webturing
/
ChineseHandWritingApp


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="zh-cn">
<head>
    <meta charset="UTF-8">
    <title>sqlite数据库测试</title>
    <script src="https://unpkg.com/axios/dist/axios.min.js"></script>
    <script src="https://cdn.bootcss.com/sql.js/0.5.0/js/sql-optimized.js"></script>
</head>
<body>

<p>sqlite数据库测试，使用js操作sqlite数据库</p>
<p>这里使用axios读取test.db文件，进行初始化数据库连接，</p>
<p>查询速度不快，除非不想写后台要直接操作数据库，不然没什么用。</p>
<p>具体效果可查看代码和控制台打印的数据。</p>

<script>

    // 读取数据库数据
    axios.get("chinese.db", {responseType: 'arraybuffer'})
        .then(function (response) {
            let db = new window.SQL.Database(new Uint8Array(response.data));
            // 执行查询
            let s = new Date().getTime();
            let r = db.exec("SELECT * FROM chinese WHERE id between 13000 and 13010;");
            let e = new Date().getTime();
            document.write("查询数据耗时：" + (e - s) + "ms");
            // 解析数据
            let obj = dbToObj(r);
            console.info(obj);
            document.write('<table border="1">');
            obj.forEach(
                function (value) {
                    document.write('<tr>');
                    document.write('<td>'+value.id+'</td>');
                    document.write('<td>'+value.font+'</td>');
                    document.write('<td>'+value.type+'</td>');
                    document.write('<td>'+value.time+'</td>');
                    document.write('<td>'+value.author+'</td>');
                    var path='../res/';
                    path+=value.font+"_"+value.time+"_"+value.author+'_'+value.type;
                    path+='.png';
                    document.write('<td><img src='+path+"></td>");
                    document.write('</tr>');

                }
            );

            document.write('</table>');

        })
        .catch(function (error) {
            console.info(error);
        });

    // 方法传入两个数组，第一个数组为key，第二个数组对应位置为value，此方法在Python中为zip()函数。
    const ArraytoObj = (keys = [], values = []) => {
        if (keys.length === 0 || values.length === 0) return {};
        const len = keys.length > values.length ? values.length : keys.length;
        const obj = {};
        for (let i = 0; i < len; ++i) {
            obj[keys[i]] = values[i]
        }
        return obj;
    };

    // 转驼峰表示：func.camel('USER_ROLE',true) => UserRole
    // 转驼峰表示：func.camel('USER_ROLE',false) => userRole
    const camel = (str, firstUpper = false) => {
        let ret = str.toLowerCase();
        ret = ret.replace(/_([\w+])/g, function (all, letter) {
            return letter.toUpperCase();
        });
        if (firstUpper) {
            ret = ret.replace(/\b(\w)(\w*)/g, function ($0, $1, $2) {
                return $1.toUpperCase() + $2;
            });
        }
        return ret;
    };

    // 把数组里面的所有转化为驼峰命名
    const camelArr = (arrs = []) => {
        let _arrs = [];
        arrs.map(function (item) {
            _arrs.push(camel(item));
        });
        return _arrs;
    };

    // 读取数据库
    // 1.把columns转化为驼峰；
    // 2.把columns和values进行组合；
    const dbToObj = (_data = {}) => {
        let _res = [];
        _data.map(function (item) {
            let _columns = camelArr(item.columns);
            item.values.map(function (values) {
                _res.push(ArraytoObj(_columns, values));
            });
        });
        return _res;
    };
</script>
</body>
</html>