在Java中實現GET請求可以使用HttpURLConnection類來實現。以下是一個簡單的示例：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpGetRequest {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://example.com/api");
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");

            BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String inputLine;
            StringBuffer response = new StringBuffer();

            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
            in.close();

            System.out.println(response.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

在上面的示例中，我們創建了一個URL對象，然后通過調用openConnection()方法獲取HttpURLConnection對象。接著設置請求方法為GET，并發送請求。最后讀取響應內容并輸出到控制臺。