Java – what is the best way to create an InputStream from Jackson jsonnode?

I want to find the smartest way to create the Java library Jackson's jsonnode's InputStream

So far, I have done:

IoUtils.toInputStream(jsonNode.toString());

However, this method converts jsonnode to string before creating InputStream

unwanted:

org.apache.http.entity.InputStreamEntity entity = new InputStreamEntity(IoUtils.toInputStream(jsonNode.toString()));

Solution

>In most cases, if you use objectmapper to directly generate byte arrays, JSON will be written as UTF - 8 and some memory can be saved

ObjectMapper objectMapper = new ObjectMapper();
JsonNode json = ...; 
byte[] bytes = objectMapper.writeValueAsBytes(json);

Specifically, the Apache HTTP client provides bytearrayentity for byte arrays For other purposes, there is a bytearrayinputstream

Of course, objectmapper should only be created once and reused. > If you really want to write JSON as a stream, you can use a pair of pipedinputstream and pipedoutputstream, but as described in Javadoc

Example:

ObjectMapper objectMapper = new ObjectMapper();
JsonNode json = ...; 

PipedInputStream in = new PipedInputStream();

new Thread(() -> {
    try {
        IoUtils.copy(in,System.out);
    } catch (IOException e) {
        ...
    }
}).start();

try (
    PipedOutputStream out = new PipedOutputStream(in);
    JsonGenerator gen = objectMapper.getFactory().createGenerator(out);
) {
    gen.writeTree(json);
} catch (IOException e) {
    ...
}