前端之MVC应用
1、indexedDB（Model） -- 前端浏览器对象型数据库，一般我们后台用的数据库都是关系型数据库。那么indexeddb有什么特点呢：
首先，从字义上它是索引型数据库，从实际使用中可以体现为，它需要为表创建索引才可以根据某个字段来获取数据，而在关系型数据库中，这明显是不需要的。
其次，我不需要行列数据的转化，我只需要通过类似于数组的处理方式：
objectStore.push(data);
有点像是把一个json对象塞入数据库，是不是很暴力？
2、bootstrap（View） -- bootstrap，老实说，我不是很熟悉这个东西，毕竟我是后端java开发出身。以我的理解，这就是一个以响应式布局为特点的前端框架，至于说比较特别的，应该就是它比较流行吧？！老实说，我这边只用到css，而我也认为，后现代的前端开发，将不会需要bootstrap的js部分，毕竟那还是以jquery为主的方式。
3、angularjs（Controller） -- 必须承认这个东西东西的诞生完全颠覆了我对前端开发的看法，以前和现在我们依然困在前后端无法彻底分离的窘境中，但我认为如果后期，前端人员普遍采用应用式的angularjs脚本来开发（还有一些类似的框架），我们将不再需要让后端开发工程师套用诸多的前端样式、结构等等。
这么说，很多后端人员可能还是不能体会得到，举个例子：angularjs的使用方式有点像是jsp、freemarker等渲染html的东西，只是一个在客户端渲染，另一个在后台服务器渲染。我们只要改变数据的结构和属性，对应渲染出来的页面就会不同，angularjs就是让我们更加关注数据的变化，而非DOM的变化，就是说：你将很少会去写到$("btnSave").click(function() {});这样需要获取到html节点的脚本代码，可以说，这完全脱离了jQuery的范畴。所以这可以算是一个跨时代的改变？
接下来就上例子吧（最终必须运行到服务器上）：
user.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width"/>
<!-- 新 Bootstrap 核心 CSS 文件 -->
<link rel="stylesheet" href="//cdn.bootcss.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="http://apps.bdimg.com/libs/angular.js/1.4.6/angular.min.js"></script>
</head>
<body ng-app="myApp" ng-controller="userCtrl">
<div class="container">
<h3>Users</h3>
<table class="table table-striped">
<thead>
<tr>
<th>Edit</th>
<th>First Name</th>
<th>Last Name</th>
</tr>
</thead>
<tbody>
<tr ng-repeat="one in users">
<td>
<button class="btn" ng-click="editUser(one)">
<span class="glyphicon glyphicon-pencil"></span> Edit
</button>
<button class="btn" ng-click="deleteUser(one.id)">
<span class="glyphicon glyphicon-remove"></span> Delete
</button>
</td>
<td>{{ one.fName }}</td>
<td>{{ one.lName }}</td>
<td>{{ one.telephone }}</td>
</tr>
</tbody>
</table>
<hr>
<button class="btn btn-success" ng-click="editUser()">
<span class="glyphicon glyphicon-user"></span> Create New User
</button>
<hr>
<h3 ng-show="edit">Create New User:</h3>
<h3 ng-hide="edit">Edit User:</h3>
<form class="form-horizontal">
<div class="form-group">
<label class="col-sm-2 control-label">First Name:</label>
<div class="col-sm-10">
<input type="text" ng-model="user.fName" ng-disabled="!edit" placeholder="First Name">
</div>
</div>
<div class="form-group">
<label class="col-sm-2 control-label">Last Name:</label>
<div class="col-sm-10">
<input type="text" ng-model="user.lName" ng-disabled="!edit" placeholder="Last Name">
</div>
</div>
<div class="form-group">
<label class="col-sm-2 control-label">telephone:</label>
<div class="col-sm-10">
<input type="tel" ng-model="user.telephone" placeholder="telephone">
</div>
</div>
</form>
<hr>
<button class="btn btn-success" ng-click="saveCustomer()">
<span class="glyphicon glyphicon-save"></span> Save Changes
</button>
</div>
<script src="jdbc.js?v=2323"></script>
<script src="myUsers.js"></script>
</body>
</html>
jdbc.js(作为一个数据访问的模块，可供各个应用加载调用)
‘use strict‘;
!(function (w, angular) {
angular.module(‘db‘, []).service(‘jdbc‘, function ($http, $q) {
var _self = this;
var myDB = {
name: ‘roma‘,
version: 1,
db: null,
schema: {
2: function(db) {
// 初始化 用户
var customer = db.createObjectStore(‘customer‘, {keyPath:"id", autoIncrement: true});
customer.createIndex("customer_fName_index", "fName", {unique: true});
}
}
};
// 用于处理跟回调函数相反的方式,当defer调用resolve方法之后,就会触发defer.promise.then(callback)传入的callback方法,并且resolve可以传入任意的变量
/**
*
* function test() {
* var defer = $q.defer();
* setTimeout(2000, function() {
* defer.resolve("hello");
* });
* return defer.promise;
* }
*
* test().then(function(say) {
* console.log(say);
* });
*
* 2秒之后将会打印出"hello"
*
* @type {Deferred|*}
*/
var defer = $q.defer();
_self.onload = function(cb) {
return defer.promise.then(cb);
};
var getDb = function(db) {
var d = $q.defer();
if (db) {
d.resolve(db);
}
// 打开数据库
var result = window.indexedDB.open(myDB.name);
result.onerror = function (e) {
console.log("Open DB Error!");
d.reject("error");
};
// 正确打开
result.onsuccess = function (e) {
var db = e.target.result;
myDB.db = db;
d.resolve(db);
};
return d.promise;
};
_self.openDB = function (name, version, success, upgrade) {
var d = $q.defer();
var name = name || myDB.name;
var version = version || myDB.version;
// 打开数据库
var result = window.indexedDB.open(name, version);
// 错误
result.onerror = function (e) {
console.log("Open DB Error!");
d.reject(e);
};
// 正确打开
result.onsuccess = function (e) {
myDB.db = e.target.result;
if (success) success(myDB.db);
d.resolve(e);
};
// 数据库版本变更
result.onupgradeneeded = function (e) {
myDB.db = e.target.result;
if (upgrade) upgrade(myDB.db);
d.resolve("upgradeneeded");
};
return d.promise;
};
var schema = function (schema) {
angular.forEach(schema, function(upgrade, version, o) {
_self.openDB(myDB.name, version, function() {
defer.resolve();
}, function(db) {
upgrade(db);
});
})
};
schema(myDB.schema);
_self.get = function (storeName, key) {
var d = $q.defer(); //promise
getDb(myDB.db).then(function (db) {
var transaction = db.transaction(storeName, ‘readonly‘);
var store = transaction.objectStore(storeName);
var result = store.get(key);
result.onsuccess = function (e) {
_self.result = e.target.result;
d.resolve();
};
result.onerror = function (e) {
d.reject();
};
});
return d.promise;
};
_self.find = function (storeName, key, value) {
var d = $q.defer();//promise
getDb(myDB.db).then(function(db) {
var transaction = db.transaction(storeName, ‘readonly‘);
var store = transaction.objectStore(storeName);
var keyRange = IDBKeyRange.only(value);
var result = store.index(key).openCursor(keyRange, "next");
var results = [];
result.onsuccess = function(event) {
var cursor = event.target.result;
if (cursor) {
results.push(cursor.value);
cursor.continue();
} else {
d.resolve(results);
}
};
result.onerror = function (e) {
d.reject();
};
});
return d.promise;
};
_self.put = function (storeName, value) {
var d = $q.defer();
var db = myDB.db || getDb();
var transaction = db.transaction(storeName, ‘readwrite‘);
var store = transaction.objectStore(storeName);
if (value !== null && value !== undefined) {
store.put(value);
d.resolve();
} else {
d.reject();
}
return d.promise;
};
_self.remove = function (storeName, value) {
var d = $q.defer();//promise
var db = myDB.db || getDb();
var transaction = db.transaction(storeName, ‘readwrite‘);
var store = transaction.objectStore(storeName);
var result = store.delete(value);
result.onsuccess = function (e) {
d.resolve();
};
result.onerror = function (e) {
d.reject();
};
return d.promise;
};
_self.findAll = function (storeName) {
var d = $q.defer();//promise
getDb(myDB.db).then(function(db) {
var transaction = db.transaction(storeName, ‘readonly‘);
var store = transaction.objectStore(storeName);
var result = store.openCursor();
var results = [];
result.onsuccess = function (event) {
var cursor = event.target.result;
if (cursor) {
results.push(cursor.value);
cursor.continue();
} else {
d.resolve(results);
}
};
result.onerror = function (e) {
d.reject();
};
});
return d.promise;
};
return _self;
});
}(window, window.angular));
myUsers.js (应用的controller层脚本)
‘use strict‘;
angular.module(‘myApp‘, [‘db‘]).controller("userCtrl", function($scope, $http, jdbc) {
// 刷新数据结构,angularjs的双向绑定会自动帮我们渲染界面
function reload() {
jdbc.findAll("customer").then(function(response) {
if (!response) {
$http.get("data.json").success(function(response) {
$scope.users = response;
});
return;
}
$scope.users = response;
});
}
// 数据结构完成之后刷新界面
jdbc.onload(reload);
$scope.edit = true;
var _user = $scope.user = {};
$scope.editUser = function(user) {
if (user) {
_user.id = user.id;
_user.fName = user.fName;
_user.lName = user.lName;
_user.telephone = user.telephone;
} else {
_user.fName = "";
_user.lName = "";
_user.telephone = "";
_user.id = "";
}
};
$scope.deleteUser = function(id) {
// 从数据库删除记录之后刷新表格数据
jdbc.remove("customer", id).then(reload);
};
$scope.saveCustomer = function() {
// 从数据库添加或更新记录之后刷新表格数据
jdbc.put("customer", _user).then(reload);
};
jdbc.find("customer", "customer_fName_index", "林").then(function(data) {
console.log(data);
});
});
data.json(当indexedDB无法正常获取的时候用来显示数据用)
[
{
"id": 1,
"fName": "林",
"lName": "嘉斌",
"telephone": "13514087953"
},
{
"id": 2,
"fName": "陈",
"lName": "晓",
"telephone": "13509890786"
}
]
时间： 2024-08-09 14:24:42