在Android/Java和Web/JavaScript之间使用AES-GCM加密算法，可以通过以下步骤来实现兼容性：

1. 生成随机的16字节密钥和12字节的随机IV：

SecureRandom secureRandom = new SecureRandom();
byte[] key = new byte[16];
secureRandom.nextBytes(key);

byte[] iv = new byte[12];
secureRandom.nextBytes(iv);

2. 在Android/Java端使用javax.crypto库进行加密和解密：

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;

public class AesGcmEncryption {

    public static byte[] encrypt(String plaintext, byte[] key, byte[] iv) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
        SecretKey secretKey = new SecretKeySpec(key, "AES");
        GCMParameterSpec parameterSpec = new GCMParameterSpec(128, iv);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, parameterSpec);
        return cipher.doFinal(plaintext.getBytes(StandardCharsets.UTF_8));
    }

    public static String decrypt(byte[] ciphertext, byte[] key, byte[] iv) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
        SecretKey secretKey = new SecretKeySpec(key, "AES");
        GCMParameterSpec parameterSpec = new GCMParameterSpec(128, iv);
        cipher.init(Cipher.DECRYPT_MODE, secretKey, parameterSpec);
        byte[] plaintextBytes = cipher.doFinal(ciphertext);
        return new String(plaintextBytes, StandardCharsets.UTF_8);
    }
}

3. 在Web/JavaScript端使用Crypto.subtle库进行加密和解密：

async function encrypt(plaintext, key, iv) {
    const encodedKey = await crypto.subtle.importKey(
        'raw', key, 'AES-GCM', false, ['encrypt']
    );
    const encryptedData = await crypto.subtle.encrypt(
        {name: 'AES-GCM', iv}, encodedKey, new TextEncoder().encode(plaintext)
    );
    return new Uint8Array(encryptedData);
}

async function decrypt(ciphertext, key, iv) {
    const encodedKey = await crypto.subtle.importKey(
        'raw', key, 'AES-GCM', false, ['decrypt']
    );
    const decryptedData = await crypto.subtle.decrypt(
        {name: 'AES-GCM', iv}, encodedKey, ciphertext
    );
    return new TextDecoder().decode(decryptedData);
}

这样，你就可以在Android/Java和Web/JavaScript之间使用相同的AES-GCM加密算法进行数据加密和解密了。请注意，这只是一个简单的示例，实际使用时还需要考虑更多的安全性和错误处理。