springmvc 通过AbstractHttpMessageConverter自定义返回

场景:公司使用springmvc @ResponseBody返回json,由于接口数据比较多,需要对数据进行一次压缩

解决方案:

1.通过继承 AbstractHttpMessageConverter,重写 writeInternal,处理需要返回的数据

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.hhly.base.util.GzipUtil;
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 java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.charset.Charset;

public class JsonZipMessageConvert extends AbstractHttpMessageConverter<Object> {

    public final static Charset UTF8 = Charset.forName("UTF-8");

    private Charset charset = UTF8;

    private SerializerFeature[] features = new SerializerFeature[0];

    public JsonZipMessageConvert() {
        super(new MediaType("application", "json", UTF8), new MediaType("application", "*+json", UTF8));
    }

    @Override
    protected boolean supports(Class<?> clazz) {
        return true;
    }

    public Charset getCharset() {
        return this.charset;
    }

    public void setCharset(Charset charset) {
        this.charset = charset;
    }

    public SerializerFeature[] getFeatures() {
        return features;
    }

    public void setFeatures(SerializerFeature... features) {
        this.features = features;
    }

    @Override
    protected Object readInternal(Class<? extends Object> clazz, HttpInputMessage inputMessage) throws IOException,
            HttpMessageNotReadableException {

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        InputStream in = inputMessage.getBody();

        byte[] buf = new byte[1024];
        for (; ; ) {
            int len = in.read(buf);
            if (len == -1) {
                break;
            }

            if (len > 0) {
                baos.write(buf, 0, len);
            }
        }

        byte[] bytes = baos.toByteArray();
        return JSON.parseObject(bytes, 0, bytes.length, charset.newDecoder(), clazz);
    }

    @Override
    protected void writeInternal(Object obj, HttpOutputMessage outputMessage) throws IOException,
            HttpMessageNotWritableException {

        OutputStream out = outputMessage.getBody();
        String text = JSON.toJSONString(obj, features);
        //这里做一次压缩处理
        String gzip = GzipUtil.gZip(text);
        byte[] bytes = gzip.getBytes(charset);
        out.write(bytes);
    }

}

2.在springmvc servlet.xml增加以下代码

 <mvc:annotation-driven>
        <mvc:message-converters>
            <!--<bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">-->
            <bean class="com.base.strutsext.JsonZipMessageConvert">
                <property name="supportedMediaTypes">
                    <list>
                        <value>application/json</value>
                    </list>
                </property>
                <property name="features">
                    <list>
                        <value>DisableCircularReferenceDetect</value>
                        <value>WriteMapNullValue</value>
                        <value>WriteNullListAsEmpty</value>
                        <value>WriteNullStringAsEmpty</value>
                        <value>WriteNullNumberAsZero</value>
                        <value>WriteNullBooleanAsFalse</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>