Spring Cloud Gateway 网关拦截转发

1.application.yml配置

1.  
   spring:
2.  
   cloud:
3.  
   gateway:
4.  
   routes:
5.  
   - id: remoteaddr_route
6.  
   uri: http://localhost:8080
7.  
   predicates:
8.  
   - Path=/test
9.  
   filters:
10.  
    - RewritePath=/test, /add
11.  
    - Test

参数解析：

predicates：当满足predicates下的条件时，即path路径为/test时网关生效。

uri：跳转到uri(注意:此处为uri不是url)。

filters：filters 下的RewritePath会将路径重定义将/test换为/add。若不加此处就会将path所带路径自动拼接到uri后面。

最后一行的- Test 是文件名，下面会写到

2.网关实现

网关的主要实现由Filter，Mono，GatewayFilterFactory三部分组成。

解析：

GatewayFilterFactory：上面的-Test的文件名就是此处的名称应为TestGatewayFilterFactory，网关匹配时会自动忽略后面的GatewayFilterFactory，从而通过Test找到TestGatewayFilterFactory。

1.  
   @Component
2.  
   @Slf4j
3.  
   @Lazy
4.  
   public class TestGatewayFilterFactory extends AbstractGatewayFilterFactory {
5.  
   @Autowired
6.  
   TestFilter TestFilter;
7.  
    
8.  
   @Override
9.  
   public GatewayFilter apply(Object config) {
10.  
    return TestFilter;
11.  
    }
12.  
    }

Filter：相当于一个中间层

1.  
   @Component
2.  
   public class TestFilter implements GatewayFilter, Ordered {
3.  
   @Autowired
4.  
   TestMono TestMono;
5.  
    
6.  
   @Override
7.  
   public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
8.  
   return TestMono.testMono(exchange, chain);
9.  
   }
10.  
     
11.  
    @Override
12.  
    public int getOrder() {
13.  
    return -2;
14.  
    }
15.  
    }

Mono：主要的逻辑实现层

主要实现由testMono来协调，网关转发的请求的解析在此方法内实现，若有解密需求在此方法内添加方法即可。

requestDecorator：此方法用于请求的转换，代码中实现的是将post请求转为get。

urlEncodeUTF8：在此代码的实现中用于解析post请求的参数将其拼接到get请求中。

responseDecorator：网关处理完毕后返回的结果将在这里包装后输出，若有加密在此方法内执行。

1.  
   @Component
2.  
   @Slf4j
3.  
   public class TestMono {
4.  
    
5.  
   //主方法
6.  
   public Mono<Void> testMono(ServerWebExchange exchange, GatewayFilterChain chain) {
7.  
   ServerHttpRequest request = exchange.getRequest();
8.  
   ServerHttpResponse response = exchange.getResponse();
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   return DataBufferUtils.join(request.getBody())
10.  
    .flatMap(dataBuffer -> {
11.  
    DataBufferUtils.retain(dataBuffer);
12.  
    byte[] bytes = new byte[dataBuffer.readableByteCount()];
13.  
    dataBuffer.read(bytes);
14.  
    //释放掉内存
15.  
    DataBufferUtils.release(dataBuffer);
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    String body = new String(bytes, StandardCharsets.UTF_8);
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    URI url = request.getURI();
18.  
    log.info("url: {}", url);
19.  
    JSONObject bodyJson = JSON.parseObject(body);
20.  
    JSONObject innerBody = bodyJson.getJSONObject("BODY");
21.  
     
22.  
    return chain.filter(exchange.mutate().request(requestDecorator(request, innerBody)).response(responseDecorator(response)).build());
23.  
    });
24.  
    }
25.  
     
26.  
    //将post请求转换成get（若是get可连同下面的方法省略）
27.  
    private static ServerHttpRequestDecorator requestDecorator(ServerHttpRequest request, JSONObject body) {
28.  
    return new ServerHttpRequestDecorator(request) {
29.  
    // 重新设置http method
30.  
    @Override
31.  
    public HttpMethod getMethod() {
32.  
    return HttpMethod.GET;
33.  
    }
34.  
     
35.  
    @Override
36.  
    public String getMethodValue() {
37.  
    return "GET";
38.  
    }
39.  
     
40.  
    // 转换请求参数
41.  
    @Override
42.  
    public URI getURI() {
43.  
    String params = urlEncodeUTF8(body);
44.  
    return URI.create(request.getURI() "?" params);
45.  
    }
46.  
    };
47.  
    }
48.  
     
49.  
    /**
50.  
    * 转换urlparam
51.  
    *（post请求忽略）
52.  
    * @param jsonObject
53.  
    * @return
54.  
    */
55.  
    private static String urlEncodeUTF8(JSONObject jsonObject) {
56.  
    StringBuilder sb = new StringBuilder();
57.  
    for (Map.Entry<String, Object> entry : jsonObject.entrySet()) {
58.  
    if (sb.length() > 0) {
59.  
    sb.append("&");
60.  
    }
61.  
    sb.append(String.format("%s=%s",
62.  
    entry.getKey(),
63.  
    entry.getValue()
64.  
    ));
65.  
    }
66.  
    log.info("format param: {}", sb);
67.  
    return sb.toString();
68.  
    }
69.  
     
70.  
     
71.  
    //网关转出
72.  
    private ServerHttpResponseDecorator responseDecorator
73.  
    (ServerHttpResponse response) {
74.  
    return new ServerHttpResponseDecorator(response) {
75.  
     
76.  
    @Override
77.  
    public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
78.  
    if (body instanceof Flux) {
79.  
    Flux<? extends DataBuffer> flux = Flux.from(body);
80.  
    return super.writeWith(flux.buffer().map(dataBuffers -> {
81.  
    DataBufferFactory dataBufferFactory = new NettyDataBufferFactory(ByteBufAllocator.DEFAULT);
82.  
    StringBuilder sb = new StringBuilder("");
83.  
    DataBuffer join = dataBufferFactory.join(dataBuffers);
84.  
    byte[] bytes = new byte[join.readableByteCount()];
85.  
    join.read(bytes);
86.  
    DataBufferUtils.release(join);
87.  
    String s = new String(bytes, StandardCharsets.UTF_8);
88.  
    sb.append(s);
89.  
    //去掉字符串最外层的[]
90.  
    //sb.deleteCharAt(0).deleteCharAt(sb.length() - 1);`
91.  
    // 构造返回报文
92.  
    JSONObject jsonBody = JSON.parseObject(sb.toString(), JSONObject.class, Feature.OrderedField);
93.  
     
94.  
     
95.  
    String content = JSON.toJSONString(jsonBody, SerializerFeature.WRITE_MAP_NULL_FEATURES, SerializerFeature.QuoteFieldNames, SerializerFeature.PrettyFormat);
96.  
    byte[] contentByte = content.getBytes();
97.  
    // 重置content-length
98.  
    response.getHeaders().setContentLength(contentByte.length);
99.  
    return response.bufferFactory().wrap(contentByte);
100.  
     }));
101.  
     }
102.  
     return super.writeWith(body);
103.  
     }
104.  
     };
105.  
     }
106.  
      
107.  
      
108.  
     }

Spring cloud gateway学习地址：Spring Cloud Gateway 2.1.0 中文官网文档 - 云 社区 - 腾讯云

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