diff --git a/retrofitLib/build.gradle b/retrofitLib/build.gradle
index d8cb126..2e0801e 100644
--- a/retrofitLib/build.gradle
+++ b/retrofitLib/build.gradle
@@ -39,10 +39,11 @@ dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.0"
 
-    implementation 'com.github.zeropercenthappy:ZPHAndroidUtils:1.2.4'
+    implementation 'com.github.zeropercenthappy:ZPHAndroidUtils:1.2.7'
     api "com.squareup.okhttp3:okhttp:$okhttp_version"
     api "com.squareup.retrofit2:retrofit:$retrofit_version"
     api "com.squareup.retrofit2:converter-gson:$retrofit_version"
+    api 'org.conscrypt:conscrypt-android:2.2.1'
     api 'me.jessyan:progressmanager:1.5.0'
 }
 
diff --git a/retrofitLib/src/main/java/com/zeropercenthappy/retrofitutil/service/download/DownloadApi.kt b/retrofitLib/src/main/java/com/zeropercenthappy/retrofitutil/service/download/DownloadApi.kt
index 91f9e92..31236af 100644
--- a/retrofitLib/src/main/java/com/zeropercenthappy/retrofitutil/service/download/DownloadApi.kt
+++ b/retrofitLib/src/main/java/com/zeropercenthappy/retrofitutil/service/download/DownloadApi.kt
@@ -4,7 +4,7 @@ import okhttp3.ResponseBody
 import retrofit2.http.GET
 import retrofit2.http.Url
 
-interface DownloadApi {
+internal interface DownloadApi {
 
     @GET
     suspend fun download(@Url url: String): ResponseBody
diff --git a/retrofitLib/src/main/java/com/zeropercenthappy/retrofitutil/service/download/DownloadService.kt b/retrofitLib/src/main/java/com/zeropercenthappy/retrofitutil/service/download/DownloadService.kt
index 88696de..2462bc7 100644
--- a/retrofitLib/src/main/java/com/zeropercenthappy/retrofitutil/service/download/DownloadService.kt
+++ b/retrofitLib/src/main/java/com/zeropercenthappy/retrofitutil/service/download/DownloadService.kt
@@ -6,7 +6,6 @@ import android.content.Context
 import android.content.Intent
 import com.zeropercenthappy.retrofitutil.RetrofitBuilder
 import com.zeropercenthappy.utilslibrary.utils.FileUtils
-import com.zeropercenthappy.utilslibrary.utils.ZPHLogger
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.runBlocking
 import java.io.File
@@ -15,13 +14,10 @@ import java.io.Serializable
 private const val EXTRA_DOWNLOAD_MAP = "DownloadService.download.map"
 
 /**
- * Start a download service running in a independent process.
+ * Download service which is running in a independent process.
  *
- * Warning: The result of download is not reliable. Because download task may be terminated in progress.
- *
- * So you have to check the file integrity before use it.
  */
-class DownloadService : IntentService("DownloadService"), ZPHLogger {
+class DownloadService : IntentService("DownloadService") {
 
     private lateinit var api: DownloadApi
     private lateinit var downloadMap: Map<String, File>
@@ -66,8 +62,25 @@ class DownloadService : IntentService("DownloadService"), ZPHLogger {
         downloadTask = this
         for (url in downloadMap.keys) {
             val destinationFile = downloadMap[url] ?: continue
+            val cacheFile = checkCacheFile(destinationFile)
+            if (destinationFile.exists()) {
+                continue
+            }
             val responseBody = api.download(url)
-            FileUtils.writeFileByIS(destinationFile, responseBody.byteStream(), false)
+            val result = FileUtils.writeFileByIS(cacheFile, responseBody.byteStream())
+
+            // Download success, move cache file to destination file
+            if (result) {
+                cacheFile.renameTo(destinationFile)
+            }
         }
     }
+
+    /**
+     * @return Download cache file.
+     */
+    private fun checkCacheFile(destinationFile: File): File {
+        val dir = destinationFile.parent
+        return File(dir, "${destinationFile.name}.cache")
+    }
 }
\ No newline at end of file
diff --git a/sample/src/main/java/com/zeropercenthappy/retrofitutilsample/MainActivity.kt b/sample/src/main/java/com/zeropercenthappy/retrofitutilsample/MainActivity.kt
index 3cc36c1..565461c 100644
--- a/sample/src/main/java/com/zeropercenthappy/retrofitutilsample/MainActivity.kt
+++ b/sample/src/main/java/com/zeropercenthappy/retrofitutilsample/MainActivity.kt
@@ -250,12 +250,12 @@ class MainActivity : AppCompatActivity(), AnkoLogger {
                 // download completely
                 doAsync {
                     if (response.isSuccessful && response.body() != null) {
-                        val cacheFile = CacheUtils.createFormatedCacheFile(this@MainActivity, "jpg")
+                        val cacheFile =
+                            CacheUtils.createFormatedCacheFile(this@MainActivity, "jpg", true)
                         if (cacheFile != null) {
                             val result = FileUtils.writeFileByIS(
                                 cacheFile,
-                                response.body()!!.byteStream(),
-                                false
+                                response.body()!!.byteStream()
                             )
                             info { if (result) "download success" else "download failed" }
                         }