java – 从Jackson JsonNode创建InputStream的最佳方法是什么？

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

具体来说,Apache HTTP客户端提供ByteArrayEntity以用于字节数组.对于其他用途,有一个ByteArrayInputStream.

当然,ObjectMapper应该只创建一次并重用.
>如果您真的希望以流方式编写JSON,则可以使用一对PipedInputStream和PipedOutputStream,但是,如JavaDoc所述

Typically,data is read from a PipedInputStream object by one thread and data is written to the corresponding PipedOutputStream by some other thread. Attempting to use both objects from a single thread is not recommended,as it may deadlock the thread.

例：

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) {
    ...
}