AI 助理
备案控制台
开发者社区 开发与运维 文章 正文

用Java实现JVM第七章《方法调用和返回》

2022-01-12 93
版权
版权声明：
本文内容由阿里云实名注册用户自发贡献，版权归原作者所有，阿里云开发者社区不拥有其著作权，亦不承担相应法律责任。具体规则请查看《 阿里云开发者社区用户服务协议》和 《阿里云开发者社区知识产权保护指引》。如果您发现本社区中有涉嫌抄袭的内容，填写 侵权投诉表单进行举报，一经查实，本社区将立刻删除涉嫌侵权内容。
简介： 本章节主要用java实现；方法调用指令、返回指令、解析方法符号引用、参数传递等。实现新的指令后我们的虚拟机就可以执行稍微复杂的运算并输出结果。

2.jpg案例介绍

本章节主要用java实现；方法调用指令、返回指令、解析方法符号引用、参数传递等。实现新的指令后我们的虚拟机就可以执行稍微复杂的运算并输出结果。

从调用的角度来看，方法可以分为两类：静态方法（或者类方法）和实例方法。静态方法通过类类调用，实例方法则通过对象引用来调用。静态方法是静态绑定的，也就是说，最终调用的是哪给方法在编译期就已经确定。实例方法则支持动态绑定，最终要调用哪给方法可能要推迟到运行期才能知道。

从实现的角度来看，方法可以分为三类：没有实现（也就是抽象方法）、用Java语言（或者JVM上其他的语言，如Groovy和Scala等）实现和用本地语言（如C或者C++）实现。静态方法和抽象方法是互斥的。在Java 8之前，接口只能包括抽象方法。为了实现Lambda表达式，Java 8放宽了这一限制，在接口中也可以定义静态方法和默认方法。

在Java 7之前，Java虚拟机规范一共提供了4条方法调用指令。其中invokestatic指令用来调用静态方法。invokespecial指令用来调用无须动态绑定的实例方法，包括构造函数、私有方法和通过super关键字调用的超类方法。剩下的情况则属于动态绑定。如果是针对接口类型的引用调用方法，就使用invokeinterface指令，否则使用invokevirtual指令。

环境准备

1、jdk 1.8.0

2、IntelliJ IDEA Community Edition 2018.3.1 x64

配置信息

1、调试配置

2.1、配置位置：Run/Debug Configurations -> program arguments

2.2、配置内容（选配 verbose true）：-Xjre "C:\Program Files\Java\jdk1.8.0_161\jre" E:\itstack\git\istack-demo\itstack-demo-jvm\itstack-demo-jvm-07\target\test-classes\org\itstack\demo\test\HelloWorld verbose true

代码示例

itstack-demo-jvm-07
├── pom.xml
└── src
    └── main
    │    └── java
    │        └── org.itstack.demo.jvm
    │             ├── classfile
    │             │   ├── attributes   {BootstrapMethods/Code/ConstantValue...}
    │             │   ├── constantpool {CONSTANT_TAG_CLASS/CONSTANT_TAG_FIELDREF/CONSTANT_TAG_METHODREF...}
    │             │   ├── ClassFile.java
    │             │   ├── ClassReader.java
    │             │   └── MemberInfo.java
    │             ├── classpath
    │             │   ├── impl
    │             │   │   ├── CompositeEntry.java
    │             │   │   ├── DirEntry.java
    │             │   │   ├── WildcardEntry.java
    │             │   │   └── ZipEntry.java
    │             │   ├── Classpath.java
    │             │   └── Entry.java
    │             ├── classpath
    │             │   ├── base
    │             │   │   ├── BytecodeReader.java
    │             │   │   ├── ClassInitLogic.java
    │             │   │   ├── Instruction.java
    │             │   │   ├── InstructionBranch.java
    │             │   │   ├── InstructionIndex8.java
    │             │   │   ├── InstructionIndex16.java
    │             │   │   ├── InstructionNoOperands.java
    │             │   │   └── MethodInvokeLogic.java
    │             │   ├── comparisons
    │             │   ├── constants
    │             │   ├── control
    │             │   ├── conversions
    │             │   ├── extended
    │             │   ├── loads
    │             │   ├── math
    │             │   ├── references
    │             │   │   ├── CHECK_CAST.java
    │             │   │   ├── GET_FIELD.java
    │             │   │   ├── GET_STATIC.java
    │             │   │   ├── INSTANCE_OF.java
    │             │   │   ├── INVOKE_INTERFACE.java
    │             │   │   ├── INVOKE_SPECIAL.java
    │             │   │   ├── INVOKE_STATIC.java
    │             │   │   ├── INVOKE_VIRTUAL.java
    │             │   │   ├── NEW.java
    │             │   │   ├── PUT_FIELD.java
    │             │   │   └── PUT_STATIC.java
    │             │   ├── stack
    │             │   ├── store
    │             │   └── Factory
    │             ├── rtda
    │             │   ├── heap
    │             │   │   ├── constantpool
    │             │   │   ├── methodarea
    │             │   │   │   ├── Class.java    
    │             │   │   │   ├── ClassMember.java  
    │             │   │   │   ├── Field.java    
    │             │   │   │   ├── Method.java 
    │             │   │   │   ├── MethodDescriptor.java 
    │             │   │   │   ├── MethodDescriptorParser.java 
    │             │   │   │   ├── MethodLookup.java     
    │             │   │   │   ├── Object.java   
    │             │   │   │   └── Slots.java        
    │             │   │   └── ClassLoader.java  
    │             │   ├── Frame.java
    │             │   ├── JvmStack.java
    │             │   ├── LocalVars.java
    │             │   ├── OperandStack.java
    │             │   ├── Slot.java 
    │             │   └── Thread.java
    │             ├── Cmd.java
    │             ├── Interpret.java    
    │             └── Main.java
    └── test
         └── java
             └── org.itstack.demo.test
                 └── HelloWorld.java

代码篇幅较长，只列重点代码块

MethodInvokeLogic.java

package org.itstack.demo.jvm.instructions.base;
import org.itstack.demo.jvm.rtda.Frame;
import org.itstack.demo.jvm.rtda.Slot;
import org.itstack.demo.jvm.rtda.Thread;
import org.itstack.demo.jvm.rtda.heap.methodarea.Method;
/**
 * http://www.itstack.org
 * create by fuzhengwei on 2019/4/28
 */
public class MethodInvokeLogic {
    public static void invokeMethod(Frame invokerFrame, Method method) {
        Thread thread = invokerFrame.thread();
        Frame newFrame = thread.newFrame(method);
        thread.pushFrame(newFrame);
        int argSlotCount = method.argSlotCount();
        if (argSlotCount > 0) {
            for (int i = argSlotCount - 1; i >= 0; i--) {
                Slot slot = invokerFrame.operandStack().popSlot();
                newFrame.localVars().setSlot(i, slot);
            }
        }
        //hack
        if (method.isNative()) {
            if ("registerNatives".equals(method.name())) {
                thread.popFrame();
            } else {
                throw new RuntimeException("native method " + method.name());
            }
        }
    }
}

INVOKE_INTERFACE.java

package org.itstack.demo.jvm.instructions.references;
import org.itstack.demo.jvm.instructions.base.BytecodeReader;
import org.itstack.demo.jvm.instructions.base.Instruction;
import org.itstack.demo.jvm.instructions.base.MethodInvokeLogic;
import org.itstack.demo.jvm.rtda.Frame;
import org.itstack.demo.jvm.rtda.heap.constantpool.InterfaceMethodRef;
import org.itstack.demo.jvm.rtda.heap.constantpool.RunTimeConstantPool;
import org.itstack.demo.jvm.rtda.heap.methodarea.Method;
import org.itstack.demo.jvm.rtda.heap.methodarea.MethodLookup;
import org.itstack.demo.jvm.rtda.heap.methodarea.Object;
/**
 * http://www.itstack.org
 * create by fuzhengwei on 2019/4/28
 */
public class INVOKE_INTERFACE implements Instruction {
    private int idx;
    @Override
    public void fetchOperands(BytecodeReader reader) {
        this.idx = reader.readShort();
        reader.readByte();
        reader.readByte();
    }
    @Override
    public void execute(Frame frame) {
        RunTimeConstantPool runTimeConstantPool = frame.method().clazz().constantPool();
        InterfaceMethodRef methodRef = (InterfaceMethodRef) runTimeConstantPool.getConstants(this.idx);
        Method resolvedMethod = methodRef.resolvedInterfaceMethod();
        if (resolvedMethod.isStatic() || resolvedMethod.isPrivate()) {
            throw new IncompatibleClassChangeError();
        }
        Object ref = frame.operandStack().getRefFromTop(resolvedMethod.argSlotCount() - 1);
        if (null == ref) {
            throw new NullPointerException();
        }
        if (!ref.clazz().isImplements(methodRef.resolvedClass())) {
            throw new IncompatibleClassChangeError();
        }
        Method methodToBeInvoked = MethodLookup.lookupMethodInClass(ref.clazz(), methodRef.name(), methodRef.descriptor());
        if (null == methodToBeInvoked || methodToBeInvoked.isAbstract()) {
            throw new AbstractMethodError();
        }
        if (!methodToBeInvoked.isPublic()) {
            throw new IllegalAccessError();
        }
        MethodInvokeLogic.invokeMethod(frame, methodToBeInvoked);
    }
}

INVOKE_SPECIAL.java

package org.itstack.demo.jvm.instructions.references;
import org.itstack.demo.jvm.instructions.base.InstructionIndex16;
import org.itstack.demo.jvm.instructions.base.MethodInvokeLogic;
import org.itstack.demo.jvm.rtda.Frame;
import org.itstack.demo.jvm.rtda.heap.constantpool.MethodRef;
import org.itstack.demo.jvm.rtda.heap.constantpool.RunTimeConstantPool;
import org.itstack.demo.jvm.rtda.heap.methodarea.Class;
import org.itstack.demo.jvm.rtda.heap.methodarea.Method;
import org.itstack.demo.jvm.rtda.heap.methodarea.MethodLookup;
import org.itstack.demo.jvm.rtda.heap.methodarea.Object;
public class INVOKE_SPECIAL extends InstructionIndex16 {
    @Override
    public void execute(Frame frame) {
        Class currentClass = frame.method().clazz();
        RunTimeConstantPool runTimeConstantPool = currentClass.constantPool();
        MethodRef methodRef = (MethodRef) runTimeConstantPool.getConstants(this.idx);
        Class resolvedClass = methodRef.resolvedClass();
        Method resolvedMethod = methodRef.ResolvedMethod();
        if ("<init>".equals(resolvedMethod.name()) && resolvedMethod.clazz() != resolvedClass) {
            throw new NoSuchMethodError();
        }
        if (resolvedMethod.isStatic()) {
            throw new IncompatibleClassChangeError();
        }
        Object ref = frame.operandStack().getRefFromTop(resolvedMethod.argSlotCount() - 1);
        if (null == ref) {
            throw new NullPointerException();
        }
        if (resolvedMethod.isProtected() &&
                resolvedMethod.clazz().isSubClassOf(currentClass) &&
                !resolvedMethod.clazz().getPackageName().equals(currentClass.getPackageName()) &&
                ref.clazz() != currentClass &&
                !ref.clazz().isSubClassOf(currentClass)) {
            throw new IllegalAccessError();
        }
        Method methodToBeInvoked = resolvedMethod;
        if (currentClass.isSuper() &&
                resolvedClass.isSubClassOf(currentClass) &&
                !resolvedMethod.name().equals("<init>")) {
            MethodLookup.lookupMethodInClass(currentClass.superClass, methodRef.name(), methodRef.descriptor());
        }
        if (methodToBeInvoked.isAbstract()) {
            throw new AbstractMethodError();
        }
        MethodInvokeLogic.invokeMethod(frame, methodToBeInvoked);
    }
}

INVOKE_STATIC.java

package org.itstack.demo.jvm.instructions.references;
import org.itstack.demo.jvm.instructions.base.ClassInitLogic;
import org.itstack.demo.jvm.instructions.base.InstructionIndex16;
import org.itstack.demo.jvm.instructions.base.MethodInvokeLogic;
import org.itstack.demo.jvm.rtda.Frame;
import org.itstack.demo.jvm.rtda.heap.constantpool.MethodRef;
import org.itstack.demo.jvm.rtda.heap.constantpool.RunTimeConstantPool;
import org.itstack.demo.jvm.rtda.heap.methodarea.Class;
import org.itstack.demo.jvm.rtda.heap.methodarea.Method;
/**
 * http://www.itstack.org
 * create by fuzhengwei on 2019/4/28
 */
public class INVOKE_STATIC extends InstructionIndex16 {
    @Override
    public void execute(Frame frame) {
        RunTimeConstantPool runTimeConstantPool = frame.method().clazz().constantPool();
        MethodRef methodRef = (MethodRef) runTimeConstantPool.getConstants(this.idx);
        Method resolvedMethod = methodRef.ResolvedMethod();
        if (!resolvedMethod.isStatic()) {
            throw new IncompatibleClassChangeError();
        }
        Class clazz = resolvedMethod.clazz();
        if (!clazz.initStarted()) {
            frame.revertNextPC();
            ClassInitLogic.initClass(frame.thread(), clazz);
            return;
        }
        MethodInvokeLogic.invokeMethod(frame, resolvedMethod);
    }
}

INVOKE_VIRTUAL.java

package org.itstack.demo.jvm.instructions.references;
import org.itstack.demo.jvm.instructions.base.InstructionIndex16;
import org.itstack.demo.jvm.instructions.base.MethodInvokeLogic;
import org.itstack.demo.jvm.rtda.Frame;
import org.itstack.demo.jvm.rtda.OperandStack;
import org.itstack.demo.jvm.rtda.heap.constantpool.MethodRef;
import org.itstack.demo.jvm.rtda.heap.constantpool.RunTimeConstantPool;
import org.itstack.demo.jvm.rtda.heap.methodarea.Class;
import org.itstack.demo.jvm.rtda.heap.methodarea.Method;
import org.itstack.demo.jvm.rtda.heap.methodarea.MethodLookup;
import org.itstack.demo.jvm.rtda.heap.methodarea.Object;
public class INVOKE_VIRTUAL extends InstructionIndex16 {
    @Override
    public void execute(Frame frame) {
        Class currentClass = frame.method().clazz();
        RunTimeConstantPool runTimeConstantPool = currentClass.constantPool();
        MethodRef methodRef = (MethodRef) runTimeConstantPool.getConstants(this.idx);
        Method resolvedMethod = methodRef.ResolvedMethod();
        if (resolvedMethod.isStatic()) {
            throw new IncompatibleClassChangeError();
        }
        Object ref = frame.operandStack().getRefFromTop(resolvedMethod.argSlotCount() - 1);
        if (null == ref) {
            if ("println".equals(methodRef.name())) {
                _println(frame.operandStack(), methodRef.descriptor());
                return;
            }
            throw new NullPointerException();
        }
        if (resolvedMethod.isProtected() &&
                resolvedMethod.clazz().isSubClassOf(currentClass) &&
                !resolvedMethod.clazz().getPackageName().equals(currentClass.getPackageName()) &&
                ref.clazz() != currentClass &&
                !ref.clazz().isSubClassOf(currentClass)) {
            throw new IllegalAccessError();
        }
        Method methodToBeInvoked = MethodLookup.lookupMethodInClass(ref.clazz(), methodRef.name(), methodRef.descriptor());
        if (null == methodToBeInvoked || methodToBeInvoked.isAbstract()) {
            throw new AbstractMethodError();
        }
        MethodInvokeLogic.invokeMethod(frame, methodToBeInvoked);
    }
    //hack
    private void _println(OperandStack stack, String descriptor) {
        switch (descriptor) {
            case "(Z)V":
                System.out.println(stack.popInt() != 0);
                break;
            case "(C)V":
                System.out.println(stack.popInt());
                break;
            case "(I)V":
            case "(B)V":
            case "(S)V":
                System.out.println(stack.popInt());
                break;
            case "(F)V":
                System.out.println(stack.popFloat());
                break;
            case "(J)V":
                System.out.println(stack.popLong());
                break;
            case "(D)V":
                System.out.println(stack.popDouble());
                break;
            default:
                System.out.println(descriptor);
                break;
        }
        stack.popRef();
    }
}

MethodDescriptor.java

package org.itstack.demo.jvm.rtda.heap.methodarea;
import java.util.ArrayList;
import java.util.List;
/**
 * http://www.itstack.org
 * create by fuzhengwei on 2019/4/28
 */
public class MethodDescriptor {
    public List<String> parameterTypes = new ArrayList<>();
    public String returnType;
    public void addParameterType(String type){
        this.parameterTypes.add(type);
    }
}

MethodDescriptorParser.java

package org.itstack.demo.jvm.rtda.heap.methodarea;
import javax.management.ObjectName;
/**
 * http://www.itstack.org
 * create by fuzhengwei on 2019/4/28
 */
public class MethodDescriptorParser {
    private String raw;
    private int offset;
    private MethodDescriptor parsed;
    public static MethodDescriptor parseMethodDescriptorParser(String descriptor) {
        MethodDescriptorParser parser = new MethodDescriptorParser();
        return parser.parse(descriptor);
    }
    public MethodDescriptor parse(String descriptor) {
        this.raw = descriptor;
        this.parsed = new MethodDescriptor();
        this.startParams();
        this.parseParamTypes();
        this.endParams();
        this.parseReturnType();
        this.finish();
        return this.parsed;
    }
    private void startParams() {
        if (this.readUint8() != '(') {
            causePanic();
        }
    }
    private void endParams() {
        if (this.readUint8() != ')') {
            causePanic();
        }
    }
    public void finish(){
        if (this.offset != this.raw.length()){
            this.causePanic();
        }
    }
    public void causePanic() {
        throw new RuntimeException("BAD descriptor：" + this.raw);
    }
    public byte readUint8() {
        byte[] bytes = this.raw.getBytes();
        byte b = bytes[this.offset];
        this.offset++;
        return b;
    }
    public void unreadUint8() {
        this.offset--;
    }
    public void parseParamTypes() {
        while (true) {
            String type = this.parseFieldType();
            if ("".equals(type)) break;
            this.parsed.addParameterType(type);
        }
    }
    public void parseReturnType() {
        if (this.readUint8() == 'V'){
            this.parsed.returnType = "V";
            return;
        }
        this.unreadUint8();
        String type = this.parseFieldType();
        if (!"".equals(type)){
            this.parsed.returnType = type;
            return;
        }
        this.causePanic();
    }
    public String parseFieldType() {
        switch (this.readUint8()) {
            case 'B':
                return "B";
            case 'C':
                return "C";
            case 'D':
                return "D";
            case 'F':
                return "F";
            case 'I':
                return "I";
            case 'J':
                return "J";
            case 'S':
                return "S";
            case 'Z':
                return "Z";
            case 'L':
                return this.parseObjectType();
            case '[':
                return this.parseArrayType();
            default:
                this.unreadUint8();
                return "";
        }
    }
    private String parseObjectType() {
        String unread = this.raw.substring(this.offset);
        int semicolonIndx = unread.indexOf(";");
        if (semicolonIndx == -1) {
            this.causePanic();
            return "";
        }
        int objStart = this.offset - 1;
        int ojbEnd = this.offset + semicolonIndx + 1;
        this.offset = ojbEnd;
        //descriptor
        return this.raw.substring(objStart, ojbEnd);
    }
    private String parseArrayType() {
        int arrStart = this.offset - 1;
        this.parseFieldType();
        int arrEnd = this.offset;
        //descriptor
        return this.raw.substring(arrStart, arrEnd);
    }
}

MethodLookup.java

package org.itstack.demo.jvm.rtda.heap.methodarea;
/**
 * http://www.itstack.org
 * create by fuzhengwei on 2019/4/28
 */
public class MethodLookup {
    static public Method lookupMethodInClass(Class clazz, String name, String descriptor) {
        for (Class c = clazz; c != null; c = c.superClass) {
            for (Method method : c.methods) {
                if (method.name.equals(name) && method.descriptor.equals(descriptor)) {
                    return method;
                }
            }
        }
        return null;
    }
    static public Method lookupMethodInInterfaces(Class[] ifaces, String name, String descriptor) {
        for (Class inface : ifaces) {
            for (Method method : inface.methods) {
                if (method.name.equals(name) && method.descriptor.equals(descriptor)) {
                    return method;
                }
            }
        }
        return null;
    }
}

Interpret.java

//指令集解释器
class Interpret {
    Interpret(Method method, boolean logInst) {
        Thread thread = new Thread();
        Frame frame = thread.newFrame(method);
        thread.pushFrame(frame);
        loop(thread, logInst);
    }
    private void loop(Thread thread, boolean logInst) {
        BytecodeReader reader = new BytecodeReader();
        while (true) {
            Frame frame = thread.currentFrame();
            int pc = frame.nextPC();
            thread.setPC(pc);
            reader.reset(frame.method().code, pc);
            byte opcode = reader.readByte();
            Instruction inst = Factory.newInstruction(opcode);
            if (null == inst) {
                System.out.println("Unsupported opcode " + byteToHexString(new byte[]{opcode}));
                break;
            }
            inst.fetchOperands(reader);
            frame.setNextPC(reader.pc());
            if (logInst) {
                logInstruction(frame, inst, opcode);
            }
            //exec
            inst.execute(frame);
            if (thread.isStackEmpty()) {
                break;
            }
        }
    }
    private static void logInstruction(Frame frame, Instruction inst, byte opcode) {
        Method method = frame.method();
        String className = method.clazz().name();
        String methodName = method.name();
        String outStr = (className + "." + methodName + "() \t") +
                "寄存器(指令)：" + byteToHexString(new byte[]{opcode}) + " -> " + inst.getClass().getSimpleName() + " => 局部变量表：" + JSON.toJSONString(frame.operandStack().getSlots()) + " 操作数栈：" + JSON.toJSONString(frame.operandStack().getSlots());
        System.out.println(outStr);
    }
    private static String byteToHexString(byte[] codes) {
        StringBuilder sb = new StringBuilder();
        sb.append("0x");
        for (byte b : codes) {
            int value = b & 0xFF;
            String strHex = Integer.toHexString(value);
            if (strHex.length() < 2) {
                strHex = "0" + strHex;
            }
            sb.append(strHex);
        }
        return sb.toString();
    }
}

HelloWorld.java

public class HelloWorld {
    public static void main(String[] args) {
        long x = fibonacci(10);
        System.out.println(x);
    }
    //斐波那契数列（Fibonacci sequence）
    private static long fibonacci(long n) {
        if (n <= 1) {
            return n;
        } else {
            return fibonacci(n - 1) + fibonacci(n - 2);
        }
    }
}

斐波那契数列（Fibonacci sequence），又称黄金分割数列、因数学家列昂纳多·斐波那契（Leonardoda Fibonacci）以兔子繁殖为例子而引入，故又称为“兔子数列”，指的是这样一个数列：1、1、2、3、5、8、13、21、34、……在数学上，斐波纳契数列以如下被以递推的方法定义：F(1)=1，F(2)=1, F(n)=F(n-1)+F(n-2)（n>=3，n∈N*）在现代物理、准晶体结构、化学等领域，斐波纳契数列都有直接的应用，为此，美国数学会从1963年起出版了以《斐波纳契数列季刊》为名的一份数学杂志，用于专门刊载这方面的研究成果。

测试结果 {jvm执行复杂计算：斐波那契数列，输出结果55}

HelloWorld.fibonacci 指令：

lload_0
lconst_1
lcmp
ifgt 7
lload_0
lreturn
lload_0
lconst_1
lsub
invokestatic org/itstack/demo/test/HelloWorld/fibonacci(J)J
lload_0
ldc2_w 2
lsub
invokestatic org/itstack/demo/test/HelloWorld/fibonacci(J)J
ladd
lreturn

执行过程：

org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0x14 -> LDC2_W => 局部变量表：[{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0xb8 -> INVOKE_STATIC => 局部变量表：[{"num":10},{"num":0},{"num":0}] 操作数栈：[{"num":10},{"num":0},{"num":0}]
java/lang/Object.<clinit>()     寄存器(指令)：0xb8 -> INVOKE_STATIC => 局部变量表：null 操作数栈：null
java/lang/Object.<clinit>()     寄存器(指令)：0xb1 -> RETURN => 局部变量表：null 操作数栈：null
org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0xb8 -> INVOKE_STATIC => 局部变量表：[{"num":10},{"num":0},{"num":0}] 操作数栈：[{"num":10},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x1e -> LLOAD_0 => 局部变量表：[{"num":0},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":0},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x0a -> LCONST_1 => 局部变量表：[{"num":10},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":10},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x94 -> LCMP => 局部变量表：[{"num":10},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":10},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x9d -> IFGT => 局部变量表：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x1e -> LLOAD_0 => 局部变量表：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x0a -> LCONST_1 => 局部变量表：[{"num":10},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":10},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x65 -> LSUB => 局部变量表：[{"num":10},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":10},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0xb8 -> INVOKE_STATIC => 局部变量表：[{"num":9},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":9},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x1e -> LLOAD_0 => 局部变量表：[{"num":0},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":0},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x0a -> LCONST_1 => 局部变量表：[{"num":9},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":9},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x94 -> LCMP => 局部变量表：[{"num":9},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":9},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x9d -> IFGT => 局部变量表：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x1e -> LLOAD_0 => 局部变量表：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x0a -> LCONST_1 => 局部变量表：[{"num":9},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":9},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x65 -> LSUB => 局部变量表：[{"num":9},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":9},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0xb8 -> INVOKE_STATIC => 局部变量表：[{"num":8},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":8},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x1e -> LLOAD_0 => 局部变量表：[{"num":0},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":0},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x0a -> LCONST_1 => 局部变量表：[{"num":8},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":8},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x94 -> LCMP => 局部变量表：[{"num":8},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":8},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x9d -> IFGT => 局部变量表：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x1e -> LLOAD_0 => 局部变量表：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":1},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x0a -> LCONST_1 => 局部变量表：[{"num":8},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":8},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x65 -> LSUB => 局部变量表：[{"num":8},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":8},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0xb8 -> INVOKE_STATIC => 局部变量表：[{"num":7},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":7},{"num":0},{"num":1},{"num":0},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x1e -> LLOAD_0 => 局部变量表：[{"num":0},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}] 操作数栈：[{"num":0},{"num":0},{"num":0},{"num":0},{"num":0},{"num":0}]
... ...
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0xad -> LRETURN => 局部变量表：[{"num":1},{"num":0},{"num":0},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":1},{"num":0},{"num":0},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x61 -> LADD => 局部变量表：[{"num":2},{"num":0},{"num":1},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":2},{"num":0},{"num":1},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0xad -> LRETURN => 局部变量表：[{"num":3},{"num":0},{"num":1},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":3},{"num":0},{"num":1},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x61 -> LADD => 局部变量表：[{"num":5},{"num":0},{"num":3},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":5},{"num":0},{"num":3},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0xad -> LRETURN => 局部变量表：[{"num":8},{"num":0},{"num":3},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":8},{"num":0},{"num":3},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x61 -> LADD => 局部变量表：[{"num":13},{"num":0},{"num":8},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":13},{"num":0},{"num":8},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0xad -> LRETURN => 局部变量表：[{"num":21},{"num":0},{"num":8},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":21},{"num":0},{"num":8},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0x61 -> LADD => 局部变量表：[{"num":34},{"num":0},{"num":21},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":34},{"num":0},{"num":21},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.fibonacci()    寄存器(指令)：0xad -> LRETURN => 局部变量表：[{"num":55},{"num":0},{"num":21},{"num":0},{"num":2},{"num":0}] 操作数栈：[{"num":55},{"num":0},{"num":21},{"num":0},{"num":2},{"num":0}]
org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0x40 -> LSTORE_1 => 局部变量表：[{"num":55},{"num":0},{"num":0}] 操作数栈：[{"num":55},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0xb2 -> GET_STATIC => 局部变量表：[{"num":55},{"num":0},{"num":0}] 操作数栈：[{"num":55},{"num":0},{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0xb8 -> INVOKE_STATIC => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0x01 -> ACONST_NULL => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0xb3 -> PUT_STATIC => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0x01 -> ACONST_NULL => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0xb3 -> PUT_STATIC => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0x01 -> ACONST_NULL => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0xb3 -> PUT_STATIC => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0x01 -> ACONST_NULL => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0xb3 -> PUT_STATIC => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0x01 -> ACONST_NULL => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0xb3 -> PUT_STATIC => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
java/lang/System.<clinit>()     寄存器(指令)：0xb1 -> RETURN => 局部变量表：[{"num":0}] 操作数栈：[{"num":0}]
org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0xb2 -> GET_STATIC => 局部变量表：[{"num":55},{"num":0},{"num":0}] 操作数栈：[{"num":55},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0x1f -> LLOAD_1 => 局部变量表：[{"num":55},{"num":0},{"num":0}] 操作数栈：[{"num":55},{"num":0},{"num":0}]
org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0xb6 -> INVOKE_VIRTUAL => 局部变量表：[{"num":55},{"num":55},{"num":0}] 操作数栈：[{"num":55},{"num":55},{"num":0}]
55
org/itstack/demo/test/HelloWorld.main()     寄存器(指令)：0xb1 -> RETURN => 局部变量表：[


文章标签：
Java
C++
开发工具
机器学习/深度学习
git
Scala
关键词：
Java JVM
Java方法调用
JVM java
JVM方法调用
Java实现
小傅哥
目录
相关文章
aliyun0641063962-48771
|
1月前
|
监控 算法 Java
Java虚拟机（JVM）的垃圾回收机制深度解析####
本文深入探讨了Java虚拟机（JVM）的垃圾回收机制，旨在揭示其背后的工作原理与优化策略。我们将从垃圾回收的基本概念入手，逐步剖析标记-清除、复制算法、标记-整理等主流垃圾回收算法的原理与实现细节。通过对比不同算法的优缺点及适用场景，为开发者提供优化Java应用性能与内存管理的实践指南。 ####
aliyun0641063962-48771
94 3
jiashufen
|
26天前
|
监控 算法 Java
Java虚拟机（JVM）垃圾回收机制深度剖析与优化策略####
本文作为一篇技术性文章，深入探讨了Java虚拟机（JVM）中垃圾回收的工作原理，详细分析了标记-清除、复制算法、标记-压缩及分代收集等主流垃圾回收算法的特点和适用场景。通过实际案例，展示了不同GC（Garbage Collector）算法在应用中的表现差异，并针对大型应用提出了一系列优化策略，包括选择合适的GC算法、调整堆内存大小、并行与并发GC调优等，旨在帮助开发者更好地理解和优化Java应用的性能。 ####
jiashufen
32 0
游客vsgxb64qlj7cg
|
23天前
|
存储 监控 算法
深入探索Java虚拟机（JVM）的内存管理机制
本文旨在为读者提供对Java虚拟机（JVM）内存管理机制的深入理解。通过详细解析JVM的内存结构、垃圾回收算法以及性能优化策略，本文不仅揭示了Java程序高效运行背后的原理，还为开发者提供了优化应用程序性能的实用技巧。不同于常规摘要仅概述文章大意，本文摘要将简要介绍JVM内存管理的关键点，为读者提供一个清晰的学习路线图。
游客vsgxb64qlj7cg
59 3
游客kwe6k52lwpmug
|
25天前
|
存储 监控 算法
Java虚拟机（JVM）垃圾回收机制深度解析与优化策略####
本文旨在深入探讨Java虚拟机（JVM）的垃圾回收机制，揭示其工作原理、常见算法及参数调优方法。通过剖析垃圾回收的生命周期、内存区域划分以及GC日志分析，为开发者提供一套实用的JVM垃圾回收优化指南，助力提升Java应用的性能与稳定性。 ####
游客kwe6k52lwpmug
51 1
潇洒洒
|
1月前
|
安全 Java
Java中WAIT和NOTIFY方法调用时机的深层解析
在Java多线程编程中，`wait()`和`notify()`方法的正确使用对于线程间的协调至关重要。这两个方法必须在同步块或同步方法中调用，这一规定的深层原因是什么呢？本文将深入探讨这一机制。
潇洒洒
40 5
jiashufen
|
29天前
|
机器学习/深度学习 监控 算法
Java虚拟机（JVM）的垃圾回收机制深度剖析####
本文深入探讨Java虚拟机（JVM）的垃圾回收机制，揭示其工作原理、常见算法、性能调优策略及未来趋势。通过实例解析，为开发者提供优化Java应用性能的思路与方法。 ####
jiashufen
46 1
最好zzz
|
29天前
|
Oracle 安全 Java
深入理解Java生态：JDK与JVM的区分与协作
Java作为一种广泛使用的编程语言，其生态中有两个核心组件：JDK（Java Development Kit）和JVM（Java Virtual Machine）。本文将深入探讨这两个组件的区别、联系以及它们在Java开发和运行中的作用。
最好zzz
75 1
131王
|
1月前
|
监控 Java 开发者
Java虚拟机（JVM）深度优化指南####
本文深入探讨了Java虚拟机（JVM）的工作原理及其性能优化策略，旨在帮助开发者通过理解JVM的内部机制来提升Java应用的运行效率。不同于传统的技术教程，本文采用案例分析与实战技巧相结合的方式，为读者揭示JVM调优的艺术。 ####
131王
58 8
131王
|
1月前
|
监控 算法 Java
深入理解Java虚拟机（JVM）的垃圾回收机制
【10月更文挑战第21天】 本文将带你深入了解Java虚拟机（JVM）的垃圾回收机制，包括它的工作原理、常见的垃圾收集算法以及如何优化JVM垃圾回收性能。通过本文，你将对JVM垃圾回收有一个全新的认识，并学会如何在实际开发中进行有效的调优。
131王
53 0
aliyun0641063962-48771
|
2月前
|
存储 算法 Java
Java虚拟机（JVM）的内存管理与性能优化
本文深入探讨了Java虚拟机（JVM）的内存管理机制，包括堆、栈、方法区等关键区域的功能与作用。通过分析垃圾回收算法和调优策略，旨在帮助开发者理解如何有效提升Java应用的性能。文章采用通俗易懂的语言，结合具体实例，使读者能够轻松掌握复杂的内存管理概念，并应用于实际开发中。
aliyun0641063962-48771
53 2

热门文章

最新文章

  • 1
    Java volatile关键字：你真的懂了吗？
  • 2
    java小工具util系列2：字符串工具
  • 3
    Java爬虫：数据采集的强大工具
  • 4
    Java多线程并发编程：同步机制与实践应用
  • 5
    Java中的异常处理：从基础到高级
  • 6
    深入理解Java异常处理机制
  • 7
    Liunx部署java项目Tomcat、Redis、Mysql教程
  • 8
    Java爬虫：深入解析商品详情的利器
  • 9
    java实现从HDFS上下载文件及文件夹的功能，以流形式输出，便于用户自定义保存任何路径下
  • 10
    Java 异常处理：机制、策略与最佳实践
  • 1
    linux上如何排查JVM内存过高？
    1097
  • 2
    JVM参数太多？一网打尽常用JVM参数！
    86
  • 3
    深入浅出JVM（十八）之并发垃圾收集器G1
    80
  • 4
    深入浅出JVM（十七）之并发垃圾收集器CMS
    70
  • 5
    深入浅出JVM（十六）之三色标记法与并发可达性分析
    101
  • 6
    深入浅出JVM（十五）之垃圾收集器（上篇）
    75
  • 7
    深入浅出JVM（十四）之内存溢出、泄漏与引用
    58
  • 8
    深入浅出JVM（十三）之垃圾回收算法细节
    64
  • 9
    深入浅出JVM（十二）之垃圾回收算法
    56
  • 10
    深入浅出JVM（十一）之如何判断对象“已死”
    75

    • 相关课程

    更多
  • Java面试疑难点解析 - 面试技巧及语言基础
  • Java面试疑难点解析 - Java Web开发
  • Java面试疑难点解析 - 系统架构及项目设计
  • Java编程入门
  • Java面向对象编程
  • Java高级编程

    • 相关电子书

    更多
  • Spring Cloud Alibaba - 重新定义 Java Cloud-Native
  • The Reactive Cloud Native Arch
  • JAVA开发手册1.5.0

    • 相关实验场景

    更多
  • 对象和接口-2：常见用法
  • 阿里云平台上进行Java程序的编译与运行
  • 使用Java面向对象编写网络通信程序应用
  • 手动部署Java Web环境（Alibaba Cloud Linux 2）
  • 搭建Java Web开发环境（Anolis OS）
  • RocketMQ中使用Java客户端发送消息和消费的应用
    • 下一篇
    手把手教你白嫖阿里云服务器(免费领服务器)