Spring-Cloud-Gateway之ResponseBod

网关中经常需要通过获取ServerHttpResponse响应的信息后进行业务逻辑处理以及一些辅助的处理，例如：完整的请求，响应日志打印；登录成功后创建会话业务等等。
下面通过代码来说明拦截ServerHttpResponse的body并重写body

BodyHandlerFunction 响应body拦截处理接口

public interface BodyHandlerFunction extends
        BiFunction<ServerHttpResponse, Publisher<? extends DataBuffer>, Mono<Void>> {
}

• 此接口用于在writeWith中拦截body转化处理body

BodyHandlerServerHttpResponseDecorator

/**
 * ServerHttpResponse包装类，通过BodyHandlerFunction处理响应body
 *
 * @author 
 * @version 
 * @see [相关类/方法]
 * @since [产品/模块版本]
 */
public class BodyHandlerServerHttpResponseDecorator
        extends ServerHttpResponseDecorator {

    /**
     * body 处理拦截器
     */
    private BodyHandlerFunction bodyHandler = initDefaultBodyHandler();

    /**
     * 构造函数
     *
     * @param bodyHandler
     * @param delegate
     */
    public BodyHandlerServerHttpResponseDecorator(
            BodyHandlerFunction bodyHandler, ServerHttpResponse delegate) {
        super(delegate);
        if (bodyHandler != null) {
            this.bodyHandler = bodyHandler;
        }
    }

    @Override
    public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
        //body 拦截处理器处理响应
        return bodyHandler.apply(getDelegate(), body);
    }

    @Override
    public Mono<Void> writeAndFlushWith(
            Publisher<? extends Publisher<? extends DataBuffer>> body) {
        return writeWith(Flux.from(body).flatMapSequential(p -> p));
    }

    /**
     * 默认body拦截处理器
     *
     * @return
     */
    private BodyHandlerFunction initDefaultBodyHandler() {
        return (resp, body) -> resp.writeWith(body);
    }
}

• 1.此类实现ServerHttpResponseDecorator
• 2.此类包含BodyHandlerFunction用于body的处理转化

测试代码

public class Test1GlobalFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange,
            GatewayFilterChain chain) {
        System.out.println("Test1GlobalFilter进入此方法");
        //构建响应拦截处理器
        BodyHandlerFunction bodyHandler = (resp, body) -> Flux.from(body)
                .map(dataBuffer -> {
                    //响应信息转换为字符串
                    String reqBody = null;
                    try {
                        //dataBuffer 转换为String
                        reqBody = IOUtils
                                .toString(dataBuffer.asInputStream(), "UTF-8")
                                .replaceAll(">\\s{1,}<", "><");
                        System.out.println(reqBody);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    return reqBody;
                }).flatMap(orgBody -> {
                    //根据原有的响应信息构建新响应信息并写入到resp中
                    //此处可以根据业务进行组装新的响应信息，
                    // 例如：登录后创建会话
                    //- 拿到登录请求的响应信息，判断登录是否成功
                    //- 登录成功调用创建会话接口，根据创建会话接口返回组装登录的真实响应
                    System.out.println("orgBody=" + orgBody);
                    String rbody = orgBody + "new1234";
                    HttpHeaders headers = resp.getHeaders();
                    headers.setContentLength(rbody.length());
                    return resp.writeWith(Flux.just(rbody)
                            .map(bx -> resp.bufferFactory()
                                    .wrap(bx.getBytes())));
                }).then();

        //构建响应包装类
        BodyHandlerServerHttpResponseDecorator responseDecorator = new BodyHandlerServerHttpResponseDecorator(
                bodyHandler, exchange.getResponse());
        return chain
                .filter(exchange.mutate().response(responseDecorator).build());
    }

    @Override
    public int getOrder() {
        //WRITE_RESPONSE_FILTER 之前执行
        return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER - 1;
    }

}

1. 测试代码创建了一个全局的过滤器
2. 在过滤其中构建了具有业务功能BodyHandlerFunction
3. 构建带有业务功能BodyHandlerFunction的Response包装类
4. 将Response包装类写入到exchange中

测试类BodyHandlerFunction功能主要是将resqbody 转化成字符串后并在原始的body上追加新字符串new1234。最后将新的body写入到response中；测试类只是为了验证整个代码逻辑是否正常。