Android- 使用 addJavaScriptInterface 从 Javascript 返回值
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Android- using addJavaScriptInterface to return a value from Javascript
提问by aamiri
So i know there are other posts addressing the same issue, and I think I've followed them to the letter but alas to no avail. I'm trying to learn how to get my app to interact with javascript. I just want to be able to return a value from my javascript to my activity.
here is my activity:
所以我知道还有其他帖子解决了同样的问题，我想我已经按照他们的要求写了信，但可惜无济于事。我正在尝试学习如何让我的应用程序与 javascript 交互。我只是希望能够从我的 javascript 返回一个值到我的活动。
这是我的活动：
public class JSExample extends Activity {
WebView mWebView;
String mString;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mWebView = (WebView)findViewById(R.id.mWebView);
mWebView.addJavascriptInterface(new ClsAccessor(), "accessor");
String html = getAssetsContent("jsinterface.html");
mWebView.loadDataWithBaseURL(null, html, "text/html", "UTF-8", null);
// Log.d("YO!", mString);
}
private String getAssetsContent(String filename){
.....
}
private void closeStream(BufferedReader stream) {
.....
}
class ClsAccessor{
public void setValue(String value){
JSExample.this.mString = value;
}
}
Here is the html file loaded by my WebView that contains the javascript i want to run:
这是我的 WebView 加载的 html 文件，其中包含我要运行的 javascript：
<!DOCTYPE html>
<html>
<head>
<script language="javascript">
accessor.setValue('Hello!');
</script>
</head>
<body>
<h1>Testing</h1>
</body>
</html>
This does not work. When i run the code with "Log.d("YO!", mString);" uncommented I get a null pointer exception, which means that the javascript never assigned a value to mString. what am i doing wrong?
这不起作用。当我使用“Log.d("YO!", mString); 运行代码时 取消注释我得到一个空指针异常，这意味着 javascript 从未将值分配给 mString。我究竟做错了什么？
采纳答案by Quintin Robinson
This may not be correct, I will have to double check but it may be due to the reference being lost..
这可能不正确，我将不得不仔细检查，但这可能是由于参考丢失了..
Try making your ClsAccessorreference a member level one..
尝试使您的ClsAccessor参考成为会员一级..
public class JSExample extends Activity {
...
ClsAccessor _accessor = new ClsAccessor();
...
public void onCreate(Bundle savedInstanceState) {
...
mWebView.addJavascriptInterface(_accessor, "accessor");
...
Also if you debug line by line does setValue()ever get called in managed code?
此外，如果您逐行调试是否setValue()曾经在托管代码中被调用？
For what it is worth, I have code that is doing as I have described above and the script to managed interface works fine, however I am not in a position currently to test and see if not having a reference to the class also works.
值得一提的是，我有我上面描述的代码，并且托管接口的脚本工作正常，但是我目前无法测试并查看没有对类的引用是否也有效。
回答by Anonymous
Try enabling javascript on your webview :
尝试在您的 webview 上启用 javascript：
mWebview.getSettings().setJavaScriptEnabled(true);
回答by bMon
I do it by utilizing the onLoadResource in my Webview class.
我通过在我的 Webview 类中使用 onLoadResource 来做到这一点。
Html page:
html页面：
<html>
<head>
function Submit(){
var username = $('#username').val();
var urlNew = 'processing.php';
urlNew = urlNew + '?' + 'username=' + username;
$('#submit').attr('href', urlNew);
return true;
}
</head>
<body>
<form>
<input id="username" name="username" type="text" />
<a href="" id="submit" onclick="return Submit();" ><img src="images/button.png" /></a>
</form>
</body>
</html>
So then in my onLoadResource I listen for that url:
然后在我的 onLoadResource 中我监听那个 url：
public void onLoadResource(WebView view, String url)
{
if(url.contains("http://domain.com/processing.php")){
//process the url and suck out the data
}
This might not be what you need, but there were reasons I had to do it this way so figured it may help you. Also note that I didn't do form submit, I did <a>submit, thats because the onLoadResource won't pick up the form submit.
这可能不是您所需要的，但有一些原因我不得不这样做，所以我认为它可以帮助您。还要注意，我没有做表单提交，我确实<a>提交了，那是因为 onLoadResource 不会选择表单提交。
Edit: This might help.
编辑： 这可能会有所帮助。
