基于Java代码的PDF文件索引检索

我试图用Java代码在弹性搜索6.3.2中索引PDF文件。到目前为止,我已经编写了以下代码来将PDF保存在ES中。代码运行良好,我可以将PDF的base64编码字符串保存在es中。我想知道我所采用的方法是否正确?有更好的方法吗? 以下是我的代码:

            InputStream inputStream = new FileInputStream(new File("mypdf.pdf"));
        try {
            byte[]  fileByteStream = IOUtils.toByteArray(inputStream );
            String base64String = new String(Base64.getEncoder().encodeToString(fileByteStream).getBytes(),"UTF-8");
            String strEncoded = Base64.getEncoder().encodeToString( base64String.getBytes( "utf-8" ));
            this.stream.close();

                    JSONObject correspondenceNode = new JSONObject(); 
                    correspondenceNode.put("data",strEncoded );

                    String strSsonValues = correspondenceNode.toString();
                    HttpEntity entity = new NStringEntity(strSsonValues , ContentType.APPLICATION_JSON);
                    elasticrestClient.put("/2018/documents/"1, entity);

        } catch (IOException e) {
            e.printStackTrace();
        }

基本上,我在这里做的是,我将PDF文档转换成base64string,并将其保存为es,在阅读时,我将它转换回来。

以下是解码代码:

String responseBody = elasticrestClient.get("/2018/documents/1");
//some code to fetch the hits
JSONObject h = hitsArray.getJSONObject(0);
source = h.getJSONObject("_source");
String object = (source.getString("data"));
byte[] decodedStr = Base64.getDecoder().decode( object );

FileOutputStream fos = new FileOutputStream("download.pdf");
fos.write(Base64.getDecoder().decode(new String( decodedStr, "utf-8" )));
fos.close();