java jackson 中的意外字符（'\'（代码 92））
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Unexpected character ('\' (code 92)) in Hymanson
提问by basit raza
Am facing issue while parsing JSON string with Hymanson in some cases.
在某些情况下，使用 Hymanson 解析 JSON 字符串时遇到问题。
String jsonString = "{\"Age\":40, \"Name\":\"Sample User\"}";
ObjectMapper mapper = new ObjectMapper();
mapper.readValue(jsonString,JsonNode.class);
System.out.println(jsonstirng)
{"Age":40, "Name":"Sample User"}
Above code works well when I pass jsonStringvalue.
当我传递jsonString值时，上面的代码运行良好。
In some cases I need to escape invalid string characters like ",'etc
在某些情况下，我需要转义无效的字符串字符",'等
For escaping I am using ApacheStringEscapeUtils.
为了逃避，我正在使用ApacheStringEscapeUtils。
String escapedString = StringEscapeUtils.escapeJson(jsonStirng);
Escaped String output
转义字符串输出
{\"Age\":40,\"Name\":\"Sample User\"}
When I pass escapedString to mapperits throw Unexpected character exception.
当我将 escapedString 传递给mapper它的 throw 意外字符异常时。
ObjectMapper mapper = new ObjectMapper();
mapper.readValue(escapedString,JsonNode.class);
Exception
例外
Unexpected character ('\' (code 92)): was expecting double-quote to start field name
Actually Am parsing ModSecurity audit logs. Response body of audit log has (html,css,javascript etc) stuff that's why I need to escape JSON string other wise its breaks the JSON format.
实际上是解析 ModSecurity 审计日志。审核日志的响应正文具有（html、css、javascript 等）内容，这就是为什么我需要转义 JSON 字符串，否则它会破坏 JSON 格式。
回答by Peter Lawrey
The purpose of escaping a String is to make it unparsable as piece of JSON.
转义字符串的目的是使其无法解析为 JSON。
In your cause you are replacing all the "with \"so that it can be used inside a String value and the parser will NOT see it as part of the JSON.
在您的原因中，您将所有的替换为"with，\"以便它可以在字符串值中使用，并且解析器不会将其视为 JSON 的一部分。
e.g. this is just one field and value;
例如，这只是一个字段和值；
"myJson": "{\"Age\":40,\"Name\":\"Sample User\"}"
what you can't do is the following which is why you need this method. It can't tell the difference between "which starts/ends the string and the "inside the string.
您不能做的是以下这就是您需要此方法的原因。它无法分辨"哪个开始/结束字符串和"字符串内部之间的区别。
"myJson": "{"Age":40,"Name":"Sample User"}"
If you then try to parse this escaped String, it shouldn't be able to parse it.
如果您随后尝试解析此转义字符串，它应该无法解析它。
EDIT: Here is an example
编辑：这是一个例子
String text = "{\"Age\":40,\"Name\":\"Sample User\"}";
String escaped = StringEscapeUtils.escapeJson(text);
System.out.println("escaped= " + escaped);
String unescaped = StringEscapeUtils.unescapeJson(escaped);
System.out.println("unescaped= " + unescaped);
prints
印刷
escaped= {\"Age\":40,\"Name\":\"Sample User\"}
unescaped= {"Age":40,"Name":"Sample User"}
you can see that the escaped string has \"however the unescaped string doesn't. If you are still seeing \I would assume the String hasn't been unescaped.
你可以看到转义的字符串有\"但未转义的字符串没有。如果您仍然看到\我会假设 String 没有被转义。
