JSON parse error: Cannot deserialize instance of `java.util.ArrayList` out of VALUE_STRING token

一例JSON数组转化错误记录

错误信息如下:

org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize instance of `java.util.ArrayList` out of VALUE_STRING token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.util.ArrayList` out of VALUE_STRING token
 at [Source: (PushbackInputStream); line: 1, column: 56]

传入的 JSON 字符串是:

{"role":"product_engineer","user_id":"2","permissions":"[]"}

对应的类是:
public class UserPermissionParam {

    private Integer user_id;

    private List permissions;

    private String role;

}

经过一系列的排查和对比,发现是多了两个双引号,见红色部分:

{"role":"product_engineer","user_id":"2","permissions":"[]"}

用org.json 包构建这个json串的permissions部分时,没有使用jsonArray,而使用了jsonObject+StringBuild,导致了错误的串。

改用JsonArray后OK。

 

 

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