檢測到支付寶時會調起原生APP，檢測不到支付寶時會調起網頁版支付寶

package cn.showmac.simpledemo;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.KeyEvent;
import android.view.View;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;

import com.alipay.sdk.app.PayTask;
import com.alipay.sdk.util.H5PayResultModel;

import java.lang.ref.WeakReference;

public class H5Activity extends BaseActivity {

    private WebView mWebView;
    private ProgressBar bar;
    private String baseUrl = "http://5000.gr2c5266.showmac.ali-sh.goodrain.net:10080";

    private TestHandler mHandler = new TestHandler(this);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_h5);
        bar = (ProgressBar) findViewById(R.id.progressBar);
        mWebView = (WebView) findViewById(R.id.webView);
        WebSettings settings = mWebView.getSettings();
        settings.setJavaScriptEnabled(true);
        settings.setAllowFileAccess(true);
        settings.setCacheMode(WebSettings.LOAD_NO_CACHE);
        settings.setDomStorageEnabled(true);
        settings.setGeolocationEnabled(true);
        mWebView.loadUrl(baseUrl);
        mWebView.setWebChromeClient(new WebChromeClient() {
            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                super.onProgressChanged(view, newProgress);
                if (newProgress == 100) {
                    bar.setVisibility(View.INVISIBLE);
                } else {
                    bar.setVisibility(View.VISIBLE);
                    bar.setProgress(newProgress);
                }
            }
        });
        mWebView.setWebViewClient(
                new WebViewClient() {
                    @Override
                    public boolean shouldOverrideUrlLoading(final WebView view, String url) {
                        final PayTask task = new PayTask(H5Activity.this);
                        //處理訂單資訊
                        final String ex = task.fetchOrderInfoFromH5PayUrl(url);
                        if (!TextUtils.isEmpty(ex)) {
                            //呼叫支付介面進行支付
                            new Thread(new Runnable() {
                                public void run() {
                                    H5PayResultModel result = task.h5Pay(ex, true);
                                    Message message = new Message();
                                    message.what = 0;
                                    mHandler.sendMessage(message);
                                }
                            }).start();
                        } else {
                            view.loadUrl(url);
                        }
                        return true;
                    }
                }
        );

        findViewById(R.id.back).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
            }
        });
    }


    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
            mWebView.goBack();  //goBack()表示返回WebView的上一頁面
            return true;
        }
        finish();
        return false;
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mWebView != null) {
            mWebView.removeAllViews();
            mWebView.destroy();
        }
        if (mHandler != null) {
            mHandler.removeCallbacksAndMessages(null);
            mHandler = null;
        }

    }


    public class TestHandler extends Handler {
        WeakReference<Activity> mActivity;

        public TestHandler(Activity activity) {
            mActivity = new WeakReference<>(activity);
        }

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            Activity activity = mActivity.get();
            if (activity != null) {
                if (msg.what == 0) {
                    mWebView.loadUrl(baseUrl);
                }
            }
        }
    }
}