Merge pull request #29 from Jiandan1357/master

Master

group23/601689050/4LRU&JVM/JVM/ClassFileLoader.java

@@ -0,0 +1,63 @@
+package com.loader;
+
+import java.io.*;
+import java.util.ArrayList;
+import java.util.Dictionary;
+import java.util.List;
+
+
+
+public class ClassFileLoader {
+
+	private List<String> clzPaths = new ArrayList<>();
+
+	public byte[] readBinaryCode(String className) throws ClassNotFoundException {
+
+		String fileName = className.replace('.',File.separatorChar)+".class";
+		InputStream is = null;
+		try{
+			is = new FileInputStream(fileName);
+			ByteArrayOutputStream baos = new ByteArrayOutputStream();
+			byte[] buffer = new byte[1024];
+			int length = 0;
+			while((length = is.read(buffer)) != -1){
+				baos.write(buffer,0,length);
+			}
+			return baos.toByteArray();
+		} catch (IOException e){
+			e.printStackTrace();
+		} finally {
+			if(is!=null){
+				try{
+					is.close();
+				} catch (IOException e){
+					e.printStackTrace();
+				}
+			}
+		}
+		return null;
+	}
+
+
+
+
+	public void addClassPath(String path) {
+
+		StringBuilder str = new StringBuilder(path);
+
+	}
+
+
+
+	public String getClassPath(){
+
+		String path = Thread.currentThread().getContextClassLoader().getResource("/").getPath();
+
+		return path;
+	}
+
+
+
+
+
+}

group23/601689050/4LRU&JVM/JVM/ClassFileloaderTest.java

@@ -0,0 +1,88 @@
+package com.test;
+
+import com.loader.ClassFileLoader;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.Before;
+import org.junit.After;
+
+
+public class ClassFileloaderTest {
+
+
+	public static String path1 = "C:\\Users\\liuxin\\git\\coding2017\\liuxin\\mini-jvm\\bin";
+	public 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() throws ClassNotFoundException {
+
+		ClassFileLoader loader = new ClassFileLoader();
+		loader.addClassPath(path1);
+
+		String className = "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-1);
+
+	}
+
+
+    @Test	
+	public void testMagicNumber() throws ClassNotFoundException {
+    	ClassFileLoader loader = new ClassFileLoader();
+		loader.addClassPath(path1);
+		String className = "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();
+	}
+
+}

group23/601689050/4LRU&JVM/JVM/EmployeeV1.java

@@ -0,0 +1,28 @@
+package com.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();    
+
+    }
+}

group23/601689050/4LRU&JVM/LRU/Iterator.java

@@ -0,0 +1,5 @@
+public interface Iterator {
+	public boolean hasNext();
+	public Object next();
+
+}

group23/601689050/4LRU&JVM/LRU/LRUPageFrame.java

@@ -0,0 +1,117 @@
+/**
+ * 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() {
+		}
+	}
+
+	private int capacity;
+
+
+	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
+	 * @return
+	 */
+	int size = 0;
+	public void access(int pageNum) {
+
+		if(size == 0){
+			Node node = new Node();
+			node.pageNum = pageNum;
+			node.prev = node.next = null;
+			first = last = node;
+			size++;
+		}else{
+			if(first.pageNum == pageNum){
+				return;
+			}
+			if(size == 1){
+				addToFirst(pageNum);
+			}else {
+				if (last.pageNum == pageNum) {
+					moveLastToFirst();
+					return;
+				}
+				Node iteratorNode = first;
+				while (iteratorNode.next != null && iteratorNode.pageNum != pageNum) {
+					iteratorNode = iteratorNode.next;
+				}
+				if (iteratorNode == last) {
+					addToFirst(pageNum);
+					if (size > capacity) {
+						last = last.prev;
+						last.next = null;
+					}
+				} else {
+				moveToFirst(iteratorNode);
+			}
+			}
+		}
+
+	}
+
+	private void moveLastToFirst() {
+		last.next = first;
+		first.prev = last;
+		first = last;
+		last = last.prev;
+		last.next = null;
+		first.prev = null;
+	}
+	private void moveToFirst(Node iteratorNode){
+		iteratorNode.prev.next = iteratorNode.next;
+		iteratorNode.next.prev = iteratorNode.prev;
+		iteratorNode.prev = null;
+		iteratorNode.next = first;
+		first.prev = iteratorNode;
+		first = iteratorNode;
+	}
+
+	private void addToFirst(int pageNum) {
+		Node node = new Node();
+		node.pageNum = pageNum;
+		node.prev = null;
+		node.next = first;
+		first.prev = node;
+		first = node;
+		size++;
+	}
+
+
+	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();
+	}
+
+}

group23/601689050/4LRU&JVM/LRU/LRUPageFrameTest.java

@@ -0,0 +1,29 @@
+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());
+	}
+
+}