Question

我正在测试我的应用，现在我已经从我上一篇文章中更新了它们。当我按下设备上的后退按钮时，应用程序卡住并且屏幕上出现错误。我无法按下模拟器上的按钮，所以我无法给出错误。

我还希望当我点击没有 http：// 的链接时，它会在网页浏览中打开，当网址为 http：// 时，它会打开在浏览器中。

问候Christophe

main.java

import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.view.KeyEvent;
import android.view.Menu;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import be.my.app.ConnectionDetector;

public class MainActivity extends Activity {
    @SuppressLint("SetJavaScriptEnabled")

    WebView myWebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        /*=== instellingen ===*/
        String url = "http://app.site.be?av=1"; //starturl

        /*=== verwerkingdsdata ===*/
        WebView view = (WebView) this.findViewById(R.id.webView1); //koppeling layout aan id

        view.getSettings().setJavaScriptEnabled(true); // javascript aan

        // flag for Internet connection status
        Boolean isInternetPresent = false;
     // Connection detector class
        ConnectionDetector cd;
     // creating connection detector class instance
        cd = new ConnectionDetector(getApplicationContext());
        // get Internet status
        isInternetPresent = cd.isConnectingToInternet();

        // check for Internet status
        if (isInternetPresent) {
            view.loadUrl(url); // laad de url
        } else {
            setContentView(R.layout.niet_verbonden); //geen verbinding error weergeven
        }
        view.setWebViewClient(new MyWebViewClient());
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(event.getAction() == KeyEvent.ACTION_DOWN){
            switch(keyCode)
            {
            case KeyEvent.KEYCODE_BACK:
                if(myWebView.canGoBack() == true){
                    myWebView.goBack();
                }else{
                    finish();
                }
                return true;
            }

        }
        return super.onKeyDown(keyCode, event);
    }

}

class MyWebViewClient extends WebViewClient {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if(url.contains("http://")){ // Could be cleverer and use a regex
            return super.shouldOverrideUrlLoading(view, url); // Leave webview and use browser
        } else {
            view.loadUrl(url); // Stay within this webview and load url
            return true;
        }
    }
}

Answer 1

if(myWebView.canGoBack() == true){

这里你引用myWebView由于没有设置它总是为空，

以后你有

WebView view = (WebView) this.findViewById(R.id.webView1);

将其替换为

myWebView = (WebView) this.findViewById(R.id.webView1);

这肯定是问题

希望这会有所帮助

编辑：用这个替换你的代码：

import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.view.KeyEvent;
import android.view.Menu;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import be.my.app.ConnectionDetector;

public class MainActivity extends Activity {
    @SuppressLint("SetJavaScriptEnabled")

    WebView myWebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        /*=== instellingen ===*/
        String url = "http://app.site.be?av=1"; //starturl

        /*=== verwerkingdsdata ===*/
        myWebView= (WebView) this.findViewById(R.id.webView1); //koppeling layout aan id

        myWebView.getSettings().setJavaScriptEnabled(true); // javascript aan

        // flag for Internet connection status
        Boolean isInternetPresent = false;
     // Connection detector class
        ConnectionDetector cd;
     // creating connection detector class instance
        cd = new ConnectionDetector(getApplicationContext());
        // get Internet status
        isInternetPresent = cd.isConnectingToInternet();

        // check for Internet status
        if (isInternetPresent) {
            myWebView.loadUrl(url); // laad de url
        } else {
            setContentView(R.layout.niet_verbonden); //geen verbinding error weergeven
        }
        myWebView.setWebViewClient(new MyWebViewClient());
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(event.getAction() == KeyEvent.ACTION_DOWN){
            switch(keyCode)
            {
            case KeyEvent.KEYCODE_BACK:
                if(myWebView.canGoBack() == true){
                    myWebView.goBack();
                }else{
                    finish();
                }
                return true;
            }

        }
        return super.onKeyDown(keyCode, event);
    }

}

class MyWebViewClient extends WebViewClient {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if(url.contains("http://")){ // Could be cleverer and use a regex
            return super.shouldOverrideUrlLoading(view, url); // Leave webview and use browser
        } else {
            view.loadUrl(url); // Stay within this webview and load url
            return true;
        }
    }
}

按下后退按钮后，我的Android应用程序卡住了

1 个答案: