生產中遇到過這種問題，記錄下java的接口調用問題。

一種是json方式；

 public static String sendPost(String url, JSONObject obj)throws IOException{
                   OutputStreamWriter out = null;
                   BufferedReader reader = null;
                   String response="";
                   
/*                   String paramStr = "";
                if (null != param) { //遍歷參數Map添加到集合中
                    Set<String> keySet = param.keySet();
                    for (String key : keySet) {
                        paramStr = paramStr + key + ":" + param.get(key) + "&";
                    }
                }
                int lastAndIndex = paramStr.lastIndexOf("&");
                if (lastAndIndex != -1) {
                    paramStr = paramStr.substring(0, lastAndIndex);
                }
                
                System.out.println("地址===" + url);
                System.out.println("入參===" + paramStr);
 
*/
                
                   try {
                       URL httpUrl = null; //HTTP URL類 用這個類來創建連接
                       //創建URL
                       httpUrl = new URL(url);
                       //建立連接
                       HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection();
                       conn.setRequestProperty(
 
"accept", "*/*");// 設置通用的請求屬性
                       conn.setRequestProperty("Charset", "UTF-8");
                       conn.setRequestMethod("POST");
                       conn.setRequestProperty("Content-Type", "application/json");
                       conn.setRequestProperty("connection", "keep-alive");
                       conn.setUseCaches(
 
false);//設置不要緩存
                       conn.setInstanceFollowRedirects(true);
                       conn.setDoOutput(true);
                       conn.setDoInput(true);
                       conn.connect();
                       //POST請求
                       out = new OutputStreamWriter(
                               conn.getOutputStream());
                       out.write(obj.toJSONString());
                       out.flush();
                       //讀取響應
                       reader = new BufferedReader(new InputStreamReader(
                               conn.getInputStream()));
                       String lines;
                       while ((lines = reader.readLine()) != null) {
                           lines = new String(lines.getBytes(), "utf-8");
                           response+=lines;
                       }
                       reader.close();
                       // 斷開連接
                       conn.disconnect();
                   } catch (Exception e) {
                   System.out.println("發送 POST 請求出現異常！"+e);
                   e.printStackTrace();
                   }
                   //使用finally塊來關閉輸出流、輸入流
                   finally{
                   try{
                       if(out!=null){
                           out.close();
                       }
                       if(reader!=null){
                           reader.close();
                       }
                   }
                   catch(IOException ex){
                       ex.printStackTrace();
                   }
               }
           
                   return response;
               }

再來一個普通的str 調用接口；

    /**
     * 向指定 URL 發送POST方法的請求
     * @param url 發送請求的 URL
     * @param param 請求參數，請求參數應該是 name1=value1&name2=value2 的形式。
     * @return 所代表遠程資源的響應結果
     */
    public static String sendPostWebReq(String url, Map<String, Object> param,int i) throws Exception {
        String paramStr = "";
        if (null != param) { //遍歷參數Map添加到集合中
            Set<String> keySet = param.keySet();
            for (String key : keySet) {
                paramStr = paramStr + key + "=" + param.get(key) + "&";
            }
        }
        int lastAndIndex = paramStr.lastIndexOf("&");
        if (lastAndIndex != -1) {
            paramStr = paramStr.substring(0, lastAndIndex);
        }
        
        System.out.println("地址===" + url);
        System.out.println("入參===" + paramStr);
        
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL(url);
            HttpURLConnection conn = (HttpURLConnection) realUrl.openConnection();// 打開和URL之間的連接
            conn.setRequestProperty("accept", "*/*");// 設置通用的請求屬性
            conn.setRequestProperty("Content-Type", "application/json");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("Charset", "UTF-8");
            conn.setDoOutput(true);// 發送POST請求必須設置如下兩行
            conn.setDoInput(true);// 獲取URLConnection對象對應的輸出流
            out = new PrintWriter(new OutputStreamWriter(conn.getOutputStream(), "UTF-8"));// 發送請求參數
            out.print(paramStr);// flush輸出流的緩沖
            out.flush();
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));// 定義BufferedReader輸入流來讀取URL的響應
            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);
            throw e;
        } finally { // 使用finally塊來關閉輸出流、輸入流
            try {
                if (in != null) in.close();
            } catch (IOException ex) { }
            if (out != null) out.close();
        }
        return result;
    }

java 接口調用