使用Jackson将JSON字符串转换为Java中的映射错误 [英] Error converting JSON string to map in Java using Jackson

问题描述

我有一小段代码，我正在尝试将JSON字符串转换为地图。

I have this little piece of code, and I'm trying to convert a JSON string to a map.

String json = "[{'code':':)','img':'<img src=/faccine/sorriso.gif>'}]";
ObjectMapper mapper = new ObjectMapper();
Map<String,String> userData = mapper.readValue(json,new TypeReference<HashMap<String,String>>() { });

但它返回以下错误：

org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.util.HashMap out of START_ARRAY token
 at [Source: java.io.StringReader@1b1756a4; line: 1, column: 1]
    at org.codehaus.jackson.map.JsonMappingException.from(JsonMappingException.java:163)
    at org.codehaus.jackson.map.deser.StdDeserializationContext.mappingException(StdDeserializationContext.java:198)
    at org.codehaus.jackson.map.deser.MapDeserializer.deserialize(MapDeserializer.java:151)
    at org.codehaus.jackson.map.deser.MapDeserializer.deserialize(MapDeserializer.java:25)
    at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2131)
    at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1402)
    at CodeSnippet_19.run(CodeSnippet_19.java:13)
    at org.eclipse.jdt.internal.debug.ui.snippeteditor.ScrapbookMain1.eval(ScrapbookMain1.java:20)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.eclipse.jdt.internal.debug.ui.snippeteditor.ScrapbookMain.evalLoop(ScrapbookMain.java:54)
    at org.eclipse.jdt.internal.debug.ui.snippeteditor.ScrapbookMain.main(ScrapbookMain.java:35)

什么是我做错了？

推荐答案

从我以前记得的杰克逊用于将json转换为java类 - 它可能是期待第一个对象读取为地图，如

From what I remember Jackson is used to convert json to java classes - it is probably expecting the first object is reads to be a map, like

String json = "{'code':':)','img':'<img src=/faccine/sorriso.gif>'}";

这篇关于使用Jackson将JSON字符串转换为Java中的映射错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！