html5如何操纵indexedDB-
发布时间：08/01 来源：未知 浏览：
关键词：
indexedDB是存储批量构造化数据的API，demo中用到的是异步API，费事的就是所有对indexedDB的操纵都会产生一个异步的‘要求’，只有熟知了API操纵起来也很简略。
大体流程是这样
1.打开数据库
var indexedDB = window.indexedDB || window.webkitIndexedDB || window.mozIndexedDB;
if ('webkitIndexedDB' in window) {
window.IDBTransaction = window.webkitIDBTransaction;
window.IDBKeyRange = window.webkitIDBKeyRange;
}
//这个就不解释了
var request = indexedDB.open("adsageIDB"); //open ： indexedDB只要这一个办法 打开（数据库名）
request.onsuccess = function(e) { //异步
var v = "1.00";
var db = e.target.result;
if (v!= db.version) {
var setVrequest = db.setVersion(v);
setVrequest.onsuccess = function(e) { //异步
if(db.objectStoreNames.contains("todo")) {
db.deleteObjectStore("todo");
}
var store = db.createObjectStore("todo", {keyPath: "adsid"});//onsuccess 后新建ObjectStore 临时用到两个参数，数据库&&主键
}
}
}这样就 新建/连贯 了一个数据库
2.新建交互对象 && 监听dom事件 && 处置数据
然后就是要操纵数据库了
//插入数据 临时只插入一列
var trans = db.transaction(["todo"], IDBTransaction.READ_WRITE);//新建transaction
var store = trans.objectStore("todo");//新建Store
//要操纵数据必需创立transaction 和 Store
var data = {
"text": todoText,
"adsid": new Date().getTime()
};//一个小数据 adsid是主键
var request = store.put(data); //‘强行’插入
request.onsuccess = function(e) {
//成功后施行一些操纵
};
request.onerror = function(e) {
console.log("Error Adding: ", e);
};
//读取数据
var trans = db.transaction(["todo"], IDBTransaction.READ_WRITE);
var store = trans.objectStore("todo");
var keyRange = IDBKeyRange.lowerBound(0);
var cursorRequest = store.openCursor(keyRange);
//这里用到指针cursor ,openCursor的参数 keyRange是遍历范畴 还可以增加遍历标的目的参数
//另一种办法是get() 这个就比拼简略了直接store.get('键值')就行
cursorRequest.onsuccess = function(e) {
var result = e.target.result;
if(!!result == false)
return;
console.log(result.value);
result.continue(); //轮回读取所有数据
};
//删除数据
...
store.delete('键值')
...
《script》
var indexedDB = window.indexedDB || window.webkitIndexedDB ||
window.mozIndexedDB;
if ('webkitIndexedDB' in window) {
windowwindow.IDBTransaction = window.webkitIDBTransaction;
windowwindow.IDBKeyRange = window.webkitIDBKeyRange;
}
adsageIDB = {};
adsageIDB.db = null;
adsageIDB.onerror = function(e) {
console.log(e);
};
adsageIDB.open = function() {
var request = indexedDB.open("adsageIDB");
request.onsuccess = function(e) {
var v = "1.00";
adsageIDB.db = e.target.result;
var db = adsageIDB.db;
if (v!= db.version) {
var setVrequest = db.setVersion(v);
setVrequest.onerror = adsageIDB.onerror;
setVrequest.onsuccess = function(e) {
if(db.objectStoreNames.contains("todo")) {
db.deleteObjectStore("todo");
}
var store = db.createObjectStore("todo",
{keyPath: "adsid"});
adsageIDB.getAllTodoItems();
};
}
else {
adsageIDB.getAllTodoItems();
}
};
request.onerror = adsageIDB.onerror;
}
adsageIDB.addTodo = function(todoText) {
var db = adsageIDB.db;
var trans = db.transaction(["todo"], IDBTransaction.READ_WRITE);
var store = trans.objectStore("todo");
var data = {
"text": todoText,
"adsid": new Date().getTime()
};
var request = store.put(data);
request.onsuccess = function(e) {
adsageIDB.getAllTodoItems();
};
request.onerror = function(e) {
console.log("Error Adding: ", e);
};
};
adsageIDB.deleteTodo = function(id) {
var db = adsageIDB.db;
var trans = db.transaction(["todo"], IDBTransaction.READ_WRITE);
var store = trans.objectStore("todo");
var request = store.delete(id);
request.onsuccess = function(e) {
adsageIDB.getAllTodoItems();
};
request.onerror = function(e) {
console.log("Error Adding: ", e);
};
};
adsageIDB.getAllTodoItems = function() {
var todos = document.getElementById("todoItems");
todos.innerHTML = "";
var db = adsageIDB.db;
var trans = db.transaction(["todo"], IDBTransaction.READ_WRITE);
var store = trans.objectStore("todo");
var keyRange = IDBKeyRange.lowerBound(0);
var cursorRequest = store.openCursor(keyRange);
cursorRequest.onsuccess = function(e) {
var result = e.target.result;
if(!!result == false)
return;
renderTodo(result.value);
result.continue();
};
cursorRequest.onerror = adsageIDB.onerror;
};
function renderTodo(row) {
var todos = document.getElementById("todoItems");
var li = document.createElement("li");
var a = document.createElement("a");
var t = document.createTextNode(row.text);
a.addEventListener("click", function() {
adsageIDB.deleteTodo(row.adsid);
}, false);
a.textContent = " [删除]";
li.appendChild(t);
li.appendChild(a);
todos.appendChild(li)
}
function addTodo() {
var todo = document.getElementById("todo");
adsageIDB.addTodo(todo.value);
todo.value = "";
}
function init() {
adsageIDB.open();
}
window.addEventListener("DOMContentLoaded", init, false);
《script》
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