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update JavaExecutionEngine 更新注释

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wangxiang
2023-07-31 11:31:25 +08:00
parent 2e93bdc523
commit 598a3b184d
1 changed files with 7 additions and 3 deletions
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10
src/main/java/haidnor/jvm/core/JavaExecutionEngine.java
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@@ -41,9 +41,10 @@ public class JavaExecutionEngine {
*/ */
public static void callMethod(Frame lastFrame, KlassMethod klassMethod) { public static void callMethod(Frame lastFrame, KlassMethod klassMethod) {
JVMThread jvmThread = JvmThreadHolder.get(); JVMThread jvmThread = JvmThreadHolder.get();
// 调用方法时会创建新的栈帧
Frame newFrame = new Frame(jvmThread, klassMethod); Frame newFrame = new Frame(jvmThread, klassMethod);
// 如果有上一个栈帧, 代表需要传参 // 如果线程栈内存在栈帧, 代表可能需要方法调用传参
if (lastFrame != null) { if (lastFrame != null) {
Method method = klassMethod.javaMethod; Method method = klassMethod.javaMethod;
String signature = method.getSignature(); String signature = method.getSignature();
@@ -54,8 +55,7 @@ public class JavaExecutionEngine {
argumentSlotSize++; argumentSlotSize++;
} }
// 方法调用传参 // 方法调用传参 (原理: 将顶部栈帧的操作数栈中的数据弹出, 存入新栈帧的局部变量表中)
// 将上一个栈帧操作数栈中数据弹出,存入下一个栈帧的局部变量表中
LocalVariableTable localVariableTable = method.getLocalVariableTable(); LocalVariableTable localVariableTable = method.getLocalVariableTable();
if (localVariableTable != null) { if (localVariableTable != null) {
for (int i = argumentSlotSize - 1; i >= 0; i--) { for (int i = argumentSlotSize - 1; i >= 0; i--) {
@@ -68,6 +68,7 @@ public class JavaExecutionEngine {
} }
} }
// 将新栈帧压入线程栈顶部, 并执行新栈帧中的代码
jvmThread.push(newFrame); jvmThread.push(newFrame);
executeFrame(newFrame); executeFrame(newFrame);
} }
@@ -124,8 +125,11 @@ public class JavaExecutionEngine {
frame.push(new StackValue(Const.T_OBJECT, exception)); frame.push(new StackValue(Const.T_OBJECT, exception));
handlerPC = codeException.getHandlerPC(); handlerPC = codeException.getHandlerPC();
} else { } else {
// 从常量池中查询异常表定义的异常类型
String exceptionClassName = frame.getConstantPoolUtil().constantClass_ClassName(catchType); String exceptionClassName = frame.getConstantPoolUtil().constantClass_ClassName(catchType);
exceptionClassName = Utility.compactClassName(exceptionClassName, false); exceptionClassName = Utility.compactClassName(exceptionClassName, false);
// 判断异常的泛型类型. 假如执行指令抛出的是 NullPointerException 类型, 异常表定义的是 Exception 类型, 则此异常可以被捕获
Class<?> exceptionClass = Class.forName(exceptionClassName); Class<?> exceptionClass = Class.forName(exceptionClassName);
if (exceptionClass.isAssignableFrom(exception.getClass())) { if (exceptionClass.isAssignableFrom(exception.getClass())) {
frame.push(new StackValue(Const.T_OBJECT, exception)); frame.push(new StackValue(Const.T_OBJECT, exception));