当按钮是三角形朝下时，如何从JavaScript启动安卓后退按钮？(隐藏键盘)

<button id="backButton" onclick="hideKeyboard()">▼</button>

function hideKeyboard() {
  // 调用Android的JavaScript接口方法
  AndroidInterface.hideKeyboard();
}

import android.webkit.JavascriptInterface;

public class AndroidInterface {
    private MainActivity mActivity;

    public AndroidInterface(MainActivity activity) {
        mActivity = activity;
    }

    // 该方法将在JavaScript中被调用
    @JavascriptInterface
    public void hideKeyboard() {
        mActivity.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                // 在这里执行隐藏键盘的操作
                // ...
            }
        });
    }
}

import android.os.Bundle;
import android.webkit.WebSettings;
import android.webkit.WebView;

public class MainActivity extends AppCompatActivity {
    private WebView mWebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mWebView = findViewById(R.id.webView);

        // 启用JavaScript
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setJavaScriptEnabled(true);

        // 将JavaScript接口类添加到WebView中
        mWebView.addJavascriptInterface(new AndroidInterface(this), "AndroidInterface");

        // 加载HTML文件或URL
        mWebView.loadUrl("file:///android_asset/index.html");
    }
}