websql操作类封装

　　在之前，我写了一个websql的封装类库，代码如下：

(function(win) {
    function smpwebsql(options){
        options = options || {};
        this.database = null;
        this.datebasename = options.datebasename || 'smpdb';
        this.version = options.version || '1.0';
        this.description = options.description || 'smpdb';
        this.databasesize = options.databasesize || 2 * 1024 * 1024;
        this.init();
    }
    smpwebsql.prototype = {
        init: function() {
            this.database = opendatabase(this.datebasename, this.version, this.description, this.databasesize); //初始化数据库
        },
        addblob: function (tablename, arr,index,isfirst,callback) {//批量添加字段
            /*
                注 ： 数据里面的第一个key存储类型为blob
                @param  tablename 表名
                @param  arr 更新的数据    [{key1：value1 , key2 : value2 ...},{key1：value1 , key2 : value2 ...}]
                @param  index blog字段所在的索引位置
                @param  isfirst 是否是第一次创建表
                @param  callback  回调
             */
            if (arr == null) {
                return this;
            }
            callback = this.isfunction(callback) ? callback : new function();
            var _me = this,
                _db = this.database,
                keyc = [],
                keyi = [],
                _key = '';
            arr = arr || [];
            if (arr && arr.constructor == array) {
                for (var i in arr[0]) {
                    keyc.push(i);
                    keyi.push(i);
                }
                _key = keyi.join(",");
                index = index == undefined ? 0 : index;
                keyc[index] = keyc[index] + ' blob';
                _db.transaction(function (tx, result) {
                    //var csql = 'create table if not exists ' + tablename + ' (' + keyc.join(",") + ')';
                    //console.log('csql:' + csql);
                    if (isfirst == true) {
                        tx.executesql('create table if not exists ' + tablename + ' (' + keyc.join(",") + ')');
                    }
                    //var sql = "";
                    for (var s = 0, _len = arr.length; s < _len ; s++) {
                        var _value = _me.split(arr[s]);
                        //sql += 'insert into ' + tablename + ' (' + _key + ') values (' + _value + ')';
                        //console.log("sql:" + sql);
                        tx.executesql('insert into ' + tablename + ' (' + _key + ') values (' + _value + ')',[],function (tx, result) {
                            callback(result.rowsaffected);
                            //console.log('添加成功'+result.rowsaffected);
                        },function (tx, error) {
                            console.error('添加失败');
                            callback(false);
                        });
                    }
                    _key = keyi = keyc = null;
                    callback();
                });
            }
            return this;
        },
        add: function (tablename, arr, callback, nokey) {//批量添加字段
            /*
                注 ： 数据里面的第一个key 为主键
                @param  tablename 表名
                @param  arr 更新的数据    [{key1：value1 , key2 : value2 ...},{key1：value1 , key2 : value2 ...}]
                @param  callback  回调
                @param  nokey 第一个字段是否是主键（默认是）
             */
            if(arr==null){
                return this;
            }
            callback = this.isfunction(callback) ? callback : new function();
            var _me = this,
                _db = this.database,
                keyc = [],
                keyi = [],
                _key = '';
            arr = arr || [];
            if (arr && arr.constructor == array) {
                for(var i in arr[0]){
                    keyc.push(i);
                    keyi.push(i);
                }
                if (nokey==undefined) {
                    keyc[0] = keyc[0] + ' unique';
                }
                _key = keyi.join(",");
                _db.transaction(function (tx) {
                   ///var csql = 'create table if not exists ' + tablename + ' (' + keyc.join(",") + ')';
                    // console.log('csql:' + csql);
                     tx.executesql('create table if not exists ' + tablename + ' (' + keyc.join(",") + ')');
                    //var sql = "";
                    for(var s = 0 , _len = arr.length; s < _len ; s++){
                        var _value = _me.split(arr[s]);
                        //sql += 'insert into ' + tablename + ' (' + _key + ') values (' + _value + ')';
                        //console.log("sql:" + sql);
                        tx.executesql('insert into '+tablename+' ('+_key+') values ('+_value+')',[],function (tx, result) {
                            callback(result.rowsaffected);
                            //console.log('添加成功'+result.rowsaffected);
                        },function (tx, error) {
                            console.error('添加失败');
                            callback(false);
                        });
                    }
                    _key = keyi = keyc = null;
                    callback();
                });
            }
            return this;
        },
        update : function(tablename,key,value,obj,callback){//更新指定数据
            /*
                @param  tablename 表名
                @param  key 查询的键 
                @param  value 对应键的值
                @param  obj 更新的数据    {key1：value1 , key2 : value2 ...} 
                @param  callback  回调  传递参数为真则查询成功 反之更新失败
             */
            callback = this.isfunction(callback) ? callback : new function();
            var _db = this.database,
                _value = this.splitu(obj);
            _db.transaction(function (tx) {
                //console.log('sql:' + 'update ' + tablename + ' set ' + _value + ' where ' + key + '="' + value + '"')
                tx.executesql('update '+tablename+' set '+_value+' where '+key+'="'+value+'"',[],function (tx, result) {
                    callback(result.rowsaffected);
                },function (tx, error) {
                    console.error('更新失败');
                    callback(false);
                });
            });
            return this;
        },
        updatewhere: function (tablename, where, obj, callback) {//更新指定数据
            /*
                @param  tablename 表名
                @param  查询条件 
                @param  obj 更新的数据    {key1：value1 , key2 : value2 ...} 
                @param  callback  回调  传递参数为真则查询成功 反之更新失败
             */
            callback = this.isfunction(callback) ? callback : new function();
            var _db = this.database,
                _value = this.splitu(obj);
            _db.transaction(function (tx) {
                console.log('update ' + tablename + ' set ' + _value + ' where ' + where + '"')
                tx.executesql('update ' + tablename + ' set ' + _value + ' where ' + where + '"', [], function (tx, result) {
                    callback(result.rowsaffected);
                }, function (tx, error) {
                    console.error('更新失败');
                    callback(false);
                });
            });
            return this;
        },
        read : function(tablename,condition,callback){ //读取表数据
            /*
                @param  tablename 表名
                @param  condition 查询条件   'where name="汪文君"'
                @param  callback  回调  传递参数为真则查询成功 反之查询失败
             */
            var _condition = this.isstring(condition) ? condition : '';
            var _callback = this.isfunction(condition) ? condition : this.isfunction(callback) ? callback : new function;
            var _db = this.database,
                _me = this,
                _re = [];
                _db.transaction(function (tx) {
                    tx.executesql('select * from ' + tablename + ' ' + _condition + ' ', [], function (tx, results) {
                        if(results && results.rows){
                            _re =_me.toarray(results.rows);
                            _callback(_re);
                        }else{
                            _callback([]);
                        }
                    },function(tx,error){
                        _callback([]);
                        console.error('查询失败');
                    });
                });
                return this;
        },
        remove:function(tablename,condition,callback){//删除数据
            /*
                @param  tablename 表名
                @param  condition 查询条件   'where name="汪文君"'
                @param  callback  回调  传递参数为真则删除成功 反之删除失败
             */
            var _me = this;
            var _condition = this.isstring(condition) ? condition : '';
            var _callback = this.isfunction(condition) ? condition : this.isfunction(callback) ? callback : new function;
            _me.database.transaction(function (tx) {
                tx.executesql('delete from '+tablename+ ' '+ _condition+' ',[],function (tx, result) {
                    _callback(result.rowsaffected);
                },function (tx, error) {
                    _callback(false);
                    console.error('删除失败');
                });
            });
        },
        counts: function (tablename, condition, callback) { //读取表数据
            /*
                @param  tablename 表名
                @param  condition 查询条件   'where name="汪文君"'
                @param  callback  回调  传递参数为真则查询成功 反之查询失败
             */
            var _condition = this.isstring(condition) ? condition : '';
            var _callback = this.isfunction(condition) ? condition : this.isfunction(callback) ? callback : new function;
            var _db = this.database,
                _me = this,
                _re = [];
            if (mui.os.ios) { //ios下面特有的
                _db.transaction(function (tx) {
                    tx.executesql('select no from ' + tablename + ' ' + _condition + ' ', [], function (tx, results) {// count (*) as num
                        if (results && results.rows) {
                            _re = _me.toarray(results.rows);
                            _callback(_re.length);
                        } else {
                            _callback(0);
                        }
                    }, function (tx, error) {
                        _callback(0);
                        console.error('查询失败');
                    });
                });
            } else {
                _db.transaction(function (tx) {
                    tx.executesql('select count (*) as num from ' + tablename + ' ' + _condition + ' ', [], function (tx, results) {// count (*) as num
                        if (results && results.rows) {
                            if (results.rows[0]) {
                                _callback(results.rows[0].num);
                            } else {
                                _callback(0);
                            }
                        } else {
                            _callback(0);
                        }
                    }, function (tx, error) {
                        _callback(0);
                        console.error('查询失败');
                    });
                });
            }
            return this;
        },
        deltable:function(tablename,callback){ //删除数据表
            callback = this.isfunction(callback) ? callback : new function();
            this.database.transaction(function(tx){
                tx.executesql('drop table if exists '+tablename,[],function(tx,res){
                    callback();
                },function(tx,err){
                    console.error(err);
                });
            });
            return this;
        },
        splitu: function(obj){//更新字符处理
            var _arr = [];
            for(var t in obj){
                _arr.push(t+'="'+obj[t]+'"');
            }
            return _arr.join(',');
        },
        split : function(obj){//添加字符处理
            var _arr = [];
            for(var m in obj){
                _arr.push("'"+obj[m]+"'");
            }
            return _arr.join(',');
        },
        isfunction : function(callback){
            return typeof callback != 'undefined' && callback.constructor == function ? true : false
        },
        isstring : function(string){
            return typeof string == 'string' ? true : false
        },
        toarray : function(obj){
            var _arr = [],
                _len = obj.length;
                if(_len > 0){
                    for (var i = 0; i < _len; i++) {
                        _arr.push(obj.item(i));
                    };
                }
                return _arr;
        }
    }
    win.smpwebsql = smpwebsql;
}(window))

　　上述代码存在的问题非常明显，由于websql操作都是异步操作，当我们为了获取到websql操作的结果之后再进行后续操作时，往往是通过回调函数来实现的，当回调一多的时候，回调地狱就出现了，为了解决回调地狱问题，我将通过promise来改写，后续调用时，可以直接通过await和async来调用，或者直接通过promise链式调用也是可以的。

　　现在我将通过es6的语法重写之前的封装类，为了应用es6中js面向对象的思想，我这里用到了class，最终代码如下：

import utils from '@/utils/utils.js';
class smpwebsql {
  constructor(options) {
    options = options || {};
    this.database = null;
    this.datebasename = options.datebasename || 'reddb';
    this.version = options.version || '1.0';
    this.description = options.description || '智维离线工单数据库';
    this.databasesize = options.databasesize || 2 * 1024 * 1024;
    this.init();
  }
  /**
   * 初始化数据库
   */
  init() {
    this.database = opendatabase(
      this.datebasename,
      this.version,
      this.description,
      this.databasesize
    );
  }
  /**
   * 批量添加字段
   * @param {*} tablename 表名
   * @param {*} arr 更新的数据    [{key1：value1 , key2 : value2 ...},{key1：value1 , key2 : value2 ...}]
   * @param {*} index blog字段所在的索引位置
   * @param {*} isfirst 是否是第一次创建表
   */
  addblob(tablename, arr, index, isfirst) {
    var _db = this.database;
    var _me = this;
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      if (arr == null) {
        return this;
      }
      var keyc = [];
      var keyi = [];
      var _key = '';
      arr = arr || [];
      if (arr && arr.constructor == array) {
        for (var i in arr[0]) {
          keyc.push(i);
          keyi.push(i);
        }
        _key = keyi.join(',');
        index = index == undefined ? 0 : index;
        keyc[index] = keyc[index] + ' blob';
        // eslint-disable-next-line promise/param-names

        _db.transaction(function(tx, result) {
          // var csql = 'create table if not exists ' + tablename + ' (' + keyc.join(",") + ')';
          // console.log('csql:' + csql);
          if (isfirst == true) {
            tx.executesql(
              'create table if not exists ' +
                tablename +
                ' (' +
                keyc.join(',') +
                ')'
            );
          }
          // var sql = "";
          for (var s = 0, _len = arr.length; s < _len; s++) {
            var _value = _me.split(arr[s]);
            // sql += 'insert into ' + tablename + ' (' + _key + ') values (' + _value + ')';
            // console.log("sql:" + sql);
            tx.executesql(
              'insert into ' +
                tablename +
                ' (' +
                _key +
                ') values (' +
                _value +
                ')',
              [],
              function(tx, result) {
                resovle(result.rowsaffected);
                // console.log('添加成功'+result.rowsaffected);
              },
              function(tx) {
                console.error('添加失败');
                // eslint-disable-next-line prefer-promise-reject-errors
                reject(false);
              }
            );
          }
          _key = keyi = keyc = null;
          resovle();
        });
      }
    });
  }
  /**
   * 批量添加字段 注 ： 数据里面的第一个key 为主键
   * @param {*} tablename 表名
   * @param {*} arr arr 更新的数据    [{key1：value1 , key2 : value2 ...},{key1：value1 , key2 : value2 ...}]
   * @param {*} nokey nokey 第一个字段是否是主键（默认是）
   */
  add(tablename, arr, nokey) {
    var _me = this;
    var _db = this.database;
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      if (arr == null) {
        return this;
      }
      var keyc = [];
      var keyi = [];
      var _key = '';
      arr = arr || [];
      if (arr && arr.constructor == array) {
        for (var i in arr[0]) {
          keyc.push(i);
          keyi.push(i);
        }
        if (nokey == undefined) {
          keyc[0] = keyc[0] + ' unique';
        }
        _key = keyi.join(',');
        _db.transaction(function(tx) {
          // /var csql = 'create table if not exists ' + tablename + ' (' + keyc.join(",") + ')';
          // console.log('csql:' + csql);
          tx.executesql(
            'create table if not exists ' +
              tablename +
              ' (' +
              keyc.join(',') +
              ')'
          );
          // var sql = "";
          for (var s = 0, _len = arr.length; s < _len; s++) {
            var _value = _me.split(arr[s]);
            // sql += 'insert into ' + tablename + ' (' + _key + ') values (' + _value + ')';
            // console.log("sql:" + sql);
            tx.executesql(
              'insert into ' +
                tablename +
                ' (' +
                _key +
                ') values (' +
                _value +
                ')',
              [],
              function(tx, result) {
                resovle(result.rowsaffected);
                // console.log('添加成功'+result.rowsaffected);
              },
              function(tx, error) {
                console.error('添加失败');
                // eslint-disable-next-line prefer-promise-reject-errors
                reject(false);
              }
            );
          }
          _key = keyi = keyc = null;
          // resovle();
        });
      }
    });
  }
  /**
   * 更新指定数据
   * @param {*} tablename 表名
   * @param {*} key 查询的键
   * @param {*} value 对应键的值
   * @param {*} obj obj 更新的数据    {key1：value1 , key2 : value2 ...}
   */
  update(tablename, key, value, obj) {
    var _db = this.database;
    var _value = this.splitu(obj);
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      _db.transaction(function(tx) {
        // console.log('sql:' + 'update ' + tablename + ' set ' + _value + ' where ' + key + '="' + value + '"')
        tx.executesql(
          'update ' +
            tablename +
            ' set ' +
            _value +
            ' where ' +
            key +
            '="' +
            value +
            '"',
          [],
          function(tx, result) {
            resovle(result.rowsaffected);
          },
          function(tx, error) {
            console.error('更新失败');
            // eslint-disable-next-line prefer-promise-reject-errors
            reject(false);
          }
        );
      });
    });
  }
  /**
   * 更新指定数据
   * @param {*} tablename 表名
   * @param {*} where 查询条件
   * @param {*} obj obj 更新的数据    {key1：value1 , key2 : value2 ...}
   */
  updatewhere(tablename, where, obj) {
    var _db = this.database;
    var _value = this.splitu(obj);
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      _db.transaction(function(tx) {
        console.log(
          'update ' + tablename + ' set ' + _value + ' where ' + where + '"'
        );
        tx.executesql(
          'update ' + tablename + ' set ' + _value + ' where ' + where + '"',
          [],
          function(tx, result) {
            resovle(result.rowsaffected);
          },
          function(tx, error) {
            console.error('更新失败');
            // eslint-disable-next-line prefer-promise-reject-errors
            reject(false);
          }
        );
      });
    });
  }
  /**
   * 读取表数据
   * @param {*} tablename 表名
   * @param {*} condition 查询条件   'where name="jiekzou"'
   */
  read(tablename, condition) {
    var _db = this.database;
    var _me = this;
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      var _condition = this.isstring(condition) ? condition : '';
      var _re = [];
      _db.transaction(function(tx) {
        tx.executesql(
          'select * from ' + tablename + ' ' + _condition + ' ',
          [],
          function(tx, results) {
            if (results && results.rows) {
              _re = _me.toarray(results.rows);
              resovle(_re);
            } else {
              resovle([]);
            }
          },
          function(tx, error) {
            // eslint-disable-next-line prefer-promise-reject-errors
            reject([]);
            console.error('查询失败');
          }
        );
      });
    });
  }
  /**
   * 删除数据
   * @param {*} tablename 表名
   * @param {*} condition 查询条件   'where name="jiekzou"'
   */
  remove(tablename, condition) {
    var _me = this;
    var _condition = this.isstring(condition) ? condition : '';
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      _me.database.transaction(function(tx) {
        tx.executesql(
          'delete from ' + tablename + ' ' + _condition + ' ',
          [],
          function(tx, result) {
            resovle(result.rowsaffected);
          },
          function(tx, error) {
            // eslint-disable-next-line prefer-promise-reject-errors
            reject(false);
            console.error('删除失败');
          }
        );
      });
    });
  }
  /**
   * 根据查询条件读取表记录数
   * @param {*} tablename 表名
   * @param {*} condition 查询条件   'where name="jiekzou"'
   */
  counts(tablename, condition) {
    if (utils.browserversions.android) {
      return this.androidcounts(tablename, condition);
    } else {
      return this.ioscounts(tablename, condition);
    }
  }
  // ios下面特有的
  /**
   * 读取表数据(ios下面特有的)
   * @param {*} tablename 表名
   * @param {*} condition  查询条件   'where name="jiekzou"'
   */
  ioscounts(tablename, condition) {
    var _condition = this.isstring(condition) ? condition : '';
    var _db = this.database;
    var _me = this;
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      var _re = [];
      _db.transaction(function(tx) {
        tx.executesql(
          'select no from ' + tablename + ' ' + _condition + ' ',
          [],
          function(tx, results) {
            // count (*) as num
            if (results && results.rows) {
              _re = _me.toarray(results.rows);
              resovle(_re.length);
            } else {
              resovle(0);
            }
          },
          function(tx, error) {
            // eslint-disable-next-line prefer-promise-reject-errors
            reject(0);
            console.error('查询失败');
          }
        );
      });
    });
  }
  /**
   * 读取表数据（android）
   * @param {*} tablename 表名
   * @param {*} condition 查询条件   'where name="jiekzou"'
   */
  androidcounts(tablename, condition) {
    var _condition = this.isstring(condition) ? condition : '';
    var _db = this.database;
    var _me = this;
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      var _re = [];
      _db.transaction(function(tx) {
        tx.executesql(
          'select count (*) as num from ' + tablename + ' ' + _condition + ' ',
          [],
          function(tx, results) {
            // count (*) as num
            if (results && results.rows) {
              if (results.rows[0]) {
                resovle(results.rows[0].num);
              } else {
                resovle(0);
              }
            } else {
              resovle(0);
            }
          },
          function(tx, error) {
            // eslint-disable-next-line prefer-promise-reject-errors
            reject(0);
            console.error('查询失败');
          }
        );
      });
    });
  }
  /**
   * 删除数据表
   * @param {*} tablename 表名
   */
  deltable(tablename) {
    // eslint-disable-next-line promise/param-names
    return new promise(function(resovle, reject) {
      this.database.transaction(function(tx) {
        tx.executesql(
          'drop table if exists ' + tablename,
          [],
          function(tx, res) {
            resovle();
          },
          function(tx, err) {
            console.error(err);
            // eslint-disable-next-line prefer-promise-reject-errors
            reject(0);
          }
        );
      });
    });
  }
  // 更新字符处理
  splitu(obj) {
    var _arr = [];
    for (var t in obj) {
      _arr.push(t + '="' + obj[t] + '"');
    }
    return _arr.join(',');
  }
  // 添加字符处理
  split(obj) {
    var _arr = [];
    for (var m in obj) {
      _arr.push('\'' + obj[m] + '\'');
    }
    return _arr.join(',');
  }
  isfunction(callback) {
    return !!(
      typeof callback != 'undefined' && callback.constructor == function
    );
  }
  isstring(string) {
    return typeof string == 'string';
  }
  toarray(obj) {
    var _arr = [];
    var _len = obj.length;
    if (_len > 0) {
      for (var i = 0; i < _len; i++) {
        _arr.push(obj.item(i));
      }
    }
    return _arr;
  }
}

export default smpwebsql;