聊聊springboot中如何自定义消息转换器

public interface HttpMessageConverter<T> {
    boolean canRead(Class<?> clazz, @Nullable MediaType mediaType);
    boolean canWrite(Class<?> clazz, @Nullable MediaType mediaType);
    List<MediaType> getSupportedMediaTypes();
    default List<MediaType> getSupportedMediaTypes(Class<?> clazz) {
        return !this.canRead(clazz, (MediaType)null) && !this.canWrite(clazz, (MediaType)null) ? Collections.emptyList() : this.getSupportedMediaTypes();
    }
    T read(Class<? extends T> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException;
    void write(T t, @Nullable MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException;
}

import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.support.config.FastJsonConfig;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.lang.NonNull;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
public class FastJsonHttpMessageConverter extends AbstractHttpMessageConverter<Object> {
    private final FastJsonConfig fastJsonConfig = new FastJsonConfig();
    public FastJsonHttpMessageConverter() {
        // 支持多种媒体类型
        List<MediaType> supportedMediaTypes = new ArrayList<>();
        supportedMediaTypes.add(MediaType.APPLICATION_JSON);
        supportedMediaTypes.add(new MediaType("application", "*+json"));
        setSupportedMediaTypes(supportedMediaTypes);
        // 配置FastJson
        fastJsonConfig.setDateFormat("yyyy-MM-dd HH:mm:ss");
        fastJsonConfig.setCharset(StandardCharsets.UTF_8);
    }
    @Override
    protected boolean supports(@NonNull Class<?> clazz) {
        return true; // 支持所有类型
    }
    @Override
    protected Object readInternal(
            @NonNull Class<?> clazz,
            @NonNull HttpInputMessage inputMessage
    ) throws IOException, HttpMessageNotReadableException {
        try (InputStream in = inputMessage.getBody()) {
            return JSON.parseObject(
                    in,
                    fastJsonConfig.getCharset(),
                    clazz,
                    fastJsonConfig.getFeatures()
            );
        } catch (Exception e) {
            throw new HttpMessageNotReadableException(
                    "JSON parse error: " + e.getMessage(),
                    inputMessage
            );
        }
    }
    @Override
    protected void writeInternal(
            @NonNull Object object,
            @NonNull HttpOutputMessage outputMessage
    ) throws IOException, HttpMessageNotWritableException {
        try (OutputStream out = outputMessage.getBody()) {
            JSON.writeTo(
                    out,
                    object,
                    fastJsonConfig.getCharset(),
                    fastJsonConfig.getFeatures(),
                    fastJsonConfig.getFilters(),
                    fastJsonConfig.getDateFormat(),
                    JSON.DEFAULT_GENERATE_FEATURE,
                    fastJsonConfig.getWriterFeatures()
            );
        } catch (Exception e) {
            throw new HttpMessageNotWritableException(
                    "JSON write error: " + e.getMessage(),
                    e
            );
        }
    }
    public FastJsonConfig getFastJsonConfig() {
        return fastJsonConfig;
    }
    public void setFastJsonConfig(FastJsonConfig fastJsonConfig) {
        this.fastJsonConfig.setDateFormat(fastJsonConfig.getDateFormat());
        this.fastJsonConfig.setCharset(fastJsonConfig.getCharset());
        this.fastJsonConfig.setFeatures(fastJsonConfig.getFeatures());
        this.fastJsonConfig.setReaderFeatures(fastJsonConfig.getReaderFeatures());
        this.fastJsonConfig.setWriterFeatures(fastJsonConfig.getWriterFeatures());
        this.fastJsonConfig.setFilters(fastJsonConfig.getFilters());
    }
}

import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import java.util.List;
@Configuration
public class FastJsonWebConfig implements WebMvcConfigurer {
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        // 创建FastJson消息转换器
        FastJsonHttpMessageConverter fastJsonConverter = new FastJsonHttpMessageConverter();
        // 可以在这里进一步配置FastJson
        // fastJsonConverter.getFastJsonConfig().setDateFormat("yyyy-MM-dd");
        // 将FastJson转换器添加到转换器列表的最前面
        converters.add(0, fastJsonConverter);
    }
}