對接Content-Type="application/json;"的接口示例

url：調用目標接口的路徑

headers:請求頭屬性

params：目標接口需要的入參

public static String sendPostJson(String url, Map<String, String> headers, Map<String, Object> params) {
    String param = JSONUtils.toJSONString(params);
    PrintWriter out = null;
    BufferedReader in = null;
    String result = "";
    try {
        URL realUrl = new URL(url);
        // 打開和URL之間的連接
        URLConnection conn = realUrl.openConnection();
        // 設置通用的請求屬性
        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<NameValuePair> nvps = Lists.newArrayList();
            Set<Map.Entry<String, String>> entrySet = headers.entrySet();
            for (Map.Entry<String, String> entry : entrySet) {
                conn.setRequestProperty(entry.getKey(), entry.getValue());
            }
        }
        // 發送POST請求必須設置如下兩行
        conn.setDoOutput(true);
        conn.setDoInput(true);
        // 獲取URLConnection對象對應的輸出流
        out = new PrintWriter(conn.getOutputStream());
        // 發送請求參數
        out.print(param);
        // flush輸出流的緩沖
        out.flush();
        // 定義BufferedReader輸入流來讀取URL的響應
        in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        while ((line = in.readLine()) != null) {
            result += line;
        }
    } catch (Exception e) {
        System.out.println("發送 POST 請求出現異常！" + e);
        log.error(e.getMessage());
    }
    //使用finally塊來關閉輸出流、輸入流
    finally {
        try {
            if (out != null) {
                out.close();
            }
            if (in != null) {
                in.close();
            }
        } catch (IOException ex) {
            log.error(ex.getMessage());
        }
    }
    return result;
}