react-native本地数据库react-native-sqlite-storage

import React,{Component} from 'react';
import{
    ToastAndroid,
    NativeModules,
    Alert,
    BackHandler
} from 'react-native';
import SQLiteStorage from 'react-native-sqlite-storage';


SQLiteStorage.DEBUG(true);
//项目中用的是可以插SD卡的android设备 
///storage/EDB8-F24B/Handheld/handheld.db /sdcard/Handheld/
var database_version = "1.0";//版本号
var database_displayname = "MySQLite";
var database_size = -1;//-1应该是表示无限制
var db;
var localDb;

export default class  SQLite extends Component{
    componentWillUnmount(){
        if(db){
            this._successCB('close');
            db.close();
        }else {
            console.log("SQLiteStorage not open");
        }
    }
    componentWillMount(){
    
    }
    //
    openCardDb(){
        db = SQLiteStorage.openDatabase(
            cardPath+"/Handheld/"+dbName+".db",//数据库文件 SD卡指定路径
            database_version,
            database_displayname,
            database_size,
            ()=>{
                this._successCB('open');
            },
            (err)=>{
                this._errorCB('open',err);
            });
        return db;
    }
    openLocalDb(){
        console.log("调用打开数据库openLocalDb");
        localDb = SQLiteStorage.openDatabase(
            "/sdcard/Handheld/"+dbName+".db",//数据库文件 内部存储路径
            database_version,
            database_displayname,
            database_size,
            ()=>{
                this._successCB('open');
            },
            (err)=>{
                this._errorCB('open',err);
            });
        return localDb;
    }
    createTable(){
        if (!db) {
            this.open();
        }
        //创建用户表
        db.transaction((tx)=> {
            tx.executeSql('CREATE TABLE IF NOT EXISTS USER(' +
                'id INTEGER PRIMARY KEY  AUTOINCREMENT,' +
                'name varchar,'+
                'age VARCHAR,' +
                'sex VARCHAR,' +
                'phone VARCHAR,' +
                'email VARCHAR,' +
                'qq VARCHAR)'
                , [], ()=> {
                    this._successCB('executeSql');
                }, (err)=> {
                    this._errorCB('executeSql', err);
                });
        }, (err)=> {//所有的 transaction都应该有错误的回调方法
            this._errorCB('transaction', err);
        }, ()=> {
            this._successCB('transaction');
        })
    }
    deleteData(){//删除表中的数据
        if (!db) {
            this.open();
        }
        db.transaction((tx)=>{
            tx.executeSql('delete from user',[],()=>{

            });
        });
    }
    dropTable(){//删除表
        db.transaction((tx)=>{
            tx.executeSql('drop table user',[],()=>{

            });
        },(err)=>{
            this._errorCB('transaction', err);
        },()=>{
            this._successCB('transaction');
        });
    }
    close(){
        if(db){
            this._successCB('close');
            db.close();
        }else {
            console.log("SQLiteStorage not open");
        }
        db = null;
    }
    _successCB(name){
        console.log("SQLiteStorage "+name+" success");
    }
    _errorCB(name, err){
        console.log("SQLiteStorage "+name);
        console.log(err);
    }
   
    async execSql(localDb,cardDb,sql,successFunction,endFunction){
        if(cardPath!="/sdcard"){
            //如果获取到的路径有SD卡
            if(!localDb){
                localDb = this.openLocalDb();
            }
            if(!cardDb){
                cardDb = this.openCardDb();
            }
            //项目中需要两个地方存储数据库
            await cardDb.transaction((tx)=>{
                tx.executeSql(sql, [],(tx,results)=>{
                    
                    successFunction(tx,results);
                });
            },(error)=>{//打印异常信息
                
            },()=>{
                endFunction();
            });

            localDb.transaction((tx)=>{
                tx.executeSql(sql, [],(tx,results)=>{
                    console.log("数据库执行成功"+sql)
                });
            },(error)=>{//打印异常信息
            },()=>{
            });
        }else{
            //如果获取到的路径有SD卡
            if(!localDb){
                localDb = this.openLocalDb();
            }
        
            localDb.transaction((tx)=>{
                tx.executeSql(sql, [],(tx,results)=>{
                    successFunction(tx,results);
                });
            },(error)=>{//打印异常信息
                
            },()=>{

                endFunction();
            });
        }

    }
    render(){
        return null;
    }
};