httpclient的整理

1.首先实例化一个连接池管理器(类:PoolingHttpClientConnectionManager),设置最大连接数,并发连接数,

    @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;
    }

2.实例化连接池(HttpClientBuilder),设置连接池管理器,直接注入上面生成的连接池管理器

 @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;
    }

3.注入连接池,用于获取httpclient

@Bean
    public CloseableHttpClient getCloseableHttpClient(@Qualifier("httpClientBuilder") HttpClientBuilder httpClientBuilder){
        return httpClientBuilder.build();
    }

4.生成配置类RequestConfig的构建类builder,并设置需要的属性信息;其中Builder是RequestConfig类的内部类

@Bean(name = "builder")
    public RequestConfig.Builder getBuilder(){
        RequestConfig.Builder builder = RequestConfig.custom();
        return builder.setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout)
                .setSocketTimeout(socketTimeout)
                .setStaleConnectionCheckEnabled(staleConnectionCheckEnabled);
    }

5.利用内部类Builder构建一个RequestConfig类的对象

    @Bean
    public RequestConfig getRequestConfig(@Qualifier("builder") RequestConfig.Builder builder){
        return builder.build();
    }

6.注入CloseableHttpClient,RequestConfig

    @Autowired(required=false)
    private CloseableHttpClient httpClient;

    @Autowired(required=false)
    private RequestConfig config;

7.利用httpClient和config发送请求

　　<1>get请求不带参数,如果状态码为200,则返回body,如果不为200,则返回null

　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,并接受响应
        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;
    }

　　<2>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

　public String doGet(String url, Map<String, Object> map) throws Exception {
        URIBuilder uriBuilder = new URIBuilder(url);//内部调用了digest(new URL())解析url,然后构架新的url,后续调用api将参数拼接上
        if (map != null) {
            // 遍历map,拼接请求参数
            for (Map.Entry<String, Object> 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());

    }

　　<3>带参数的post请求,参数为map

　public HttpResult doPost(String url, Map<String, Object> 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<NameValuePair> list = new ArrayList<NameValuePair>();
            for (Map.Entry<String, Object> entry : map.entrySet()) {
                list.add(new BasicNameValuePair(entry.getKey(), entry.getValue().toString()));
            }
            // 构造from表单实体类对象
            UrlEncodedFormEntity urlEncodedFormEntity = new UrlEncodedFormEntity(list, "UTF-8");
            // 把表单实体类对象放到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"));
    }

　　<4>不带参数的post请求

　    public HttpResult doPost(String url) throws Exception {
        return this.doPost(url, null);
    }

　　<5>带参数的请求,参数格式为json

　　public String doPostJson(String url, String json) throws Exception {
        // 创建http POST请求
        HttpPost httpPost = new HttpPost(url);
        httpPost.setConfig(config);
        if(null != json){
            //设置请求体为 字符串
            StringEntity stringEntity = new StringEntity(json,"UTF-8");
            httpPost.setEntity(stringEntity);
        }
        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) {
                return EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } finally {
            if (response != null) {
                response.close();
            }
        }
        return null;
    }