HttpClient以及整合SpringBoot

ゝ一世哀愁。 2022-04-17 00:14 409阅读 0赞

# 一、HttpClient #

## 1.1、 **前台系统访问后台接口的方式** ##

两个系统间如何互相访问？两个tomcat上的项目如何互相访问

采用HttpClient实现跨系统的接口调用。

## 1.2、 **什么是HttpClient** ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjUyNTA5_size_16_color_FFFFFF_t_70]

官网：http://hc.apache.org/index.html

现在也叫：HttpComponents ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjUyNTA5_size_16_color_FFFFFF_t_70 1]

特点：

1.  HttpClient别名：HttoComponents
2.  HttpClient可以发送get、post、put、delete、…等请求

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjUyNTA5_size_16_color_FFFFFF_t_70 2]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjUyNTA5_size_16_color_FFFFFF_t_70 3]

## 1.3、 HttpClient入门案例 ##

<dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.4</version>
    </dependency>

### 1.3.1、 发起Get请求 ###

1创建一个客户端 CloseableHttpClient

2创建一个get方法请求实例 HttpGet

3发送请求 execute

4获取响应的头信息

5获取响应的主题内容

6关闭响应对象

使用HttpClient发起Get请求的案例代码：

public class DoGET { 
    
        public static void main(String[] args) throws Exception { 
            // 创建Httpclient对象,相当于打开了浏览器
            CloseableHttpClient httpclient = HttpClients.createDefault();
    
            // 创建HttpGet请求，相当于在浏览器输入地址
            HttpGet httpGet = new HttpGet("http://www.baidu.com/");
    
            CloseableHttpResponse response = null;
            try { 
                // 执行请求，相当于敲完地址后按下回车。获取响应
                response = httpclient.execute(httpGet);
                // 判断返回状态是否为200
                if (response.getStatusLine().getStatusCode() == 200) { 
                    // 解析响应，获取数据
                    String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                    System.out.println(content);
                }
            } finally { 
                if (response != null) { 
                    // 关闭资源
                    response.close();
                }
                // 关闭浏览器
                httpclient.close();
            }
    
        }
    }

执行日志：

请求头：

![在这里插入图片描述][20181110090053210.jpg]

响应头：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjUyNTA5_size_16_color_FFFFFF_t_70 4]

数据：

![在这里插入图片描述][20181110090115289.jpg]

### 1.3.2、 **带参数的Get请求** ###

1创建一个客户端 CloseableHttpClient

2 通过URIBuilder传递参数

3创建一个get方法请求实例 HttpGet

4发送请求 execute

5获取响应的头信息

6获取响应的主题内容

7关闭响应对象

访问网站的爬虫协议：

![在这里插入图片描述][20181110090128291.png]

public class DoGETParam { 
    
       public static void main(String[] args) throws Exception { 
           // 创建Httpclient对象
           CloseableHttpClient httpclient = HttpClients.createDefault();
           // 创建URI对象，并且设置请求参数
           URI uri = new URIBuilder("http://www.baidu.com/s").setParameter("wd", "java").build();
           // 创建http GET请求
           HttpGet httpGet = new HttpGet(uri);
    
           CloseableHttpResponse response = null;
           try { 
               // 执行请求
               response = httpclient.execute(httpGet);
               // 判断返回状态是否为200
               if (response.getStatusLine().getStatusCode() == 200) { 
                   // 解析响应数据
                   String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                   System.out.println(content);
               }
           } finally { 
               if (response != null) { 
                   response.close();
               }
               httpclient.close();
           }
       }
    }

### 1.3.3、 **发起POST请求** ###

/* * 演示：使用HttpClient发起POST请求 */
    public class DoPOST { 
       public static void main(String[] args) throws Exception { 
           // 创建Httpclient对象
           CloseableHttpClient httpclient = HttpClients.createDefault();
           // 创建http POST请求
           HttpPost httpPost = new HttpPost("http://www.oschina.net/");
           // 把自己伪装成浏览器。否则开源中国会拦截访问
           httpPost.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36");
    
           CloseableHttpResponse response = null;
           try { 
               // 执行请求
               response = httpclient.execute(httpPost);
               // 判断返回状态是否为200
               if (response.getStatusLine().getStatusCode() == 200) { 
                   // 解析响应数据
                   String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                   System.out.println(content);
               }
           } finally { 
               if (response != null) { 
                   response.close();
               }
               // 关闭浏览器
               httpclient.close();
           }
    
       }
    }

### 1.3.4、 带参数POST请求 ###

/* * 演示：使用HttpClient发起带有参数的POST请求 */
    public class DoPOSTParam { 
    
       public static void main(String[] args) throws Exception { 
           // 创建Httpclient对象
           CloseableHttpClient httpclient = HttpClients.createDefault();
           // 创建http POST请求，访问开源中国
           HttpPost httpPost = new HttpPost("http://www.oschina.net/search");
    
           // 根据开源中国的请求需要，设置post请求参数
           List<NameValuePair> parameters = new ArrayList<NameValuePair>(0);
           parameters.add(new BasicNameValuePair("scope", "project"));
           parameters.add(new BasicNameValuePair("q", "java"));
           parameters.add(new BasicNameValuePair("fromerr", "8bDnUWwC"));
           // 构造一个form表单式的实体
           UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(parameters);
           // 将请求实体设置到httpPost对象中
           httpPost.setEntity(formEntity);
    
           CloseableHttpResponse response = null;
           try { 
               // 执行请求
               response = httpclient.execute(httpPost);
               // 判断返回状态是否为200
               if (response.getStatusLine().getStatusCode() == 200) { 
                   // 解析响应体
                   String content = EntityUtils.toString(response.getEntity(), "UTF-8");
                   System.out.println(content);
               }
           } finally { 
               if (response != null) { 
                   response.close();
               }
               // 关闭浏览器
               httpclient.close();
           }
       }
    }

# 二、项目整合HttpClient—与SpringBoot整合 #

SpringBoot官方并没有对HttpClient的启动器。所以我们需要自己完成配置，还好，我们刚才在测试案例中已经写过了。

不过，SpringBoot虽然没有提供启动器，但是却提供了一个对Restful服务进行调用的模板类：RestTemplate，底层可以使用HttpClient来实现。有了这个我们就无需自己定义APIService了。

1、导入maven坐标

<dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
    </dependency>

2、在bos\_management中创建HttpClientConfig类

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQzNjUyNTA5_size_16_color_FFFFFF_t_70 5]

2、在application.properties添加如下配置:

#The config for HttpClient 
    http.maxTotal=300
    http.defaultMaxPerRoute=50
    http.connectTimeout=1000
    http.connectionRequestTimeout=500
    http.socketTimeout=5000
    http.staleConnectionCheckEnabled=true

3、在类中编写代码

/** * HttpClient的配置类 */
    @Configuration
    @ConfigurationProperties(prefix = "http", ignoreUnknownFields = true)
    public class HttpClientConfig { 
    
        private Integer maxTotal;// 最大连接
    
        private Integer defaultMaxPerRoute;// 每个host的最大连接
    
        private Integer connectTimeout;// 连接超时时间
    
        private Integer connectionRequestTimeout;// 请求超时时间
    
        private Integer socketTimeout;// 响应超时时间
    
        /** * HttpClient连接池 * @return */
        @Bean
        public HttpClientConnectionManager httpClientConnectionManager() { 
            PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();
            connectionManager.setMaxTotal(maxTotal);
            connectionManager.setDefaultMaxPerRoute(defaultMaxPerRoute);
            return connectionManager;
        }
    
        /** * 注册RequestConfig * @return */
        @Bean
        public RequestConfig requestConfig() { 
            return RequestConfig.custom().setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout).setSocketTimeout(socketTimeout)
                .build();
        }
    
        /** * 注册HttpClient * @param manager * @param config * @return */
        @Bean
        public HttpClient httpClient(HttpClientConnectionManager manager, RequestConfig config) { 
            return HttpClientBuilder.create().setConnectionManager(manager).setDefaultRequestConfig(config)
                .build();
        }
    
        @Bean
        public ClientHttpRequestFactory requestFactory(HttpClient httpClient) { 
            return new HttpComponentsClientHttpRequestFactory(httpClient);
        }
        /** * 使用HttpClient来初始化一个RestTemplate * @param requestFactory * @return */
        @Bean
        public RestTemplate restTemplate(ClientHttpRequestFactory requestFactory) { 
            RestTemplate template = new RestTemplate(requestFactory);
    
            List<HttpMessageConverter<?>> list = template.getMessageConverters();
            for (HttpMessageConverter<?> mc : list) { 
                if (mc instanceof StringHttpMessageConverter) { 
                    ((StringHttpMessageConverter) mc).setDefaultCharset(Charset.forName("UTF-8"));
                }
            }
            return template;
        }
    
        public Integer getMaxTotal() { 
            return maxTotal;
        }
    
        public void setMaxTotal(Integer maxTotal) { 
            this.maxTotal = maxTotal;
        }
    
        public Integer getDefaultMaxPerRoute() { 
            return defaultMaxPerRoute;
        }
    
        public void setDefaultMaxPerRoute(Integer defaultMaxPerRoute) { 
            this.defaultMaxPerRoute = defaultMaxPerRoute;
        }
    
        public Integer getConnectTimeout() { 
            return connectTimeout;
        }
    
        public void setConnectTimeout(Integer connectTimeout) { 
            this.connectTimeout = connectTimeout;
        }
    
        public Integer getConnectionRequestTimeout() { 
            return connectionRequestTimeout;
        }
    
        public void setConnectionRequestTimeout(Integer connectionRequestTimeout) { 
            this.connectionRequestTimeout = connectionRequestTimeout;
        }
    
        public Integer getSocketTimeout() { 
            return socketTimeout;
        }
    
        public void setSocketTimeout(Integer socketTimeout) { 
            this.socketTimeout = socketTimeout;
        }
    }

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[20181110090053210.jpg]: /images/20220417/1fe93c6444b74ead8626612aea7ca77e.png
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[20181110090115289.jpg]: /images/20220417/a0ca9271b089470fa64ba60324333397.png
[20181110090128291.png]: /images/20220417/6c91bc54e25842a6b127de277650fd82.png
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