无API场景下使用Java获取指定网站上传歌曲BPM值的方案咨询

Hey there! Since the BPM detector site you mentioned doesn't provide an official API, web scraping is your go-to solution here. Below are two practical Java-based methods to get the BPM value after uploading your song:

1. Static Scraping with Jsoup + HttpURLConnection #

If the site returns the BPM value directly in the HTML response (no heavy JavaScript rendering), Jsoup is a lightweight, easy-to-use library for parsing HTML. Here's a rough outline of how to do it:

• First, use your browser's dev tools (Network tab) to inspect the form parameters: look for the file input name, any CSRF tokens, and the actual form action URL.
• Use Jsoup's built-in multipart support to send the file along with required form data.
• Parse the response HTML to extract the BPM value by targeting the specific HTML element that displays it.

Here's a simplified code snippet to get you started:

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.select.Elements;

import java.io.File;
import java.io.IOException;

public class BpmScraper {
    public static void main(String[] args) throws IOException {
        String uploadUrl = "https://www.conversion-tool.com/bpmdetector/"; // Double-check the actual form action URL
        File songFile = new File("path/to/your/song.mp3");

        // Send multipart request to upload the file
        Document doc = Jsoup.connect(uploadUrl)
                .data("file", songFile.getName(), songFile)
                .post();

        // Extract BPM - update the selector to match the site's actual HTML structure
        Elements bpmElements = doc.select("div.bpm-result span.value");
        if (!bpmElements.isEmpty()) {
            String bpmValue = bpmElements.first().text();
            System.out.println("Detected BPM: " + bpmValue);
        } else {
            System.out.println("Could not find BPM value in response");
        }
    }
}

2. Dynamic Scraping with Selenium WebDriver #

If the site uses JavaScript to load the BPM result after upload (common in modern sites), Jsoup won't work because it can't execute JS. Selenium simulates a real browser, so it can handle dynamic content:

• Set up Selenium with a browser driver (like ChromeDriver or FirefoxDriver).
• Automate opening the site, locating the file upload input, uploading your song, waiting for the result to load, then extracting the BPM text.

Example code snippet:

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;

import java.time.Duration;

public class BpmSeleniumScraper {
    public static void main(String[] args) {
        // Set path to your ChromeDriver executable
        System.setProperty("webdriver.chrome.driver", "path/to/chromedriver");
        WebDriver driver = new ChromeDriver();
        WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));

        try {
            driver.get("https://www.conversion-tool.com/bpmdetector/");

            // Locate file upload input and send the file path
            WebElement uploadInput = driver.findElement(By.cssSelector("input[type='file']"));
            uploadInput.sendKeys("path/to/your/song.mp3");

            // Wait for the BPM result to appear and extract it
            WebElement bpmResult = wait.until(ExpectedConditions.visibilityOfElementLocated(By.cssSelector("div.bpm-result span.value")));
            System.out.println("Detected BPM: " + bpmResult.getText());
        } finally {
            driver.quit();
        }
    }
}

Important Notes #

• Respect the Site's Terms: Make sure you're not violating the site's terms of service or robots.txt rules. Excessive scraping could get your IP blocked.
• Element Selectors: The CSS selectors in the examples are placeholders. Use your browser's dev tools to inspect the actual HTML elements that hold the BPM value and update the selectors accordingly.
• Error Handling: Add try-catch blocks to handle network issues, element not found exceptions, or unexpected site structure changes.

内容的提问来源于stack exchange，提问作者dcfg