在Android客户端访问服务器，通常使用HTTP协议进行通信，以下是详细的步骤和小标题：

1、添加网络权限

在AndroidManifest.xml文件中添加网络权限：

<usespermission android:name="android.permission.INTERNET" />

2、创建网络请求类

创建一个名为NetworkRequest的类，用于封装网络请求的方法：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class NetworkRequest {
    private static final String REQUEST_METHOD = "GET";
    private static final int READ_TIMEOUT = 15000;
    private static final int CONNECTION_TIMEOUT = 15000;
    public String sendGetRequest(String requestUrl) {
        StringBuilder result = new StringBuilder();
        try {
            URL url = new URL(requestUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setReadTimeout(READ_TIMEOUT);
            connection.setConnectTimeout(CONNECTION_TIMEOUT);
            connection.setRequestMethod(REQUEST_METHOD);
            connection.connect();
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line;
                while ((line = reader.readLine()) != null) {
                    result.append(line);
                }
                reader.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result.toString();
    }
}

3、发送网络请求并处理响应结果

在需要发送网络请求的地方，调用NetworkRequest类的sendGetRequest方法，并处理响应结果：

public class MainActivity extends AppCompatActivity {
    private NetworkRequest networkRequest;
    private TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.textView);
        networkRequest = new NetworkRequest();
        getDataFromServer("https://api.example.com/data");
    }
    private void getDataFromServer(String requestUrl) {
       networkRequest.sendGetRequest(requestUrl) { response >
            runOnUiThread(() > {
                textView.setText(response);
            });
        };
    }
}

4、单元表格：Android客户端访问服务器的主要步骤和代码示例：