Merge pull request #27 from yanghaitao0410/master

Master

group06/1454385822/src/com/coding/basic/homework_04/jvm/loader/ClassFileLoader.java

@@ -0,0 +1,114 @@
+package com.coding.basic.homework_04.jvm.loader;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+
+
+public class ClassFileLoader {
+
+	private List<String> clzPaths = new ArrayList<String>();
+	private static final int BUFFER_SIZE = 1024;
+
+	public byte[] readBinaryCode(String className) {
+		byte[] result = null;
+		for(String path : clzPaths){
+			File file = new File(getPath(path, className));
+			if(!file.exists()){
+				continue;
+			}
+			result = readFile(file);	
+		}
+		return result;
+	}
+
+	/**
+	 * 文件数据存放在字节数组中返回
+	 * @param file
+	 * @return
+	 */
+	private byte[] readFile(File file){
+		FileInputStream fileInputStream;
+		byte[] buffer = new byte[BUFFER_SIZE];
+		ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+
+		try {
+			fileInputStream = new FileInputStream(file);
+			while(byteArrayOutputStream.size() < file.length()){
+				int len = fileInputStream.read(buffer);
+				if(len < 0){
+					break;
+				}
+				byteArrayOutputStream.write(buffer, 0, len);
+			}	
+		} catch (Exception e) {
+			e.printStackTrace();
+		}
+
+		if(byteArrayOutputStream.size() > file.length()){
+			byte[] result = byteArrayOutputStream.toByteArray();
+			return Arrays.copyOf(result, (int)file.length());
+		}
+		return byteArrayOutputStream.toByteArray();
+	}
+
+	/**
+	 * 获取真实路径路径
+	 * @param className
+	 * @return
+	 */
+	private String getPath(String path ,String className){
+		System.out.println(className);
+		String [] ways = className.split("\\.");
+		for (String string : ways) {
+			System.out.println(string);
+		}
+		StringBuilder builder = new StringBuilder();
+		builder.append(path);
+		for (String string : ways) {
+
+			builder.append("\\");
+			builder.append(string);
+		}
+		builder.append(".class");
+		System.out.println(builder.toString());
+		return builder.toString();
+	}
+
+	private byte[] loadClassFile(String clzFileName) {
+
+		return null;
+	}
+
+
+
+	public void addClassPath(String path) {
+		clzPaths.add(path);
+	}
+
+	public String getClassPath_V1(){
+
+		return  null;
+	}
+
+
+	public String getClassPath(){
+		StringBuilder builder = new StringBuilder();
+		for(int i = 0; i < clzPaths.size(); i++){
+			builder.append(clzPaths.get(i));
+			if(i < clzPaths.size() - 1){
+				builder.append(";");
+			}
+		}
+		return builder.toString();
+	}
+
+
+
+
+
+}

group06/1454385822/src/com/coding/basic/homework_04/jvm/test/ClassFileloaderTest.java

@@ -0,0 +1,89 @@
+package com.coding.basic.homework_04.jvm.test;
+
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.coding.basic.homework_04.jvm.loader.ClassFileLoader;
+
+public class ClassFileloaderTest {
+
+
+	static String path1 = "C:\\Users\\yanght\\Documents\\mygit\\coding2017-1\\group06\\1454385822\\bin";
+	static String path2 = "D:\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.coding.basic.homework_04.jvm.test.EmployeeV1";
+//		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(1084, byteCodes.length);
+
+	}
+
+
+    @Test	
+	public void testMagicNumber(){
+    	ClassFileLoader loader = new ClassFileLoader();
+		loader.addClassPath(path1);
+		String className = "com.coding.basic.homework_04.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();
+	}
+
+}

group06/1454385822/src/com/coding/basic/homework_04/jvm/test/EmployeeV1.java

@@ -0,0 +1,29 @@
+package com.coding.basic.homework_04.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();    
+
+    }
+}

group06/1454385822/src/com/coding/basic/homework_04/lru/LRUPageFrame.java

@@ -0,0 +1,137 @@
+package com.coding.basic.homework_04.lru;
+
+/**
+ * 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){
+			this.pageNum = pageNum;
+		}
+	}
+
+	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 key
+	 * @return
+	 */
+	public void access(int pageNum) {
+		if(first == null){ //缓存第一个数据
+			first = new Node(pageNum);
+			first.next = first.prev = null;
+			last = first;
+		}else if(size() < capacity && first != null){ //缓存页未满时
+			Node node = new Node(pageNum);
+			if(last.prev == null){
+				last.prev = node;
+				node.next = last;
+			}else{
+				node.next = first;
+				first.prev = node;
+				node.prev = null;
+			}
+			first = node;
+		}else if(size() >= capacity){ //缓存页满了
+			Node node = getNode(pageNum);
+			LRU(node, pageNum);
+		}
+	}
+
+	/**
+	 * lru算法
+	 * @param node
+	 * @param pageNum
+	 */
+	private void LRU(Node node, int pageNum){
+		if(node != null){
+			if(last.pageNum == node.pageNum){ //缓存是last
+				last = node.prev;
+				last.next = null;
+				node.next = first;
+				first.prev = node;
+				node.prev = null;
+				first = node;
+			}else if(last.pageNum != node.pageNum && first.pageNum != node.pageNum){ 
+				//缓存在first和last的中间范围
+				node.prev.next = node.next;
+				node.next.prev = node.prev;
+				node.prev = null;
+				node.next = first;
+				first = node;
+			}	
+		}else{
+			//新缓存
+			last = last.prev;
+			last.next = null;
+			node = new Node(pageNum);
+			node.next = first;
+			first.prev = node;
+			first = node;
+		}
+	}
+
+	/**
+	 * 根据数据在缓存中获取节点
+	 * @param pageNum
+	 * @return
+	 */
+	private Node getNode(int pageNum){
+		Node node = first;
+		while(node != null){
+			if(node.pageNum == pageNum){
+				return node;
+			}
+			node = node.next;
+		}
+		return null;
+	}
+
+	public int size(){
+		int num = 0;
+		Node node = first;
+		while(node != null){
+			num++;
+			node = node.next;
+		}
+		return num;
+	}
+
+	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();
+	}
+
+}