相关对象

IDBFactory

作用：用于创建或打开数据库，并管理数据库的版本

获取方式：var IDBFactory =window.indexedDB

IDBOpenDBRequest

作用：为请求对象，而对数据库的访问、操作都是基于请求的

获取方式：var IDBOpenDBRequest = window.indexedDB.open(name,version)

IDBDatabase

作用：为真正的数据库对象，封装了对数据库表的创建、编辑等功能

获取方式：基于请求对象IDBOpenDBRequest，当IDBOpenDBRequest申请成功时，该对象的result属性就是IDBDatabase数据库对象。

IDBOpenDBRequest.onsuccess= function (e){

    var IDBDatabase =IDBOpenDBRequest.result;

    //或者

    var IDBDatabase =e.target.result;

}

关闭数据库：调用IDBDatabase对象的close()方法

IDBDatabase.close();

删除数据库：调用indexedDB对象的deleteDatabase方法

indexedDB.deleteDatabase(name);

IDBObjectStore

作用：相当于一张表，里面存储的每条数据和一个键相关联

初始化方式：在创建数据库的时候初始化IDBObjectStore，即在IDBOpenDBRequest. Onupgradeneeded事件中。

IDBOpenDBRequest.onupgradeneeded= function(e){

    var db = e.target.result;

    if(!db.objectStoreNames.contains('students')){

        db.createObjectStore('students',{keyPath:"id"});

    }

console.log('DB version changedto ' + version);

};

获取方式：需要通过事务获取

var transaction=db.transaction(['students']); 

var objectStore=transaction.objectStore('students');

添加数据：通过IDBObjectStore对象的add方法添加

objectStore.add({

    id:1001,

    name:'huahua',

    age:25

})

获取数据：通过IDBObjectStore对象的get方法通过键获取数据

function getDataByKey(db,storeName,value){

    var transaction =db.transaction(storeName,'readwrite');

    var store =transaction.objectStore(storeName);

    var request = store.get(value);

    request.onsuccess = function(e){

        var student = e.target.result;

        console.log(student.age);

    }

}

删除数据：通过IDBObjectStore对象的delete方法根据键值删除数据

function deleteDataByKey(db,storeName,value){

    vartransaction = db.transaction(storeName,'readwrite');

    var store =transaction.objectStore(storeName);

    store.delete(value);

}

清空数据：通过IDBObjectStore对象的clear方法清除数据

function clearObjectStore(db,storeName) {

    var transaction = db.transaction(storeName,'readwrite');

    var store =transaction.objectStore(storeName);

    store.clear();

}

所有代码如下:

var iDBFactory = window.indexedDB;

var iDBOpenDBRequest = window.indexedDB.open('student',1);

iDBOpenDBRequest.onsuccess = function(){

    var iDBDatabase = iDBOpenDBRequest.result;

    var transaction = iDBDatabase.transaction(['student'],'readwrite');

    var objectStore = transaction.objectStore('student');

    objectStore.add({

        id: 1001,

        name: 'huahua',

        age: 25

    });

    getDataByKey(iDBDatabase,'student',1001);

};

iDBOpenDBRequest.onerror = function(){

};

iDBOpenDBRequest.onupgradeneeded = function(e){

    var db = e.target.result;

    if(!db.objectStoreNames.contains('student')) {

        db.createObjectStore('student',{

            keyPath: 'id'

        });

    }

};

function getDataByKey(db, storeName, value){

    var transaction = db.transaction(storeName, 'readwrite');

    var store = transaction.objectStore(storeName);

    var request = store.get(value);

    request.onsuccess = function(e) {

        var student = e.target.result;

        console.log(student.age);

    }

}

function deleteDataByKey(db, storeName, value){

    var transaction = db.transaction(storeName, 'readwrite');

    var store = transaction.objectStore(storeName);

    store.delete(value);

}

function clearObjectStore(db,storeName) {

    var transaction = db.transaction(storeName,'readwrite');

    var store = transaction.objectStore(storeName);

    store.clear();

}