Merge pull request #47 from GZ-RXP/master

Jvm first week - Magical Number

group11/283091182/mini-jvm/com/coderising/jvm/loader/ClassFileLoader.java

@@ -0,0 +1,93 @@
+package com.coderising.jvm.loader;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+
+
+public class ClassFileLoader {
+
+	private List<String> clzPaths = new ArrayList<String>();
+
+	public byte[] readBinaryCode(String className) {
+
+		File classFile = getClassFileFromPath(className);	
+
+		byte[] buffer = new byte[1024];
+		try {
+			FileInputStream fis = new FileInputStream(classFile);
+			ByteArrayOutputStream baos = new ByteArrayOutputStream();
+
+			int readLen;
+			while((readLen = fis.read(buffer))>-1){
+				baos.write(buffer, 0, readLen);
+			}
+
+			return baos.toByteArray();
+
+		} catch (FileNotFoundException e) {
+			e.printStackTrace();
+			throw new RuntimeException(e);
+		} catch (IOException e) {
+			e.printStackTrace();
+			throw new RuntimeException(e);
+		}
+	}
+
+
+	public void addClassPath(String path) {
+		File clzPath = new File(path);
+		if(clzPath.exists() && clzPath.isDirectory()){
+			this.clzPaths.add(path);
+		}else{
+			System.out.println("Invalid path:"+ path);
+		}
+	}
+
+
+
+	public String getClassPath(){
+		StringBuilder sb = new StringBuilder();
+		Iterator it = this.clzPaths.iterator();
+		while(it.hasNext()){
+			if(sb.length()>0){
+				sb.append(";");
+			}
+			sb.append(it.next());
+		}
+		return sb.toString();
+	}
+
+	public File getClassFileFromPath(String className) {
+		Iterator it = this.clzPaths.iterator();
+
+		//replace "." with "\\" in windows
+		String fullclassPath = className.replaceAll("\\.", (File.separatorChar=='\\')?"\\\\":"/")+".class";
+
+		while(it.hasNext()){
+			File clzFile;
+			String path = (String)it.next();
+			if(path.endsWith(String.valueOf(File.separatorChar))){
+				clzFile = new File(path+fullclassPath);
+			}else{
+				clzFile = new File(path+File.separatorChar+fullclassPath);
+			}
+
+			//Check file before further proceed
+			if(clzFile.exists()&&clzFile.isFile()){
+				return clzFile;
+			}
+		}
+
+		throw new RuntimeException("Class not found:"+className);
+	}
+
+
+
+}

group11/283091182/mini-jvm/com/coderising/jvm/test/ClassFileloaderTest.java

@@ -0,0 +1,92 @@
+package com.coderising.jvm.test;
+
+import org.junit.After;
+import  org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.coderising.jvm.loader.ClassFileLoader;
+
+
+
+
+
+public class ClassFileloaderTest {
+
+
+	static String path1 = "C:\\Users\\Administrator\\mygit\\coding2017\\liuxin\\bin";
+	static String path2 = "C:\\temp";
+
+
+
+	@Before
+	public void setUp() throws Exception {		 
+	}
+
+	@After
+	public void tearDown() throws Exception {
+	}
+
+	@Test
+	public void testClassPath(){		
+
+		ClassFileLoader loader = new ClassFileLoader();
+		loader.addClassPath(path1);
+		loader.addClassPath(path2);
+
+		String clzPath = loader.getClassPath();
+
+		Assert.assertEquals(path1+";"+path2,clzPath);
+
+	}
+
+	@Test
+	public void testClassFileLength() {		
+
+		ClassFileLoader loader = new ClassFileLoader();
+		loader.addClassPath(path1);
+
+		String className = "com.coderising.jvm.test.EmployeeV1";
+
+		byte[] byteCodes = loader.readBinaryCode(className);
+
+		// 注意：这个字节数可能和你的JVM版本有关系， 你可以看看编译好的类到底有多大
+		Assert.assertEquals(1056, byteCodes.length);
+
+	}
+
+
+    @Test	
+	public void testMagicNumber(){
+    	ClassFileLoader loader = new ClassFileLoader();
+		loader.addClassPath(path1);
+		String className = "com.coderising.jvm.test.EmployeeV1";
+		byte[] byteCodes = loader.readBinaryCode(className);
+		byte[] codes = new byte[]{byteCodes[0],byteCodes[1],byteCodes[2],byteCodes[3]};
+
+
+		String acctualValue = this.byteToHexString(codes);
+
+		Assert.assertEquals("cafebabe", acctualValue);
+	}
+
+
+
+
+
+
+	private String byteToHexString(byte[] codes ){
+		StringBuffer buffer = new StringBuffer();
+		for(int i=0;i<codes.length;i++){
+			byte b = codes[i];
+			int value = b & 0xFF;
+			String strHex = Integer.toHexString(value);
+			if(strHex.length()< 2){
+				strHex = "0" + strHex;
+			}		
+			buffer.append(strHex);
+		}
+		return buffer.toString();
+	}
+
+}

group11/283091182/mini-jvm/com/coderising/jvm/test/EmployeeV1.java

@@ -0,0 +1,28 @@
+package com.coderising.jvm.test;
+
+public class EmployeeV1 {
+
+
+	private String name;
+    private int age;
+
+    public EmployeeV1(String name, int age) {
+        this.name = name;
+        this.age = age;        
+    }    
+
+    public void setName(String name) {
+        this.name = name;
+    }
+    public void setAge(int age){
+    	this.age = age;
+    }
+    public void sayHello() {        
+    	System.out.println("Hello , this is class Employee ");    	
+    }
+    public static void main(String[] args){
+    	EmployeeV1 p = new EmployeeV1("Andy",29);
+    	p.sayHello();    
+
+    }
+}

group11/283091182/src/com/coding/basic/linklist/LRUPageFrame.java

@@ -0,0 +1,141 @@
+package com.coding.basic.linklist;
+
+/**
+ * 用双向链表实现LRU算法
+ * @author liuxin
+ *
+ */
+public class LRUPageFrame {
+
+	private static class Node {
+
+		Node prev;
+		Node next;
+		int pageNum;
+
+		Node() {
+		}
+
+		Node(int pageNum, Node prev, Node next){
+			this.pageNum = pageNum;
+			this.next = next;
+			this.prev = prev;
+		}
+	}
+
+	private int capacity;
+
+	private int size;
+
+
+	private Node first;// 链表头
+	private Node last;// 链表尾
+
+
+	public LRUPageFrame(int capacity) {
+
+		this.capacity = capacity;
+
+	}
+
+	/**
+	 * 获取缓存中对象
+	 * 
+	 * @param key
+	 * @return
+	 */
+	public void access(int pageNum) {
+		System.out.println("CurrentList= "+this.toString()+"; accessing - "+pageNum);
+		Node target = find(pageNum);
+		if(target==null){
+			createNewNodeAsHead(pageNum);
+		}else{
+			moveExistingNodeToHead(target);
+		}
+
+	}
+
+	private void removeLast(){
+		Node secToLast = last.prev;
+		last = null;
+		secToLast.next = null;
+		last = secToLast;
+		size--;
+	}
+
+	private void moveExistingNodeToHead(Node node){
+
+		Node prev = node.prev;
+		Node next = node.next;
+
+		if(prev==null){
+			//already in the head,do nothing;
+			return;
+		}
+
+		if(next==null){
+			//currently in the tail
+			last = prev;
+		}
+
+		//in the middle
+		prev.next = next;
+		if(next!=null){
+			next.prev = prev;
+		}
+		node.prev = null;
+		node.next = first;
+		first = node;
+	}
+
+	private void createNewNodeAsHead(int value){
+		Node node = new Node(value,null,null);
+		//first node
+		if(size==0){
+			this.first = node;
+			this.last = node;
+			this.size ++;
+		}else{
+			//linklist already exists
+			this.first.prev = node;
+			node.next = this.first;
+			this.first = node;
+			this.size++;
+
+			if(size>capacity){
+				removeLast();
+			}
+		}
+
+	}
+
+	private Node find(int value){
+		if(size==0){
+			return null;
+		}
+		Node temp = first;
+		while(temp!=null){
+			if(temp.pageNum==value){
+				return temp;
+			}else{
+				temp = temp.next;
+			}
+		}
+		return null;
+	}
+
+	public String toString(){
+		StringBuilder buffer = new StringBuilder();
+		Node node = first;
+		while(node != null){
+			buffer.append(node.pageNum);			
+
+			node = node.next;
+			if(node != null){
+				buffer.append(",");
+			}
+		}
+		return buffer.toString();
+	}
+
+}

group11/283091182/src/com/coding/basic/linklist/LRUPageFrameTest.java

@@ -0,0 +1,31 @@
+package com.coding.basic.linklist;
+
+import  org.junit.Assert;
+
+import org.junit.Test;
+
+
+public class LRUPageFrameTest {
+
+	@Test
+	public void testAccess() {
+		LRUPageFrame frame = new LRUPageFrame(3);
+		frame.access(7);
+		frame.access(0);
+		frame.access(1);
+		Assert.assertEquals("1,0,7", frame.toString());
+		frame.access(2);
+		Assert.assertEquals("2,1,0", frame.toString());
+		frame.access(0);
+		Assert.assertEquals("0,2,1", frame.toString());
+		frame.access(0);
+		Assert.assertEquals("0,2,1", frame.toString());
+		frame.access(3);
+		Assert.assertEquals("3,0,2", frame.toString());
+		frame.access(0);
+		Assert.assertEquals("0,3,2", frame.toString());
+		frame.access(4);
+		Assert.assertEquals("4,0,3", frame.toString());
+	}
+
+}