update JavaExecutionEngine.java

src/main/java/haidnor/jvm/Main.java

@@ -1,11 +1,6 @@
 package haidnor.jvm;
 
-import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.*;
-import org.apache.commons.cli.CommandLineParser;
-import org.apache.commons.cli.DefaultParser;
-import org.apache.commons.cli.Option;
-import org.apache.commons.cli.OptionGroup;
-import org.apache.commons.cli.Options;
 
 import haidnor.jvm.classloader.ClassLoader;
 import haidnor.jvm.core.JavaExecutionEngine;
@@ -28,21 +23,11 @@ public class Main {
 
     @SneakyThrows
     public static void main(String[] args) {
-        Option jarOption = new Option("jar", true, "运行 jar 程序");
+        CommandLine cmd = initCommandLine(args);
-        Option classOption = new Option("class", true, "运行 .class 字节码文件");
-
-        OptionGroup optionGroup = new OptionGroup();
-        optionGroup.addOption(jarOption).addOption(classOption);
-
-        Options options = new Options();
-        options.addOptionGroup(optionGroup);
-
-        CommandLineParser parser = new DefaultParser();
-        CommandLine cmd = parser.parse(options, args);
 
+        // 指定从 .jar 文件运行
         if (cmd.hasOption("jar")) {
             String jarFilePath = cmd.getOptionValue("jar");
-
             try (JarFile jarFile = new JarFile(jarFilePath)) {
                 ClassLoader bootClassLoader = new ClassLoader(jarFile, "ApplicationClassLoader");
                 String mainClass = jarFile.getManifest().getMainAttributes().getValue("Main-Class");
@@ -64,6 +49,8 @@ public class Main {
                 }
             }
         }
+
+        // 指定从 .class 文件运行
         if (cmd.hasOption("class")) {
             JvmThreadHolder.set(new JVMThread());
             String path = cmd.getOptionValue("class");
@@ -76,4 +63,18 @@ public class Main {
         }
     }
 
+    private static  CommandLine initCommandLine(String[] args) throws ParseException {
+        Option jarOption = new Option("jar", true, "运行 jar 程序");
+        Option classOption = new Option("class", true, "运行 .class 字节码文件");
+
+        OptionGroup optionGroup = new OptionGroup();
+        optionGroup.addOption(jarOption).addOption(classOption);
+
+        Options options = new Options();
+        options.addOptionGroup(optionGroup);
+
+        CommandLineParser parser = new DefaultParser();
+        return parser.parse(options, args);
+    }
+
 }

src/main/java/haidnor/jvm/core/JavaExecutionEngine.java

@@ -63,18 +63,16 @@ public class JavaExecutionEngine {
         executeFrame(newFrame);
     }
 
+    /**
+     * 执行 JVM 线程栈栈帧 (haidnorJVM 中最关键的代码)
+     *
+     * @author wang xiang
+     */
     @SneakyThrows
     public static void executeFrame(Frame frame) {
         int stackSize = frame.getJvmThread().stackSize();
 
-        StringBuilder blank = new StringBuilder();
+        String blank = getDebugStackInfoBlank(stackSize);
-        blank.append("                    ".repeat(stackSize - 1));
-        int index = 0;
-        for (int i = 0; i < stackSize - 1; i++) {
-            blank.replace(index, index + 1, "│");
-            index += 20;
-        }
-
         log.debug("{}┌──────────────────[{}] {} | {}", blank, stackSize, frame.klass.getClassName(), frame.getMethod());
 
         // 解析方法中的字节码指令
@@ -93,21 +91,25 @@ public class JavaExecutionEngine {
             Instruction instruction = instructionMap.get(pc);
             log.debug("{}│ {}", blank, instruction);
             try {
+                // 执行栈帧
                 instruction.execute(frame);
                 if (instruction instanceof RETURN || instruction instanceof ARETURN || instruction instanceof DRETURN || instruction instanceof FRETURN || instruction instanceof IRETURN) {
                     break;
                 }
+                // 程序计数器值增加. 指向下一次执行的字节码行号
                 pc += instruction.offSet();
             }
-            // catch instruction.execute() Exception
+            // 捕获执行栈帧运行抛出的异常
             catch (Exception exception) {
-                Integer handlerPC = null;
+                // 从类元信息中获取异常表
-
                 CodeException[] exceptionTable = frame.getMethod().getCode().getExceptionTable();
+
+                // handlerPC 是从异常表中获取的处理异常的字节码行号 (如果查询不到就会一直为 null. 代表方法无异常处理代码)
+                Integer handlerPC = null;
                 for (CodeException codeException : exceptionTable) {
                     if (codeException.getStartPC() <= pc & pc <= codeException.getEndPC()) {
                         int catchType = codeException.getCatchType();
-                        // 0, if the handler catches any exception, otherwise it points to the exception class which is to be caught.
+                        // catchType == 0 代表捕获所有类型的异常
                         if (catchType == 0) {
                             frame.push(new StackValue(Const.T_OBJECT, exception));
                             handlerPC = codeException.getHandlerPC();
@@ -123,8 +125,10 @@ public class JavaExecutionEngine {
                     }
                 }
                 if (handlerPC != null) {
+                    // 将程序计数器跳转到处理异常的字节码指令上
                     pc = handlerPC;
                 } else {
+                    // 方法无异常处理. 异常退出.结束栈帧
                     log.debug("{}└──────────────────[{}] No Exception Handler Return!", blank, stackSize);
                     throw exception;
                 }
@@ -135,5 +139,21 @@ public class JavaExecutionEngine {
         log.debug("{}└──────────────────[{}] {} | {}", blank, stackSize, frame.klass.getClassName(), frame.getMethod());
     }
 
+    /**
+     * 计算绘画 jvm 线程栈 debug 日志信息的空格
+     * 用于表现栈的调用关系.
+     *
+     * @param stackSize 当前 JVM 栈的深度
+     */
+    private static String getDebugStackInfoBlank(int stackSize) {
+        StringBuilder blank = new StringBuilder();
+        blank.append("                    ".repeat(stackSize - 1));
+        int index = 0;
+        for (int i = 0; i < stackSize - 1; i++) {
+            blank.replace(index, index + 1, "│");
+            index += 20;
+        }
+        return blank.toString();
+    }
 
 }

src/main/java/haidnor/jvm/rtda/Klass.java

@@ -41,7 +41,7 @@ public class Klass {
     /**
      * 静态字段
      */
-    private Map<String, KlassField> staticFieldMap = new HashMap<>();
+    private final Map<String, KlassField> staticFieldMap = new HashMap<>();
 
     /**
      * 加载类元数据并将类放入元空间

src/main/java/haidnor/jvm/runtime/Frame.java

@@ -264,27 +264,14 @@ public class Frame {
 
     public void slotSet(int index, StackValue stackValue) {
         switch (stackValue.getType()) {
-            case Const.T_CHAR:
+            case Const.T_CHAR -> throw new Error("T_CHAR，未作处理");
-                throw new Error("T_CHAR，未作处理");
+            case Const.T_INT -> slotSetInt(index, (int) stackValue.getValue());
-            case Const.T_INT:
+            case Const.T_OBJECT -> slotSetRef(index, stackValue.getValue());
-                slotSetInt(index, (int) stackValue.getValue());
+            case Const.T_LONG -> slotSetLong(index, (long) stackValue.getValue());
-                break;
+            case Const.T_DOUBLE -> slotSetDouble(index, (double) stackValue.getValue());
-            case Const.T_OBJECT:
+            case Const.T_FLOAT -> slotSetFloat(index, (float) stackValue.getValue());
-                slotSetRef(index, stackValue.getValue());
+            case Const.T_ARRAY -> throw new Error("T_ARRAY，未作处理");
-                break;
+            default -> throw new Error("无法识别的参数类型");
-            case Const.T_LONG:
-                slotSetLong(index, (long) stackValue.getValue());
-                break;
-            case Const.T_DOUBLE:
-                slotSetDouble(index, (double) stackValue.getValue());
-                break;
-            case Const.T_FLOAT:
-                slotSetFloat(index, (float) stackValue.getValue());
-                break;
-            case Const.T_ARRAY:
-                throw new Error("T_ARRAY，未作处理");
-            default:
-                throw new Error("无法识别的参数类型");
         }
     }
 

src/main/java/haidnor/jvm/util/SignatureUtil.java

@@ -18,34 +18,17 @@ public abstract class SignatureUtil {
         for (int i = 0; i < argumentTypeArr.length; i++) {
             Class<?> argumentClass;
             String argumentType = argumentTypeArr[i];
-            switch (argumentType) {
+            argumentClass = switch (argumentType) {
-                case "byte":
+                case "byte" -> byte.class;
-                    argumentClass = byte.class;
+                case "short" -> short.class;
-                    break;
+                case "boolean" -> boolean.class;
-                case "short":
+                case "char" -> char.class;
-                    argumentClass = short.class;
+                case "int" -> int.class;
-                    break;
+                case "long" -> long.class;
-                case "boolean":
+                case "float" -> float.class;
-                    argumentClass = boolean.class;
+                case "double" -> double.class;
-                    break;
+                default -> Class.forName(argumentType);
-                case "char":
+            };
-                    argumentClass = char.class;
-                    break;
-                case "int":
-                    argumentClass = int.class;
-                    break;
-                case "long":
-                    argumentClass = long.class;
-                    break;
-                case "float":
-                    argumentClass = float.class;
-                    break;
-                case "double":
-                    argumentClass = double.class;
-                    break;
-                default:
-                    argumentClass = Class.forName(argumentType);
-            }
             argumentClassArr[i] = argumentClass;
         }
         return argumentClassArr;