SpringBoot: 自定义HttpMessageConverter

一、定义类继承自AbstractHttpMessageConverter

package cn.edu.tju.config;

import cn.edu.tju.UserInfo;
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.util.StreamUtils;

import java.io.IOException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;

public class MyHttpMessageConverter extends AbstractHttpMessageConverter<UserInfo> {
    public MyHttpMessageConverter() {
        super(new MediaType("application", "amadeus", Charset.forName("UTF-8")));
    }
    @Override
    protected boolean supports(Class<?> clazz) {
        return UserInfo.class.isAssignableFrom(clazz);
    }

    @Override
    protected UserInfo readInternal(Class<? extends UserInfo> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
        String temp = StreamUtils.copyToString(inputMessage.getBody(), Charset.forName("UTF-8"));
        String[] stringArray = temp.split("-");
        UserInfo userInfo= new UserInfo();
        userInfo.setUsername(stringArray[0]);
        userInfo.setPassword(stringArray[1]);
        return userInfo;
    }

    @Override
    protected void writeInternal(UserInfo userInfo, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
        String stringToWrite=userInfo.getUsername()+":"+userInfo.getPassword();
        outputMessage.getBody().write(stringToWrite.getBytes());
    }

/*    @Override
    public List<MediaType> getSupportedMediaTypes(Class<?> clazz) {
        MediaType mediaType = new MediaType("application", "amadeus", Charset.forName("UTF-8"));
        List<MediaType> mediaTypeList=new ArrayList<>();
        mediaTypeList.add(mediaType);
        return mediaTypeList;
    }*/
}

其中构造方法中super(new MediaType(“application”, “amadeus”, Charset.forName(“UTF-8”)));指定了要处理的请求头的类型为：
application/amadeus;charset=utf-8
二、将上述converter注册到Spring Mvc

package cn.edu.tju.config;

import org.springframework.context.annotation.Bean;
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 MyWebMvcConfig implements WebMvcConfigurer {

    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(converter());
    }

    @Bean
    public MyHttpMessageConverter converter() {
        return new MyHttpMessageConverter();
    }

}

三、请求时设定请求头：

四、定义controller

@RequestMapping("/info4")
    public UserInfo info4(@RequestBody UserInfo info) {
        UserInfo userInfo=new UserInfo();
        String prefix="[pre]";
        userInfo.setUsername(prefix+info.getUsername());
        userInfo.setPassword(prefix+info.getPassword());
        return userInfo;
    }

五、请求和响应：