1、添加依赖

在demo中会用到路径等多个插件库，一并加载

在pubspec.yaml添加

dependencies:

flutter:

sdk: flutter

# The following adds the Cupertino Icons font to your application.

# Use with the CupertinoIcons class for iOS style icons.

cupertino_icons: ^0.1.2

event_bus: ^1.0.1

sqflite: ^1.1.0

shared_preferences: ^0.5.1

path_provider: ^0.5.0

dart文件中导入包

import 'package:flutter/material.dart';

import 'package:sqflite/sqflite.dart';

import 'package:shared_preferences/shared_preferences.dart';

import 'package:path_provider/path_provider.dart';

import 'package:path/path.dart';

import 'dart:io';

2、数据库的创建、打开

//创建数据库

Future _createNewDb(String dbName) async {

//获取数据库文件路径

var dbPath = await getDatabasesPath();

print('dbPath:' + dbPath);

String path = join(dbPath, dbName);

if (await new Directory(dirname(path)).exists()) {

await deleteDatabase(path);

} else {

try {

await new Directory(dirname(path)).create(recursive: true);

} catch (e) {

print(e);

}

}

return path;

}

_create() async {

dbPath = await _createNewDb(dbName);

Database db = await openDatabase(dbPath);

await db.execute(sql_createTable);

await db.close();

setState(() {

_result = '创建user.db成功，创建user_table成功';

});

}

//打开数据库，获取数据库对象

_open() async {

if(null == dbPath){

var path = await getDatabasesPath();

dbPath = join(path, dbName);

print('dbPath:' + dbPath);

}

return await openDatabase(dbPath);

}

数据库的创建、打开，都需要先获取数据库文件的路径，获取到path之后Database db = await openDatabase(dbPath);获取数据库对象，注意数据库的操作全都是异步的，要用关键字await。

3、数据库的增删改查

_add() async {

Database db = await _open();

String sql =

"INSERT INTO user_table(username,pwd) VALUES('$username','$pwd')";

//开启事务

await db.transaction((txn) async {

int id = await txn.rawInsert(sql);

});

await db.close();

setState(() {

_result = "插入username=$username,pwd=$pwd数据成功";

});

}

_delete() async {

Database db = await _open();

//删除最近一条

String sql = "DELETE FROM user_table where id in (select id from user_table order by id desc limit 1)";

int count = await db.rawDelete(sql);

await db.close();

setState(() {

if (count == 1) {

_result = "删除成功，请查看";

} else {

_result = "删除0条数据或删除失败，请看log";

}

});

}

_update() async {

Database db = await _open();

String sql = "UPDATE user_table SET pwd = ? WHERE id = ?";

int count = await db.rawUpdate(sql, ["654321", '1']);

print(count);

await db.close();

setState(() {

_result = "更新数据成功，请查看";

});

}

//批量增、改、删数据

_batch() async {

Database db = await _open();

var batch = db.batch();

batch.insert("user_table", {"username": "batchName1"});

batch.update("user_table", {"username": "batchName2"}, where: "username = ?",whereArgs: ["batchName1"]);

batch.delete("user_table", where: "username = ?", whereArgs: ["Leon"]);

//返回每个数据库操作的结果组成的数组 [6, 3, 0]：新增返回id=6，修改了3条数据，删除了0条数据

var results = await batch.commit();

await db.close();

setState(() {

_result = "批量增、改数据成功 "+results.toString();

});

}

_queryNum() async {

Database db = await _open();

int count = Sqflite.firstIntValue(await db.rawQuery(sql_query_count));

await db.close();

setState(() {

_result = "数据条数：$count";

});

}

_query() async {

Database db = await _open();

List list = await db.rawQuery(sql_query);

await db.close();

setState(() {

_result = "数据详情：$list";

});

}

上面的增加数据代码中开启了事务，可以进行批量插入，每次数据库操作结束都要记得关闭await db.close();

注意，当使用transaction对象访问数据时，不能再使用database对象访问数据库

await database.transaction((txn) async {

await txn.execute("CREATE TABLE Test1 (id INTEGER PRIMARY KEY)");

// 不能在transaction对象里面使用database对象，这会发生死锁

// await database.execute("CREATE TABLE Test2 (id INTEGER PRIMARY KEY)");

});

支持批量操作，但是真正操作被执行是在事务被提交的时候，比如上面代码中的var results = await batch.commit();

后续待补充...