Burp Suite base64 encoder gist

BurpExtender.java

package burp;

import java.awt.*;
import java.io.PrintWriter;
import java.util.List;

public class BurpExtender implements IBurpExtender, IMessageEditorTabFactory {
    private IBurpExtenderCallbacks callbacks;
    private PrintWriter stdout;
    private IExtensionHelpers helpers;
    @Override
    public void registerExtenderCallbacks(IBurpExtenderCallbacks callbacks) {
        this.callbacks = callbacks;
        callbacks.setExtensionName("Test Extension");

        callbacks.registerMessageEditorTabFactory(this);
        helpers = callbacks.getHelpers();

        stdout = new PrintWriter(callbacks.getStdout(), true);
        stdout.println("Hello test");

    }
    @Override
    public IMessageEditorTab createNewInstance(IMessageEditorController iMessageEditorController, boolean editable) {
        return new Base64Encoder(iMessageEditorController, false);
    }

     class Base64Encoder implements IMessageEditorTab{


         private boolean editable;
         private ITextEditor txtInput;
         private byte[] currentMessage;

         public Base64Encoder(IMessageEditorController controller, boolean editable)
         {
             this.editable = editable;
             txtInput = callbacks.createTextEditor();
             txtInput.setEditable(editable);
         }
         @Override
         public String getTabCaption() {
             return "base64encoder";
         }

         @Override
         public Component getUiComponent() {
             return txtInput.getComponent();
         }

         @Override
         public boolean isEnabled(byte[] content, boolean isRequest) {
             return isRequest;
         }

         @Override
         public void setMessage(byte[] content, boolean isRequest) {
             IRequestInfo analyzedRequest = helpers.analyzeRequest(content);
             //if request has parameter
             if (isRequest && !analyzedRequest.getParameters().isEmpty())
             {
                
                 String urlencodedValue = new String();
                 //get all query string parameter
                 List<IParameter> parameter = analyzedRequest.getParameters();
                 for (IParameter param : parameter) {
                     urlencodedValue += param.getName() + "=";
                     urlencodedValue += param.getValue() + "&";
                 }
                 //remove the "&" at the end of the string
                 urlencodedValue = urlencodedValue.replaceAll("&$", "");

                 txtInput.setText(helpers.base64Encode(urlencodedValue).getBytes());
                 txtInput.setEditable(editable);
             }
             else
             {
                 // clear our display
                 txtInput.setText(null);
                 txtInput.setEditable(false);
             }

             // remember the displayed content
             currentMessage = content;
         }

         @Override
         public byte[] getMessage() {
             return currentMessage;
         }

         @Override
         public boolean isModified() {
             return txtInput.isTextModified();
         }

         @Override
         public byte[] getSelectedData() {
             return txtInput.getSelectedText();
         }
     }
}