From 64d9fa7c6b37596f262768473f5657a426a15d22 Mon Sep 17 00:00:00 2001
From: huanghongxun <i@huangyuhui.net>
Date: Sun, 14 Jun 2020 19:51:46 +0800
Subject: [PATCH] fix: #729

---
 .../java/org/jackhuang/hmcl/upgrade/RemoteVersion.java    | 3 ++-
 .../jackhuang/hmcl/download/game/LibraryDownloadTask.java | 3 ++-
 .../org/jackhuang/hmcl/util/platform/SystemUtils.java     | 4 ++++
 README.md                                                 | 8 ++++++++
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/HMCL/src/main/java/org/jackhuang/hmcl/upgrade/RemoteVersion.java b/HMCL/src/main/java/org/jackhuang/hmcl/upgrade/RemoteVersion.java
index 6a7c0df66..82142b8ef 100644
--- a/HMCL/src/main/java/org/jackhuang/hmcl/upgrade/RemoteVersion.java
+++ b/HMCL/src/main/java/org/jackhuang/hmcl/upgrade/RemoteVersion.java
@@ -23,6 +23,7 @@ import com.google.gson.JsonParseException;
 import org.jackhuang.hmcl.task.FileDownloadTask.IntegrityCheck;
 import org.jackhuang.hmcl.util.gson.JsonUtils;
 import org.jackhuang.hmcl.util.io.NetworkUtils;
+import org.jackhuang.hmcl.util.platform.SystemUtils;
 
 import java.io.IOException;
 import java.util.Optional;
@@ -37,7 +38,7 @@ public class RemoteVersion {
             String jarHash = Optional.ofNullable(response.get("jarsha1")).map(JsonElement::getAsString).orElse(null);
             String packXZUrl = Optional.ofNullable(response.get("packxz")).map(JsonElement::getAsString).orElse(null);
             String packXZHash = Optional.ofNullable(response.get("packxzsha1")).map(JsonElement::getAsString).orElse(null);
-            if (packXZUrl != null && packXZHash != null) {
+            if (SystemUtils.JRE_CAPABILITY_PACK200 && packXZUrl != null && packXZHash != null) {
                 return new RemoteVersion(version, packXZUrl, Type.PACK_XZ, new IntegrityCheck("SHA-1", packXZHash));
             } else if (jarUrl != null && jarHash != null) {
                 return new RemoteVersion(version, jarUrl, Type.JAR, new IntegrityCheck("SHA-1", jarHash));
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/LibraryDownloadTask.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/LibraryDownloadTask.java
index e202f2d8c..871d17942 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/LibraryDownloadTask.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/LibraryDownloadTask.java
@@ -28,6 +28,7 @@ import org.jackhuang.hmcl.task.Task;
 import org.jackhuang.hmcl.util.io.FileUtils;
 import org.jackhuang.hmcl.util.io.IOUtils;
 import org.jackhuang.hmcl.util.io.NetworkUtils;
+import org.jackhuang.hmcl.util.platform.SystemUtils;
 import org.tukaani.xz.XZInputStream;
 
 import java.io.*;
@@ -125,7 +126,7 @@ public class LibraryDownloadTask extends Task<Void> {
             }
         }
 
-        if (testURLExistence(url)) {
+        if (SystemUtils.JRE_CAPABILITY_PACK200 && testURLExistence(url)) {
             List<URL> urls = dependencyManager.getDownloadProvider().injectURLWithCandidates(url + ".pack.xz");
             task = new FileDownloadTask(urls, xzFile, null);
             task.setCacheRepository(cacheRepository);
diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/platform/SystemUtils.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/platform/SystemUtils.java
index ec4766eb9..b1dd73bfb 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/util/platform/SystemUtils.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/util/platform/SystemUtils.java
@@ -17,6 +17,8 @@
  */
 package org.jackhuang.hmcl.util.platform;
 
+import org.jackhuang.hmcl.util.Lang;
+
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
@@ -26,6 +28,8 @@ import java.util.List;
 public final class SystemUtils {
     private SystemUtils() {}
 
+    public static final boolean JRE_CAPABILITY_PACK200 = Lang.test(() -> Class.forName("java.util.jar.Pack200"));
+
     public static int callExternalProcess(String... command) throws IOException, InterruptedException {
         return callExternalProcess(Arrays.asList(command));
     }
diff --git a/README.md b/README.md
index 4817b27d4..cece0897c 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,14 @@ If you want to submit a pull request, there're some requirements:
 * Compiler: Java 1.8.
 * Do NOT modify `gradle` files.
 
+### Compilation
+
+Simply execute following command:
+```bash
+./gradlew clean build
+```
+Make sure you have Java installed with Pack200 and JavaFX 8 at least. Liberica full JDK 8~11 is recommended.
+
 ## JVM Options (for debugging)
 |Parameter|Description|
 |---------|-----------|