如何在 spring-boot 中注册自定义 HttpMessageConvertor? [英] How to register a custom HttpMessageConvertor in spring-boot?

问题描述

我正在使用 spring-boot REST 服务，它需要将传入的 json 字段转换为自定义实体.但我无法让自定义转换器工作.

I am using spring-boot REST service and it need to transform incoming json field to custom entities. But I am not able to get the custom converter working.

我确定我在这里遗漏了一些非常明显的东西，但无法弄清楚是什么！

I am sure I am missing something very obvious here but can't figure out what!

我有以下 JSON，我想将其转换为项目实体

I have the following JSON which I want to convert into Item Entity

{
    'item_name':'some item name',
    'item_category':'some item catagory',
    'status_date_flag':'T',
    'item_sale_date':'2015-10-28' 
} 

物品实体

class Item{

    private String itemName;
    private String catagory;
    private boolean isDateFlagOn;
    private LocalDate saleDate;

    //...
    //public getters/setters
}

我创建了一个自定义消息转换器

I have created a custom message converter

@Component
public class ItemMessageConverter extends AbstractHttpMessageConverter<Item> {

    public ProductMessageConverter() {
        super(MediaType.ALL);
    }

    @Override
    protected boolean supports(Class<?> clazz) {
        return clazz.getSimpleName().equalsIgnoreCase(Item.class.getSimpleName());
    }

    @Override
    protected Product readInternal(Class<? extends Item> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
         System.out.println("readInternal GETTING called......................");

        return null;
    }

    @Override
    protected void writeInternal(Product product, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
        System.out.println("writeInternal GETTING called......................");
    }
}

我已经创建了一个用于注册 HttpMessageConverter 的配置类

I have created a configuration class for registering the HttpMessageConverter

@Configuration
public class MyBootConfiguration {
    @Bean public HttpMessageConverters customConverters(){
        HttpMessageConverter itemMessageConverter = new ItemMessageConverter();
        return new HttpMessageConverters(itemMessageConverter);
    }

}

推荐答案

您尝试做的事情可以通过自定义 Jackson 转换器来实现.像这样更改您的 Item 类定义:

What you are trying to do is achievable by a custom Jackson converter. Change your Item class definition like this:

import com.fasterxml.jackson.databind.annotation.JsonDeserialize;

@JsonDeserialize(using = ItemDeserializer.class)
public class Item {
    private String itemName;
    private String category;
    private boolean isDateFlagOn;
//constructor, getters and setters
}

注解表明这个类应该通过ItemDeserializer反序列化，这里是它的实现:

The annotation indicates this class should be deserialized via ItemDeserializer, here is the implementation of it:

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.JsonNode;

import java.io.IOException;
import java.util.Objects;

public class ItemDeserializer extends JsonDeserializer {
    @Override
    public Object deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
        JsonNode node = jsonParser.getCodec().readTree(jsonParser);
        String itemName = node.get("itemName").textValue();
        String category = node.get("category").textValue();
        String flagStr = node.get("isDateFlagOn").textValue();

        return new Item(itemName, category, Objects.equals(flagStr, "T"));
    }
}

此代码在具有以下处理程序的 Spring 4.2 中工作正常:

This code works fine in Spring 4.2 with following handler:

@Controller
public class GreetingController {
    @RequestMapping("jsonGreeting")
    public ResponseEntity jsonGreeting(@RequestBody Item item, BindingResult result) throws Exception {
        if (result.hasErrors()){
            return ResponseEntity.badRequest().body("parse error: " + result.getAllErrors().toString());
        }
        return ResponseEntity.ok(item.toString());
    }
}

这篇关于如何在 spring-boot 中注册自定义 HttpMessageConvertor?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！