【移动应用开发技术】怎么在Flutter中自定义Plugin

【移动应用开发技术】怎么在Flutter中自定义Plugin

怎么在Flutter中自定义Plugin？很多新手对此不是很清楚，为了帮助大家解决这个难题，下面在下将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。1.在AndroidStudio中创建一个FlutterPlugin项目，如下图上图中你能看到项目描述中写到，如果需要暴露Andorid或iOS的API给开发者时，选择"Plugin"项目类型。这个项目我们命名为:flutter_native_log_plugin,当我们完成创建项目后，有两个文件我们需要看一看，一个是位于android/src下的FlutterNativeLogPlugin.java，这段代码是用来和本地设备交互，然后将交互结果返回供flutter前端调用，如下所示：package

com.cube8.flutter_native_log_plugin;

import

mon.MethodCall;

import

mon.MethodChannel;

import

mon.MethodChannel.MethodCallHandler;

import

mon.MethodChannel.Result;

import

mon.PluginRegistry.Registrar;

/**

FlutterNativeLogPlugin

*/

public

class

FlutterNativeLogPlugin

implements

MethodCallHandler

{

/**

Plugin

registration.

*/

public

static

void

registerWith(Registrar

registrar)

{

final

MethodChannel

channel

=

new

MethodChannel(registrar.messenger(),

"flutter_native_log_plugin");

channel.setMethodCallHandler(new

FlutterNativeLogPlugin());

}

@Override

public

void

onMethodCall(MethodCall

call,

Result

result)

{

if

(call.method.equals("getPlatformVersion"))

{

result.success("Android

"

+

android.os.Build.VERSION.RELEASE);

}

else

{

result.notImplemented();

}

}

}另一个/lib/mian.dart文件，这段代码是主要用来和native代码交互，如下所示：import

'dart:async';

import

'package:flutter/services.dart';

class

FlutterNativeLogPlugin

{

static

const

MethodChannel

_channel

=

const

MethodChannel('flutter_native_log_plugin');

static

Future<String>

get

platformVersion

async

{

final

String

version

=

await

_channel.invokeMethod('getPlatformVersion');

return

version;

}

}2.现在我们开始编写我们的Plugin.在lib/flutter_native_log_plugin.dart文件中，我们先创建一个新的方法，代码如下：import

'dart:async';

import

'package:flutter/material.dart';

import

'package:flutter/services.dart';

enum

Log

{

DEBUG,

WARNING,

ERROR

}

class

FlutterNativeLogPlugin

{

static

const

MethodChannel

_channel

=

const

MethodChannel('flutter_native_log_plugin');

static

Future<String>

printLog(

{Log

logType,

@required

String

tag,

@required

String

msg})

async

{

String

log

=

"debug";

if

(logType

==

Log.WARNING)

{

log

=

"warning";

}

else

if

(logType

==

Log.ERROR)

{

log

=

"error";

}

else

{

log

=

"debug";

}

final

Map<String,

dynamic>

params

=

<String,

dynamic>{

'tag':

tag,

'msg':

msg,

'logType':

log

};

final

String

result

=

await

_channel.invokeMethod('printLog',

params);

return

result;

}

}在Android端，我们将android/src下的FlutterNativePlugin.java改写如下：package

com.cube8.flutter_native_log_plugin;

import

android.util.Log;

import

mon.MethodCall;

import

mon.MethodChannel;

import

mon.MethodChannel.MethodCallHandler;

import

mon.MethodChannel.Result;

import

mon.PluginRegistry.Registrar;

/**

*

FlutterNativeLogPlugin

*/

public

class

FlutterNativeLogPlugin

implements

MethodCallHandler

{

/**

*

Plugin

registration.

*/

public

static

void

registerWith(Registrar

registrar)

{

final

MethodChannel

channel

=

new

MethodChannel(registrar.messenger(),

"flutter_native_log_plugin");

channel.setMethodCallHandler(new

FlutterNativeLogPlugin());

}

@Override

public

void

onMethodCall(MethodCall

call,

Result

result)

{

if

(call.method.equals("printLog"))

{

String

msg

=

call.argument("msg");

String

tag

=

call.argument("tag");

String

logType

=

call.argument("logType");

if

(logType.equals("warning"))

{

Log.w(tag,

msg);

}

else

if

(logType.equals("error"))

{

Log.e(tag,

msg);

}

else

{

Log.d(tag,

msg);

}

result.success("Logged

Successfully!");

}

else

{

result.notImplemented();

}

}

}3.测试plugin。当开发完了我们的plugin之后，我们需要测试这个新plugin是否可用，于是对example/lib的main.dart文件作如下修改：import

'package:flutter/material.dart';

import

'package:flutter_native_log_plugin/flutter_native_log_plugin.dart';

void

main()

=>

runApp(MyApp());

class

MyApp

extends

StatefulWidget

{

@override

_MyAppState

createState()

=>

_MyAppState();

}

class

_MyAppState

extends

State<MyApp>

{

@override

void

initState()

{

super.initState();

}

void

printLogs()

async

{

print(await

FlutterNativeLogPlugin.printLog(

tag:

"Debug",

msg:

"This

is

ordinary

Log"));

//

default

logType

print(await

FlutterNativeLogPlugin.printLog(

tag:

"Debug",

msg:

"This

is

warning

Log",

logType:

Log.WARNING));

//

logType

=

warning

print(await

FlutterNativeLogPlugin.printLog(

tag:

"Debug",

msg:

"This

is

error

Log",

logType:

Log.ERROR));

//

logType

=

error

print(await

FlutterNativeLogPlugin.printLog(

tag:

"Debug",

msg:

"This

is

debug

Log",

logType:

Log.DEBUG));

//

logType

=

debug

}

@override

Widget

build(BuildContext

context)

{

return

MaterialApp(

home:

Scaffold(

appBar:

AppBar(

title:

const

Text('Plugin

example

app'),

),

body:

Center(

child:

RaisedButton(

child:

Text("PrintLogs"),

onPressed:

printLogs,

),

),

),

);

}

}点击app中的按钮，控