我有以下两个类:
@JsonIgnoreProperties(ignoreUnknown = true)
public class ChangesJSON {
@JsonProperty("changes")
List<ChangeJSON> changes;
@JsonProperty("more")
Boolean more;
}
public class ChangeJSON {
@JsonProperty("epoch")
Long epoch;
@JsonProperty("payload")
Map<String, Object> payload;
}
当我尝试使用此测试反序列化时:
String test = "{\"changes\":[{\"epoch\":1441556306522,\"payload\":\"{\"to\":1}\"},{\"epoch\":1441555481524,\"payload\":\"{\"to\":-1}\"}],\"more\":false}";
@Test
public void myTest() {
ObjectMapper mapper = new ObjectMapper();
ChangesJSON result = null;
try {
result = mapper.readValue(test, ChangesJSON.class);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
assertNotNull(result);
}
我得到以下异常:
com.fasterxml.jackson.databind.JsonMappingException: Can not instantiate value of type java.util.LinkedHashMap from String value ('{'); no single-String constructor/factory method at [Source: {"changes":[{"epoch":1441556306522,"payload":"{"to":1}"},{"epoch":1441555481524,"payload":"{"to":-1}"}],"more":false}; line: 1, column: 35] (through reference chain: demo.ChangesJSON["changes"]->java.util.ArrayList[0]->demo.ChangeJSON["payload"])
map 似乎有问题,但我认为 Jackson 应该能够处理 map 。当我将 map 更改为 map 时,我也会遇到同样的问题。但我确实需要支持各种类作为 map 的值。
最佳答案
payload
对象有引号。尝试更改此部分:
\"payload\":\"{\"to\":1}\"
进入这个:
\"payload\":{\"to\":1}
关于java - 无法从字符串值 ('{' 实例化 java.util.LinkedHashMap 类型的值;没有单字符串构造函数/工厂方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/32432104/