webview使用总结（一）

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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" onclick="onAlert()"/>  
<input type="button" value="confirm" onclick="onConfirm()"/>  
<input type="button" value="prompt" onclick="onPrompt()"/>  
  
<a href="http://www.google.com"/>Google</a>  
</pre>  
</html>  