ClassFileloaderTest.java

package com.coderising.jvm.test;

import com.coderising.jvm.clz.ClassFile;
import com.coderising.jvm.clz.ClassIndex;
import com.coderising.jvm.constant.ClassInfo;
import com.coderising.jvm.constant.ConstantPool;
import com.coderising.jvm.constant.MethodRefInfo;
import com.coderising.jvm.constant.NameAndTypeInfo;
import com.coderising.jvm.constant.UTF8Info;
import com.coderising.jvm.field.Field;
import com.coderising.jvm.loader.ClassFileLoader;
import com.coderising.jvm.method.Method;
import java.util.List;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

public class ClassFileloaderTest {

    private static final String FULL_QUALIFIED_CLASS_NAME = "com/coderising/jvm/test/EmployeeV1";

    static String path1 = "/Users/Korben/Downloads";
    static String path2 = "C:\temp";

    static ClassFile clzFile = null;

    static {
        ClassFileLoader loader = new ClassFileLoader();
        loader.addClassPath(path1);
        String className = "com.coderising.jvm.test.EmployeeV1";

        clzFile = loader.loadClass(className);
        clzFile.print();
    }

    @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();
    }

    /**
     * ----------------------------------------------------------------------
     */

    @Test
    public void testVersion() {

        Assert.assertEquals(0, clzFile.getMinorVersion());
        Assert.assertEquals(52, clzFile.getMajorVersion());
    }

    @Test
    public void testConstantPool() {

        ConstantPool pool = clzFile.getConstantPool();

        Assert.assertEquals(53, pool.getSize());

        {
            ClassInfo clzInfo = (ClassInfo) pool.getConstantInfo(1);
            Assert.assertEquals(2, clzInfo.getUtf8Index());

            UTF8Info utf8Info = (UTF8Info) pool.getConstantInfo(2);
            Assert.assertEquals(FULL_QUALIFIED_CLASS_NAME, utf8Info.getValue());
        }
        {
            ClassInfo clzInfo = (ClassInfo) pool.getConstantInfo(3);
            Assert.assertEquals(4, clzInfo.getUtf8Index());

            UTF8Info utf8Info = (UTF8Info) pool.getConstantInfo(4);
            Assert.assertEquals("java/lang/Object", utf8Info.getValue());
        }
        {
            UTF8Info utf8Info = (UTF8Info) pool.getConstantInfo(5);
            Assert.assertEquals("name", utf8Info.getValue());

            utf8Info = (UTF8Info) pool.getConstantInfo(6);
            Assert.assertEquals("Ljava/lang/String;", utf8Info.getValue());

            utf8Info = (UTF8Info) pool.getConstantInfo(7);
            Assert.assertEquals("age", utf8Info.getValue());

            utf8Info = (UTF8Info) pool.getConstantInfo(8);
            Assert.assertEquals("I", utf8Info.getValue());

            utf8Info = (UTF8Info) pool.getConstantInfo(9);
            Assert.assertEquals("<init>", utf8Info.getValue());

            utf8Info = (UTF8Info) pool.getConstantInfo(10);
            Assert.assertEquals("(Ljava/lang/String;I)V", utf8Info.getValue());

            utf8Info = (UTF8Info) pool.getConstantInfo(11);
            Assert.assertEquals("Code", utf8Info.getValue());
        }

        {
            MethodRefInfo methodRef = (MethodRefInfo) pool.getConstantInfo(12);
            Assert.assertEquals(3, methodRef.getClassInfoIndex());
            Assert.assertEquals(13, methodRef.getNameAndTypeIndex());
        }

        {
            NameAndTypeInfo nameAndType = (NameAndTypeInfo) pool.getConstantInfo(13);
            Assert.assertEquals(9, nameAndType.getIndex1());
            Assert.assertEquals(14, nameAndType.getIndex2());
        }
        //抽查几个吧
        {
            MethodRefInfo methodRef = (MethodRefInfo) pool.getConstantInfo(45);
            Assert.assertEquals(1, methodRef.getClassInfoIndex());
            Assert.assertEquals(46, methodRef.getNameAndTypeIndex());
        }

        {
            UTF8Info utf8Info = (UTF8Info) pool.getConstantInfo(53);
            Assert.assertEquals("EmployeeV1.java", utf8Info.getValue());
        }
    }

    @Test
    public void testClassIndex() {

        ClassIndex clzIndex = clzFile.getClzIndex();
        ClassInfo thisClassInfo = (ClassInfo) clzFile.getConstantPool().getConstantInfo(clzIndex.getThisClassIndex());
        ClassInfo superClassInfo = (ClassInfo) clzFile.getConstantPool().getConstantInfo(clzIndex.getSuperClassIndex());

        Assert.assertEquals(FULL_QUALIFIED_CLASS_NAME, thisClassInfo.getClassName());
        Assert.assertEquals("java/lang/Object", superClassInfo.getClassName());
    }

    /**
     * 下面是第三次JVM课应实现的测试用例
     */
    @Test
    public void testReadFields() {

        List<Field> fields = clzFile.getFields();
        Assert.assertEquals(2, fields.size());
        {
            Field f = fields.get(0);
            Assert.assertEquals("name:Ljava/lang/String;", f.toString());
        }
        {
            Field f = fields.get(1);
            Assert.assertEquals("age:I", f.toString());
        }
    }

    @Test
    public void testMethods() {

        List<Method> methods = clzFile.getMethods();
        ConstantPool pool = clzFile.getConstantPool();

        {
            Method m = methods.get(0);
            assertMethodEquals(pool, m,
                    "<init>",
                    "(Ljava/lang/String;I)V",
                    "2ab7000c2a2bb5000f2a1cb50011b1");
        }
        {
            Method m = methods.get(1);
            assertMethodEquals(pool, m,
                    "setName",
                    "(Ljava/lang/String;)V",
                    "2a2bb5000fb1");
        }
        {
            Method m = methods.get(2);
            assertMethodEquals(pool, m,
                    "setAge",
                    "(I)V",
                    "2a1bb50011b1");
        }
        {
            Method m = methods.get(3);
            assertMethodEquals(pool, m,
                    "sayHello",
                    "()V",
                    "b2001c1222b60024b1");
        }
        {
            Method m = methods.get(4);
            assertMethodEquals(pool, m,
                    "main",
                    "([Ljava/lang/String;)V",
                    "bb000159122b101db7002d4c2bb6002fb1");
        }
    }

    private void assertMethodEquals(ConstantPool pool, Method m, String expectedName, String expectedDesc,
            String expectedCode) {
        String methodName = pool.getUTF8String(m.getNameIndex());
        String methodDesc = pool.getUTF8String(m.getDescriptorIndex());
        String code = m.getCodeAttr().getCode();
        Assert.assertEquals(expectedName, methodName);
        Assert.assertEquals(expectedDesc, methodDesc);
        Assert.assertEquals(expectedCode, code);
    }
}