop/certs folder using a button in a web application. What would be the best way to do this?

[Eranga]

It is a file uploader then.

What are the technologies are you using?

[Scarlet Sphere]

I am trying to use a jsp page to copy certain files from one location to another with the click of a button. I tried

String cmd = "cp /home/user/ejbca/p12/pem/"+usernames[i]+".pem"+" /home/user/Desktop/certs/"; 
Process proc = Runtime.getRuntime().exec(cmd,null,null);

but it didn't work. Is there another way to do this?

[Eranga]

When comes to JSP, there are no cleaner way to copy files. However, Java I/O classes are enough powerful to write your own file copy.

With the use of File class initialize two handles for the source and destination. Same as using FileInputStream and FileOutputStream initialize streams for the job. Define a byte array to hold data (with the preferable size, smaller the better) and write to the destination through the source. You may do some validations like the destination folder path has write permissions and so on.

[Eranga]

but it didn't work. Is there another way to do this?

Did you come across any exception or like that?

[Scarlet Sphere]

When comes to JSP, there are no cleaner way to copy files. However, Java I/O classes are enough powerful to write your own file copy.

With the use of File class initialize two handles for the source and destination. Same as using FileInputStream and FileOutputStream initialize streams for the job. Define a byte array to hold data (with the preferable size, smaller the better) and write to the destination through the source. You may do some validations like the destination folder path has write permissions and so on.

I'm not really sure how to use FileInputStream and FileOutputStream to copy files.

[Scarlet Sphere]

Did you come across any exception or like that?

I got an error that said "cp" and cannot allocate memory. Something like that.

[Eranga]

I'm not really sure how to use FileInputStream and FileOutputStream to copy files.

Then you can start from here,

Lesson: Basic I/O (The Java™ Tutorials > Essential Classes)

Copying a File or Directory (The Java™ Tutorials > Essential Classes > Basic I/O)

[Scarlet Sphere]

I tried it but I am still unsure. I tried the file reader example and got:

Compiling 1 source file to /home/cbis/workspace/ejbca/modules/admin-gui/tmp-jasper/classes
    [javac] /home/cbis/workspace/ejbca/modules/admin-gui/tmp-jasper/jspc/org/apache/jasper/jspc/ra/listendentities_jsp.java:365: illegal start of expression
    [javac]                 throws IOException {
    [javac]                 ^
    [javac] /home/cbis/workspace/ejbca/modules/admin-gui/tmp-jasper/jspc/org/apache/jasper/jspc/ra/listendentities_jsp.java:365: not a statement
    [javac]                 throws IOException {
    [javac]                        ^

and 18 others. Is it not possible to just use runtime?

[Scarlet Sphere]

.....

[Eranga]

Check what you have written on

listendentities_jsp.java:365

[Scarlet Sphere]

Ant build was successful until I put the code in the middle which I got fromByte Streams (The Java™ Tutorials > Essential Classes > Basic I/O)

for(int i = 0; i < indexes.size(); i++){
                index = ((java.lang.Integer) indexes.elementAt(i)).intValue();
                usernames[i] = java.net.URLDecoder.decode(request.getParameter(HIDDEN_USERNAME+index),"UTF-8");
                name=usernames[i];

Added code:

throws IOException {

        FileInputStream in = null;
        FileOutputStream out = null;
        try {
            in = new FileInputStream(
                         "xanadu.txt");
            out = new FileOutputStream(
                         "outagain.txt");
            int c;

            while ((c = in.read()) != -1) {
                out.write(c);
            }

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

}

When I remove the "throws IOException", it gives another error:

[javac] Compiling 1 source file to /home/cbis/workspace/ejbca/modules/admin-gui/tmp-jasper/classes
    [javac] /home/cbis/workspace/ejbca/modules/admin-gui/tmp-jasper/jspc/org/apache/jasper/jspc/ra/listendentities_jsp.java:5197: 'catch' without 'try'
    [javac]     } catch (Throwable t) {
    [javac]       ^
    [javac] /home/cbis/workspace/ejbca/modules/admin-gui/tmp-jasper/jspc/org/apache/jasper/jspc/ra/listendentities_jsp.java:5197: ')' expected
    [javac]     } catch (Throwable t) {
    [javac]                       ^

and 15 others. I'm not sure what is wrong here.

[Eranga]

Is it possible to post the complete code here?

[Scarlet Sphere]

Its too long to post the complete code but this is the part which I am modifying:

if( request.getParameter(BUTTON_EXPORT_CERTS) != null){
    	  editbuttonpressed=true;
          java.util.Enumeration parameters = request.getParameterNames();
          java.util.Vector indexes = new  java.util.Vector();
          int index;
          while(parameters.hasMoreElements()){
           String parameter = (String) parameters.nextElement();
            if(parameter.startsWith(CHECKBOX_SELECT_USER) && request.getParameter(parameter).equals(CHECKBOX_VALUE)) {
              index = java.lang.Integer.parseInt(parameter.substring(CHECKBOX_SELECT_USER.length())); //Without []
              indexes.addElement(Integer.valueOf(index));
            }
          }
          String name = "";
          //Process proc;
          if(indexes.size() > 0){
              String[] usernames = new String[indexes.size()];
              for(int i = 0; i < indexes.size(); i++){
                index = ((java.lang.Integer) indexes.elementAt(i)).intValue();
                usernames[i] = java.net.URLDecoder.decode(request.getParameter(HIDDEN_USERNAME+index),"UTF-8");
                name=usernames[i];
//////////////////////////////////////Added
                throws IOException {

                 FileInputStream in = null;
                 FileOutputStream out = null;
                 try {
                   in = new FileInputStream(
                         "xanadu.txt");
                   out = new FileOutputStream(
                         "outagain.txt");
                   int c;

                   while ((c = in.read()) != -1) {
                       out.write(c);
                   }
                 }      
                finally {
                   if (in != null) {
                     in.close();
                   }
                   if (out != null) {
                     out.close();
                   }
                }
/////////////////////////////////////            
            }
        }
          //String cmd = "cp /home/cbis/ejbca/p12/pem/"+"User2.pem"+" /home/cbis/Desktop/certs/"; 
          //Process proc = Runtime.getRuntime().exec(cmd,null,null);
      }