英文:
Jackson XmlMaaper fails to decode null Double
问题
我遇到了一个奇怪的Jackson问题。XmlMapper无法反序列化自身序列化的内容。
而且只有在Double数组中有null时才会出现错误。下面是重现此问题的示例测试案例：
@Test
public void testDerSer(){
Double[] testDouble = new Double[]{null, null, null, 3.0d, 34.5d};
try {
ObjectMapper xmlMapper = new XmlMapper();
byte[] bytes = xmlMapper.writeValueAsBytes(testDouble);
System.out.println(new String(bytes));
Double[] doubles = xmlMapper.readValue(bytes, Double[].class);
System.out.println(doubles);
}
catch (IOException e) {
e.printStackTrace();
}
}
序列化的数据如下：
<Doubles><item/><item/><item/><item>3.0</item><item>34.5</item></Doubles>
错误信息为：
com.fasterxml.jackson.databind.exc.MismatchedInputException: 无法从START_OBJECT标记中反序列化`java.lang.Double`的实例
英文:
I’m experiencing a strange Jackson issue. The XmlMapper could not deserialize what is serialized by itself.
And the error only occurs when there’re nulls in the Double array. A sample test case to reproduce the issue is below:
@Test
public void testDerSer(){
Double[] testDouble = new Double[]{null, null, null, 3.0d, 34.5d};
try {
ObjectMapper xmlMapper = new XmlMapper();
byte[] bytes = xmlMapper.writeValueAsBytes(testDouble);
System.out.println(new String(bytes));
Double[] doubles = xmlMapper.readValue(bytes, Double[].class);
System.out.println(doubles);
}
catch (IOException e) {
e.printStackTrace();
}
}
The serialized payload looks like this:
<Doubles><item/><item/><item/><item>3.0</item><item>34.5</item></Doubles>
And the error is:
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.lang.Double` out of START_OBJECT token
答案1
得分: 1
如果将Double[]替换为ArrayList，你会得到结果：
xmlMapper.readValue(bytes, ArrayList.class)
然后你会得到：
[{}, {}, {}, 3.0, 34.5]
英文:
If you replace Double[] with ArrayList you get result
xmlMapper.readValue(bytes, ArrayList.class)
then you get
[{}, {}, {}, 3.0, 34.5]
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