1# 全局配置项功能场景
2
3对于需要使用进程单例的场景，例如不同并发实例间需要数据保持一致的全局配置项业务，可以采用共享模块来实现。
4
5如下示例实现了只有Wi-Fi打开且用户登陆后才能下载的业务功能，具体步骤如下。
6
71. 编写全局配置文件。
8
9   ```ts
10   // Config.ets
11
12   import { ArkTSUtils } from '@kit.ArkTS';
13
14   "use shared"
15
16   @Sendable
17   class Config {
18     lock: ArkTSUtils.locks.AsyncLock = new ArkTSUtils.locks.AsyncLock
19     isLogin: boolean = false;
20     loginUser?: string;
21     wifiOn: boolean = false
22
23     async login(user: string) {
24       return this.lock.lockAsync(() => {
25         this.isLogin = true;
26         this.loginUser = user
27       }, ArkTSUtils.locks.AsyncLockMode.EXCLUSIVE)
28     }
29
30     async logout(user?: string) {
31       return this.lock.lockAsync(() => {
32         this.isLogin = false
33         this.loginUser = ""
34       }, ArkTSUtils.locks.AsyncLockMode.EXCLUSIVE)
35     }
36
37     async getIsLogin(): Promise<boolean> {
38       return this.lock.lockAsync(() => {
39         return this.isLogin
40       }, ArkTSUtils.locks.AsyncLockMode.SHARED)
41     }
42
43     async getUser(): Promise<string> {
44       return this.lock.lockAsync(() => {
45         return this.loginUser!
46       }, ArkTSUtils.locks.AsyncLockMode.SHARED)
47     }
48
49     async setWifiState(state: boolean) {
50       return this.lock.lockAsync(() => {
51         this.wifiOn = state
52       }, ArkTSUtils.locks.AsyncLockMode.EXCLUSIVE)
53     }
54
55     async isWifiOn() {
56       return this.lock.lockAsync(() => {
57         return this.wifiOn;
58       }, ArkTSUtils.locks.AsyncLockMode.SHARED)
59     }
60   }
61
62   export let config = new Config()
63   ```
64
652. UI主线程及子线程访问全局配置项。
66
67   ```ts
68   import { config } from './Config'
69   import { taskpool } from '@kit.ArkTS';
70
71   @Concurrent
72   async function download() {
73     if (!await config.isWifiOn()) {
74       console.info("wifi is off")
75       return false;
76     }
77     if (!await config.getIsLogin()) {
78       console.info("not login")
79       return false;
80     }
81     console.info(`User[${await config.getUser()}] start download ...`)
82     return true;
83   }
84
85   @Entry
86   @Component
87   struct Index {
88     @State message: string = 'not login';
89     @State wifiState: string = "wifi off";
90     @State downloadResult: string = "";
91     input: string = ""
92
93     build() {
94       Row() {
95         Column() {
96           Text(this.message)
97             .fontSize(50)
98             .fontWeight(FontWeight.Bold)
99             .alignRules({
100               center: { anchor: '__container__', align: VerticalAlign.Center },
101               middle: { anchor: '__container__', align: HorizontalAlign.Center }
102             })
103           TextInput({ placeholder: "请输入用户名" })
104             .fontSize(20)
105             .fontWeight(FontWeight.Bold)
106             .alignRules({
107               center: { anchor: '__container__', align: VerticalAlign.Center },
108               middle: { anchor: '__container__', align: HorizontalAlign.Center }
109             })
110             .onChange((value) => {
111               this.input = value;
112             })
113           Text("login")
114             .fontSize(50)
115             .fontWeight(FontWeight.Bold)
116             .alignRules({
117               center: { anchor: '__container__', align: VerticalAlign.Center },
118               middle: { anchor: '__container__', align: HorizontalAlign.Center }
119             })
120             .onClick(async () => {
121               if (!await config.getIsLogin() && this.input) {
122                 this.message = "login: " + this.input
123                 config.login(this.input)
124               }
125             })
126             .backgroundColor(0xcccccc)
127           Text("logout")
128             .fontSize(50)
129             .fontWeight(FontWeight.Bold)
130             .alignRules({
131               center: { anchor: '__container__', align: VerticalAlign.Center },
132               middle: { anchor: '__container__', align: HorizontalAlign.Center }
133             })
134             .onClick(async () => {
135               if (await config.getIsLogin()) {
136                 this.message = "not login"
137                 config.logout()
138               }
139             })
140             .backgroundColor(0xcccccc)
141           Text(this.wifiState)
142             .fontSize(50)
143             .fontWeight(FontWeight.Bold)
144             .alignRules({
145               center: { anchor: '__container__', align: VerticalAlign.Center },
146               middle: { anchor: '__container__', align: HorizontalAlign.Center }
147             })
148           Toggle({ type: ToggleType.Switch })
149             .onChange(async (isOn: boolean) => {
150               await config.setWifiState(isOn)
151               this.wifiState = isOn ? "wifi on" : "wifi off";
152             })
153           Text("download")
154             .fontSize(50)
155             .fontWeight(FontWeight.Bold)
156             .alignRules({
157               center: { anchor: '__container__', align: VerticalAlign.Center },
158               middle: { anchor: '__container__', align: HorizontalAlign.Center }
159             })
160             .onClick(async () => {
161               let ret = await taskpool.execute(download)
162               this.downloadResult = ret ? "download success" : "download fail";
163             })
164           Text(this.downloadResult)
165             .fontSize(20)
166             .fontWeight(FontWeight.Bold)
167             .alignRules({
168               center: { anchor: '__container__', align: VerticalAlign.Center },
169               middle: { anchor: '__container__', align: HorizontalAlign.Center }
170             })
171         }
172         .width('100%')
173       }
174       .height('100%')
175     }
176   }
177   ```
178