POST表单数据

public String postContent(String url, Map<String, String> formData) {
    // okHttpClient 实例
    OkHttpClient okHttpClient = new OkHttpClient();
    //post方式提交的数据
    FormBody.Builder builder =new FormBody.Builder();
  // 放入表单数据
    for(String key:formData.keySet()){
      builder.add(key,formData.get(key));
    }
    // 构建 FormBody 对象
    FormBody formBody = builder.build();
    // 指定 post 方式提交FormBody
    Request request = new Request.Builder()
            .url(url)
            // addHeader("Referer", ...) 这个知识点在后面的章节中学到，目前不要纠结
            .addHeader("Referer", "https://www.taobao.com")
            .post(formBody)
            .build();
    // 使用client去请求
    Call call = okHttpClient.newCall(request);
    // 返回结果字符串
    String result = null;
    try {
      // 获得返回结果
      result = call.execute().body().string();
    } catch (IOException e) {
      // 抓取异常
      System.out.println("request " + url + " error . ");
      e.printStackTrace();
    }
    return result;
  }