feat: 优化代码

app/src/main/java/io/legado/app/help/coroutine/Coroutine.kt

@@ -6,7 +6,7 @@ import kotlin.coroutines.CoroutineContext
 
 
 class Coroutine<T>(
-    scope: CoroutineScope,
+    val scope: CoroutineScope,
     context: CoroutineContext = Dispatchers.IO,
     block: suspend CoroutineScope.() -> T
 ) {
@@ -31,6 +31,7 @@ class Coroutine<T>(
     private var success: Callback<T?>? = null
     private var error: Callback<Throwable>? = null
     private var finally: VoidCallback? = null
+    private var cancel: VoidCallback? = null
 
     private var timeMillis: Long? = null
     private var errorReturn: Result<T>? = null
@@ -45,7 +46,7 @@ class Coroutine<T>(
         get() = job.isCompleted
 
     init {
-        this.job = executeInternal(scope, context, block)
+        this.job = executeInternal(context, block)
     }
 
     fun timeout(timeMillis: () -> Long): Coroutine<T> {
@@ -100,9 +101,28 @@ class Coroutine<T>(
         return this@Coroutine
     }
 
+    fun onCancel(
+        context: CoroutineContext? = null,
+        block: suspend CoroutineScope.() -> Unit
+    ): Coroutine<T> {
+        this.cancel = VoidCallback(context, block)
+        return this@Coroutine
+    }
+
     //取消当前任务
     fun cancel(cause: CancellationException? = null) {
         job.cancel(cause)
+        cancel?.let {
+            scope.plus(Dispatchers.Main).launch {
+                if (null == it.context) {
+                    it.block.invoke(scope)
+                } else {
+                    withContext(scope.coroutineContext.plus(it.context)) {
+                        it.block.invoke(this)
+                    }
+                }
+            }
+        }
     }
 
     fun invokeOnCompletion(handler: CompletionHandler): DisposableHandle {
@@ -110,7 +130,6 @@ class Coroutine<T>(
     }
 
     private fun executeInternal(
-        scope: CoroutineScope,
         context: CoroutineContext,
         block: suspend CoroutineScope.() -> T
     ): Job {
@@ -118,21 +137,27 @@ class Coroutine<T>(
             try {
                 start?.let { dispatchVoidCallback(this, it) }
                 val value = executeBlock(scope, context, timeMillis ?: 0L, block)
-                success?.let { dispatchCallback(this, value, it) }
+                if (isActive) {
+                    success?.let { dispatchCallback(this, value, it) }
+                }
             } catch (e: Throwable) {
                 if (BuildConfig.DEBUG) {
                     e.printStackTrace()
                 }
                 val consume: Boolean = errorReturn?.value?.let { value ->
-                    success?.let { dispatchCallback(this, value, it) }
+                    if (isActive) {
+                        success?.let { dispatchCallback(this, value, it) }
+                    }
                     true
                 } ?: false
 
-                if (!consume) {
+                if (!consume && isActive) {
                     error?.let { dispatchCallback(this, e, it) }
                 }
             } finally {
-                finally?.let { dispatchVoidCallback(this, it) }
+                if (isActive) {
+                    finally?.let { dispatchVoidCallback(this, it) }
+                }
             }
         }
     }

app/src/main/java/io/legado/app/ui/book/changecover/ChangeCoverViewModel.kt

@@ -51,7 +51,6 @@ class ChangeCoverViewModel(application: Application) : BaseViewModel(application
 
     fun search() {
         task = execute {
-            searchStateData.postValue(true)
             val bookSourceList = App.db.bookSourceDao().allEnabled
             for (item in bookSourceList) {
                 //task取消时自动取消 by （scope = this@execute）
@@ -72,6 +71,10 @@ class ChangeCoverViewModel(application: Application) : BaseViewModel(application
                         }
                     }
             }
+        }.onStart {
+            searchStateData.postValue(true)
+        }.onCancel {
+            searchStateData.postValue(false)
         }
 
         task?.invokeOnCompletion {

app/src/main/java/io/legado/app/ui/book/changesource/ChangeSourceViewModel.kt

@@ -72,7 +72,6 @@ class ChangeSourceViewModel(application: Application) : BaseViewModel(applicatio
 
     fun search() {
         task = execute {
-            searchStateData.postValue(true)
             val bookSourceList = App.db.bookSourceDao().allEnabled
             for (item in bookSourceList) {
                 //task取消时自动取消 by （scope = this@execute）
@@ -95,6 +94,10 @@ class ChangeSourceViewModel(application: Application) : BaseViewModel(applicatio
                         }
                     }
             }
+        }.onStart {
+            searchStateData.postValue(true)
+        }.onCancel {
+            searchStateData.postValue(false)
         }
 
         task?.invokeOnCompletion {

app/src/main/java/io/legado/app/ui/book/search/SearchViewModel.kt

@@ -43,7 +43,6 @@ class SearchViewModel(application: Application) : BaseViewModel(application) {
             searchKey = key
             searchBooks.clear()
         }
-        isSearchLiveData.postValue(true)
         task = execute {
             val searchGroup = context.getPrefString("searchGroup") ?: ""
             val bookSourceList = if (searchGroup.isBlank()) {
@@ -71,6 +70,11 @@ class SearchViewModel(application: Application) : BaseViewModel(application) {
                         }
                     }
             }
+        }.onStart {
+            isSearchLiveData.postValue(true)
+        }.onCancel {
+            isSearchLiveData.postValue(false)
+            isLoading = false
         }
 
         task?.invokeOnCompletion {