springboot系列十: 自定义转换器，处理JSON，内容协商

在Spring Boot中，你可以通过实现HttpMessageConverter接口来创建自定义转换器，用于处理JSON数据。以下是一个简单的自定义转换器示例，它将实现HttpMessageConverter<MyObject>，其中MyObject是你想要转换的对象类型。

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
 
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
 
public class MyCustomConverter implements HttpMessageConverter<MyObject> {
 
    @Override
    public boolean canRead(Class<?> clazz, MediaType mediaType) {
        return MyObject.class.isAssignableFrom(clazz) && MediaType.APPLICATION_JSON.isCompatibleWith(mediaType);
    }
 
    @Override
    public boolean canWrite(Class<?> clazz, MediaType mediaType) {
        return MyObject.class.isAssignableFrom(clazz) && MediaType.APPLICATION_JSON.isCompatibleWith(mediaType);
    }
 
    @Override
    public List<MediaType> getSupportedMediaTypes() {
        return Arrays.asList(MediaType.APPLICATION_JSON);
    }
 
    @Override
    public MyObject read(Class<? extends MyObject> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
        // 实现从HttpInputMessage读取数据到MyObject的逻辑
        String json = new String(inputMessage.getBody(), StandardCharsets.UTF_8);
        // 这里只是示例，实际应该使用JSON解析库来解析json
        return new MyObject();
    }
 
    @Override
    public void write(MyObject myObject, MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
        // 实现将MyObject写入HttpOutputMessage的逻辑
        String json = "{\"property\":\"value\"}"; // 这里只是示例，实际应该使用JSON生成库来生成json
        outputMessage.getBody().write(json.getBytes(StandardCharsets.UTF_8));
    }
}

要注册自定义转换器，你可以在Spring Boot应用的配置类中添加如下代码：

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.