利用html5开发android
2016-02-29 09:25
531 查看
● Android设备多分辨率的问题Android浏览器默认预览模式浏览 会缩小页面 WebView中则会以原始大小显示Android浏览器和WebView默认为mdpi。hdpi相当于mdpi的1.5倍 ldpi相当于0.75倍三种解决方式：1 viewport属性 2 CSS控制 3 JS控制1 viewport属性放在HTML的<meta>中Html代码 <SPAN style="FONT-SIZE: x-small"> <head>
<title>Exmaple</title>
<meta name=”viewport” content=”width=device-width,user-scalable=no”/>
</head></SPAN>meta中viewport的属性如下Html代码 <SPAN style="FONT-SIZE: x-small"> <meta name="viewport"
content="height = [pixel_value | device-height] ,width = [pixel_value | device-width ] ,initial-scale = float_value ,minimum-scale = float_value ,maximum-scale = float_value ,user-scalable = [yes | no] ,target-densitydpi = [dpi_value | device-dpi |high-dpi | medium-dpi | low-dpi]
"
/></SPAN>2 CSS控制设备密度为每种密度创建独立的样式表（注意其中的webkit-device-pixel-ratio 3个数值对应3种分辨率）Html代码 <link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio: 1.5)" href="hdpi.css" />
<link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio: 1.0)" href="mdpi.css" />
<link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio: 0.75)" href="ldpi.css" />在一个样式表中，指定不同的样式Html代码 #header {
<SPAN style="WHITE-SPACE: pre"> </SPAN> background:url(medium-density-image.png);
}
@media screen and (-webkit-device-pixel-ratio: 1.5) {
// CSS for high-density screens
#header {
background:url(high-density-image.png);
}
}
@media screen and (-webkit-device-pixel-ratio: 0.75) {
// CSS for low-density screens
#header {
background:url(low-density-image.png);
}
}Html代码 <meta name="viewport" content="target-densitydpi=device-dpi, width=device-width" />3 JS控制Android浏览器和WebView支持查询当前设别密度的DOM特性window.devicePixelRatio 同样值有3个（0.75,1,1.5对应3种分辨率）JS中查询设备密度的方法Js代码if (window.devicePixelRatio == 1.5) {alert("This is a high-density screen");} else if (window.devicePixelRation == 0.75) {alert("This is a low-density screen");}● Android中构建HTML5应用使用WebView控件 与其他控件的使用方法相同 在layout中使用一个<WebView>标签WebView不包括导航栏，地址栏等完整浏览器功能，只用于显示一个网页在WebView中加载Web页面，使用loadUrl()Java代码WebView myWebView = (WebView) findViewById(R.id.webview);
myWebView.loadUrl("http://www.example.com");注意在manifest文件中加入访问互联网的权限：Xml代码 <uses-permission android:name="android.permission.INTERNET" />在Android中点击一个链接，默认是调用应用程序来启动，因此WebView需要代为处理这个动作 通过WebViewClientJava代码 //设置WebViewClient
webView.setWebViewClient(new WebViewClient(){
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
public void onPageFinished(WebView view, String url) {super.onPageFinished(view, url);}
public void onPageStarted(WebView view, String url, Bitmap favicon) {super.onPageStarted(view, url, favicon);}
});这个WebViewClient对象是可以自己扩展的，例如Java代码 private class MyWebViewClient extends WebViewClient {public boolean shouldOverrideUrlLoading(WebView view, String url) {if (Uri.parse(url).getHost().equals("www.example.com")) {return false;}
Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));startActivity(intent);
return true;}
}之后：Java代码 WebView myWebView = (WebView) findViewById(R.id.webview);
myWebView.setWebViewClient(new MyWebViewClient());另外出于用户习惯上的考虑 需要将WebView表现得更像一个浏览器，也就是需要可以回退历史记录因此需要覆盖系统的回退键 goBack，goForward可向前向后浏览历史页面Java代码 public boolean onKeyDown(int keyCode, KeyEvent event) {if ((keyCode == KeyEvent.KEYCODE_BACK) && myWebView.canGoBack() {myWebView.goBack();
return true;}
return super.onKeyDown(keyCode, event);}Java代码WebView myWebView = (WebView) findViewById(R.id.webview);
WebSettings webSettings = myWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
TextView show = (TextView) findViewById(R.id.textview);
show.setText(str);
}
});
}
}Java代码//把本类的一个实例添加到js的全局对象window中，
//这样就可以使用windows.injs来调用它的方法
webView.addJavascriptInterface(new InJavaScript(), "injs");
}
button.setOnClickListener(new OnClickListener() {public void onClick(View arg0) {//调用javascript中的方法
webView.loadUrl("javascript:getFromAndroid('Cookie call the js function from Android')");}
});
webView.setWebChromeClient(new WebChromeClient(){//处理javascript中的alert
public boolean onJsAlert(WebView view, String url, String message, final JsResult result) {//构建一个Builder来显示网页中的对话框
Builder builder = new Builder(MainActivity.this);builder.setTitle("Alert");builder.setMessage(message);
builder.setPositiveButton(android.R.string.ok,
new AlertDialog.OnClickListener() {public void onClick(DialogInterface dialog, int which) {result.confirm();
}
});
builder.setCancelable(false);builder.create();
builder.show();
return true;};
//处理javascript中的confirm
public boolean onJsConfirm(WebView view, String url, String message, final JsResult result) {Builder builder = new Builder(MainActivity.this);builder.setTitle("confirm");builder.setMessage(message);
builder.setPositiveButton(android.R.string.ok,
new AlertDialog.OnClickListener() {public void onClick(DialogInterface dialog, int which) {result.confirm();
}
});
builder.setNegativeButton(android.R.string.cancel,
new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int which) {result.cancel();
}
});
builder.setCancelable(false);builder.create();
builder.show();
return true;};@Override
//设置网页加载的进度条
public void onProgressChanged(WebView view, int newProgress) {MainActivity.this.getWindow().setFeatureInt(Window.FEATURE_PROGRESS, newProgress * 100);super.onProgressChanged(view, newProgress);}//设置应用程序的标题title
public void onReceivedTitle(WebView view, String title) {MainActivity.this.setTitle(title);super.onReceivedTitle(view, title);}
});
WebView myWebView = (WebView) findViewById(R.id.webview);
myWebView.setWebChromeClient(new WebChromeClient() {public void onConsoleMessage(String message, int lineNumber, String sourceID) {Log.d("MyApplication", message + " -- From line "
+ lineNumber + " of "
+ sourceID);
}
});
myWebView.setWebChromeClient(new WebChromeClient() {public boolean onConsoleMessage(ConsoleMessage cm) {Log.d("MyApplication", cm.message() + " -- From line "
+ cm.lineNumber() + " of "
+ cm.sourceId() );
return true;}
});
localStorage.lastname="Smith";
document.write(localStorage.lastname);
</script>
<script type="text/javascript">
sessionStorage.lastname="Smith";
document.write(sessionStorage.lastname);
</script>
localStorage.clear();
//设置一个键值
localStorage.setItem(“yarin”,“yangfegnsheng”);
//获取一个键值
localStorage.getItem(“yarin”);
//获取指定下标的键的名称（如同Array）
localStorage.key(0);
//return “fresh” //删除一个键值
localStorage.removeItem(“yarin”);
注意一定要在设置中开启哦
setDomStorageEnabled（true）
webSettings.setDatabaseEnabled(true);
String dir = this.getApplicationContext().getDir("database", Context.MODE_PRIVATE).getPath();//设置数据库路径
webSettings.setDatabasePath(dir);
//使用localStorage则必须打开
webSettings.setDomStorageEnabled(true);//扩充数据库的容量（在WebChromeClinet中实现）
public void onExceededDatabaseQuota(String url, String databaseIdentifier, long currentQuota,
long estimatedSize, long totalUsedQuota, WebStorage.QuotaUpdater quotaUpdater) {quotaUpdater.updateQuota(estimatedSize * 2);}
YARINDB = openDatabase(shortName, version, displayName, maxSize);
createTables();
selectAll();
}
} catch(e) {if (e == 2) {// Version mismatch.
console.log("Invalid database version.");} else {console.log("Unknown error "+ e +".");}
return;}
}function createTables(){YARINDB.transaction(
function (transaction) {transaction.executeSql('CREATE TABLE IF NOT EXISTS yarin(id INTEGER NOT NULL PRIMARY KEY, name TEXT NOT NULL,desc TEXT NOT NULL);', [], nullDataHandler, errorHandler);}
);
insertData();
}function insertData(){YARINDB.transaction(
function (transaction) {//Starter data when page is initialized
var data = ['1','yarin yang','I am yarin'];transaction.executeSql("INSERT INTO yarin(id, name, desc) VALUES (?, ?, ?)", [data[0], data[1], data[2]]);}
);
}function errorHandler(transaction, error){if (error.code==1){// DB Table already exists
} else {// Error is a human-readable string.
console.log('Oops. Error was '+error.message+' (Code '+error.code+')');}
return false;}function nullDataHandler(){console.log("SQL Query Succeeded");}function selectAll(){
YARINDB.transaction(
function (transaction) {transaction.executeSql("SELECT * FROM yarin;", [], dataSelectHandler, errorHandler);}
);
}function dataSelectHandler(transaction, results){// Handle the results
for (var i=0; i<results.rows.length; i++) {var row = results.rows.item(i);var newFeature = new Object();newFeature.name = row['name'];newFeature.decs = row['desc'];document.getElementByIdx_x_x_x("name").innerHTML="name:"+newFeature.name;document.getElementByIdx_x_x_x("desc").innerHTML="desc:"+newFeature.decs;}
}function updateData(){YARINDB.transaction(
function (transaction) {var data = ['fengsheng yang','I am fengsheng'];
transaction.executeSql("UPDATE yarin SET name=?, desc=? WHERE id = 1", [data[0], data[1]]);}
);
selectAll();
}function ddeleteTables(){YARINDB.transaction(
function (transaction) {transaction.executeSql("DROP TABLE yarin;", [], nullDataHandler, errorHandler);}
);
console.log("Table 'page_settings' has been dropped.");}
注意onLoad中的初始化工作
function initLocalStorage(){if (window.localStorage) {textarea.addEventListener("keyup", function() {window.localStorage["value"] = this.value;window.localStorage["time"] = new Date().getTime();}, false);} else {alert("LocalStorage are not supported in this browser.");}
}window.onload = function() {initDatabase();
initLocalStorage();
}
webSettings.setGeolocationEnabled(true);//设置定位的数据库路径
webSettings.setGeolocationDatabasePath(dir);//配置权限（同样在WebChromeClient中实现）
public void onGeolocationPermissionsShowPrompt(String origin,
GeolocationPermissions.Callback callback) {
callback.invoke(origin, true, false);super.onGeolocationPermissionsShowPrompt(origin, callback);}
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
navigator.geolocation.getCurrentPosition(success_callback_function, error_callback_function, position_options)
//持续获取地理位置
navigator.geolocation.watchPosition(success_callback_function, error_callback_function, position_options)
//清除持续获取地理位置事件
navigator.geolocation.clearWatch(watch_position_id)
function get_location() {if (navigator.geolocation) {navigator.geolocation.getCurrentPosition(show_map,handle_error,{enableHighAccuracy:false,maximumAge:1000,timeout:15000});} else {alert("Your browser does not support HTML5 geoLocation");}
}function show_map(position) {var latitude = position.coords.latitude;var longitude = position.coords.longitude;var city = position.coords.city;//telnet localhost 5554
//geo fix -82.411629 28.054553
//geo fix -121.45356 46.51119 4392
//geo nmea $GPGGA,001431.092,0118.2653,N,10351.1359,E,0,00,,-19.6,M,4.1,M,,0000*5B
document.getElementByIdx_x_x_x("Latitude").innerHTML="latitude:"+latitude;document.getElementByIdx_x_x_x("Longitude").innerHTML="longitude:"+longitude;document.getElementByIdx_x_x_x("City").innerHTML="city:"+city;}function handle_error(err) {switch (err.code) {case 1:alert("permission denied");break;case 2:alert("the network is down or the position satellites can't be contacted");break;case 3:alert("time out");break;default:alert("unknown error");break;}
}
#这是注释
images/sound-icon.png
images/background.png
clock.html
clock.css
clock.jsNETWORK:
test.cgiCACHE:
style/default.cssFALLBACK:
/files/projects /projects
｝
webSettingssetAppCacheEnabled(true);String dir = this.getApplicationContext().getDir("cache", Context.MODE_PRIVATE).getPath();//设置应用缓存的路径
webSettings.setAppCachePath(dir);
//设置缓存的模式
webSettings.setCacheMode(WebSettings.LOAD_DEFAULT);
//设置应用缓存的最大尺寸
webSettings.setAppCacheMaxSize(1024*1024*8);//扩充缓存的容量
public void onReachedMaxAppCacheSize(long spaceNeeded,long totalUsedQuota, WebStorage.QuotaUpdater quotaUpdater) {quotaUpdater.updateQuota(spaceNeeded * 2);}
<title>Exmaple</title>
<meta name=”viewport” content=”width=device-width,user-scalable=no”/>
</head></SPAN>meta中viewport的属性如下Html代码 <SPAN style="FONT-SIZE: x-small"> <meta name="viewport"
content="height = [pixel_value | device-height] ,width = [pixel_value | device-width ] ,initial-scale = float_value ,minimum-scale = float_value ,maximum-scale = float_value ,user-scalable = [yes | no] ,target-densitydpi = [dpi_value | device-dpi |high-dpi | medium-dpi | low-dpi]
"
/></SPAN>2 CSS控制设备密度为每种密度创建独立的样式表（注意其中的webkit-device-pixel-ratio 3个数值对应3种分辨率）Html代码 <link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio: 1.5)" href="hdpi.css" />
<link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio: 1.0)" href="mdpi.css" />
<link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio: 0.75)" href="ldpi.css" />在一个样式表中，指定不同的样式Html代码 #header {
<SPAN style="WHITE-SPACE: pre"> </SPAN> background:url(medium-density-image.png);
}
@media screen and (-webkit-device-pixel-ratio: 1.5) {
// CSS for high-density screens
#header {
background:url(high-density-image.png);
}
}
@media screen and (-webkit-device-pixel-ratio: 0.75) {
// CSS for low-density screens
#header {
background:url(low-density-image.png);
}
}Html代码 <meta name="viewport" content="target-densitydpi=device-dpi, width=device-width" />3 JS控制Android浏览器和WebView支持查询当前设别密度的DOM特性window.devicePixelRatio 同样值有3个（0.75,1,1.5对应3种分辨率）JS中查询设备密度的方法Js代码if (window.devicePixelRatio == 1.5) {alert("This is a high-density screen");} else if (window.devicePixelRation == 0.75) {alert("This is a low-density screen");}● Android中构建HTML5应用使用WebView控件 与其他控件的使用方法相同 在layout中使用一个<WebView>标签WebView不包括导航栏，地址栏等完整浏览器功能，只用于显示一个网页在WebView中加载Web页面，使用loadUrl()Java代码WebView myWebView = (WebView) findViewById(R.id.webview);
myWebView.loadUrl("http://www.example.com");注意在manifest文件中加入访问互联网的权限：Xml代码 <uses-permission android:name="android.permission.INTERNET" />在Android中点击一个链接，默认是调用应用程序来启动，因此WebView需要代为处理这个动作 通过WebViewClientJava代码 //设置WebViewClient
webView.setWebViewClient(new WebViewClient(){
public boolean shouldOverrideUrlLoading(WebView view, String url) {
view.loadUrl(url);
return true;
}
public void onPageFinished(WebView view, String url) {super.onPageFinished(view, url);}
public void onPageStarted(WebView view, String url, Bitmap favicon) {super.onPageStarted(view, url, favicon);}
});这个WebViewClient对象是可以自己扩展的，例如Java代码 private class MyWebViewClient extends WebViewClient {public boolean shouldOverrideUrlLoading(WebView view, String url) {if (Uri.parse(url).getHost().equals("www.example.com")) {return false;}
Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));startActivity(intent);
return true;}
}之后：Java代码 WebView myWebView = (WebView) findViewById(R.id.webview);
myWebView.setWebViewClient(new MyWebViewClient());另外出于用户习惯上的考虑 需要将WebView表现得更像一个浏览器，也就是需要可以回退历史记录因此需要覆盖系统的回退键 goBack，goForward可向前向后浏览历史页面Java代码 public boolean onKeyDown(int keyCode, KeyEvent event) {if ((keyCode == KeyEvent.KEYCODE_BACK) && myWebView.canGoBack() {myWebView.goBack();
return true;}
return super.onKeyDown(keyCode, event);}Java代码WebView myWebView = (WebView) findViewById(R.id.webview);
WebSettings webSettings = myWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
（这里的webSetting用处非常大 可以开启很多设置 在之后的本地存储，地理位置等之中都会使用到） 1 在JS中调用Android的函数方法 首先 需要在Android程序中建立接口Java代码final class InJavaScript {public void runOnAndroidJavaScript(final String str) {handler.post(new Runnable() {public void run() {
TextView show = (TextView) findViewById(R.id.textview);
show.setText(str);
}
});
}
}Java代码//把本类的一个实例添加到js的全局对象window中，
//这样就可以使用windows.injs来调用它的方法
webView.addJavascriptInterface(new InJavaScript(), "injs");
在JavaScript中调用Js代码function sendToAndroid(){var str = "Cookie call the Android method from js";windows.injs.runOnAndroidJavaScript(str);//调用android的函数
}
Js代码function getFromAndroid(str){document.getElementByIdx_x_x_x("android").innerHTML=str;}
2 在Android中调用JS的方法在JS中的方法：
在Android调用该方法Java代码Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new OnClickListener() {public void onClick(View arg0) {//调用javascript中的方法
webView.loadUrl("javascript:getFromAndroid('Cookie call the js function from Android')");}
});
3 Android中处理JS的警告，对话框等 在Android中处理JS的警告，对话框等需要对WebView设置WebChromeClient对象Java代码 //设置WebChromeClient
webView.setWebChromeClient(new WebChromeClient(){//处理javascript中的alert
public boolean onJsAlert(WebView view, String url, String message, final JsResult result) {//构建一个Builder来显示网页中的对话框
Builder builder = new Builder(MainActivity.this);builder.setTitle("Alert");builder.setMessage(message);
builder.setPositiveButton(android.R.string.ok,
new AlertDialog.OnClickListener() {public void onClick(DialogInterface dialog, int which) {result.confirm();
}
});
builder.setCancelable(false);builder.create();
builder.show();
return true;};
//处理javascript中的confirm
public boolean onJsConfirm(WebView view, String url, String message, final JsResult result) {Builder builder = new Builder(MainActivity.this);builder.setTitle("confirm");builder.setMessage(message);
builder.setPositiveButton(android.R.string.ok,
new AlertDialog.OnClickListener() {public void onClick(DialogInterface dialog, int which) {result.confirm();
}
});
builder.setNegativeButton(android.R.string.cancel,
new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int which) {result.cancel();
}
});
builder.setCancelable(false);builder.create();
builder.show();
return true;};@Override
//设置网页加载的进度条
public void onProgressChanged(WebView view, int newProgress) {MainActivity.this.getWindow().setFeatureInt(Window.FEATURE_PROGRESS, newProgress * 100);super.onProgressChanged(view, newProgress);}//设置应用程序的标题title
public void onReceivedTitle(WebView view, String title) {MainActivity.this.setTitle(title);super.onReceivedTitle(view, title);}
});
● Android中的调试 通过JS代码输出log信息Js代码 Js代码： console.log("Hello World");Log信息： Console: Hello World http://www.example.com/hello.html :82
在WebChromeClient中实现onConsoleMesaage()回调方法，让其在LogCat中打印信息Java代码
WebView myWebView = (WebView) findViewById(R.id.webview);myWebView.setWebChromeClient(new WebChromeClient() {public void onConsoleMessage(String message, int lineNumber, String sourceID) {Log.d("MyApplication", message + " -- From line "
+ lineNumber + " of "
+ sourceID);
}
});
以及Java代码 WebView myWebView = (WebView) findViewById(R.id.webview);
myWebView.setWebChromeClient(new WebChromeClient() {public boolean onConsoleMessage(ConsoleMessage cm) {Log.d("MyApplication", cm.message() + " -- From line "
+ cm.lineNumber() + " of "
+ cm.sourceId() );
return true;}
});
Js代码<script type="text/javascript">
*ConsoleMessage 还包括一个 MessageLevel 表示控制台传递信息类型。 您可以用messageLevel()查询信息级别，以确定信息的严重程度，然后使用适当的Log方法或采取其他适当的措施。● HTML5本地存储在Android中的应用
HTML5提供了2种客户端存储数据新方法：
localStorage 没有时间限制
sessionStorage 针对一个Session的数据存储
localStorage.lastname="Smith";
document.write(localStorage.lastname);
</script>
<script type="text/javascript">
sessionStorage.lastname="Smith";
document.write(sessionStorage.lastname);
</script>
WebStorage的API:Js代码//清空storage
localStorage.clear();
//设置一个键值
localStorage.setItem(“yarin”,“yangfegnsheng”);
//获取一个键值
localStorage.getItem(“yarin”);
//获取指定下标的键的名称（如同Array）
localStorage.key(0);
//return “fresh” //删除一个键值
localStorage.removeItem(“yarin”);
注意一定要在设置中开启哦
setDomStorageEnabled（true）
在Android中进行操作Java代码//启用数据库
webSettings.setDatabaseEnabled(true);
String dir = this.getApplicationContext().getDir("database", Context.MODE_PRIVATE).getPath();//设置数据库路径
webSettings.setDatabasePath(dir);
//使用localStorage则必须打开
webSettings.setDomStorageEnabled(true);//扩充数据库的容量（在WebChromeClinet中实现）
public void onExceededDatabaseQuota(String url, String databaseIdentifier, long currentQuota,
long estimatedSize, long totalUsedQuota, WebStorage.QuotaUpdater quotaUpdater) {quotaUpdater.updateQuota(estimatedSize * 2);}
在JS中按常规进行数据库操作Js代码function initDatabase() {try {if (!window.openDatabase) {alert('Databases are not supported by your browser');} else {var shortName = 'YARINDB';var version = '1.0';var displayName = 'yarin db';var maxSize = 100000; // in bytes
YARINDB = openDatabase(shortName, version, displayName, maxSize);
createTables();
selectAll();
}
} catch(e) {if (e == 2) {// Version mismatch.
console.log("Invalid database version.");} else {console.log("Unknown error "+ e +".");}
return;}
}function createTables(){YARINDB.transaction(
function (transaction) {transaction.executeSql('CREATE TABLE IF NOT EXISTS yarin(id INTEGER NOT NULL PRIMARY KEY, name TEXT NOT NULL,desc TEXT NOT NULL);', [], nullDataHandler, errorHandler);}
);
insertData();
}function insertData(){YARINDB.transaction(
function (transaction) {//Starter data when page is initialized
var data = ['1','yarin yang','I am yarin'];transaction.executeSql("INSERT INTO yarin(id, name, desc) VALUES (?, ?, ?)", [data[0], data[1], data[2]]);}
);
}function errorHandler(transaction, error){if (error.code==1){// DB Table already exists
} else {// Error is a human-readable string.
console.log('Oops. Error was '+error.message+' (Code '+error.code+')');}
return false;}function nullDataHandler(){console.log("SQL Query Succeeded");}function selectAll(){
YARINDB.transaction(
function (transaction) {transaction.executeSql("SELECT * FROM yarin;", [], dataSelectHandler, errorHandler);}
);
}function dataSelectHandler(transaction, results){// Handle the results
for (var i=0; i<results.rows.length; i++) {var row = results.rows.item(i);var newFeature = new Object();newFeature.name = row['name'];newFeature.decs = row['desc'];document.getElementByIdx_x_x_x("name").innerHTML="name:"+newFeature.name;document.getElementByIdx_x_x_x("desc").innerHTML="desc:"+newFeature.decs;}
}function updateData(){YARINDB.transaction(
function (transaction) {var data = ['fengsheng yang','I am fengsheng'];
transaction.executeSql("UPDATE yarin SET name=?, desc=? WHERE id = 1", [data[0], data[1]]);}
);
selectAll();
}function ddeleteTables(){YARINDB.transaction(
function (transaction) {transaction.executeSql("DROP TABLE yarin;", [], nullDataHandler, errorHandler);}
);
console.log("Table 'page_settings' has been dropped.");}
注意onLoad中的初始化工作
function initLocalStorage(){if (window.localStorage) {textarea.addEventListener("keyup", function() {window.localStorage["value"] = this.value;window.localStorage["time"] = new Date().getTime();}, false);} else {alert("LocalStorage are not supported in this browser.");}
}window.onload = function() {initDatabase();
initLocalStorage();
}
● HTML5地理位置服务在Android中的应用Java代码//启用地理定位
Android中
webSettings.setGeolocationEnabled(true);//设置定位的数据库路径
webSettings.setGeolocationDatabasePath(dir);//配置权限（同样在WebChromeClient中实现）
public void onGeolocationPermissionsShowPrompt(String origin,
GeolocationPermissions.Callback callback) {
callback.invoke(origin, true, false);super.onGeolocationPermissionsShowPrompt(origin, callback);}
在Manifest中添加权限Xml代码<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
HTML5中 通过navigator.geolocation对象获取地理位置信息Js代码//获取当前地理位置
常用的navigator.geolocation对象有以下三种方法：
navigator.geolocation.getCurrentPosition(success_callback_function, error_callback_function, position_options)
//持续获取地理位置
navigator.geolocation.watchPosition(success_callback_function, error_callback_function, position_options)
//清除持续获取地理位置事件
navigator.geolocation.clearWatch(watch_position_id)
其中success_callback_function为成功之后处理的函数，error_callback_function为失败之后返回的处理函数，参数position_options是配置项在JS中的代码Js代码//定位
function get_location() {if (navigator.geolocation) {navigator.geolocation.getCurrentPosition(show_map,handle_error,{enableHighAccuracy:false,maximumAge:1000,timeout:15000});} else {alert("Your browser does not support HTML5 geoLocation");}
}function show_map(position) {var latitude = position.coords.latitude;var longitude = position.coords.longitude;var city = position.coords.city;//telnet localhost 5554
//geo fix -82.411629 28.054553
//geo fix -121.45356 46.51119 4392
//geo nmea $GPGGA,001431.092,0118.2653,N,10351.1359,E,0,00,,-19.6,M,4.1,M,,0000*5B
document.getElementByIdx_x_x_x("Latitude").innerHTML="latitude:"+latitude;document.getElementByIdx_x_x_x("Longitude").innerHTML="longitude:"+longitude;document.getElementByIdx_x_x_x("City").innerHTML="city:"+city;}function handle_error(err) {switch (err.code) {case 1:alert("permission denied");break;case 2:alert("the network is down or the position satellites can't be contacted");break;case 3:alert("time out");break;default:alert("unknown error");break;}
}
其中position对象包含很多数据 error代码及选项 可以查看文档● 构建HTML5离线应用Manifest代码CACHE MANIFEST
需要提供一个cache manifest文件，理出所有需要在离线状态下使用的资源
例如
#这是注释
images/sound-icon.png
images/background.png
clock.html
clock.css
clock.jsNETWORK:
test.cgiCACHE:
style/default.cssFALLBACK:
/files/projects /projects
在html标签中声明 <html manifest="clock.manifest">HTML5离线应用更新缓存机制Js代码if (window.applicationCache.status == window.applicationCache.UPDATEREADY) ｛window.applicationCache.update();
分为手动更新和自动更新2种
自动更新：
在cache manifest文件本身发生变化时更新缓存 资源文件发生变化不会触发更新
手动更新：
使用window.applicationCache
｝
Java代码//开启应用程序缓存
在线状态检测
HTML5 提供了两种检测是否在线的方式：navigator.online（true/false） 和 online/offline事件。在Android中构建离线应用
webSettingssetAppCacheEnabled(true);String dir = this.getApplicationContext().getDir("cache", Context.MODE_PRIVATE).getPath();//设置应用缓存的路径
webSettings.setAppCachePath(dir);
//设置缓存的模式
webSettings.setCacheMode(WebSettings.LOAD_DEFAULT);
//设置应用缓存的最大尺寸
webSettings.setAppCacheMaxSize(1024*1024*8);//扩充缓存的容量
public void onReachedMaxAppCacheSize(long spaceNeeded,long totalUsedQuota, WebStorage.QuotaUpdater quotaUpdater) {quotaUpdater.updateQuota(spaceNeeded * 2);}
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