Android - 如何在Android WebView中使用Javascript？ [英] Android - How to use Javascript in an Android WebView?
问题描述
我的混合Android应用程序中存在问题。我需要一个带有HTML的WebView，在这个HTML中我有一个按钮。
I have a problem in my Hybrid Android App.I need to have a WebView with an HTML and in this HTML I have a button.
我有一个带有WebView的布局，我在HTML中有一个按钮，我正在尝试用另一个屏幕启动第二个Activity（也是一个带有WebView的布局）当用户点击此按钮时。
I have a layout with a WebView and I have a button inside the HTML, I'm trying to launch a second Activity with another screen(also a layout with a WebView) when the user click this button.
我的问题是这个按钮没有启动第二个活动。
My problem is that this button is not launching the second activity.
我正在使用Cordova。
I'm using Cordova.
这是我的布局（ pruebas.xml ）：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<WebView
android:id="@+id/webview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="@+id/textView" />
</LinearLayout>
这是我的 MainActivity.java ：
public class MainActivity extends CordovaActivity{
WebView wv;
JavaScriptInterface JSInterface;
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
StrictMode.setVmPolicy(builder.build());
setContentView(R.layout.pruebas);
wv = (WebView)findViewById(R.id.webview);
wv.getSettings().setJavaScriptEnabled(true);
wv.getSettings().setDomStorageEnabled(true);
// register class containing methods to be exposed to JavaScript
JSInterface = new MainActivity.JavaScriptInterface(this);
wv.addJavascriptInterface(JSInterface, "JSInterface");
wv.loadUrl("file:///android_asset/www/description.html");
}
public class JavaScriptInterface {
Context mContext;
/** Instantiate the interface and set the context */
JavaScriptInterface(Context c) {
mContext = c;
}
@android.webkit.JavascriptInterface
public void changeActivity(){
Intent i = new Intent(MainActivity.this, JavascriptInterfaceActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
finish();
}
}
}
这是我的第二项活动（ JavascriptInterfaceActivity.java ）：
And this is my second activity (JavascriptInterfaceActivity.java):
public class JavascriptInterfaceActivity extends Activity {
WebView wv;
JavaScriptInterface JSInterface;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
StrictMode.setVmPolicy(builder.build());
setContentView(R.layout.pruebas);
wv = (WebView)findViewById(R.id.webview);
wv.getSettings().setJavaScriptEnabled(true);
wv.getSettings().setDomStorageEnabled(true);
JSInterface = new JavaScriptInterface(this);
wv.addJavascriptInterface(JSInterface, "JSInterface");
wv.loadUrl("file:///android_asset/www/description-long.html");
}
public class JavaScriptInterface {
Context mContext;
/** Instantiate the interface and set the context */
JavaScriptInterface(Context c) {
mContext = c;
}
@android.webkit.JavascriptInterface
public void changeActivity(){
Intent i = new Intent(JavascriptInterfaceActivity.this, MainActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
finish();
}
}
}
这是 description.html ，其他HTML（ description-long.html ）类似：
This is the description.html, the other HTML (description-long.html) is similar:
<!DOCTYPE html>
<html>
<head>
<script src='changeactivity.js'></script>
<meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap: https://ssl.gstatic.com 'unsafe-eval'; style-src 'self' 'unsafe-inline'; media-src *">
<meta name="format-detection" content="telephone=no">
<meta name="msapplication-tap-highlight" content="no">
<meta name="viewport" content="user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1, width=device-width">
<link rel="stylesheet" type="text/css" href="css/index.css">
<title>Main activity</title>
</head>
<body>
<button id='changeactivity'>Changue activity</button>
</body>
</html>
这是我的 changeactivity.js 文件 assets / www ：
function displaymessage(){
JSInterface.changeActivity();
}
document.addEventListener('DOMContentReady', function () {
document.getElementById('changeactivity').addEventListener('click', displaymessage);
});
有任何建议吗？我查看这些帖子：
Any suggestion? I check these posts:
https://stackoverflow.com/a/ 10481108/3739382
https://stackoverflow.com/ a / 31631068/3739382
推荐答案
注意：绑定到JavaScript的对象在另一个线程中运行，而不是在构造它的线程中运行。
Note: The object that is bound to your JavaScript runs in another thread and not in the thread in which it was constructed.
您正在非UI线程上启动活动。您应该在UI线程上运行它，如下所示：
You are starting the activity on non-UI thread. You should run it on UI thread as follows:
@android.webkit.JavascriptInterface
public void changeActivity(){
runOnUiThread(new Runnable() {
@Override
public void run() {
Intent i = new Intent(MainActivity.this, JavascriptInterfaceActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
finish();
}
});
}
或者你也可以使用Handler。
Alternatively you can also use Handler.
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