用杰克逊写yaml？

Question

I'm using Jackson to read and modify yaml files. Works great. I can't find the magic incantations needed to write the yaml, though.

ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
ObjectNode root = (ObjectNode)mapper.readTree(yamlFileIn);
// modify root here
mapper.writeValue(yamlFileOut, root); // writes json, not yaml. not sure why.

I'm sure it's some combination of writers, JsonGenerators, and something else. Anyone got sample code?

Answer 1

For v2.8.3 the following should work:

YAMLFactory yf = new YAMLFactory();
ObjectMapper mapper = new ObjectMapper(yf);
ObjectNode root = (ObjectNode) mapper.readTree(yamlFileIn);
// modify root here     
FileOutputStream fos = new FileOutputStream(yamlFileOut);
SequenceWriter sw = mapper.writerWithDefaultPrettyPrinter().writeValues(fos);
sw.write(root);

Answer 2

Try:

YAMLFactory yf = new YAMLFactory();
ObjectMapper mapper = new ObjectMapper(yf);
ObjectNode root = (ObjectNode) mapper.readTree(yamlFileIn);
// modify root here     
FileOutputStream fos = new FileOutputStream(yamlFileOut);
yf.createGenerator(fos).writeObject(root); // works. yay.