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将数据库从服务器移到浏览器--indexedDB基本操作封装

时间：2021-07-01 10:21:17 帮助过：19人阅读

DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> </head> <body> <button type="" id=‘conbtn‘>链接数据库</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(‘数据库链接成功！‘); success(e.target.result); } dbConnect.onerror = function(e){ console.log(‘数据库链接失败！‘); error(e); } dbConnect.onupgradeneeded = function(e){ success(e.target.result); let oldVersion = e.oldVersion; let newVersion = e.newVersion; console.log(‘数据库更新成功，旧的版本号为：‘+oldVersion+",新的版本号为："+newVersion); } } window.onload=function(){ let btn = document.getElementById(‘conbtn‘); btn.onclick = function(){ connectDB(‘haha‘,1,function(){ console.log(‘链接成功，或者更新成功回调函数‘); },function(){ console.log(‘链接失败回调函数！‘) }); } } </script> </body> </html>

　　我点了两次链接数据库，结果是这样的。

技术分享

　　在Application的indexedDB中我们发现多了一个东西。

　　技术分享

　　可以看到haha数据库已经成功建立了。

　　indexedDB的open方法用来链接或者更新数据库，第一次创建也认为是一次更新。第一个参数是数据库的名字，第二个参数为版本号。第一次创建或者版本号发生改变时出发更新事件upgradeneeded，链接成功后出发success事件，链接出错时触发error事件。

二、建表和索引

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>

</head>
<body>
    <button type="" id=‘conbtn‘>链接数据库</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(‘数据库链接成功！‘);
                success(e.target.result);            
            }
            dbConnect.onerror = function(e){
                console.log(‘数据库链接失败！‘);
                error(e);
            }
            dbConnect.onupgradeneeded = function(e){
                update(e.target.result);
                let oldVersion = e.oldVersion;
                let newVersion = e.newVersion;
                console.log(‘数据库更新成功，旧的版本号为：‘+oldVersion+",新的版本号为："+newVersion);
            }
   }
       function createTable(idb,storeName,key,idxs){
        if(!idb){
            console.log(idb);
            return ;
        }
        if(!key || !idxs){
            console.log(‘参数错误‘);
            return ;
        }
        if(!storeName){
            console.log(‘storeName必须‘);
            return ;
        }

        try{
            var store = idb.createObjectStore(storeName,key);
            console.log(‘数据库存储对象(table)创建成功‘);
            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+‘创建成功‘);
            }
        }catch(e){
            console.log(‘建表出现错误‘);
            console.log(JSON.stringify(e))
        }
    }
   window.onload=function(){
           let btn  = document.getElementById(‘conbtn‘);
           btn.onclick = function(){
               connectDB(‘haha‘,1,
                 function(idb){
                   console.log(‘链接成功，或者更新成功回调函数‘);
               },function(idb){
                   createTable(idb,‘test‘,{keyPath:‘id‘,autoIncrement:true},[
                       {
                       indexName:‘testIndex‘,
                     keyPath:‘name‘,
                     optionalParameters:{
                         unique:true,
                         multiEntry:false
                     }}]);                   
               },function(){
                   console.log(‘链接失败回调函数！‘)
               });
           }
   }
</script>
</body>
</html>

　　我点了一下按钮结果时这样的。

　　技术分享

　　这里用到的两个核心方法时createObjectStore，和createIndex,这两个方法必须在数据库发生更新的事件中执行。

　　createObjectStore方法可以理解成是创建表，接受第一个参数为一个字符串，表示表名，第二个参数是一个对象，指定主键相关的东西，{keyPath:‘主键是哪个字段‘,autoIncrement:是否自增}。

　　createIndex方法是创建索引的，接受三个参数，第一个是一个字符串，表示索引的名字，第二个参数表示字段名（谁的索引），第三个参数是个对象，具体自己查去。索引的作用是在查询操作时可以用到，不详讲，自行google吧。

三、添加数据

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>

</head>
<body>
    <button type="" id=‘conbtn‘>链接数据库</button>
    <button type="" id=‘add‘>添加数据</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(‘数据库链接成功！‘);
                success(e.target.result);            
            }
            dbConnect.onerror = function(e){
                console.log(‘数据库链接失败！‘);
                error(e);
            }
            dbConnect.onupgradeneeded = function(e){
                update(e.target.result);
                let oldVersion = e.oldVersion;
                let newVersion = e.newVersion;
                console.log(‘数据库更新成功，旧的版本号为：‘+oldVersion+",新的版本号为："+newVersion);
            }
   }
       function createTable(idb,storeName,key,idxs){
        if(!idb){
            console.log(idb);
            return ;
        }
        if(!key || !idxs){
            console.log(‘参数错误‘);
            return ;
        }
        if(!storeName){
            console.log(‘storeName必须‘);
            return ;
        }

        try{
            var store = idb.createObjectStore(storeName,key);
            console.log(‘数据库存储对象(table)创建成功‘);
            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+‘创建成功‘);
            }
        }catch(e){
            console.log(‘建表出现错误‘);
            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+"个数据成功");
                }
                req.onerror = function(e){
                    console.log("添加第"+i+"个数据失败");
                    console.log(JSON.stringify(e));
                }                            
            })(i)

        }
        ts.oncomplete = function(){
            console.log(‘添加数据事务结束！‘);
        }
    },function(){},function(){});

                
    }
   window.onload=function(){
           let btn  = document.getElementById(‘conbtn‘);
           btn.onclick = function(){
               connectDB(‘haha‘,1,
                 function(idb){
                   console.log(‘链接成功，或者更新成功回调函数‘);
               },function(idb){
                   createTable(idb,‘test‘,{keyPath:‘id‘,autoIncrement:true},[
                       {
                       indexName:‘testIndex‘,
                     keyPath:‘name‘,
                     optionalParameters:{
                         unique:true,
                         multiEntry:false
                     }}]);                   
               },function(){
                   console.log(‘链接失败回调函数！‘)
               });
           }
           let add1 = document.getElementById(‘add‘);
           add1.onclick = function(){
               add(‘test‘,[{name:"fjidfji",a:‘uuuu‘}])
           }
   }
</script>
</body>
</html>

技术分享

　　比较神奇的是你在建表的时候不需要指定你的字段，再添加数据时可以随便加。添加数据用到的是表对象的put方法，之前需要一个事务，从事务调个方法拿到存储对象（可以理解为表），具体看看例子就明白了。

四、查询数据

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>

</head>
<body>
    <button type="" id=‘conbtn‘>链接数据库</button>
    <button type="" id=‘add‘>添加数据</button>
    <button type="" id="selectBtn">查询</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(‘数据库链接成功！‘);
                success(e.target.result);            
            }
            dbConnect.onerror = function(e){
                console.log(‘数据库链接失败！‘);
                error(e);
            }
            dbConnect.onupgradeneeded = function(e){
                update(e.target.result);
                let oldVersion = e.oldVersion;
                let newVersion = e.newVersion;
                console.log(‘数据库更新成功，旧的版本号为：‘+oldVersion+",新的版本号为："+newVersion);
            }
   }
       function createTable(idb,storeName,key,idxs){
        if(!idb){
            console.log(idb);
            return ;
        }
        if(!key || !idxs){
            console.log(‘参数错误‘);
            return ;
        }
        if
                        
                            
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将数据库从服务器移到浏览器--indexedDB基本操作封装

二、建表和索引

三、添加数据

四、查询数据

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