我使用的是Jackson,我想漂亮地打印JSON,使数组中的每个元素都指向每一行,比如:
{"foo":"bar","废话":[1.2.3.]}
将SerializationFeature.INDENT_OUTPUT
设置为true只为对象字段插入换行符,而不是数组元素,而是以这种方式打印对象:
{"foo":"bar","废话":[1,2,3]}
有人知道如何做到这一点吗?谢谢
如果不想扩展DefaultPrettyPrinter
,也可以从外部设置indentArraysWith
属性:
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.enable(SerializationFeature.INDENT_OUTPUT);
DefaultPrettyPrinter prettyPrinter = new DefaultPrettyPrinter();
prettyPrinter.indentArraysWith(DefaultIndenter.SYSTEM_LINEFEED_INSTANCE);
String json = objectMapper.writer(prettyPrinter).writeValueAsString(object);
多亏了这些有用的提示,我能够用所需的缩进配置我的ObjectMapper
,如下所示:
private static class PrettyPrinter extends DefaultPrettyPrinter {
public static final PrettyPrinter instance = new PrettyPrinter();
public PrettyPrinter() {
_arrayIndenter = Lf2SpacesIndenter.instance;
}
}
private static class Factory extends JsonFactory {
@Override
protected JsonGenerator _createGenerator(Writer out, IOContext ctxt) throws IOException {
return super._createGenerator(out, ctxt).setPrettyPrinter(PrettyPrinter.instance);
}
}
{
ObjectMapper mapper = new ObjectMapper(new Factory());
mapper.configure(SerializationFeature.INDENT_OUTPUT, true);
}
您可以扩展DefaultPrettyPrinter,并覆盖方法beforeArrayValues(…)和writeArrayValueSeparator(…)[/em>,以归档所需的行为。之后,您必须通过setPrettyPrinter(…)将新的实现添加到JsonGenerator中。
映射器可以配置(jackson-2.6):
ObjectMapper mapper = ...
DefaultPrettyPrinter prettyPrinter = new DefaultPrettyPrinter();
prettyPrinter.indentArraysWith(DefaultIndenter.SYSTEM_LINEFEED_INSTANCE);
mapper.setDefaultPrettyPrinter(prettyPrinter);
//use mapper
感谢OP提供的答案显示了从writeValueAsString
获得每行格式化JSON String
的单个数组元素的方法。在此基础上,提出了一种将相同格式的JSON直接写入writeValue
文件的解决方案,代码更少:
private static class PrettyPrinter extends DefaultPrettyPrinter {
public static final PrettyPrinter instance = new PrettyPrinter();
public PrettyPrinter() {
_arrayIndenter = Lf2SpacesIndenter.instance;
}
}
{
ObjectMapper mapper = new ObjectMapper();
ObjectWriter writer = mapper.writer(PrettyPrinter.instance);
writer.writeValue(destFile, objectToSerialize);
}
试用JSON生成器。。。
API参考
的好例子