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21.04. Android/Ktor.md

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+---
+tags: 
+aliases: 
+date: 2024-06-05
+time: 19:06:00
+description:
+---
+
+Ktor是由Kotlin提供的一個framwork。
+要在Android使用Ktor，需要在build.gradle加入以下的dependency:
+```
+implementation "io.ktor:ktor-server-core:2.0.1"            // Ktor的核心包  
+implementation "io.ktor:ktor-server-jetty:2.0.1"           // 供Ktor使用的引擎包，另外有Jetty, Tomcat, CIO可用
+implementation "io.ktor:ktor-gson:1.2.5"
+//    implementation "io.ktor:ktor-server-call-logging:2.0.1"    // 用於印出Request及Response的log用  
+//    implementation "io.ktor:ktor-server-partial-content:2.0.1" // 用於支援PartialContent用  
+//    implementation "io.ktor:ktor-server-cors:2.0.1"            // 用於支援CORS用  
+//    implementation "io.ktor:ktor-server-html-builder:2.0.1"    // 用於回傳客製html用
+```
+
+在`packagingOptions`裡，也需要加入以下的設定來必面編譯問題[[Ktor#^68d958 ]] ：
+```
+packagingOptions {
+    exclude 'META-INF/*'
+}
+```
+
+在`AndroidManifest.xml`中，記得加入internet的權限：
+```
+<uses-permission android:name="android.permission.INTERNET"/>
+```
+
+然後就是 HTTP Server 的 code 了，注意 Netty 在 Android 上不能用，要改用 Jetty 或是 CIO：
+```kotlin
+import io.ktor.server.jetty.Jetty  
+import io.ktor.server.engine.embeddedServer  
+import io.ktor.server.routing.routing  
+import io.ktor.server.routing.get  
+import io.ktor.server.application.*  
+import io.ktor.server.response.respondText
+
+embeddedServer(Jetty, 9000) {  
+    routing {  
+        get("/") {  
+            call.respondText("Hello, world!")  
+        }  
+    }
+}.start(wait = false)
+```
+
+但是這段code會block，所以需要一個thread把它包起來：
+```kotlin
+Thread {
+    httpEngine = embeddedServer(Netty, 8080) {  
+        install(ContentNegotiation) {  
+            gson {}  
+        } 
+        routing {  
+            get("/") {  
+                call.respond(mapOf("message" to "Hello world"))  
+            }  
+
+            get("/say/{something}") {  
+                call.respond(mapOf("message" to "You say: " + call.parameters["something"]))  
+
+                activity?.findViewById<TextView>(R.id.textView)?.text = "You say: " + call.parameters["something"]  
+            }  
+        } 
+    }.start(wait = false)  
+}.start()
+```
+
+
+# 參考來源
+
+- 如果沒有這一段會產生如下錯誤 ^68d958
+```
+13 files found with path 'META-INF/INDEX.LIST'.
+Adding a packagingOptions block may help, please refer to
+https://developer.android.com/reference/tools/gradle-api/7.4/com/android/build/api/dsl/ResourcesPackagingOptions
+for more information
+```