Spring Cloud之Ribbon转发请求头(header参数)_justlpf的专栏-CSDN博客

目录

简介

1.自定义RestTemplate

2.将MyRestTemplate注册为Bean

3.构建spring拦截器

4.构建拦截器配置类

5.controller调用

简介

使用spring cloud的ribbon组件可以实现对下游微服务的负载均衡调度，但是官方ribbon是没有header转发功能的，这里我们在ribbon的restTemplate基础上，自定义实现header的转发功能。

1.自定义RestTemplate

package com.cloud.base.config.ribbon;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.client.ClientHttpRequest;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.client.*;

import java.io.IOException;
import java.net.URI;
import java.util.*;

import static feign.Util.checkNotNull;

/**
 * @author langpf 2019/2/19
 */
public class MyRestTemplate extends RestTemplate {
    private final Map<String, List<String>> headers = new LinkedHashMap<>();

    @Nullable
    @Override
    protected <T> T doExecute(URI url, @Nullable HttpMethod method, @Nullable RequestCallback requestCallback,
                              @Nullable ResponseExtractor<T> responseExtractor) throws RestClientException {

        Assert.notNull(url, "URI is required");
        Assert.notNull(method, "HttpMethod is required");
        ClientHttpResponse response = null;
        try {
            ClientHttpRequest request = createRequest(url, method);

            // lpf: 添加headers
            HttpHeaders myHeaders = request.getHeaders();
            addAllHeaders(myHeaders);

            if (requestCallback != null) {
                requestCallback.doWithRequest(request);
            }
            response = request.execute();
            handleResponse(url, method, response);
            return (responseExtractor != null ? responseExtractor.extractData(response) : null);
        }
        catch (IOException ex) {
            String resource = url.toString();
            String query = url.getRawQuery();
            resource = (query != null ? resource.substring(0, resource.indexOf('?')) : resource);
            throw new ResourceAccessException("I/O error on " + method.name()
                    + " request for \"" + resource + "\": " + ex.getMessage(), ex);
        }
        finally {
            if (response != null) {
                response.close();
            }
        }
    }

    public void header(String name, String... values) {
        checkNotNull(name, "header name");
        if (values == null || (values.length == 1 && values[0] == null)) {
            headers.remove(name);
        } else {
            List<String> headers = new ArrayList<>(Arrays.asList(values));
            this.headers.put(name, headers);
        }
    }

    private void addAllHeaders(HttpHeaders myHeaders) {
        for (Map.Entry<String, List<String>> entry : headers.entrySet()) {
            String key = entry.getKey();
            List<String> values = entry.getValue();
            myHeaders.addAll(key, values);
        }
    }
}

2.将MyRestTemplate注册为Bean

下面代码一般放在SpringBoot工程的启动类中。

/**
 * 让restTemplate具备Ribbon负载均衡的能力。
 * 由于使用feign, 弃用该方式
 */
@Bean(name="myRestTemplate")
@LoadBalanced
MyRestTemplate restTemplate() {
	return new MyRestTemplate();
}

3.构建spring拦截器

package com.cloud.base.interceptor.ribbon;

import com.alibaba.fastjson.JSONObject;
import com.cloud.base.config.ribbon.MyRestTemplate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

// @Component("ribbonInterceptor1")
public class RibbonInterceptor implements HandlerInterceptor {
    private static final Logger log = LoggerFactory.getLogger(RibbonInterceptor.class);

    private MyRestTemplate myRestTemplate;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, 
                             Object handler) throws Exception {
        String lpfId = request.getHeader("lpf");

        if (myRestTemplate == null) {  //解决service为null无法注入问题
            BeanFactory factory = 
              WebApplicationContextUtils.getRequiredWebApplicationContext(request.getServletContext());
            myRestTemplate = (MyRestTemplate) factory.getBean("myRestTemplate");
        }

        myRestTemplate.header("lpf", lpfId);

        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
                           ModelAndView modelAndView) throws Exception {
        // TODO Auto-generated method stub;
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, 
                              Object handler, Exception ex)
            throws Exception {
        // TODO Auto-generated method stub;
    }
}

4.构建拦截器配置类

package com.cloud.base.config;

import com.cloud.base.interceptor.ribbon.RibbonInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * 拦截器配置类
 */
@Configuration
public class WebMvcSessionConfigurer implements WebMvcConfigurer {
    // @Autowired
    // RibbonInterceptor ribbonInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // 多个拦截器组成一个拦截器链
        // addPathPatterns 用于添加拦截规则
        // excludePathPatterns 用于排除拦截
        // old: new RedisSessionInterceptor()
        // registry.addInterceptor(ribbonInterceptor).addPathPatterns("/**");
        registry.addInterceptor(new RibbonInterceptor()).addPathPatterns("/**");
    }
}

5.controller调用

通过controller调用ribbon时会自动转发header

package com.cloud.controller;

import com.cloud.base.config.ribbon.MyRestTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.*;

import java.util.Map;

import static com.cloud.base.constant.Constants.SPRING_DATA_SRV;
import static com.cloud.base.constant.Constants.SPRING_SIDECAR_SRV_URL;

/**
 * ribbon调用方式, 参考博客: https://www.jianshu.com/p/470a30f493cf
 * @author langpf 2019/2/19
 */
@RestController
public class RibbonController {
    @Autowired
    MyRestTemplate myRestTemplate;

    /**
     * ribbon -- get请求
     */
    @RequestMapping("ribbonDataSrvHi")
    public String ribbonDataSrvHi() {
        // myRestTemplate.headForHeaders()
        return myRestTemplate.getForEntity(SPRING_DATA_SRV + "hi", String.class).getBody();
    }

    /**
     * ribbon -- get请求
     */
    @RequestMapping("ribbonGetHi")
    public String ribbonGetHi() {
        return myRestTemplate.getForEntity(SPRING_DATA_SRV + "hi", String.class).getBody();
    }

    /**
     * ribbon -- get请求
     * http://localhost:10232/python-user
     */
    @RequestMapping("python-user")
    public String pythonUser() {
        // return myRestTemplate.getForEntity("http://spring-sidecar-python-server/getUser", String.class).getBody();
        return myRestTemplate.getForEntity(SPRING_SIDECAR_SRV_URL + "getUser", String.class).getBody();
    }

    /**
     * ribbon -- post请求
     */
    @RequestMapping(value = "model/serving", method = RequestMethod.POST)
    public String modelServing(@RequestBody HttpEntity entity) {
        return myRestTemplate.postForEntity(SPRING_SIDECAR_SRV_URL + "model/serving", entity, String.class).getBody();
    }

}