如何以编程方式编写nt：file [英] How to write an nt:file programmatically

问题描述

我正在尝试在动态创建的JCR中存储二进制数据。我的问题是，JCR API提供的唯一方法是通过 InputStream ：

 会话会话= request.getResourceResolver（）。adaptTo（Session.class）; 
 ValueFactory valueFactory = session.getValueFactory（）; 
 Binary bin = valueFactory.createBinary（is）; 
  

由于CQ / Sling是RESTful，我可以理解为什么会这样，因为您通常会收到一份表格或对其他来源的httprequest，您总是可以使用 InputStream 。但就我而言，我正在即时创建二进制文件，通常表示为 OutputStream 。

1. 在JCR API中还有其他方法可以忽略吗，在那里我可以直接在nt：file节点上创建 OutputStream ，就像 FileOutputStream ？


2. 如果否，是否有一种简单的方法将 OutpuStream 转换为 InputStream ？

我知道可以从Apache Commons获得另一种方法 IOUtils.copy（）。我在SO上看到了一些示例，这些示例仅使用 ByteArrayOutputStream.toByteArray（）创建 InputStream 。但是由于数据可能会变得很大，所以这不是一个好的解决方案。除了我尝试过，而且流还不完整，所以似乎有缓冲区限制。下一种方法是使用管道流，但是还有其他问题，我提出了另一个问题：多引号导致PipedOutputStream / OutputStreamWriter失败

编辑：
删除了PipedStream代码示例，因为我在另一个问题中发布了该问题的示例。所以在这里我仍然只是在寻找一种简单的方法来创建nt：file，其中输入不是 InputStream 。

解决方案

管道在这里是很好的解决方案。但是，为了正确实现它们，您必须使用两个线程：第一个应将数据写入 PipedOutputStream ，第二个应创建 Binary 从 PipedInputStream 并将其保存到JCR：

 最终PipedInputStream pis = new PipedInputStream（）; 
 final PipedOutputStream pos = new PipedOutputStream（pis）; 
 Executors.newSingleThreadExecutor（）。submit（new Runnable（）{
 @Override 
 public void run（）{
 try {
 OutputStreamWriter writer = new OutputStreamWriter（pos ）; 
 writer.append（追加一些数据）; 
 writer.close（）; 
} catch（IOException e）{
 e.printStackTrace（）; 
} 
} 
}）； 
 Binary二进制= session.getValueFactory（）。createBinary（pis）; 
 session.getNode（ / content / myNode）。setProperty（ xyz，二进制）; 
 session.save（）; 
  

在新线程中处理JCR的对称解决方案也很好。 p>

I'm trying to store binary data in JCR, which is created on the fly. My problem is that the only way provided by the JCR API is via an InputStream:

Session session = request.getResourceResolver().adaptTo(Session.class);
ValueFactory valueFactory = session.getValueFactory();
Binary bin = valueFactory.createBinary(is);

As CQ/Sling is RESTful I can see why this is the case as you usually get a form post or an httprequest to another source, where you always have an InputStream to use. But in my case I am creating the binary on the fly which usually is represented as an OutputStream.

1. Is there any other way I overlooked in the JCR API where I could create an OutputStream directly on the nt:file node, just like a FileOutputStream?
2. If no, is there an easy way to have an OutpuStream transformed to an InputStream?

I know the other way is available from the Apache Commons IOUtils.copy(). I've seen some examples on SO where they just use the ByteArrayOutputStream.toByteArray() to create an InputStream. But as the data could get rather large, this is not a good solution. Besides I tried it and somehow the stream was incomplete, so it seems there is a buffer limmit. The next approach was with piped streams, but there I have other problems to which I opened another question: Multiple quotes cause PipedOutputStream/OutputStreamWriter to fail

EDIT: Removed PipedStream code example as I posted the issue with it in another question. So here I am still just looking for an easy way to create an nt:file where the input is not an InputStream.

解决方案

Pipes are good solution here. However, in order to implement them properly, you have to use two threads: first should write data into the PipedOutputStream and the second should create a Binary from PipedInputStream and save it into JCR:

final PipedInputStream pis = new PipedInputStream();
final PipedOutputStream pos = new PipedOutputStream(pis);
Executors.newSingleThreadExecutor().submit(new Runnable() {         
    @Override
    public void run() {
        try {
            OutputStreamWriter writer = new OutputStreamWriter(pos);
            writer.append("append here some data");
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
});
Binary binary = session.getValueFactory().createBinary(pis);
session.getNode("/content/myNode").setProperty("xyz", binary);
session.save();

The symmetrical solution, in which you handle the JCR in the new thread would be also good.

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