Improvements

.github/workflows/maven.yml

@@ -0,0 +1,32 @@
+name: Java CI with Maven
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        java: [ 17 ]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up JDK ${{ matrix.java }}
+        uses: actions/setup-java@v2
+        with:
+          java-version: ${{ matrix.java }}
+          distribution: 'adopt'
+          cache: maven
+
+      - name: Build with Maven
+        run: mvn -B package --file pom.xml
+
+      - uses: actions/upload-artifact@v2
+        with:
+          name: mymap-with-dependencies.jar
+          path: target/mymap-v*-jar-with-dependencies.jar

src/main/java/com/zfkun/plugins/mymap/MapTransformer.java

@@ -2,7 +2,9 @@
 
 import com.janetfilter.core.models.FilterRule;
 import com.janetfilter.core.plugin.MyTransformer;
+
 import java.util.List;
+
 import jdk.internal.org.objectweb.asm.ClassReader;
 import jdk.internal.org.objectweb.asm.ClassWriter;
 import jdk.internal.org.objectweb.asm.tree.ClassNode;
@@ -26,23 +28,25 @@ public String getHookClassName() {
 
     public byte[] transform(String className, byte[] classBytes, int order) throws Exception {
         PutFilter.setRules(this.rules);
+
         ClassReader reader = new ClassReader(classBytes);
         ClassNode node = new ClassNode(ASM5);
         reader.accept(node, 0);
 
-        for (MethodNode mn : node.methods) {
-            if ("put".equals(mn.name) && "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;".equals(mn.desc)) {
+        for (MethodNode methodNode : node.methods) {
+            if (methodNode.name.equals("put") && methodNode.desc.equals("(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;")) {
                 InsnList list = new InsnList();
                 list.add(new VarInsnNode(ALOAD, 1));
                 list.add(new VarInsnNode(ALOAD, 2));
                 list.add(new MethodInsnNode(INVOKESTATIC, "com/zfkun/plugins/mymap/PutFilter", "testPut", "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;", false));
                 list.add(new VarInsnNode(ASTORE, 2));
-                mn.instructions.insert(list);
+                methodNode.instructions.insert(list);
             }
         }
 
         ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
         node.accept(writer);
+
         return writer.toByteArray();
     }
 }

src/main/java/com/zfkun/plugins/mymap/PutFilter.java

@@ -3,20 +3,19 @@
 import com.janetfilter.core.commons.DebugInfo;
 import com.janetfilter.core.enums.RuleType;
 import com.janetfilter.core.models.FilterRule;
+
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 public class PutFilter {
-    private static Map<Object, Object> map;
+    private static final Map<Object, Object> map = new HashMap<>();
 
     public static void setRules(List<FilterRule> rules) {
-        map = new HashMap();
-
         for (FilterRule rule : rules) {
             if (rule.getType() == RuleType.EQUAL) {
                 String[] sections = rule.getRule().split("->", 2);
-                if (2 != sections.length) {
+                if (sections.length != 2) {
                     DebugInfo.output("Invalid record: " + rule + ", skipped.");
                 } else {
                     map.put(sections[0], sections[1]);
@@ -26,7 +25,7 @@ public static void setRules(List<FilterRule> rules) {
     }
 
     public static Object testPut(Object k, Object v) {
-        if (null == k) return v;
+        if (k == null) return v;
         return map.getOrDefault(k, v);
     }
 }