Jasper Report tidak tampil ketika project sudah di build/JAR

private void btnCetakActionPerformed(java.awt.event.ActionEvent evt)
{//GEN-FIRST:event_btnCetakActionPerformed
        // TODO add your handling code here:
        try{
            HashMap data=new HashMap();
            String buatLaporan=("./src/POSWorkshop/laporan/LapDataPembelian.jasper");
            JasperPrint cetak_laporan = JasperFillManager.fillReport(buatLaporan, data, conn);
            JasperViewer LaporanData=new JasperViewer(cetak_laporan, false);
            LaporanData.setTitle("Laporan Data Pembelian");
            LaporanData.setVisible(true);
        }catch(Exception e){
javax.swing.JOptionPane.showMessageDialog(rootPane, "Gagal Menampilkan Laporan");
    }       
    }

Silahkan ubah kodenya sperti  di bawah

        try{
            HashMap data=new HashMap();
            URL img = this.getClass().getClassLoader().getResource("persediaanbahan/gambar/logo.png");
            //File image = new
File("persediaanbahan/gambar/logo.png");
            data.put("logo",img);
            data.put("id_proyek",cbValue);
            InputStream buatLaporan = ClassLoader.getSystemResourceAsStream("persediaanbahan/laporan/LapPemPro.jasper"); 
            JasperPrint cetak_laporan = JasperFillManager.fillReport(buatLaporan, data, conn);
            JasperViewer LaporanData=new JasperViewer(cetak_laporan, false);
            LaporanData.setTitle("Laporan Data Pengeluaran Proyek");
            LaporanData.setVisible(true);
        }catch(Exception e){
            javax.swing.JOptionPane.showMessageDialog(rootPane,e);
        }