1.当只用WebView的时候,最先注意的当然是在配置文件中添加访问因特网的权限;
2.如果访问的页面中有Javascript,必须设置支持Javascript:
Java代码
webview.getSettings().setJavaScriptEnabled(true);
3.如果希望点击链接由自己处理而不是新开Android的系统browser中响应该链接.给WebView添加一个事件监听对象(WebViewClient)并重写其中的一些方法 shouldOverrideUrlLoading对网页中超链接按钮的响应
Java代码
mWebView.setWebViewClient(new WebViewClient() {
/**
* Show in webview not system webview.
*/
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return super.shouldOverrideUrlLoading(view, url);
}
}
这样就保证了每次打开的页面都是在WebView实例中显示运行的;
4.在显示WebView时,点击手机Back时,会完全退出当前Activity,如果想退到历史浏览页面:重写back监听:
Java代码
public boolean onKeyDown(int keyCode, KeyEvent event) {
WebView mWebView = (WebView) findViewById(R.id.browser);
if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
mWebView.goBack();
return true;
}
return super.onKeyDown(keyCode, event);
}
5.android sdk提供了一个schema前缀为"file:///android_asset/".WebView遇到这样的schema,就去当前包中的 assets目录中找内容.如:"file:///android_asset/demo.html"
下面一段代码是对网页中JS的类似Alert()类的函数进行相应的重写响应:
Java代码
webView.setWebChromeClient(new WebChromeClient() {
public boolean onJsAlert(WebView view, String url, String message,
final JsResult result) {
AlertDialog.Builder b = new AlertDialog.Builder(BrowserJs.this);
b.setTitle("Alert");
b.setMessage(message);
b.setPositiveButton(android.R.string.ok,
new AlertDialog.OnClickListener() {
public void onClick(DialogInterface dialog,
int which) {
result.confirm();
}
});
b.setCancelable(false);
b.create();
b.show();
return true;
};
@Override
public boolean onJsConfirm(WebView view, String url,
String message, final JsResult result) {
AlertDialog.Builder b = new AlertDialog.Builder(BrowserJs.this);
b.setTitle("Confirm");
b.setMessage(message);
b.setPositiveButton(android.R.string.ok,
new AlertDialog.OnClickListener() {
public void onClick(DialogInterface dialog,
int which) {
result.confirm();
}
});
b.setNegativeButton(android.R.string.cancel,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int which) {
result.cancel();
}
});
b.setCancelable(false);
b.create();
b.show();
return true;
};
@Override
public boolean onJsPrompt(WebView view, String url, String message,
String defaultValue, final JsPromptResult result) {
final LayoutInflater factory = LayoutInflater
.from(BrowserJs.this);
final View v = factory.inflate(
R.layout.prompt_dialog, null);
((TextView) v.findViewById(R.id.prompt_message_text))
.setText(message);
((EditText) v.findViewById(R.id.prompt_input_field))
.setText(defaultValue);
AlertDialog.Builder b = new AlertDialog.Builder(BrowserJs.this);
b.setTitle("Prompt");
b.setView(v);
b.setPositiveButton(android.R.string.ok,
new AlertDialog.OnClickListener() {
public void onClick(DialogInterface dialog,
int which) {
String value = ((EditText) v
.findViewById(R.id.prompt_input_field))
.getText().toString();
result.confirm(value);
}
});
b.setNegativeButton(android.R.string.cancel,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,
int which) {
result.cancel();
}
});
b.setOnCancelListener(new DialogInterface.OnCancelListener() {
public void onCancel(DialogInterface dialog) {
result.cancel();
}
});
b.show();
return true;
};
public void onProgressChanged(WebView view, int newProgress) {
BrowserJs.this.getWindow().setFeatureInt(
Window.FEATURE_PROGRESS, newProgress * 100);
super.onProgressChanged(view, newProgress);
}
public void onReceivedTitle(WebView view, String title) {
BrowserJs.this.setTitle(title);
super.onReceivedTitle(view, title);
}
});
go.setOnClickListener(new OnClickListener() {
public void onClick(View view) {
String url = text.getText().toString();
webView.loadUrl(url);
}
});
webView.loadUrl("file:///android_asset/index.html");
在上述代码中,用到的prompt_dialog.xml:
Java代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:gravity="center_horizontal" android:orientation="vertical"
android:layout_width="fill_parent" android:layout_height="wrap_content">
<TextView android:id="@+id/prompt_message_text"
android:layout_width="fill_parent" android:layout_height="wrap_content" />
<EditText android:id="@+id/prompt_input_field"
android:layout_width="fill_parent" android:layout_height="wrap_content"
android:selectAllOnFocus="true" android:scrollHorizontally="true"
android:minWidth="250dp" />
</LinearLayout>
还有assets中的Html文件:
Java代码
<html>
<script type="text/javascript">
function onAlert(){
alert("This is a alert sample from html");
}
function onConfirm(){
var b=confirm("are you sure to login?");
alert("your choice is "+b);
}
function onPrompt(){
var b=prompt("please input your password","aaa");
alert("your input is "+b);
}
</script>
<pre>
<input type="button" value="alert"/>
<input type="button" value="confirm"/>
<input type="button" value="prompt"/>
<a href="http://www.google.com"/>Google</a>
</pre>
</html>
接着上篇:
6.通过字符串拼凑的html页面显示:
Java代码
public void simpleJsClick() {
WebView webView = (WebView) findViewById(R.id.webview);
String html = "<html>"
+ "<body>"
+ "图书封面<br>"
+ "<table width='200' border='1' >"
+ "<tr>"
+ "<td><a onclick='alert(\"Java Web开发速学宝典\")' ><img style='margin:10px' src='http://images.china-pub.com/ebook45001-50000/48015/cover.jpg' width='100'/></a></td>"
+ "<td><a onclick='alert(\"大象--Thinking in UML\")' ><img style='margin:10px' src='http://images.china-pub.com/ebook125001-130000/129881/zcover.jpg' width='100'/></td>"
+ "</tr>"
+ "<tr>"
+ "<td><img style='margin:10px' src='http://images.china-pub.com/ebook25001-30000/27518/zcover.jpg' width='100'/></td>"
+ "<td><img style='margin:10px' src='http://images.china-pub.com/ebook30001-35000/34838/zcover.jpg' width='100'/></td>"
+ "</tr>" + "</table>" + "</body>" + "</html>";
webView.loadDataWithBaseURL(null, html, "text/html", "utf-8", null);
webView.getSettings().setJavaScriptEnabled(true);
webView.setWebChromeClient(new WebChromeClient());
}
7.在同种分辨率的情况下,屏幕密度不一样的情况下,自动适配页面:
Java代码
DisplayMetrics dm = getResources().getDisplayMetrics();
int scale = dm.densityDpi;
if (scale == 240) { //
webView.getSettings().setDefaultZoom(ZoomDensity.FAR);
} else if (scale == 160) {
webView.getSettings().setDefaultZoom(ZoomDensity.MEDIUM);
} else {
webView.getSettings().setDefaultZoom(ZoomDensity.CLOSE);
}
8.判断加载的页面URL地址是否正确:
Java代码
if(URLUtil.isNetworkUrl(url)==true)
9.设置WebView的一些缩放功能点:
Java代码
webView.getSettings().setJavaScriptEnabled(true);
webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
webView.setHorizontalScrollBarEnabled(false);
webView.getSettings().setSupportZoom(true);
webView.getSettings().setBuiltInZoomControls(true);
webView.setInitialScale(70);
webView.setHorizontalScrollbarOverlay(true);
完成java文件:
Java代码
public class MethodMutual extends Activity {
private WebView mWebView;
private Handler mHandler = new Handler();
private static final String LOG_TAG = "WebViewDemo";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
loadAssetHtml();
}
public void loadAssetHtml() {
mWebView = (WebView) findViewById(R.id.webview);
WebSettings webSettings = mWebView.getSettings();
webSettings.setSavePassword(false);
webSettings.setSaveFormData(false);
webSettings.setJavaScriptEnabled(true);
webSettings.setSupportZoom(false);
mWebView.setWebChromeClient(new MyWebChromeClient());
// 将一个java对象绑定到一个javascript对象中,javascript对象名就是interfaceName,作用域是Global.
mWebView.addJavascriptInterface(new DemoJavaScriptInterface(), "demo");
mWebView.loadUrl("file:///android_asset/demo.html");
// 通过应用中按钮点击触发JS函数响应
Button mCallJS = (Button) findViewById(R.id.mCallJS);
mCallJS.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mWebView.loadUrl("javascript：wave()");
}
});
}
private int i = 0;
final class DemoJavaScriptInterface {
DemoJavaScriptInterface() {
}
/**
* This is not called on the UI thread. Post a runnable to invoke
* loadUrl on the UI thread.
*/
public void callAndroid() {
mHandler.post(new Runnable() {
public void run() {
if (i % 2 == 0) {
mWebView.loadUrl("javascript：wave()");
} else {
mWebView.loadUrl("javascript：waveBack()");
}
i++;
}
});
}
}
/**
* Provides a hook for calling "alert" from javascript. Useful for debugging
* your javascript.
*/
final class MyWebChromeClient extends WebChromeClient {
@Override
public boolean onJsAlert(WebView view, String url, String message,
JsResult result) {
Log.d(LOG_TAG, message);
result.confirm();
return true;
}
}
}
main.xml文件:
Java代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button android:layout_width="wrap_content" android:text="CallJs"
android:layout_height="wrap_content" android:id="@+id/mCallJS" />
<WebView android:id="@+id/webview" android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</LinearLayout>
demo.html:
Java代码
<html>
<script language="javascript">
/* This function is invoked by the activity */
function wave() {
alert("1");
document.getElementById("droid").src="android_waving.png";
alert("2");
}
/* This function is invoked by the activity */
function waveBack() {
alert("1");
document.getElementById("droid").src="android_normal.png";
alert("2");
}
</script>
<body>
<!-- Calls into the javascript interface for the activity -->
<a><div style="width:80px;
margin:0px auto;
padding:10px;
text-align:center;
border:2px solid #202020;" >
<img id="droid" src="android_normal.png"/><br>
Click me!
</div></a>
</body>
</html>
