在 Springboot 中使用 Jackson2 进行反序列化 application/json 响应只是 "A String"

Question

我在我的 Springboot 应用程序中调用外部 API 并使用 MappingJackson2HttpMessageConverter 转换 application/json 响应，但我运行变成问题作为响应只是 "Some message indicating success/failure" 而不是像 { 'property': 'value' }.

这样更典型的 JSON 对象

我具体得到的错误是：

JSON parse error: Cannot construct instance of `<custom class>` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('Bundle is not available'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `<custom class>` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('Bundle is not available')\n at [Source: (ByteArrayInputStream); line: 1, column: 1]

仅供参考，我配置JSON解串器的代码是这样的：

public List<HttpMessageConverters<?>> getConverters() {
    List<HttpMessageConverter<?>> converters = new ArrayList<>();
    
    MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
    converter.setSupportedMediaTypes(Collections.singletonList(MediaType.ALL));
    converters.add(converter);

    return converters;
}

我想知道如何配置 MappingJackson2HttpMessageConverter 以支持裸字符串？

Answer 1

所以我通过编写自己的消息转换器解决了这个问题。类似于：

class StringConverter extends AbstractJsonHttpMessageConverter {
    @Override
    protected Object readInternal(Type type, Reader reader) throws Exception {
        int currentChar;
        StringBuilder str = new StringBuilder();
        while((currentChar = reader.read()) != -1) {
            str.append((char) currentChar);
        }
        ObjectMapper om = new ObjectMapper();
        return objectMapper.readValue(str.toString(), Object.class);
    }

    @Override
    protected void writeInternal(Object o, Type type, Writer writer) throws Exception {
        // not required for my use case
    }
}

有了这个，字符串响应被存储在字符串类中，JSON 响应被放入链接的哈希映射中。如果有人有更好的方法来解决这个问题，请 post 因为我确信这远不是最好的方法。

在 Springboot 中使用 Jackson2 进行反序列化 application/json 响应只是 "A String"

Deserializing using Jackson2 in Springboot an application/json response that is just "A String"

java

json

jackson

spring-boot

jackson2