自定义Gson处理器

1.介绍

Gson是一个Java库，可用于将Java对象转换为其JSON表示形式。它还可以用于将JSON字符串转换为等效的Java对象。Gson可以处理任意Java对象，包括您没有源代码的现有对象。

2.参考链接

gitup：https://github.com/google/gson

3.在java工程中的引入

<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.5</version>
</dependency>

4.编写解析器

package net.bingosoft.egw.oapi.tunnel.jsonify;

import com.google.gson.TypeAdapter;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.handler.codec.http.*;
import lombok.var;
import org.apache.commons.lang3.StringUtils;

import java.io.IOException;
import java.util.Base64;

public class FullRequestAdapter extends TypeAdapter<FullHttpRequest> {
    @Override
    public void write(JsonWriter out, FullHttpRequest value) throws IOException {
        out.beginObject();

        out.name("protocol").value(value.protocolVersion().protocolName());
        out.name("method").value(value.method().name());
        out.name("uri").value(value.uri());
        out.name("headers");
        out.beginObject();
        for (var headerName : value.headers().names()) {
            out.name(headerName);
            out.beginArray();
            for (var headerValue : value.headers().getAll(headerName)) {
                out.value(headerValue);
            }
            out.endArray();
        }
        out.endObject();

        var contentType = value.headers().get(HttpHeaderNames.CONTENT_TYPE);
        if (value.content().readableBytes() > 0) {
            out.name("body");

            var buf = new byte[value.content().readableBytes()];
            value.content().readBytes(buf);
            if(!(StringUtils.contains(contentType,"text")||StringUtils.contains(contentType,"application"))){
                out.value(Base64.getEncoder().encodeToString(buf));
            }else{
                out.value(new String(buf));
            }
            buf = null;
        }
        out.endObject();
    }

    @Override
    public FullHttpRequest read(JsonReader in) throws IOException {
        HttpVersion protocolVersion = null;
        HttpMethod method = null;
        String uri = null;
        DefaultHttpHeaders headers = new DefaultHttpHeaders();
        ByteBuf body = null;

        in.beginObject();
        while(in.hasNext()) {
            switch (in.nextName()) {
                case "protocol":
                    protocolVersion = HttpVersion.valueOf(in.nextString());
                    break;
                case "method":
                    method = HttpMethod.valueOf(in.nextString());
                    break;
                case "uri":
                    uri = in.nextString();
                    break;
                case "headers":
                    in.beginObject();
                    while(in.hasNext()) {
                        var headerName = in.nextName();
                        in.beginArray();
                        while(in.hasNext()) {
                            headers.add(headerName, in.nextString());
                        }
                        in.endArray();
                    }
                    in.endObject();
                    break;
                case "body":
                    var contentType = headers.get(HttpHeaderNames.CONTENT_TYPE);
                    if(!(StringUtils.contains(contentType,"text")||StringUtils.contains(contentType,"application"))){
                        body = Unpooled.wrappedBuffer(Base64.getDecoder().decode(in.nextString()));
                    }else{
                        body = Unpooled.wrappedBuffer(in.nextString().getBytes());
                    }
                    break;
            }
        }

        return new DefaultFullHttpRequest(protocolVersion, method, uri, body, headers, new DefaultHttpHeaders());
    }
}

5.编写完后如何使用？

• 注册

private Gson gson = new GsonBuilder()
            .registerTypeAdapter(FullHttpRequest.class, new FullRequestAdapter())
            .create();

• 使用

var jsonString = gson.toJson(new DefaultFullHttpRequest(request.protocolVersion(),
                request.method(),
                request.uri(),
                requestBody,
                request.headers(),
                new DefaultHttpHeaders()));

gson.fromJson(gson.toJson(responseBody), FullHttpResponse.class);