第四次作业提交 2017-4-5 The 13th Group

group13/2729382520/L4/src/io/github/vxzh/jvm/loader/ClassFileLoader.java

@@ -0,0 +1,79 @@
+package io.github.vxzh.jvm.loader;
+
+import java.io.*;
+import java.util.ArrayList;
+import java.util.List;
+
+
+public class ClassFileLoader {
+
+    private static final int BUFFER_MAX_SIZE = 1024;
+    private List<String> clzPaths = new ArrayList<String>();
+
+    public byte[] readBinaryCode(String className) {
+
+        className = className.replaceAll("\\.", "/");
+        File file = findFile(className);
+        if (file == null) {
+            return new byte[0];
+        }
+
+        FileInputStream fis = null;
+        ByteArrayOutputStream bos = null;
+        try {
+            fis = new FileInputStream(file);
+            bos = new ByteArrayOutputStream();
+            byte buffer[] = new byte[BUFFER_MAX_SIZE];
+            int len = -1;
+            while ((len = fis.read(buffer)) != -1) {
+                bos.write(buffer, 0, len);
+            }
+            return bos.toByteArray();
+        } catch (FileNotFoundException e) {
+            e.printStackTrace();
+        } catch (IOException e) {
+            e.printStackTrace();
+        } finally {
+            try {
+                if (fis != null)
+                    fis.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+
+            try {
+                if (bos != null)
+                    bos.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+
+        return null;
+    }
+
+    public void addClassPath(String path) {
+        clzPaths.add(path);
+    }
+
+    public String getClassPath() {
+
+        StringBuilder builder = new StringBuilder();
+        for (String path : clzPaths) {
+            builder.append(path).append(";");
+        }
+
+        return builder.toString().substring(0, builder.toString().length() - 1);
+    }
+
+    private File findFile(String className) {
+        for (String path : clzPaths) {
+            String filePath = path + "/" + className + ".class";
+            File file = new File(filePath);
+            if (file.exists()) {
+                return file;
+            }
+        }
+        return null;
+    }
+}

group13/2729382520/L4/src/io/github/vxzh/jvm/test/ClassFileloaderTest.java

@@ -0,0 +1,82 @@
+package io.github.vxzh.jvm.test;
+
+import io.github.vxzh.jvm.loader.ClassFileLoader;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ClassFileloaderTest {
+
+
+    static String path1 = "/Users/xuxiaoqing/Workspace/test";
+    static String path2 = "/Users/xuxiaoqing/Documents/demo";
+
+
+    @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 = "io.github.vxzh.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 = "io.github.vxzh.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();
+    }
+
+}

group13/2729382520/L4/src/io/github/vxzh/jvm/test/EmployeeV1.java

@@ -0,0 +1,29 @@
+package io.github.vxzh.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();
+    }
+}

group13/2729382520/L4/src/io/github/vxzh/lru/LRUPageFrame.java

@@ -0,0 +1,109 @@
+package io.github.vxzh.lru;
+
+/**
+ * 用双向链表实现LRU算法
+ */
+public class LRUPageFrame {
+
+    private static class Node {
+        Node prev;
+        Node next;
+        int pageNum;
+
+        Node(Node prev, int pageNum, Node next) {
+            this.prev = prev;
+            this.pageNum = pageNum;
+            this.next = next;
+        }
+    }
+
+    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 pageNum
+     * @return
+     */
+    public void access(int pageNum) {
+        if (first != null && first.pageNum == pageNum) {
+            return;
+        }
+
+        removeNode(pageNum);
+        if (size() + 1 > capacity) {
+            removeLast();
+        }
+        addFirst(pageNum);
+
+    }
+
+    private int size() {
+        return size;
+    }
+
+    private void addFirst(int pageNum) {
+        Node f = first;
+        Node newNode = new Node(null, pageNum, f);
+        if (f == null)
+            last = newNode;
+        else
+            f.prev = newNode;
+        first = newNode;
+        size++;
+    }
+
+    private void removeLast() {
+
+        Node l = last;
+        Node prev = l.prev;
+        prev.next = null;
+        l.prev = null;
+        last = prev;
+        size--;
+    }
+
+    private void removeNode(int pageNum) {
+        Node node = first;
+        while (node != null) {
+            if (node.pageNum == pageNum) {
+                if (node == last) {
+                    removeLast();
+                } else {
+                    final Node prev = node.prev;
+                    final Node next = node.next;
+                    prev.next = next;
+                    next.prev = prev;
+                    node.prev = null;
+                    node.next = null;
+                    size--;
+                }
+                break;
+            } else {
+                node = node.next;
+            }
+        }
+    }
+
+    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();
+    }
+
+}

group13/2729382520/L4/src/io/github/vxzh/lru/LRUPageFrameTest.java

@@ -0,0 +1,29 @@
+package io.github.vxzh.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());
+    }
+
+}

group13/2931408816/lesson4/build.gradle

@@ -0,0 +1,27 @@
+group 'cn.net.pikachu'
+version '1.0-SNAPSHOT'
+
+buildscript {
+    ext.kotlin_version = '1.1.1'
+
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+apply plugin: 'java'
+apply plugin: 'kotlin'
+
+sourceCompatibility = 1.8
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib-jre8:$kotlin_version"
+    testCompile group: 'junit', name: 'junit', version: '4.12'
+}