Java Jackson JSON ObjectMapper.readvalue
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Hymanson JSON ObjectMapper.readvalue
提问by chipmunk
I'm going through code examples on converting the Java object to a JSON and I came across this:
我正在查看将 Java 对象转换为 JSON 的代码示例，我遇到了这个：
HashMap<String, Object> filters = new ObjectMapper().readValue(filterStr, HashMap.class);
where
在哪里
String filterStr;
sorry, but what exactly is the above line of code doing? I went through other example here.I can see that readValue() has been overridden but how can a string be converted to a HashMap? Shouldn't it be a JSON object and not a string? Thanks.
抱歉，上面这行代码到底在做什么？我在这里经历了其他例子。我可以看到 readValue() 已被覆盖，但是如何将字符串转换为 HashMap？它不应该是一个 JSON 对象而不是一个字符串吗？谢谢。
采纳答案by Nikhil Talreja
ObjectMapper().readValue()
is overloaded to do several types of conversions.
被重载以进行多种类型的转换。
If the filterStr is compatible to be converted to a HashMap this will method will do it.
如果 filterStr 兼容转换为 HashMap，则此方法将执行此操作。
E.g. filterStr = "{\"name\":\"Tom\", \"age\":\"25\"}";will give a map with key-value pairs as {age=25, name=Tom}
例如filterStr = "{\"name\":\"Tom\", \"age\":\"25\"}";将给出一个键值对为 {age=25, name=Tom} 的映射
