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這篇文章給大家分享的是有關(guān)如何將數(shù)據(jù)庫(kù)從服務(wù)器移到瀏覽器的內(nèi)容。小編覺(jué)得挺實(shí)用的，因此分享給大家做個(gè)參考，一起跟隨小編過(guò)來(lái)看看吧。
indexedDB沒(méi)有創(chuàng)建數(shù)據(jù)庫(kù)的概念，你可以直接鏈接數(shù)據(jù)庫(kù)，如果你鏈接的數(shù)據(jù)庫(kù)并不存在，那么會(huì)自動(dòng)的創(chuàng)建一個(gè)數(shù)據(jù)庫(kù)?？聪旅娴倪@個(gè)例子。
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Document</title></head><body><button type="" id='conbtn'>鏈接數(shù)據(jù)庫(kù)</button><script>// In the following line, you should include the prefixes of implementations you want to test. window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB; // DON'T use "var indexedDB = ..." if you're not in a function.
// Moreover, you may need references to some window.IDB* objects: window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction || window.msIDBTransaction;
window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange || window.msIDBKeyRange // (Mozilla has never prefixed these objects, so we don't need window.mozIDB*)
function connectDB(name,version,success,error){
let dbConnect = indexedDB.open(name,version);
dbConnect.onsuccess = function(e){
console.log('數(shù)據(jù)庫(kù)鏈接成功！');
success(e.target.result);
}
dbConnect.onerror = function(e){
console.log('數(shù)據(jù)庫(kù)鏈接失??！');
error(e);
}
dbConnect.onupgradeneeded = function(e){
success(e.target.result);
let oldVersion = e.oldVersion;
let newVersion = e.newVersion;
console.log('數(shù)據(jù)庫(kù)更新成功，舊的版本號(hào)為：'+oldVersion+",新的版本號(hào)為："+newVersion);
}
}
window.onload=function(){
let btn = document.getElementById('conbtn');
btn.onclick = function(){
connectDB('haha',1,function(){
console.log('鏈接成功，或者更新成功回調(diào)函數(shù)');
},function(){
console.log('鏈接失敗回調(diào)函數(shù)！')
});
}
}</script></body></html>我點(diǎn)了兩次鏈接數(shù)據(jù)庫(kù)，結(jié)果是這樣的。
在Application的indexedDB中我們發(fā)現(xiàn)多了一個(gè)東西。
可以看到haha數(shù)據(jù)庫(kù)已經(jīng)成功建立了。
indexedDB的open方法用來(lái)鏈接或者更新數(shù)據(jù)庫(kù)，第一次創(chuàng)建也認(rèn)為是一次更新。第一個(gè)參數(shù)是數(shù)據(jù)庫(kù)的名字，第二個(gè)參數(shù)為版本號(hào)。第一次創(chuàng)建或者版本號(hào)發(fā)生改變時(shí)出發(fā)更新事件upgradeneeded，鏈接成功后出發(fā)success事件，鏈接出錯(cuò)時(shí)觸發(fā)error事件。
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Document</title></head><body><button type="" id='conbtn'>鏈接數(shù)據(jù)庫(kù)</button><script>// In the following line, you should include the prefixes of implementations you want to test. window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB; // DON'T use "var indexedDB = ..." if you're not in a function.
// Moreover, you may need references to some window.IDB* objects: window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction || window.msIDBTransaction;
window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange || window.msIDBKeyRange // (Mozilla has never prefixed these objects, so we don't need window.mozIDB*)
function connectDB(name,version,success,update,error){
let dbConnect = indexedDB.open(name,version);
dbConnect.onsuccess = function(e){
console.log('數(shù)據(jù)庫(kù)鏈接成功！');
success(e.target.result);
}
dbConnect.onerror = function(e){
console.log('數(shù)據(jù)庫(kù)鏈接失??！');
error(e);
}
dbConnect.onupgradeneeded = function(e){
update(e.target.result);
let oldVersion = e.oldVersion;
let newVersion = e.newVersion;
console.log('數(shù)據(jù)庫(kù)更新成功，舊的版本號(hào)為：'+oldVersion+",新的版本號(hào)為："+newVersion);
}
} function createTable(idb,storeName,key,idxs){if(!idb){
console.log(idb);return ;
}if(!key || !idxs){
console.log('參數(shù)錯(cuò)誤');return ;
}if(!storeName){
console.log('storeName必須');return ;
}try{var store = idb.createObjectStore(storeName,key);
console.log('數(shù)據(jù)庫(kù)存儲(chǔ)對(duì)象(table)創(chuàng)建成功');for(var i = 0;i<idxs.length;i++){var idx = idxs[i];
store.createIndex(idx.indexName,idx.keyPath,idx.optionalParameters);
console.log('索引'+idx.indexName+'創(chuàng)建成功');
}
}catch(e){
console.log('建表出現(xiàn)錯(cuò)誤');
console.log(JSON.stringify(e))
}
}
window.onload=function(){
let btn = document.getElementById('conbtn');
btn.onclick = function(){
connectDB('haha',1, function(idb){
console.log('鏈接成功，或者更新成功回調(diào)函數(shù)');
},function(idb){ createTable(idb,'test',{keyPath:'id',autoIncrement:true},[
{
indexName:'testIndex',
keyPath:'name',
optionalParameters:{
unique:true,
multiEntry:false }}]);
},function(){
console.log('鏈接失敗回調(diào)函數(shù)！')
});
}
}</script></body></html>我點(diǎn)了一下按鈕結(jié)果時(shí)這樣的。
這里用到的兩個(gè)核心方法時(shí)createObjectStore，和createIndex,這兩個(gè)方法必須在數(shù)據(jù)庫(kù)發(fā)生更新的事件中執(zhí)行。
createObjectStore方法可以理解成是創(chuàng)建表，接受第一個(gè)參數(shù)為一個(gè)字符串，表示表名，第二個(gè)參數(shù)是一個(gè)對(duì)象，指定主鍵相關(guān)的東西，{keyPath:'主鍵是哪個(gè)字段',autoIncrement:是否自增}。
createIndex方法是創(chuàng)建索引的，接受三個(gè)參數(shù)，第一個(gè)是一個(gè)字符串，表示索引的名字，第二個(gè)參數(shù)表示字段名（誰(shuí)的索引），第三個(gè)參數(shù)是個(gè)對(duì)象，具體自己查去。索引的作用是在查詢操作時(shí)可以用到，不詳講，自行g(shù)oogle吧。
<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Document</title></head><body><button type="" id='conbtn'>鏈接數(shù)據(jù)庫(kù)</button><button type="" id='add'>添加數(shù)據(jù)</button><script>// In the following line, you should include the prefixes of implementations you want to test. window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB; // DON'T use "var indexedDB = ..." if you're not in a function.
// Moreover, you may need references to some window.IDB* objects: window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction || window.msIDBTransaction;
window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange || window.msIDBKeyRange // (Mozilla has never prefixed these objects, so we don't need window.mozIDB*)
function connectDB(name,version,success,update,error){
let dbConnect = indexedDB.open(name,version);
dbConnect.onsuccess = function(e){
console.log('數(shù)據(jù)庫(kù)鏈接成功！');
success(e.target.result);
}
dbConnect.onerror = function(e){
console.log('數(shù)據(jù)庫(kù)鏈接失??！');
error(e);
}
dbConnect.onupgradeneeded = function(e){
update(e.target.result);
let oldVersion = e.oldVersion;
let newVersion = e.newVersion;
console.log('數(shù)據(jù)庫(kù)更新成功，舊的版本號(hào)為：'+oldVersion+",新的版本號(hào)為："+newVersion);
}
} function createTable(idb,storeName,key,idxs){if(!idb){
console.log(idb);return ;
}if(!key || !idxs){
console.log('參數(shù)錯(cuò)誤');return ;
}if(!storeName){
console.log('storeName必須');return ;
}try{var store = idb.createObjectStore(storeName,key);
console.log('數(shù)據(jù)庫(kù)存儲(chǔ)對(duì)象(table)創(chuàng)建成功');for(var i = 0;i<idxs.length;i++){var idx = idxs[i];
store.createIndex(idx.indexName,idx.keyPath,idx.optionalParameters);
console.log('索引'+idx.indexName+'創(chuàng)建成功');
}
}catch(e){
console.log('建表出現(xiàn)錯(cuò)誤');
console.log(JSON.stringify(e))
}
}function add(storeName,values){
connectDB('haha',1,function(idb){var ts = idb.transaction(storeName,"readwrite");var store = ts.objectStore(storeName); for(var i = 0;i<values.length;i++){
(function(i){var value = values[i];var req = store.put(value);
req.onsuccess = function(){
console.log("添加第"+i+"個(gè)數(shù)據(jù)成功");
}
req.onerror = function(e){
console.log("添加第"+i+"個(gè)數(shù)據(jù)失敗");
console.log(JSON.stringify(e));
}
})(i)
}
ts.oncomplete = function(){
console.log('添加數(shù)據(jù)事務(wù)結(jié)束！');
}
},function(){},function(){});
}
window.onload=function(){
let btn = document.getElementById('conbtn');
btn.onclick = function(){
connectDB('haha',1, function(idb){
console.log('鏈接成功，或者更新成功回調(diào)函數(shù)');
},function(idb){
createTable(idb,'test',{keyPath:'id',autoIncrement:true},[
{
indexName:'testIndex',
keyPath:'name',
optionalParameters:{
unique:true,
multiEntry:false }}]);
},function(){
console.log('鏈接失敗回調(diào)函數(shù)！')
});
}
let add1 = document.getElementById('add');
add1.onclick = function(){
add('test',[{name:"fjidfji",a:'uuuu'}])
}
}</script></body></html>
比較神奇的是你在建表的時(shí)候不需要指定你的字段，再添加數(shù)據(jù)時(shí)可以隨便加。添加數(shù)據(jù)用到的是表對(duì)象的put方法，之前需要一個(gè)事務(wù)，從事務(wù)調(diào)個(gè)方法拿到存儲(chǔ)對(duì)象（可以理解為表），具體看看例子就明白了。
Document鏈接數(shù)據(jù)庫(kù)添加數(shù)據(jù)查詢
查詢操作主要用到了游標(biāo)，這個(gè)說(shuō)起來(lái)還比較多，沒(méi)時(shí)間說(shuō)了，自行g(shù)oogle。還有很多的操作這里不講了。給一個(gè)我封裝的不是很好的簡(jiǎn)易庫(kù)，僅供參考。
一個(gè)簡(jiǎn)易庫(kù)。
(function(window){'use strict';
window.dbUtil={
indexedDB :(window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB),
IDBTransaction :(window.IDBTransaction || window.webkitIDBTransaction || window.msIDBTransaction),
IDBKeyRange :(window.IDBKeyRange || window.webkitIDBKeyRange || window.msIDBKeyRange),
IDBCursor : (window.IDBCursor || window.webkitIDBCursor || window.msIDBCursor),
idb:null,
dbName:"",
dbVersion:"",/**
* 初始化數(shù)據(jù)庫(kù)，創(chuàng)建表和建立鏈接
* @param {[type]} dbName [description]
* @param {[type]} dbVersion [description]
* @param {[type]} storeObjs [description]
* @return {[type]} [description] */initDB:function (dbName,dbVersion,storeObjs){this.dbName = dbName;this.dbVersion = dbVersion;var dbConnect = this.indexedDB.open(this.dbName,this.dbVersion);var self = this;
dbConnect.onsuccess = function(e){
self.idb = e.target.result;
self.log('數(shù)據(jù)庫(kù)鏈接成功！');
}
dbConnect.onerror = function(e){
console.log(e)
self.log('數(shù)據(jù)庫(kù)鏈接失敗!');
}
dbConnect.onupgradeneeded = function(e){
self.idb = e.target.result;var ts = e.target.transaction;var oldVersion = e.oldVersion;var newVersion = e.newVersion;
self.log('數(shù)據(jù)庫(kù)更新成功，舊的版本號(hào)為：'+oldVersion+",新的版本號(hào)為："+newVersion);if(storeObjs){for(var k = 0,len=storeObjs.length;k<len;k++){var storeObj = storeObjs[k];var storeName = storeObj.storeName;var key = storeObj.key;var idxs = storeObj.idxs;
self.createTable(storeName,key,idxs)
}
}
}
},/**
* 創(chuàng)建數(shù)據(jù)庫(kù)存儲(chǔ)對(duì)象（表）
* @param {[type]} key [description]
* @param {[type]} [description]
* @return {[type]} [description] */createTable:function(storeName,key,idxs){var self = this;var idb = self.idb;if(!idb){
self.log('數(shù)據(jù)庫(kù)沒(méi)有鏈接');return ;
}if(!key || !idxs){
self.log('參數(shù)錯(cuò)誤');return ;
}if(!storeName){
self.log('storeName必須');return ;
}try{var store = idb.createObjectStore(storeName,key);
self.log('數(shù)據(jù)庫(kù)存儲(chǔ)對(duì)象(table)創(chuàng)建成功');for(var i = 0;i<idxs.length;i++){var idx = idxs[i];
store.createIndex(idx.indexName,idx.keyPath,idx.optionalParameters);
self.log('索引'+idx.indexName+'創(chuàng)建成功');
}
}catch(e){
self.log('建表出現(xiàn)錯(cuò)誤');
console.log(JSON.stringify(e))
}
},/**
* [add description]
* @param {[type]} storeName [description]
* @param {[type]} values [description] */add:function(storeName,values){var dbConnect = this.indexedDB.open(this.dbName,this.dbVersion);var self = this;
dbConnect.onsuccess = function(e){var idb = e.target.result;var ts = idb.transaction(storeName,"readwrite");var store = ts.objectStore(storeName);for(var i = 0;i<values.length;i++){
(function(i){var value = values[i];var req = store.put(value);
req.onsuccess = function(){
self.log("添加第"+i+"個(gè)數(shù)據(jù)成功");
}
req.onerror = function(e){
self.log("添加第"+i+"個(gè)數(shù)據(jù)失敗");
self.log(JSON.stringify(e));
}
})(i)
}
ts.oncomplete = function(){
self.log('添加數(shù)據(jù)事務(wù)結(jié)束！');
}
}
},/**
* [select description]
* @param {[type]} storeName [description]
* @param {[type]} count [description]
* @param {Function} callback [description]
* @param {[type]} indexName [description]
* @return {[type]} [description] */select:function(storeName,count,callback,indexName){var dbConnect = this.indexedDB.open(this.dbName,this.dbVersion);var self = this;var total = 0;var data = [];
dbConnect.onsuccess = function(e){
self.log("數(shù)據(jù)庫(kù)鏈接成功！");var idb = e.target.result;var ts = idb.transaction(storeName,"readonly");var store = ts.objectStore(storeName);var req = store.count();var req2 = null;
req.onsuccess = function(){
total = this.result;var realCount = (count<=total)?count:total;if(typeof indexName == 'undefined'){var range = IDBKeyRange.bound(0,"9999999999999999999999");
req2 = store.openCursor(range,'prev');var cc = 0;
req2.onsuccess = function(){var cursor = this.result;if(total == 0){
callback([]);return;
}if(cursor){
cc++;
data.push(cursor.value);if(cc==realCount){
callback(data);return;
}
cursor.continue();
}
}
req2.onerror = function(){
self.log("檢索出錯(cuò)")
}
}else{//待寫(xiě) }
}
}
},/**
* [delete description]
* @param {[type]} storeName [description]
* @param {[type]} key [description]
* @return {[type]} [description] */delete:function(storeName,key,callback){var dbConnect = this.indexedDB.open(this.dbName,this.dbVersion);
let self = this;
dbConnect.onsuccess = function(e){var idb = e.target.result;var ts = idb.transaction(storeName,'readwrite');var store = ts.objectStore(storeName);
store.delete(key);
self.log('刪除成功！');if(callback){
callback();
}
}
},/**
* [funciton description]
* @param {[type]} storeName [description]
* @param {[type]} key [description]
* @param {[type]} existCall [description]
* @param {[type]} notExistCall [description]
* @return {[type]} [description] */isExist:function(storeName,key,existCall,notExistCall){var dbConnect = this.indexedDB.open(this.dbName,this.dbVersion);
dbConnect.onsuccess = function(e){var idb = e.target.result;var ts = idb.transaction(storeName,'readonly');var store = ts.objectStore(storeName);var req = store.get(key);
req.onsuccess = function(){if(this.result == undefined){
notExistCall();
}else{
existCall(this.result);
}
}
req.onerror = function(){
notExistCall();
}
}
},/**
* clear
* @param {[type]} storeName [description]
* @return {[type]} [description] */clear:function clearObjectStore(storeName){var dbConnect = this.indexedDB.open(this.dbName,this.dbVersion);
dbConnect.onsuccess = function(e){var idb = e.target.result;var ts = idb.transaction(storeName,'readwrite');var store = ts.objectStore(storeName);
store.clear();
}
},/**
* 刪除數(shù)據(jù)庫(kù)
* @param {[type]} dbName [description]
* @return {[type]} [description] */dropDatabase:function(dbName){this.indexedDB.deleteDatabase(dbName);this.log('成功刪除數(shù)據(jù)庫(kù):'+dbName);
},/**
* [log description]
* @param {[type]} msg [description]
* @return {[type]} [description] */log:function(msg){
console.log((new Date()).toTimeString()+":"+msg)
}
}
})(window);1、優(yōu)點(diǎn)：可以將一些數(shù)據(jù)放到瀏覽器端，不用和服務(wù)器交互就可以實(shí)現(xiàn)一些功能，減輕服務(wù)器負(fù)擔(dān)，加快響應(yīng)速度。
2、缺點(diǎn)：
(1)不可靠：用戶可能刪處indexedDB，而且更換瀏覽器或者設(shè)備后這些數(shù)據(jù)就沒(méi)了。
2）不便于數(shù)據(jù)采集：有很多時(shí)候?qū)?shù)據(jù)存到服務(wù)器是為了獲得一些數(shù)據(jù)，如果放到瀏覽器端，這些數(shù)據(jù)比較難獲取。
（3）無(wú)法共享：不同用戶沒(méi)辦法共享數(shù)據(jù)，甚至?xí)r一個(gè)設(shè)備的不同瀏覽器也沒(méi)法共享。
所以，是否適用indexedDB要進(jìn)行一下利弊權(quán)衡，不是有了indexedDB就啥也不管，一骨腦將數(shù)據(jù)放進(jìn)去。
感謝各位的閱讀！關(guān)于“如何將數(shù)據(jù)庫(kù)從服務(wù)器移到瀏覽器”這篇文章就分享到這里了，希望以上內(nèi)容可以對(duì)大家有一定的幫助，讓大家可以學(xué)到更多知識(shí)，如果覺(jué)得文章不錯(cuò)，可以把它分享出去讓更多的人看到吧！
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