对接Content-Type=“application/json；“、Content-Type=“application/x-www-form-urlencoded；“类型接口代码示例

因为我们做的项目都是分布式的，所以经常需要调用其他系统的接口。
下面两个方法是本人参与项目中的工具类代码，个人感觉比较实用。
Content-Type="application/json;类型的接口，
主要是通过URLConnection对象建立连接、输出流发送入参、输入流接收反参。
Content-Type="application/x-www-form-urlencoded;类型接口，
主要是通过CloseableHttpClient对象建立连接发送请求、CloseableHttpResponse对象接收结果。

url：调用目标接口的路径
headers:请求头属性
params：目标接口需要的入参

public static String sendPostJson(String url, Map headers, Map params) {
    String param = JSONUtils.toJSONString(params);
    PrintWriter out = null;
    BufferedReader in = null;
    String result = "";
    try {
        URL realUrl = new URL(url);
        // 打开和URL之间的连接
        URLConnection conn = realUrl.openConnection();
        // 设置通用的请求属性
        conn.setRequestProperty("accept", "*/*");
        conn.setRequestProperty("connection", "Keep-Alive");
        conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
        if (headers != null) {
            List nvps = Lists.newArrayList();
            Set> entrySet = headers.entrySet();
            for (Map.Entry entry : entrySet) {
                conn.setRequestProperty(entry.getKey(), entry.getValue());
            }
        }
        // 发送POST请求必须设置如下两行
        conn.setDoOutput(true);
        conn.setDoInput(true);
        // 获取URLConnection对象对应的输出流
        out = new PrintWriter(conn.getOutputStream());
        // 发送请求参数
        out.print(param);
        // flush输出流的缓冲
        out.flush();
        // 定义BufferedReader输入流来读取URL的响应
        in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        while ((line = in.readLine()) != null) {
            result += line;
        }
    } catch (Exception e) {
        System.out.println("发送 POST 请求出现异常！" + e);
        log.error(e.getMessage());
    }
    //使用finally块来关闭输出流、输入流
    finally {
        try {
            if (out != null) {
                out.close();
            }
            if (in != null) {
                in.close();
            }
        } catch (IOException ex) {
            log.error(ex.getMessage());
        }
    }
    return result;
}

public static JSONObject doHttpPost(String url,Map headers ,Map params) {
    // 创建Httpclient对象
    CloseableHttpClient httpClient = null;
    CloseableHttpResponse response = null;
    String resultString = "";
    try {
        httpClient = HttpClients.createDefault();
        // 创建Http Post请求
        HttpPost httpPost = new HttpPost(url);
        httpPost.setHeader("X-Gaia-Api-Key",headers.get("X-Gaia-Api-Key"));//网关key
        httpPost.setHeader("Content-Type","application/x-www-form-urlencoded;");
        // 创建参数列表
        if (param != null) {
            List paramList = new ArrayList<>();
            for (String key : param.keySet()) {
                paramList.add(new BasicNameValuePair(key, param.get(key)));
            }
            // 模拟表单
            UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList,"utf-8");
            httpPost.setEntity(entity);
        }
        // 执行http请求
        response = httpClient.execute(httpPost);
        resultString = EntityUtils.toString(response.getEntity(), "utf-8");
    } catch (Exception e) {
        log.error("HttpClientUtil/doPost,error:{}",e);
    } finally {
        try {
            if (response != null) {
                response.close();
            }
            if (httpClient != null) {
                httpClient.close();
            }
        } catch (IOException e) {
            log.error("HttpClientUtil/close,error:{}",e);
        }
    }
    return JSON.parseObject(resultString);
}