Java代码无法从资源加载静态文件

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class FileLoader {
    public static String loadFile(String filePath) throws IOException {
        StringBuilder content = new StringBuilder();
        BufferedReader reader = new BufferedReader(new FileReader(filePath));
        String line;
        while ((line = reader.readLine()) != null) {
            content.append(line);
        }
        reader.close();
        return content.toString();
    }
}

import javax.servlet.ServletContext;
import java.io.IOException;
import java.io.InputStream;

public class WebFileLoader {
    public static String loadFile(String filePath, ServletContext servletContext) throws IOException {
        StringBuilder content = new StringBuilder();
        InputStream inputStream = servletContext.getResourceAsStream(filePath);
        byte[] buffer = new byte[1024];
        int bytesRead;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            content.append(new String(buffer, 0, bytesRead));
        }
        inputStream.close();
        return content.toString();
    }
}