SpringBoot整合HttpClient

1.首先加入httpclient需要的jar包

    org.apache.httpcomponents
    httpclient
    4.3.1

2.在配置文件中加入httpclient需要的一些配置参数

#最大连接数
http.maxTotal = 100
#并发数
http.defaultMaxPerRoute = 20
#创建连接的最长时间
http.connectTimeout=1000
#从连接池中获取到连接的最长时间
http.connectionRequestTimeout=500
#数据传输的最长时间
http.socketTimeout=10000
#提交请求前测试连接是否可用
http.staleConnectionCheckEnabled=true

3.注入连接池等，用于在service层获取httpclient

@Configuration
public class HttpClient {

    @Value("${http.maxTotal}")
    private Integer maxTotal;

    @Value("${http.defaultMaxPerRoute}")
    private Integer defaultMaxPerRoute;

    @Value("${http.connectTimeout}")
    private Integer connectTimeout;

    @Value("${http.connectionRequestTimeout}")
    private Integer connectionRequestTimeout;

    @Value("${http.socketTimeout}")
    private Integer socketTimeout;

    @Value("${http.staleConnectionCheckEnabled}")
    private boolean staleConnectionCheckEnabled;

    /**
     * 首先实例化一个连接池管理器，设置最大连接数、并发连接数
     * @return
     */
    @Bean(name = "httpClientConnectionManager")
    public PoolingHttpClientConnectionManager getHttpClientConnectionManager(){
        PoolingHttpClientConnectionManager httpClientConnectionManager = new PoolingHttpClientConnectionManager();
        //最大连接数
        httpClientConnectionManager.setMaxTotal(maxTotal);
        //并发数
        httpClientConnectionManager.setDefaultMaxPerRoute(defaultMaxPerRoute);
        return httpClientConnectionManager;
    }

    /**
     * 实例化连接池，设置连接池管理器。
     * 这里需要以参数形式注入上面实例化的连接池管理器
     * @param httpClientConnectionManager
     * @return
     */
    @Bean(name = "httpClientBuilder")
    public HttpClientBuilder getHttpClientBuilder(@Qualifier("httpClientConnectionManager")PoolingHttpClientConnectionManager httpClientConnectionManager){

        //HttpClientBuilder中的构造方法被protected修饰，所以这里不能直接使用new来实例化一个HttpClientBuilder，可以使用HttpClientBuilder提供的静态方法create()来获取HttpClientBuilder对象
        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();

        httpClientBuilder.setConnectionManager(httpClientConnectionManager);

        return httpClientBuilder;
    }

    /**
     * 注入连接池，用于获取httpClient
     * @param httpClientBuilder
     * @return
     */
    @Bean
    public CloseableHttpClient getCloseableHttpClient(@Qualifier("httpClientBuilder") HttpClientBuilder httpClientBuilder){
        return httpClientBuilder.build();
    }

    /**
     * Builder是RequestConfig的一个内部类
     * 通过RequestConfig的custom方法来获取到一个Builder对象
     * 设置builder的连接信息
     * 这里还可以设置proxy，cookieSpec等属性。有需要的话可以在此设置
     * @return
     */
    @Bean(name = "builder")
    public RequestConfig.Builder getBuilder(){
        RequestConfig.Builder builder = RequestConfig.custom();
        return builder.setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout)
                .setSocketTimeout(socketTimeout)
                .setStaleConnectionCheckEnabled(staleConnectionCheckEnabled);
    }

    /**
     * 使用builder构建一个RequestConfig对象
     * @param builder
     * @return
     */
    @Bean
    public RequestConfig getRequestConfig(@Qualifier("builder") RequestConfig.Builder builder){
        return builder.build();
    }

}

4.编写一个案例Controller层

@RestController
public class HttpClientController {

    @Resource
    private HttpAPIService httpAPIService;

    @RequestMapping("httpclient")
    public String test() throws Exception {
        String str = httpAPIService.doGet("http://www.baidu.com");
        System.out.println(str);
        return "hello";
    }
}

5.service层

@Service
public class HttpAPIService {

    @Autowired
    private CloseableHttpClient httpClient;

    @Autowired
    private RequestConfig config;


    /**
     * 不带参数的get请求，如果状态码为200，则返回body，如果不为200，则返回null
     * 
     * @param url
     * @return
     * @throws Exception
     */
    public String doGet(String url) throws Exception {
        // 声明 http get 请求
        HttpGet httpGet = new HttpGet(url);

        // 装载配置信息
        httpGet.setConfig(config);

        // 发起请求
        CloseableHttpResponse response = this.httpClient.execute(httpGet);

        // 判断状态码是否为200
        if (response.getStatusLine().getStatusCode() == 200) {
            // 返回响应体的内容
            return EntityUtils.toString(response.getEntity(), "UTF-8");
        }
        return null;
    }

    /**
     * 带参数的get请求，如果状态码为200，则返回body，如果不为200，则返回null
     * 
     * @param url
     * @return
     * @throws Exception
     */
    public String doGet(String url, Map map) throws Exception {
        URIBuilder uriBuilder = new URIBuilder(url);

        if (map != null) {
            // 遍历map,拼接请求参数
            for (Map.Entry entry : map.entrySet()) {
                uriBuilder.setParameter(entry.getKey(), entry.getValue().toString());
            }
        }

        // 调用不带参数的get请求
        return this.doGet(uriBuilder.build().toString());

    }

    /**
     * 带参数的post请求
     * 
     * @param url
     * @param map
     * @return
     * @throws Exception
     */
    public HttpResult doPost(String url, Map map) throws Exception {
        // 声明httpPost请求
        HttpPost httpPost = new HttpPost(url);
        // 加入配置信息
        httpPost.setConfig(config);

        // 判断map是否为空，不为空则进行遍历，封装from表单对象
        if (map != null) {
            List list = new ArrayList();
            for (Map.Entry entry : map.entrySet()) {
                list.add(new BasicNameValuePair(entry.getKey(), entry.getValue().toString()));
            }
            // 构造from表单对象
            UrlEncodedFormEntity urlEncodedFormEntity = new UrlEncodedFormEntity(list, "UTF-8");

            // 把表单放到post里
            httpPost.setEntity(urlEncodedFormEntity);
        }

        // 发起请求
        CloseableHttpResponse response = this.httpClient.execute(httpPost);
        return new HttpResult(response.getStatusLine().getStatusCode(), EntityUtils.toString(
                response.getEntity(), "UTF-8"));
    }

    /**
     * 不带参数post请求
     * 
     * @param url
     * @return
     * @throws Exception
     */
    public HttpResult doPost(String url) throws Exception {
        return this.doPost(url, null);
    }
}

6.处理关闭连接的线程

@Component
public class IdleConnectionEvictor extends Thread {

@Autowired
private HttpClientConnectionManager connMgr;

private volatile boolean shutdown;

public IdleConnectionEvictor() {
super();
super.start();
}

@Override
public void run() {
try {
while (!shutdown) {
synchronized (this) {
wait(5000);
// 关闭失效的连接
connMgr.closeExpiredConnections();
}
}
} catch (InterruptedException ex) {
// 结束
}
}

//关闭清理无效连接的线程
public void shutdown() {
shutdown = true;
synchronized (this) {
notifyAll();
}
}
}

7.自定义返回结果类型

public class HttpResult {

// 响应的状态码

private int code;​​​​​​​

// 响应的响应体

private String body;

get/set…

}