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HTML5 indexedDB数据库的入门学习

时间:2015-01-12 22:24:22      阅读:225      评论:0      收藏:0      [点我收藏+]

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笔者早些时间看过web sql database,但是不再维护和支持,所以最近初步学习了一下indexedDB数据库,首先indexedDB(简称IDB)和web sql database有很大的差别,因为IDB不像web sql database那样用数据库语句去操作浏览器本地数据库(有过数据库基础看起来会比较容易),及关系数据库,IDB更像是NoSQL数据库,不能使用sql语句去查询,所以理解上会比web sql database要难一点:下面我主要介绍indexedDB数据库的基本操作:增删改差

首先:获取indexedDB数据库对象

1 if (!window.indexedDB) {
2     window.indexedDB = window.mozIndexedDB || window.webkitIndexedDB;
3 }

然后打开数据库(如果数据库不存在当然就是创建数据库)

1 var request = indexedDB.open("data2",1);
2 var db;

第一个参数是数据库的名称,第二个参数是数据库的版本号。版本号可以在升级数据库时用来调整数据库结构和数据。

 1 request.onupgradeneeded = function(event) {
 2     db = event.target.result;
 3     var store = db.createObjectStore("table",{keyPath: "ssn"});
 4     console.log("createObjectStore success!");
 5 };
 6 request.onsuccess = function (event) {
 7     db = event.target.result; //db = request.result;或者db = this.result;     
12 }

但你增加数据库版本号时,会触发onupgradeneeded事件,这时可能会出现成功、失败和阻止事件三种情况

onupgradeneeded事件在第一次打开页面初始化数据库时会被调用,或在当有版本号变化时。所以,你应该在onupgradeneeded函数里创建你的存储数据。如果没有版本号变化,而且页面之前被打开过,你会获得一个onsuccess事件。如果有错误发生时则触发onerror事件。如果你之前没有关闭连接,则会触发onblocked事件。

做完上面的操作后你就可以进行增删改查的操作了:

1、添加数据:

 1 document.getElementById("add").onclick = function (){
 2     var obj = {
 3         "ssn" : document.getElementById("ssn").value,
 4         "name" : document.getElementById("name").value,
 5         "email" : document.getElementById("email").value
 6     };
 7     //存数据 db为数据库对象,transaction为事物,objectStore为存储对象(相当于数据表),add为数据表对象的add方法,最后是add成功的回调函数
 8     db.transaction(["table"], "readwrite").objectStore("table").add(obj).onsuccess = function(event) {
 9         console.log("add data success!");
10     };    
11 }

2、删除数据:

1 document.getElementById("del").onclick = function() {
2     //删除数据
3     db.transaction(["table"], "readwrite")
4     .objectStore("table")
5     .delete(document.getElementById("del_ssn").value)
6     .onsuccess = function(event) {
7            console.log(document.getElementById("del_ssn").value+" delete sucecess");
8     };
9 }

3、读取数据:

 1 document.getElementById("get").onclick = function() {
 2     //读数据 openCursor相当于是循环读取
 3     db.transaction("table").objectStore("table").openCursor().onsuccess = function(event) {
 4         var getString = "";
 5         var cursor = event.target.result;
 6         if (cursor) {
 7             getString += "Name for SSN " + cursor.key + " is " + cursor.value.name;
 8             console.log("Name for SSN " + cursor.key + " is " + cursor.value.name);
 9             cursor.continue();
10             //alert(getString);
11         }
12         document.getElementById("get_ssn").innerHTML += getString+"<br/>";
13     }        
14 }

4、修改数据:

 1 document.getElementById("put").onclick = function () {
 2     var obj = {
 3         "ssn" : document.getElementById("putssn").value,
 4         "name" : document.getElementById("putname").value,
 5         "email" : document.getElementById("putemail").value
 6     };
 7     //修改数据
 8     db.transaction(["table"], "readwrite").objectStore("table").put(obj).onsuccess = function(event) {
 9         console.log("put data success!");
10     };        
11 }

以下是面页的html部分:

 1 <input type="text" id="ssn" name="ssn" />
 2 <input type="text" id="name" name="name" />
 3 <input type="text" id="email" name="email" />
 4 <button id="add">增加</button>
 5 <button>重置</button><br/>
 6 
 7 <input type="text" id="putssn" name="putssn" />
 8 <input type="text" id="putname" name="putname" />
 9 <input type="text" id="putemail" name="putemail" />
10 <button id="put">修改</button><br/>
11 
12 
13 <input type="text" id="del_ssn" name="del_ssn" />
14 <button id="del">删除</button><br/>
15 <button id="get">读取</button>
16 <div id="get_ssn"></div>

初学indexedDB,有什么不对的地方望指出,后续会把比较深入的东西写出来和大家分享

整个demo文件如下:

技术分享
 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4     <title>indexedDB</title>
 5 </head>
 6 <script type="text/javascript">
 7 window.onload = function () {
 8     if (!window.indexedDB) {
 9         window.indexedDB = window.mozIndexedDB || window.webkitIndexedDB;
10     }
11     var request = indexedDB.open("data",1);
12     var db;
13     request.onupgradeneeded = function(event) {
14         db = event.target.result;
15         var store = db.createObjectStore("table",{keyPath: "ssn"});
16         console.log("createObjectStore success!");
17     };
18     request.onsuccess = function (event) {
19         db = event.target.result;
20         //读取数据
21         /*db.transaction(["table"], "readwrite").objectStore("table").get("1212").onsuccess = function () {
22             console.log(this.result.name);
23         };    */        
24     }
25     document.getElementById("add").onclick = function (){
26         var obj = {
27             "ssn" : document.getElementById("ssn").value,
28             "name" : document.getElementById("name").value,
29             "email" : document.getElementById("email").value
30         };
31         //存数据
32         db.transaction(["table"], "readwrite").objectStore("table").add(obj).onsuccess = function(event) {
33             console.log("add data success!");
34         };        
35     }
36     document.getElementById("del").onclick = function() {
37         //删除数据
38         db.transaction(["table"], "readwrite")
39         .objectStore("table")
40         .delete(document.getElementById("del_ssn").value)
41         .onsuccess = function(event) {
42                console.log(document.getElementById("del_ssn").value+" delete sucecess");
43         };
44     }
45     document.getElementById("get").onclick = function() {
46         //读数据
47         db.transaction("table").objectStore("table").openCursor().onsuccess = function(event) {
48             var getString = "";
49             var cursor = event.target.result;
50             if (cursor) {
51                 getString += "Name for SSN " + cursor.key + " is " + cursor.value.name;
52                 console.log("Name for SSN " + cursor.key + " is " + cursor.value.name);
53                 cursor.continue();
54                 //alert(getString);
55             }
56             document.getElementById("get_ssn").innerHTML += getString+"<br/>";
57         }        
58     }
59 
60     document.getElementById("put").onclick = function () {
61         var obj = {
62             "ssn" : document.getElementById("putssn").value,
63             "name" : document.getElementById("putname").value,
64             "email" : document.getElementById("putemail").value
65         };
66         //修改数据
67         db.transaction(["table"], "readwrite").objectStore("table").put(obj).onsuccess = function(event) {
68             console.log("put data success!");
69         };        
70     }
71 }
72 </script>
73 <body>
74 <input type="text" id="ssn" name="ssn" />
75 <input type="text" id="name" name="name" />
76 <input type="text" id="email" name="email" />
77 <button id="add">增加</button>
78 <button>重置</button><br/>
79 
80 <input type="text" id="putssn" name="putssn" />
81 <input type="text" id="putname" name="putname" />
82 <input type="text" id="putemail" name="putemail" />
83 <button id="put">修改</button><br/>
84 
85 
86 <input type="text" id="del_ssn" name="del_ssn" />
87 <button id="del">删除</button><br/>
88 <button id="get">读取</button>
89 <div id="get_ssn"></div>
90 </body>
91 </html>
indexedDB_demo

效果如下:

技术分享

HTML5 indexedDB数据库的入门学习

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原文地址:http://www.cnblogs.com/cdwp8/p/4219936.html

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