【项目中】关于webView上遇到的各种问题集锦

webView的相关设置：

//允许JS执行

webView.getSettings().setJavaScriptEnabled(true);

类似的还有如下这些设置【用到的时候查文档吧！】

//设置WebView的一些缩放功能点
webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
webView.setHorizontalScrollBarEnabled(false);
webView.getSettings().setSupportZoom(true);
//设置WebView可触摸放大缩小
webView.getSettings().setBuiltInZoomControls(true);
webView.setInitialScale(70);
webView.setHorizontalScrollbarOverlay(true);
//WebView双击变大，再双击后变小，当手动放大后，双击可以恢复到原始大小
//webView.getSettings().setUseWideViewPort(true);
//提高渲染的优先级
webView.getSettings().setRenderPriority(RenderPriority.HIGH);
//把图片加载放在最后来加载渲染
//webView.getSettings().setBlockNetworkImage(true);
//用WebView将字符串以HTML的形式显示出来
webView.loadDataWithBaseURL("fake://not/needed", <p>zzz</p>, "text/html", "utf-8", "");

//listview,webview中滚动拖动到顶部或者底部时的阴影
webView.setOverScrollMode(View.OVER_SCROLL_NEVER);
webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);//使用缓存
WebView.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE); //默认不使用缓存！
webView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY); //取消滚动条白边效果
1、android与js交互

参考：http://blog.csdn.net/it1039871366/article/details/46372207

2、在Android的webview中定制js的alert,confirm和prompt对话框的方法

参考：http://gundumw100.iteye.com/blog/1158719

1.首先继承android.webkit.WebChromeClient实现MyWebChromeClient。

2.在MyWebChromeClient.java中覆盖onJsAlert,onJsConfirm,onJsPrompt三个方法。

3.在初始化Webview时设置调用webview.setWebChromeClient(new MyWebChromeClient());

4.在Webview载入的html中使用window.alert,window.confirm,window.prompt方法，系统弹出的将是自定义实现的对应对话框。

MyWebChromeClient.java的代码如下：

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnCancelListener;
import android.content.DialogInterface.OnClickListener;
import android.content.DialogInterface.OnKeyListener;
import android.graphics.Bitmap;
import android.os.Message;
import android.util.Log;
import android.view.KeyEvent;
import android.webkit.JsPromptResult;
import android.webkit.JsResult;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.widget.EditText;

/**
* http://618119.com/archives/2010/12/20/199.html */

//****************************************************************************
public class MyWebChromeClient extends WebChromeClient {
@Override
public void onCloseWindow(WebView window) {
super.onCloseWindow(window);
}

@Override
public boolean onCreateWindow(WebView view, boolean dialog,
boolean userGesture, Message resultMsg) {
return super.onCreateWindow(view, dialog, userGesture, resultMsg);
}

/**
* 覆盖默认的window.alert展示界面，避免title里显示为“：来自file:////”
*/
public boolean onJsAlert(WebView view, String url, String message,
JsResult result) {
final AlertDialog.Builder builder = new AlertDialog.Builder(view.getContext());

builder.setTitle("对话框")
.setMessage(message)
.setPositiveButton("确定", null);

// 不需要绑定按键事件
// 屏蔽keycode等于84之类的按键
builder.setOnKeyListener(new OnKeyListener() {
public boolean onKey(DialogInterface dialog, int keyCode,KeyEvent event) {
Log.v("onJsAlert", "keyCode==" + keyCode + "event="+ event);
return true;
}
});
// 禁止响应按back键的事件
builder.setCancelable(false);
AlertDialog dialog = builder.create();
dialog.show();
result.confirm();// 因为没有绑定事件，需要强行confirm,否则页面会变黑显示不了内容。
return true;
// return super.onJsAlert(view, url, message, result);
}

public boolean onJsBeforeUnload(WebView view, String url,
String message, JsResult result) {
return super.onJsBeforeUnload(view, url, message, result);
}

/**
* 覆盖默认的window.confirm展示界面，避免title里显示为“：来自file:////”
*/
public boolean onJsConfirm(WebView view, String url, String message,
final JsResult result) {
final AlertDialog.Builder builder = new AlertDialog.Builder(view.getContext());
builder.setTitle("对话框")
.setMessage(message)
.setPositiveButton("确定",new OnClickListener() {
public void onClick(DialogInterface dialog,int which) {
result.confirm();
}
})
.setNeutralButton("取消", new OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
result.cancel();
}
});
builder.setOnCancelListener(new OnCancelListener() {
@Override
public void onCancel(DialogInterface dialog) {
result.cancel();
}
});

// 屏蔽keycode等于84之类的按键，避免按键后导致对话框消息而页面无法再弹出对话框的问题
builder.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(DialogInterface dialog, int keyCode,KeyEvent event) {
Log.v("onJsConfirm", "keyCode==" + keyCode + "event="+ event);
return true;
}
});
// 禁止响应按back键的事件
// builder.setCancelable(false);
AlertDialog dialog = builder.create();
dialog.show();
return true;
// return super.onJsConfirm(view, url, message, result);
}

/**
* 覆盖默认的window.prompt展示界面，避免title里显示为“：来自file:////”
* window.prompt('请输入您的域名地址', '618119.com');
*/
public boolean onJsPrompt(WebView view, String url, String message,
String defaultValue, final JsPromptResult result) {
final AlertDialog.Builder builder = new AlertDialog.Builder(view.getContext());

builder.setTitle("对话框").setMessage(message);

final EditText et = new EditText(view.getContext());
et.setSingleLine();
et.setText(defaultValue);
builder.setView(et)
.setPositiveButton("确定", new OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
result.confirm(et.getText().toString());
}

})
.setNeutralButton("取消", new OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
result.cancel();
}
});

// 屏蔽keycode等于84之类的按键，避免按键后导致对话框消息而页面无法再弹出对话框的问题
builder.setOnKeyListener(new OnKeyListener() {
public boolean onKey(DialogInterface dialog, int keyCode,KeyEvent event) {
Log.v("onJsPrompt", "keyCode==" + keyCode + "event="+ event);
return true;
}
});

// 禁止响应按back键的事件
// builder.setCancelable(false);
AlertDialog dialog = builder.create();
dialog.show();
return true;
// return super.onJsPrompt(view, url, message, defaultValue,
// result);
}

@Override
public void onProgressChanged(WebView view, int newProgress) {
super.onProgressChanged(view, newProgress);
}

@Override
public void onReceivedIcon(WebView view, Bitmap icon) {
super.onReceivedIcon(view, icon);
}

@Override
public void onReceivedTitle(WebView view, String title) {
super.onReceivedTitle(view, title);
}

@Override
public void onRequestFocus(WebView view) {
super.onRequestFocus(view);
}
}

3、Android WebView 上传文件支持
默认情况下情况下，使用Android的WebView是不能够支持上传文件的。因为Android的每个版本WebView的实现有差异，因此需要对不同版本去适配。花了一点时间，参考别人的代码，这个问题已经解决。

主要思路是重写WebChromeClient，然后在WebViewActivity中接收选择到的文件Uri，传给页面去上传就可以了。

创建一个WebViewActivity的内部类

webView.setWebChromeClient(new WebChromeClient() {
public void onProgressChanged(WebView view, int progress) {// 载入进度改变而触发
if (progress == 100) {
handler.sendEmptyMessage(1);// 如果全部载入,隐藏进度对话框
}

super.onProgressChanged(view, progress);
}

// 扩展支持alert事件
@Override
public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
AlertDialog.Builder builder = new AlertDialog.Builder(view.getContext());
builder.setTitle("项目帮").setMessage(message).setPositiveButton("确定", null);
builder.setCancelable(false);
builder.setIcon(R.drawable.ic_launcher);
AlertDialog dialog = builder.create();
dialog.show();
result.confirm();
return true;
}

// 覆盖默认的window.confirm展示界面，避免title里显示为“：来自file:////”
@Override
public boolean onJsConfirm(WebView view, String url, String message, final JsResult result) {
final AlertDialog.Builder builder = new AlertDialog.Builder(view.getContext());
builder.setTitle("项目帮").setMessage(message)
.setNegativeButton("取消", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
result.cancel();

}
}).setPositiveButton("确定", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
result.confirm();

}
});

builder.setOnCancelListener(new OnCancelListener() {
@Override
public void onCancel(DialogInterface dialog) {
result.cancel();
}
});

AlertDialog dialog = builder.create();
dialog.show();
return true;
// return super.onJsConfirm(view, url, message, result);
}

// 扩展浏览器上传文件
// 3.0++版本
public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType) {
openFileChooserImpl(uploadMsg);
}

// 3.0--版本
public void openFileChooser(ValueCallback<Uri> uploadMsg) {
openFileChooserImpl(uploadMsg);
}

public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture) {
openFileChooserImpl(uploadMsg);
}

// For Android > 5.0
public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> uploadMsg,
WebChromeClient.FileChooserParams fileChooserParams) {
openFileChooserImplForAndroid5(uploadMsg);
return true;
}
});

private void openFileChooserImpl(ValueCallback<Uri> uploadMsg) {
mUploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
startActivityForResult(Intent.createChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE);
}

private void openFileChooserImplForAndroid5(ValueCallback<Uri[]> uploadMsg) {
mUploadMessageForAndroid5 = uploadMsg;
Intent contentSelectionIntent = new Intent(Intent.ACTION_GET_CONTENT);
contentSelectionIntent.addCategory(Intent.CATEGORY_OPENABLE);
contentSelectionIntent.setType("image/*");

Intent chooserIntent = new Intent(Intent.ACTION_CHOOSER);
chooserIntent.putExtra(Intent.EXTRA_INTENT, contentSelectionIntent);
chooserIntent.putExtra(Intent.EXTRA_TITLE, "Image Chooser");

startActivityForResult(chooserIntent, FILECHOOSER_RESULTCODE_FOR_ANDROID_5);
}

特别注意的是5.0以上的版本，我在网上用了其他很多别人推荐的方法都不可以，但是以上方法亲测没问题。

以上是打开响应的选择文件的界面，我们还需要处理接收到文件之后，传给网页来响应。因为我们前面是使用startActivityForResult来打开的选择页面，我们会onActivityResult

中接收到选择的结果。Show code：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
if (requestCode == FILECHOOSER_RESULTCODE) {
if (null == mUploadMessage)
return;
Uri result = intent == null || resultCode != RESULT_OK ? null : intent.getData();
mUploadMessage.onReceiveValue(result);
mUploadMessage = null;

} else if (requestCode == FILECHOOSER_RESULTCODE_FOR_ANDROID_5) {
if (null == mUploadMessageForAndroid5)
return;
Uri result = (intent == null || resultCode != RESULT_OK) ? null : intent.getData();
if (result != null) {
mUploadMessageForAndroid5.onReceiveValue(new Uri[] { result });
} else {
mUploadMessageForAndroid5.onReceiveValue(new Uri[] {});
}
mUploadMessageForAndroid5 = null;
}
}

以上代码主要就是调用ValueCallback的onReceiveValue方法，将结果传回web。

参考：http://blog.isming.me/2015/12/21/android-webview-upload-file/
            http://blog.csdn.net/zhtsuc/article/details/49154099   （主要参考）
            http://blog.csdn.net/u014424628/article/details/51559981

4、图片照片拍照

    参考：http://blog.csdn.net/djcken/article/details/46379929

    参考：http://www.cnblogs.com/ufreedom/p/4158081.html

   参考：http://stackoverflow.com/questions/4455558/allow-user-to-select-camera-or-gallery-for-image