Java小型操作系统模拟（采用策略模式结合反射进行搭建，支持一些简单的命令）

Java小型操作系统模拟

- 项目说明
- 第一阶段：反射结合策略模式搭建基本的命令结构
- 第二阶段：注解结合反射与策略模式，将结构进一步规范
- 第三阶段：开启新的窗口，将控制台输入切换到新窗口中，同时创建右键菜单，使效果贴近命令行
- 第四阶段，发现IDEA的编译与命令行编译不一致且导致类装载出错的情况进行处理--重新编写初始化的装载方法
- 第五阶段，解决打包为jar后的装载问题及采用脚本自动编译
- 项目下载

项目说明

主要是为了学习Java反射的知识，以及对操作系统的一些概念进行回顾，搭建了一个小型的操作系统，包括基本的一些命令，如：clear、help、cd、mkdir、ls等；同时支持用户及角色创建，密码登录等，相关文件采用加密存储在本地；同时采用资源分配的形式设计了磁盘资源和内存资源，采用首次适应、循环首次适应、最佳适应、最坏适应等策略；采用Java的Socket通信设计了简单的socket通信模式

第一阶段：反射结合策略模式搭建基本的命令结构

采用配置文件的形式指定命令的名称、描述与对应类的全路径，采用反射的形式创建对象并装载到容器中；策略模式结合HashMap的形式，可以较为方便的获取到命令对象，并执行对应的策略方法。

策略模式的体现，采用Map进行命令策略的管理

package os.strategy;import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;/*** @author bbyh* @date 2023-07-27 21:19* @description*/
public abstract class BaseStrategy {private static final Map<String, BaseStrategy> STRATEGY_FACTORY = new HashMap<>(4);private static final Map<String, String> STRATEGY_DOC = new HashMap<>(4);private final String name;private final String doc;public BaseStrategy(String name, String doc) {this.name = name;this.doc = doc;}protected final void register() {STRATEGY_FACTORY.put(name, this);STRATEGY_DOC.put(name, doc);}public abstract void execute();public static BaseStrategy getStrategy(String name) {if (!STRATEGY_FACTORY.containsKey(name)) {throw new UnsupportedOperationException("该策略还不支持");}return STRATEGY_FACTORY.get(name);}public static Set<String> getCommandNameSet() {return new HashSet<>(STRATEGY_FACTORY.keySet());}public static Map<String, String> getCommandDoc() {return new HashMap<>(STRATEGY_DOC);}
}

采用配置文件结合反射装载对象；分为只装载指定目录，或装载指定目录及其子目录，要求都是基础策略类的子类

package os.util;import os.strategy.BaseStrategy;import java.io.*;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashSet;
import java.util.Properties;/*** @author bbyh* @date 2023/7/28 12:19*/
public class OsApplication {private static final String PACKAGE_PREFIX = "src/";private static final String DEFAULT_STRATEGY_PACKAGE = "strategy.impl";private static final String OS_COMMAND_PROPERTIES = "os-command-config.properties";private static final HashSet<Class<?>> CLASS_SET = new HashSet<>(4);private static void load() {for (Class<?> instance : CLASS_SET) {if (instance.getSuperclass() == BaseStrategy.class) {try (InputStream inputStream = Files.newInputStream(Paths.get(OS_COMMAND_PROPERTIES))) {Properties properties = new Properties();properties.load(inputStream);if (properties.containsKey(instance.getName())) {String[] split = properties.getProperty(instance.getName()).split(",");try {Constructor<?> constructor = instance.getConstructor(String.class, String.class);Object newInstance = constructor.newInstance(split[0], split[1]);Method register = newInstance.getClass().getSuperclass().getDeclaredMethod("register");register.setAccessible(true);register.invoke(newInstance);} catch (NoSuchMethodException | InvocationTargetException |IllegalAccessException | InstantiationException e) {throw new RuntimeException(e);}}} catch (IOException e) {throw new RuntimeException(e);}}}}public static void runWithSpecifiedDirectory(Class<?> application) {initSpecifiedDirectory(application.getPackage().getName() + "." + DEFAULT_STRATEGY_PACKAGE);load();}private static void initSpecifiedDirectory(String scanPackage) {File basePackage = new File(PACKAGE_PREFIX + scanPackage.replace(".", "/"));File[] files = basePackage.listFiles(file -> file.getName().endsWith(".java"));loadClasses(scanPackage, files);}private static void loadClasses(String scanPackage, File[] files) {if (files != null) {for (File file : files) {try {Class<?> instance = Class.forName(scanPackage + "." + file.getName().replace(".java", ""));CLASS_SET.add(instance);} catch (ClassNotFoundException e) {throw new RuntimeException(e);}}}}public static void runWithRecursiveDirectory(Class<?> application) {initRecursiveDirectory(application.getPackage().getName());load();}private static void initRecursiveDirectory(String scanPackage) {File basePackage = new File(PACKAGE_PREFIX + scanPackage.replace(".", "/"));File[] files = basePackage.listFiles(file -> {if (file.isDirectory()) {initRecursiveDirectory(scanPackage + "." + file.getName());}return file.getName().endsWith(".java");});loadClasses(scanPackage, files);}
}

配置文件

os.strategy.impl.ClearStrategy=clear,清屏命令，清空屏幕
os.strategy.impl.HelpStrategy=help,帮助命令，查看当前系统支持的命令

项目结构

第二阶段：注解结合反射与策略模式，将结构进一步规范

采用类似SpringBoot的启动方式，自动装载指定目录下的命令类，采用注解的形式设置命令的名称与描述

采用注解设置启动装载包目录名，以及各个策略类的目录名称与相关说明

package os.annotation;import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;/*** @author bbyh* @date 2023/7/2 15:29*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface StrategyScan {String value() default "strategy.impl";
}

help命令，简单输出系统支持的命令和说明

package os.strategy.impl;import os.annotation.StrategyAnnotation;
import os.annotation.StrategyDocAnnotation;
import os.strategy.BaseStrategy;import java.util.Map;
import java.util.Set;/*** @author bbyh* @date 2023-07-27 21:26* @description*/
@StrategyAnnotation(commandName = "help")
@StrategyDocAnnotation(commandDoc = "帮助命令，查看当前系统支持的命令")
public class HelpStrategy extends BaseStrategy {public HelpStrategy(String name, String doc) {super(name, doc);}@Overridepublic void execute() {System.out.println("系统支持的命令");Set<String> commandNameSet = BaseStrategy.getCommandNameSet();Map<String, String> commandDoc = BaseStrategy.getCommandDoc();for (String commandName : commandNameSet) {System.out.println(commandName + "：" + commandDoc.get(commandName));}}
}

同样加载指定目录下携带注解的策略子类，或者加载目录及其子目录的所有符合条件的类

package os.util;import os.annotation.StrategyAnnotation;
import os.annotation.StrategyDocAnnotation;
import os.annotation.StrategyScan;
import os.strategy.BaseStrategy;import java.io.File;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashSet;/*** @author bbyh* @date 2023/7/28 12:19*/
public class OsApplication {private static final String PACKAGE_PREFIX = "src/";private static final HashSet<Class<?>> CLASS_SET = new HashSet<>(4);private static void load() {for (Class<?> instance : CLASS_SET) {if (instance.getSuperclass() == BaseStrategy.class) {try {StrategyAnnotation nameAnnotation = instance.getAnnotation(StrategyAnnotation.class);StrategyDocAnnotation docAnnotation = instance.getAnnotation(StrategyDocAnnotation.class);if (nameAnnotation != null && docAnnotation != null) {Constructor<?> constructor = instance.getConstructor(String.class, String.class);Object newInstance = constructor.newInstance(nameAnnotation.commandName(), docAnnotation.commandDoc());Method register = newInstance.getClass().getSuperclass().getDeclaredMethod("register");register.setAccessible(true);register.invoke(newInstance);}} catch (NoSuchMethodException | InvocationTargetException |IllegalAccessException | InstantiationException e) {throw new RuntimeException(e);}}}}/*** 加载配置目录下的添加了StrategyAnnotation注解的类** @param application 启动类*/public static void runWithSpecifiedDirectory(Class<?> application) {StrategyScan strategyScan = application.getAnnotation(StrategyScan.class);initSpecifiedDirectory(application.getPackage().getName() + "." + strategyScan.value());load();}private static void initSpecifiedDirectory(String scanPackage) {File basePackage = new File(PACKAGE_PREFIX + scanPackage.replace(".", "/"));File[] files = basePackage.listFiles(file -> file.getName().endsWith(".java"));loadClasses(scanPackage, files);}private static void loadClasses(String scanPackage, File[] files) {if (files != null) {for (File file : files) {try {Class<?> instance = Class.forName(scanPackage + "." + file.getName().replace(".java", ""));CLASS_SET.add(instance);} catch (ClassNotFoundException e) {throw new RuntimeException(e);}}}}/*** 加载配置目录及其子目录下的添加了StrategyAnnotation注解的类** @param application 启动类*/public static void runWithRecursiveDirectory(Class<?> application) {initRecursiveDirectory(application.getPackage().getName());load();}private static void initRecursiveDirectory(String scanPackage) {File basePackage = new File(PACKAGE_PREFIX + scanPackage.replace(".", "/"));File[] files = basePackage.listFiles(file -> {if (file.isDirectory()) {initRecursiveDirectory(scanPackage + "." + file.getName());}return file.getName().endsWith(".java");});loadClasses(scanPackage, files);}
}

项目结构

第三阶段：开启新的窗口，将控制台输入切换到新窗口中，同时创建右键菜单，使效果贴近命令行

经过测试发现，上面两个系统在初始化加载类时有一些小问题，因为在实际使用时都是执行class文件，而在IDEA里面的执行是以Java文件为路径的，需要进行一些简单的小修改，当前这个阶段主要以IDEA里面的运行为主，后面再对路径和初始化逻辑进行一些调整，来保证兼容性

主窗体

package os.util;import os.strategy.BaseStrategy;import javax.swing.*;
import java.awt.*;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.event.*;
import java.io.IOException;/*** @author bbyh* @date 2023-07-29 15:51* @description*/
public class MainFrame extends JFrame {public static final JLabel DISPLAY = new JLabel();private static final String DEFAULT_WORD_DIR = "C:\\root>";public MainFrame() {setTitle("BBYH OS System");setSize(1000, 600);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setLocationRelativeTo(null);JScrollPane scrollPane = new JScrollPane(DISPLAY);DISPLAY.setOpaque(true);DISPLAY.setBackground(Color.WHITE);setLayout(new GridLayout(1, 1));add(scrollPane);setVisible(true);Font font = new Font("Consolos", Font.PLAIN, 24);DISPLAY.setFont(font);DISPLAY.setVerticalAlignment(SwingConstants.TOP);DISPLAY.setFocusable(true);init();// 右键菜单JPopupMenu rightMenu = new JPopupMenu();JMenuItem backgroundItem = new JMenuItem();JMenuItem fontItem = new JMenuItem();JMenuItem copyItem = new JMenuItem();backgroundItem.setFont(font);fontItem.setFont(font);copyItem.setFont(font);backgroundItem.setText("设置背景颜色");fontItem.setText("设置字体颜色");copyItem.setText("复制剪切版内容");rightMenu.add(backgroundItem);rightMenu.add(fontItem);rightMenu.add(copyItem);backgroundItem.addActionListener(evt -> {Color color = JColorChooser.showDialog(null, "设置背景颜色", Color.WHITE);if (color != null) {DISPLAY.setBackground(color);}});fontItem.addActionListener(evt -> {Color color = JColorChooser.showDialog(null, "设置字体颜色", Color.BLACK);if (color != null) {DISPLAY.setForeground(color);}});copyItem.addActionListener(evt -> {Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();Transferable transferable = clipboard.getContents(null);if (transferable != null) {if (transferable.isDataFlavorSupported(DataFlavor.stringFlavor)) {try {String data = (String) clipboard.getData(DataFlavor.stringFlavor);appendDisplay(data);} catch (UnsupportedFlavorException | IOException e) {throw new RuntimeException(e);}}}});DISPLAY.addKeyListener(new KeyAdapter() {@Overridepublic void keyPressed(KeyEvent e) {char keyChar = e.getKeyChar();if (keyChar == KeyEvent.VK_BACK_SPACE && !"".equals(getContent())) {DISPLAY.setText(getContent().substring(0, getContent().length() - 1));appendDisplay("");} else if (keyChar == KeyEvent.VK_ENTER) {appendDisplay("<br />");try {BaseStrategy.getStrategy(Context.getNextCommand()).execute();} catch (Exception ex) {appendDisplay(ex.getMessage() + "<br />");}appendDisplay(Context.getWorkDir());} else if (Character.isLetterOrDigit(keyChar)) {appendDisplay(String.valueOf(keyChar));}}});DISPLAY.addMouseListener(new MouseAdapter() {@Overridepublic void mouseClicked(MouseEvent e) {if (e.getButton() == MouseEvent.BUTTON3) {rightMenu.show(DISPLAY, e.getX(), e.getY() - 10);}}});}private static void init() {Context.setWorkDir(DEFAULT_WORD_DIR);appendDisplay(DEFAULT_WORD_DIR);}public static void appendDisplay(String content) {DISPLAY.setText("<html><body style='padding: 20px 10px'>" + getContent() + content + "</body></html>");}private static String getContent() {return DISPLAY.getText().replace("<html><body style='padding: 20px 10px'>", "").replace("</body></html>", "");}
}

Context上下文操作类

package os.util;/*** @author bbyh* @date 2023-07-27 22:23* @description*/
public class Context {private static String workDir;public static String getWorkDir() {return workDir;}public static void setWorkDir(String workDir) {Context.workDir = workDir;}public static String getNextCommand() {String text = MainFrame.DISPLAY.getText();return text.substring(text.lastIndexOf(getWorkDir()) + getWorkDir().length(), text.lastIndexOf("<br /></body></html>"));}
}

主程序

package os;import os.annotation.StrategyScan;
import os.util.MainFrame;
import os.util.OsApplication;/*** @author bbyh* @date 2023-07-27 21:18* @description*/
@StrategyScan
public class Main {public static void main(String[] args) {OsApplication.runWithRecursiveDirectory(Main.class);new MainFrame();}
}

测试运行效果展示

第四阶段，发现IDEA的编译与命令行编译不一致且导致类装载出错的情况进行处理–重新编写初始化的装载方法

采用getResource方法获取类路径，来装在class文件，同时采用脚本来解决javac命令行执行时无法编译不被别的文件依赖的策略实现类

重新编写的装载方法，采用递归装载，装载启动类目录下及其子目录中带有注解的策略实现类

package os.util;import os.annotation.StrategyAnnotation;
import os.annotation.StrategyDocAnnotation;
import os.strategy.BaseStrategy;import java.io.File;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Objects;/*** @author bbyh* @date 2023/7/28 12:19*/
public class OsApplication {private static final HashSet<Class<?>> CLASS_SET = new HashSet<>(4);private static String BASE_PATH;/*** 加载配置目录及其子目录下的添加了StrategyAnnotation注解的类** @param application 启动类*/public static void runWithRecursiveDirectory(Class<?> application) {BASE_PATH = Objects.requireNonNull(application.getResource("/")).getPath();initRecursiveDirectory(application.getPackage().getName());load();}private static void initRecursiveDirectory(String packageName) {File[] files = new File(BASE_PATH + packageName.replace(".", System.getProperty("file.separator"))).listFiles(file -> {if (file.isDirectory()) {initRecursiveDirectory(packageName + "." + file.getName());}return file.getName().endsWith(".class");});loadClasses(packageName, files);}private static void load() {for (Class<?> instance : CLASS_SET) {if (instance.getSuperclass() == BaseStrategy.class) {try {StrategyAnnotation nameAnnotation = instance.getAnnotation(StrategyAnnotation.class);StrategyDocAnnotation docAnnotation = instance.getAnnotation(StrategyDocAnnotation.class);if (nameAnnotation != null && docAnnotation != null) {Constructor<?> constructor = instance.getConstructor(String.class, String.class);Object newInstance = constructor.newInstance(nameAnnotation.commandName(), docAnnotation.commandDoc());Method register = newInstance.getClass().getSuperclass().getDeclaredMethod("register");register.setAccessible(true);register.invoke(newInstance);}} catch (NoSuchMethodException | InvocationTargetException |IllegalAccessException | InstantiationException e) {throw new RuntimeException(e);}}}}private static void loadClasses(String packageName, File[] files) {if (files != null) {for (File file : files) {try {Class<?> instance = Class.forName(packageName + "." + file.getName().replace(".class", ""));CLASS_SET.add(instance);} catch (ClassNotFoundException e) {throw new RuntimeException(e);}}}}
}

需要注意的一点是，目前采用getResource方法对于打包为jar包时则会报空指针错误，后续将考虑采用新方法装载来解决该问题

第五阶段，解决打包为jar后的装载问题及采用脚本自动编译

自动编译的脚本，Windows

mkdir out
cd src
javac -d ../out os/Main.java os/strategy/impl/*.java -encoding UTF-8cd ../outjava os.Main

自动编译的脚本，Linux

#!/bin/bash
mkdir out
cd src
javac -d ../out os/Main.java os/strategy/impl/*.java -encoding UTF-8
cd ../out
java os.Main

需要注意几点小问题，脚本.sh需要在Linux下创建使用，同时需要给它赋予x执行权限（chmod +x javac_os_java.sh）；然后在执行时还需要对XShell安装一下图形服务x11，参考文章：xshell-linux 启动 jmeter 报 No X11 DISPLAY variable was set, but this program performed …；不过这个Xming对中文的显示有问题，有点难办

主函数（根据启动不一样采用不一样的装载策略）

package os;import os.annotation.StrategyScan;
import os.util.MainFrame;
import os.util.OsApplication;import java.util.Objects;/*** @author bbyh* @date 2023-07-27 21:18* @description*/
@StrategyScan
public class Main {public static boolean applicationRunning = true;private static final String FILE_PROTOCOL = "file";private static final String JAR_PROTOCOL = "jar";public static void main(String[] args) {String protocol = Objects.requireNonNull(OsApplication.class.getResource("")).getProtocol();if (Objects.equals(protocol, FILE_PROTOCOL)) {OsApplication.runWithRecursiveDirectory(Main.class);} else if (Objects.equals(protocol, JAR_PROTOCOL)) {OsApplication.runWithRecursiveJar(Main.class);}new MainFrame();}
}

装载工具类

package os.util;import os.annotation.StrategyAnnotation;
import os.annotation.StrategyDocAnnotation;
import os.strategy.BaseStrategy;import java.io.File;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Objects;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;/*** @author bbyh* @date 2023/7/28 12:19*/
public class OsApplication {private static final HashSet<Class<?>> CLASS_SET = new HashSet<>(4);private static String BASE_PATH;public static final String FILE_SEPARATOR = "/";private static final String PREFIX_FILE = "file:";private static final String PREFIX_JAR = "jar:file:";private static final String SUFFIX_CLASS = ".class";/*** 加载配置目录及其子目录下的添加了StrategyAnnotation注解的类** @param application 启动类*/public static void runWithRecursiveDirectory(Class<?> application) {BASE_PATH = Objects.requireNonNull(application.getResource("")).toString().replace(PREFIX_FILE, "");String packageName = application.getPackage().getName();BASE_PATH = BASE_PATH.substring(0, BASE_PATH.lastIndexOf("/" + packageName + "/")) + FILE_SEPARATOR;initRecursiveDirectory(packageName);load();}private static void initRecursiveDirectory(String packageName) {File[] files = new File(BASE_PATH + packageName.replace(".", FILE_SEPARATOR)).listFiles(file -> {if (file.isDirectory()) {initRecursiveDirectory(packageName + "." + file.getName());}return file.getName().endsWith(SUFFIX_CLASS);});loadFileClasses(packageName, files);}private static void loadFileClasses(String packageName, File[] files) {if (files != null) {for (File file : files) {try {Class<?> instance = Class.forName(packageName + "." + file.getName().replace(SUFFIX_CLASS, ""));CLASS_SET.add(instance);} catch (ClassNotFoundException e) {throw new RuntimeException(e);}}}}private static void load() {for (Class<?> instance : CLASS_SET) {if (instance.getSuperclass() == BaseStrategy.class) {try {StrategyAnnotation nameAnnotation = instance.getAnnotation(StrategyAnnotation.class);StrategyDocAnnotation docAnnotation = instance.getAnnotation(StrategyDocAnnotation.class);if (nameAnnotation != null && docAnnotation != null) {Constructor<?> constructor = instance.getConstructor(String.class, String.class);Object newInstance = constructor.newInstance(nameAnnotation.commandName().split(" ")[0], docAnnotation.commandDoc());Method register = newInstance.getClass().getSuperclass().getDeclaredMethod("register");register.setAccessible(true);register.invoke(newInstance);}} catch (NoSuchMethodException | InvocationTargetException |IllegalAccessException | InstantiationException e) {throw new RuntimeException(e);}}}}public static void runWithRecursiveJar(Class<?> application) {BASE_PATH = Objects.requireNonNull(application.getResource("")).toString().replace(PREFIX_JAR, "");BASE_PATH = BASE_PATH.substring(0, BASE_PATH.lastIndexOf("!/" + application.getPackage().getName() + "/")) + FILE_SEPARATOR;initRecursiveJar();load();}private static void initRecursiveJar() {try (JarFile jarFile = new JarFile(BASE_PATH)) {Enumeration<JarEntry> jarEntryEnumeration = jarFile.entries();while (jarEntryEnumeration.hasMoreElements()) {JarEntry jarEntry = jarEntryEnumeration.nextElement();if (jarEntry.getName().endsWith(SUFFIX_CLASS)) {Class<?> instance = Class.forName(jarEntry.getName().replace(SUFFIX_CLASS, "").replace("/", "."));CLASS_SET.add(instance);}}} catch (IOException | ClassNotFoundException e) {throw new RuntimeException(e);}}}