第四周作业

group01/1814014897/zhouhui/src/week04/jvm/loader/ClassFileLoader.java

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+
+package week04.jvm.loader;
+
+import java.io.BufferedInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.List;
+
+
+
+public class ClassFileLoader {
+
+	private List<String> clzPaths = new ArrayList<String>();
+
+	public byte[] readBinaryCode(String className) throws Exception {
+		URL base = this.getClass().getResource("/");
+		String baseToString = ""+base;
+		String filePath = baseToString.replaceAll("file:/", "")+className.replace(".", "\\")+".class";
+		//String filePath = clzPaths.get(0)+"\\"+className.replace(".", "\\")+".class";  //符合Junit测试调用addClassPath方法
+		File file = new File(filePath);
+
+		BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));
+		ByteArrayOutputStream baos = new ByteArrayOutputStream();
+
+		byte[] buffer = new byte[1024];
+		int len = 0;
+		while((len = bis.read(buffer)) != -1){
+			baos.write(buffer,0,len);
+		}
+		return baos.toByteArray();		
+	}
+
+	public void addClassPath(String path) {
+		clzPaths.add(path);
+	}
+
+	public String getClassPath(){
+		StringBuffer strBuffer = new StringBuffer();
+		for(int i=0;i<clzPaths.size();i++){
+			if(i == (clzPaths.size() - 1)){
+				strBuffer.append(clzPaths.get(i));
+			}else{
+				strBuffer.append(clzPaths.get(i)+";");
+			}
+		}
+		return strBuffer.toString();
+	}
+
+}

group01/1814014897/zhouhui/src/week04/jvm/test/ClassFileloaderTest.java

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+package week04.jvm.test;
+
+import org.junit.After;
+import  org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import week04.jvm.loader.ClassFileLoader;
+
+
+public class ClassFileloaderTest {
+
+
+	static String path1 = "D:\\GitHub\\coding2017\\group01\\1814014897\\zhouhui\\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() throws Exception {		
+
+		ClassFileLoader loader = new ClassFileLoader();
+		loader.addClassPath(path1);
+
+		String className = "week04.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(1040, byteCodes.length);
+
+	}
+
+
+    @Test	
+	public void testMagicNumber() throws Exception{
+    	ClassFileLoader loader = new ClassFileLoader();
+		loader.addClassPath(path1);
+		String className = "week04.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();
+	}
+
+}

group01/1814014897/zhouhui/src/week04/jvm/test/EmployeeV1.java

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+package week04.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();    
+
+    }
+}

group01/1814014897/zhouhui/src/week04/lru/LRUPageFrame.java

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+package week04.lru;
+
+/**
+ * 用双向链表实现LRU算法
+ * @author Hui Zhou
+ *
+ */
+public class LRUPageFrame {
+
+	private static class Node {
+
+		Node prev;
+		Node next;
+		int pageNum;
+
+		Node(int pageNum) {
+			this.pageNum = pageNum;
+		}
+	}
+
+	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) {
+		Node node = new Node(pageNum);
+
+		if(first == null){
+			init(node);
+		}
+		else if(size == capacity){
+			if(node.pageNum == first.pageNum){
+				return;
+			}
+			else if(node.pageNum == first.next.pageNum){
+				insertOfMidEqual(node);
+			}
+			else if(node.pageNum == last.pageNum){
+				insert(node);
+			}
+			else{
+				insert(node);
+			}
+		}
+		else{
+			addNode(node);
+		}
+	}
+
+	private void init(Node node) {
+		first = node;
+		last = first;
+		size++;
+	}
+
+	private void addNode(Node node) {
+		node.next = first;
+		first.prev = node;
+		first = node;
+		size++;
+	}
+
+	private void insert(Node node) {
+		last = first.next;
+		last.next = null;
+
+		node.next = first;
+		first.prev = node;
+		first = node;
+	}
+
+	private void insertOfMidEqual(Node node) {
+		first.next = last;
+		last.prev = first;
+
+		node.next = first;
+		first.prev = node;
+		first = node;
+	}
+
+	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();
+	}
+
+}

group01/1814014897/zhouhui/src/week04/lru/LRUPageFrameTest.java

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+package week04.lru;
+
+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());
+	}
+
+}