自定义HttpMessageConverter

自定义HttpMessageConverter

HttpMessageConverter是用来处理request和response里的数据的。Spring内置了很多HttpMessageConverter，比如MappingJackson2HttpMessageConverter，StringHttpMessageConverter等。

package com.yidian.data.exptmgr.utils;

import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;
import com.data.yidian.commons.utils.FastJsonUtils;
import com.yidian.data.exptmgr.entity.DumpSettings;
import com.yidian.data.exptmgr.entity.SettingInfo;
import com.yidian.data.exptmgr.model.exptsetting.SettingInfoRequest;
import org.apache.commons.io.Charsets;
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 static com.yidian.data.exptmgr.enums.AppType.MODELDUMP;
import static com.yidian.data.exptmgr.enums.AppType.TRAINING;

/**
 * @author wangyong
 * @date 2019/1/30
 */
public class SettingConverter extends AbstractHttpMessageConverter<SettingInfoRequest> {
    /**
     * 定义字符编码，防止乱码
     */
    private static final Charset DEFAULT_CHARSET = Charsets.UTF_8;

    /**
     * 新建自定义的媒体类型
     */
    public SettingConverter() {
        super(new MediaType("application", "json", DEFAULT_CHARSET));
    }

    /**
     * 表明只处理Settings这个类
     */
    @Override
    protected boolean supports(Class<?> aClass) {
        return SettingInfoRequest.class.isAssignableFrom(aClass);
    }

    /**
     * 重写readInternal方法，处理请求的数据
     */
    @Override
    protected SettingInfoRequest readInternal(Class<? extends SettingInfoRequest> aClass, HttpInputMessage httpInputMessage) throws IOException, HttpMessageNotReadableException {
        final String temp = StreamUtils.copyToString(httpInputMessage.getBody(), DEFAULT_CHARSET);
        if (temp.contains(TRAINING.name())) {
            return JSONObject.parseObject(temp, new TypeReference<SettingInfoRequest<SettingInfo>>(){});
        } else if (temp.contains(MODELDUMP.name())) {
            return JSONObject.parseObject(temp, new TypeReference<SettingInfoRequest<DumpSettings>>(){});
        }
        return null;
    }

    /**
     * 重写writeInternal，处理如何输出数据到response
     */
    @Override
    protected void writeInternal(SettingInfoRequest request, HttpOutputMessage httpOutputMessage) throws IOException, HttpMessageNotWritableException {
        final String out = FastJsonUtils.toJSONString(request);
        StreamUtils.copy(out, DEFAULT_CHARSET, httpOutputMessage.getBody());
    }
}

配置自定义Converter

package com.yidian.data.exptmgr.config;

import com.yidian.data.exptmgr.utils.SettingConverter;
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.WebMvcConfigurerAdapter;

import java.util.List;

/**
 * WebMVC配置
 * @author wangyong
 * @date 2018/11/12
 * @since 0.0.1-SNAPSHOT
 */
@Configuration
public class AlphaWebConfig extends WebMvcConfigurerAdapter {

    /**
     * 添加自定义的httpMessageConverter
     */
    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(messageConverter());
    }

    @Bean
    public SettingConverter messageConverter(){
        return new SettingConverter();
    }

}