java - 在android studio中发送POST请求

Question

我关注了这个article之前构建过我自己的 RESTful API 服务器。现在，我想向 android studio 中的 API 服务器发送 POST 请求。我关注了这个reply ，但没有成功。

这是我的代码的一部分:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_events_create);

    ActionBar actionBar = this.getSupportActionBar();
    actionBar.setTitle("Test");
    actionBar.setDisplayHomeAsUpEnabled(true);


    URL url;
    HttpURLConnection connection = null;
    try {
        url = new URL("http://myip/task_manager/v1/register");
        connection = (HttpURLConnection)url.openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod("POST"); // hear you are telling that it is a POST request, which can be changed into "PUT", "GET", "DELETE" etc.
        connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8"); // here you are setting the `Content-Type` for the data you are sending which is `application/json`
        connection.connect();

        //Send request
        DataOutputStream wr = new DataOutputStream(
                connection.getOutputStream ());
        wr.writeBytes("Parameter String"); // I dunno how to write this string..
        wr.flush();
        wr.close ();

        InputStream is;
        int response = connection.getResponseCode();
        if (response >= 200 && response <=399){
            //return is = connection.getInputStream();
            //return true;
        } else {
            //return is = connection.getErrorStream();
            //return false;
        }


    } catch (Exception e) {

        e.printStackTrace();
        //return false;

    } finally {

        if(connection != null) {
            connection.disconnect();
        }
    }

}

这是我的问题:
1. 当“connection.connect();”时运行后，控制台出现错误。是我的网址字符串错误吗？
2.“参数字符串”应该是什么样的？ (我的参数是email=xxx，name=yyy)
3. 有没有更好的方法发送POST请求？

非常感谢!!!!!!~

Answer 1

要回答您的问题 #3，建议使用像 OkHTTP 这样的库来发出 post 请求。这将使您的代码更简单且更易于调试。

确保您对 list 拥有以下权限:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

将库添加到您的 gradle 文件中:

编译'com.squareup.okhttp3:okhttp:3.10.0'

然后，将您的 onCreate 方法更改为以下内容:

private final OkHttpClient client = new OkHttpClient();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_events_create);

    ActionBar actionBar = this.getSupportActionBar();
    actionBar.setTitle("Test");
    actionBar.setDisplayHomeAsUpEnabled(true);

    makePost();
}

private void makePost(){
    RequestBody requestBody = new MultipartBody.Builder()
        .setType(MultipartBody.FORM)
        .addFormDataPart("email", "your-email@email.com")
        .addFormDataPart("name", "your-name")
        .build();

    request = new Request.Builder()
        .url("http://myip/task_manager/v1/register")
        .post(requestBody)
        .build();

    try (Response response = client.newCall(request).execute()) {
        if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

      Headers responseHeaders = response.headers();
      for (int i = 0; i < responseHeaders.size(); i++) {
        System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));
      }

      System.out.println(response.body().string());
   }
}

这应该向您的端点发出发布请求。

如果你想记录它，你可以添加 logging interceptor到它。

希望这对您有帮助!