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这个活生生的例子会教你开发 flutter 插件，功能是封装 Android 和 iOS 端的分享到 facebook 和 twitter 的 flutter 接口。使用的分别是两端的系统分享功能，不需要集成 facebook 和 twitter 的 sdk。
例子插件网址：https://pub.dartlang.org/packages/flutter_share_go#-readme-tab-
展示一下样式：
ios 中分享到 facebook：
android 中分享到 facebook
开始开发插件
步骤一：创建插件项目
这里用的 Android studio 创建的项目，可以直接创建 flutter plugin 项目，你也可以用命令创建：
flutter create --org com.example --template=plugin "plugin_name"将上面的“plugin_name”换成你的插件名字就行了，我这个插件名字叫 flutter_share_go, 所以命令就是：
flutter create --org com.example --template=plugin flutter_share_go这里没有支持 swift 和 kotlin，原因是使用插件的很多项目可能并不支持，以免造成不必要的麻烦，但是你仍然可以选择支持，命令如下：
flutter create --template=plugin -i swift -a kotlin flutter_share_go查看创建好的项目结构：
Android 文件夹中：Android 端原生的代码
iOS 文件夹中：iOS 端原生的代码
example 文件： 是方便测试你的插件的例子代码
lib 文件： 插件对原生接口的封装，也就是直接在 dart 代码中调用的接口
分别在 Android studio 和 xcode 中编辑 Android 和 iOS 代码
先在 Android studio 中编写 Android 部分代码
用 Android studio 打开项目中的 android 文件夹，因为此时缺少 flutter 库依赖，需要配置一下：
在项目根目录建立一个 libs 文件夹，用来存放 flutter 库，flutter 库可以到你电脑的 flutter sdk 路径中寻找：
/bin/cache/artifacts/engine在 engine 路径下有很多的 android 支持库，随便拷贝一个 Android 平台的库到 libs 文件夹下，右键 flutter.jar，弹出菜单选择 Add As Library…。这里不用担心，我们等下设置一下让它只是编译时使用，不会打包进来。
然后点击菜单 File/Project Structure…，找到 flutter_text_plugin 的 Dependencies 中，将 flutter 库的 Scope 从 Implementation 改成 Compile Only。
开始添加 Android 代码
添加如下两个文件：
PackageUtils.java 工具类
package com.doglobal.flutter_share_go;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
public class PackageUtils {public static boolean isPkgInstalled(Context context, String packageName) {if (packageName == null || "".equals(packageName))
return false;
android.content.pm.ApplicationInfo info = null;
try {info = context.getPackageManager().getApplicationInfo(packageName, 0);
return info != null;
} catch (PackageManager.NameNotFoundException e) {return false;}
}
public static void goDownloadPage(Context context, String pkgName) {Context app = context.getApplicationContext();
try {
Intent intent = new Intent(Intent.ACTION_VIEW,
Uri.parse("market://details?id=" + pkgName));
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
app.startActivity(intent);
} catch (android.content.ActivityNotFoundException anfe) {
Intent intent = new Intent(Intent.ACTION_VIEW,
Uri.parse("https://play.google.com/store/apps/details?id=" + pkgName));
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
app.startActivity(intent);
}
}
}ShareHelper.java 工具类
package com.doglobal.flutter_share_go;
import android.app.Activity;
import android.content.Intent;
import android.text.TextUtils;
public class ShareHelper {
public static final String CHANNEL_FACEBOOK_PKG_NAME = "com.facebook.katana";
public static final String CHANNEL_TWITTER_PKG_NAME = "com.twitter.android";
public static void shareMain(Activity activity, String shareText) {shareText(activity, null, null, shareText, null, "");
}
public static void shareTextToChannel(Activity activity,String pkgName, String shareText,
String shareUrl) {if (PackageUtils.isPkgInstalled(activity, pkgName)) {shareText(activity, null, null, shareText, pkgName, shareUrl);
} else {PackageUtils.goDownloadPage(activity, pkgName);
}
}
/**
* @param dlgTitle 选择弹框标题
* @param subject 分享主题
* @param shareText 分享内容
*/
public static void shareText(Activity activity, String dlgTitle, String subject,
String shareText, String pkgName, String shareUrl) {if (shareText == null || "".equals(shareText)) {return;}
String content = shareText + ": " + shareUrl + " .";
Intent intent = new Intent(Intent.ACTION_SEND);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setType("text/plain");
if (!TextUtils.isEmpty(subject)) {intent.putExtra(Intent.EXTRA_SUBJECT, subject);
}
intent.putExtra(Intent.EXTRA_TEXT, content);
if (!TextUtils.isEmpty(pkgName)) {intent.setPackage(pkgName);
}
// 设置弹出框标题
if (TextUtils.isEmpty(dlgTitle)) { // 自定义标题
Intent chooser = Intent.createChooser(intent, dlgTitle);
chooser.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
activity.startActivity(chooser);
} else { // 系统默认标题
activity.startActivity(intent);
}
}
}然后在 FlutterShareGoPlugin.java 文件中添加调用逻辑。
这个文件就是 java 端对 dart 端的调用接口。我们先来看下代码，再进行解析：
package com.doglobal.flutter_share_go;
import android.app.Activity;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
import io.flutter.plugin.common.MethodChannel.Result;
import io.flutter.plugin.common.PluginRegistry.Registrar;
/** FlutterShareGoPlugin */
public class FlutterShareGoPlugin implements MethodCallHandler {
private Activity mActivity; // 分析一
private FlutterShareGoPlugin(Activity context) {mActivity = context;}
/** Plugin registration. */
public static void registerWith(Registrar registrar) {final MethodChannel channel = new MethodChannel(registrar.messenger(), "flutter_share_go");
channel.setMethodCallHandler(new FlutterShareGoPlugin(registrar.activity()));
}
@Override
public void onMethodCall(MethodCall call, Result result) {if (call.method.equals("getPlatformVersion")) {result.success("Android " + android.os.Build.VERSION.RELEASE);
} else if (call.method.equals("shareToFBPlatform")) { // 分析二
String content = call.argument("shareContent");
String shareUrl = call.argument("shareUrl");
ShareHelper.shareTextToChannel(mActivity, ShareHelper.CHANNEL_FACEBOOK_PKG_NAME, content, shareUrl);
} else if (call.method.equals("shareToTwitterPlatform")) {String content = call.argument("shareContent");
String shareUrl = call.argument("shareUrl");
ShareHelper.shareTextToChannel(mActivity, ShareHelper.CHANNEL_TWITTER_PKG_NAME, content, shareUrl);
}
else {result.notImplemented();
}
}
}- 分析一
我们添加一个构造方法，用来存储 activity
- 分析二
在方法 onMethodCall 中根据 dart 传递过来的方法名调用 java 端不同的代码逻辑
至此，Android 端代码就告一段落了。
iOS 端开发，在 xcode 中开发
如图，我们在 Android studio 中打开一个 iOS 文件，在右上角会有用 xcode 打开的按钮，我们点击打开就可以用 xcode 编辑了。
打开项目添加上图中的文件：
FlutterShareGoPlugin.m 文件
#import "FlutterShareGoPlugin.h"
#import "ShareHelper.h"
#import <Social/Social.h>
@interface FlutterShareGoPlugin()
@property (nonatomic, strong)UIViewController * rootViewController;
@end
@implementation FlutterShareGoPlugin
+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
FlutterMethodChannel* channel = [FlutterMethodChannel
methodChannelWithName:@"flutter_share_go"
binaryMessenger:[registrar messenger]];
FlutterShareGoPlugin* instance = [[FlutterShareGoPlugin alloc] init];
[registrar addMethodCallDelegate:instance channel:channel];
}
- (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {if ([@"getPlatformVersion" isEqualToString:call.method]) {result([@"iOS " stringByAppendingString:[[UIDevice currentDevice] systemVersion]]);
}
else if ([@"shareToFBPlatform" isEqualToString:call.method]) {NSDictionary *arguments = [call arguments];
NSString * shareContent = arguments[@"shareContent"];
NSString * shareUrl = arguments[@"shareUrl"];
[ShareHelper shareToPlatformType:SLServiceTypeFacebook withContent:shareContent withShareUrl:shareUrl];
result(nil);
}
else if ([@"shareToTwitterPlatform" isEqualToString:call.method]) {NSDictionary *arguments = [call arguments];
NSString * shareContent = arguments[@"shareContent"];
NSString * shareUrl = arguments[@"shareUrl"];
[ShareHelper shareToPlatformType:SLServiceTypeTwitter withContent:shareContent withShareUrl:shareUrl];
result(nil);
}
else {result(FlutterMethodNotImplemented);
}
}
@endPackageUtil.h
#import <Foundation/Foundation.h>
NS_ASSUME_NONNULL_BEGIN
@interface PackageUtil : NSObject
// Is intalled specific app or not
+ (BOOL)isInstalledWithUrlScheme:(NSString *)urlScheme;
@end
NS_ASSUME_NONNULL_ENDPackageUtil.m
#import "PackageUtil.h"
@implementation PackageUtil
+ (BOOL)isInstalledWithUrlScheme:(NSString *)urlScheme {if (urlScheme == nil || urlScheme.length == 0) {return false;}
return [[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:urlScheme]];
}
@endShareHelper.h
#import <Foundation/Foundation.h>
NS_ASSUME_NONNULL_BEGIN
@interface ShareHelper : NSObject
+(void)shareToPlatformType:(NSString *)platformType withContent:(NSString *)content withShareUrl:(NSString*)url;
@end
NS_ASSUME_NONNULL_ENDShareHelper.m
#import "ShareHelper.h"
#import <Social/Social.h>
#import "PackageUtil.h"
@implementation ShareHelper
/*
SOCIAL_EXTERN NSString *const SLServiceTypeTwitter NS_AVAILABLE(10_8, 6_0);//Twitter
SOCIAL_EXTERN NSString *const SLServiceTypeFacebook NS_AVAILABLE(10_8, 6_0);//Facebook
SOCIAL_EXTERN NSString *const SLServiceTypeSinaWeibo NS_AVAILABLE(10_8, 6_0);
SOCIAL_EXTERN NSString *const SLServiceTypeTencentWeibo NS_AVAILABLE(10_9, 7_0);
SOCIAL_EXTERN NSString *const SLServiceTypeLinkedIn NS_AVAILABLE(10_9, NA);
*/
+(void)shareToPlatformType:(NSString *)platformType withContent:(NSString *)content withShareUrl:(NSString*)url{if (platformType == nil || platformType.length == 0) {NSLog(@"unspecified platform");
return;
}
if([platformType isEqualToString:SLServiceTypeFacebook] && ![[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"fb://"]]) {[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"itms-apps://itunes.apple.com/app/id284882215"]];
NSLog(@"UnInstall facebook");
return;
}
if([platformType isEqualToString:SLServiceTypeTwitter] && ![[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"twitter://"]]) {[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"itms-apps://itunes.apple.com/app/id333903271"]];
NSLog(@"UnInstall twitter");
return;
}
// create controller for ServiceType
SLComposeViewController *composeVC = [SLComposeViewController composeViewControllerForServiceType:platformType];
// image
// [composeVC addImage:[UIImage imageNamed:@"Nameless"]];
// content
[composeVC setInitialText:content];
// share url
[composeVC addURL:[NSURL URLWithString:url]];
// share controller
if([[[UIApplication sharedApplication] keyWindow].rootViewController isKindOfClass:[UINavigationController class]]) {UINavigationController *vc = (UINavigationController *)[[UIApplication sharedApplication] keyWindow].rootViewController;
[vc pushViewController:composeVC animated:YES];
} else {UINavigationController *vc = (UINavigationController *)[[UIApplication sharedApplication] keyWindow].rootViewController;
[vc presentViewController:composeVC animated:YES completion:nil];
}
// callback user hanlder
composeVC.completionHandler = ^(SLComposeViewControllerResult result){if (result == SLComposeViewControllerResultDone) { }
else if (result == SLComposeViewControllerResultCancelled) {}};
}
@end最后需要我们在 plist 文件中添加白名单，用于 iOS9 适配，查看是否安装了 facebook 和 twitter：
iOS 部分代码到此也告一段落了。
添加 flutter 接口，供 dart 代码调用
打开项目中 lib 文件夹下的 flutter_share_go 文件
FlutterShareGo.dart
import'dart:async';
import 'package:flutter/services.dart';
class FlutterShareGo {
static const MethodChannel _channel =
const MethodChannel('flutter_share_go');
static Future<String> get platformVersion async {final String version = await _channel.invokeMethod('getPlatformVersion');
return version;
}
static Future<void> shareToFBPlatform(String shareContent, String shareUrl) async {assert(shareContent != null);
assert(shareContent.isNotEmpty);
final Map<String, dynamic> params = <String, dynamic> {
'shareContent': shareContent,
'shareUrl':shareUrl,
};
await _channel.invokeMethod("shareToFBPlatform", params);
}
static Future<void> shareToTwitterPlatform(String shareContent, String shareUrl) async {assert(shareContent != null);
assert(shareContent.isNotEmpty);
final Map<String, dynamic> params = <String, dynamic> {
'shareContent': shareContent,
'shareUrl':shareUrl,
};
await _channel.invokeMethod("shareToTwitterPlatform", params);
}
}flutter 端代码就告一段落了。
测试插件：
打开项目中 example 文件下的 main.dart：
main.dart
import'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter/services.dart';
import 'package:flutter_share_go/flutter_share_go.dart';
void main() => runApp(MyApp());
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
String _platformVersion = 'Unknown';
@override
void initState() {super.initState();
initPlatformState();}
// Platform messages are asynchronous, so we initialize in an async method.
Future<void> initPlatformState() async {
String platformVersion;
// Platform messages may fail, so we use a try/catch PlatformException.
try {platformVersion = await FlutterShareGo.platformVersion;} on PlatformException {platformVersion = 'Failed to get platform version.';}
// If the widget was removed from the tree while the asynchronous platform
// message was in flight, we want to discard the reply rather than calling
// setState to update our non-existent appearance.
if (!mounted) return;
setState(() {_platformVersion = platformVersion;});
}
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('Plugin example app'),
),
body: Column(
children: <Widget>[
Text('Running on: $_platformVersion\n'),
RaisedButton(child: Text(" 分享到 facebook 按钮 "),
color: Colors.red,
onPressed: () {FlutterShareGo.shareToFBPlatform("test share to fb content", "http://tryenough.com");
},
)
],
),
),
);
}
}运行就会出现文章最上面的效果了。祝你顺利。
最后发布可以参照如下步骤：
运行命令，并解决所有出现的问题：
flutter packages pub publish --dry-run问题解决完就可以发布了，命令：
flutter packages pub publish
正文完
