ClassFileLoaderTest.java

package com.pan.jvm;

import java.util.List;

import com.pan.jvm.clz.ClassFile;
import com.pan.jvm.clz.ClassIndex;
import com.pan.jvm.cmd.BiPushCmd;
import com.pan.jvm.cmd.ByteCodeCommand;
import com.pan.jvm.cmd.OneOperandCmd;
import com.pan.jvm.cmd.TwoOperandCmd;
import com.pan.jvm.constant.*;
import com.pan.jvm.field.Field;
import com.pan.jvm.loader.ClassFileLoader;
import com.pan.jvm.method.Method;
import com.pan.jvm.util.Util;
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/pan/jvm/EmployeeV1";

    static String path1 = EmployeeV1.class.getClassLoader().getResource("").getPath()
            .replace("test-classes", "classes");
    static String path2 = "C:/temp";

    static ClassFile clzFile = null;

    static {
        ClassFileLoader loader = new ClassFileLoader();
        loader.addClassPath(path1);
        String className = "com.pan.jvm.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.pan.jvm.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(1032, byteCodes.length);

    }


    @Test
    public void testMagicNumber() {
        ClassFileLoader loader = new ClassFileLoader();
        loader.addClassPath(path1);
        String className = "com.pan.jvm.EmployeeV1";
        byte[] byteCodes = loader.readBinaryCode(className);
        byte[] codes = new byte[]{byteCodes[0], byteCodes[1], byteCodes[2], byteCodes[3]};


        String actualValue = Util.byteToHexString(codes);

        Assert.assertEquals("cafebabe", actualValue);
    }


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


    @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);
    }

    @Test
    public void testByteCodeCommand() {
        {
            Method initMethod = this.clzFile.getMethod("<init>", "(Ljava/lang/String;I)V");
            ByteCodeCommand[] cmds = initMethod.getCmds();

            assertOpCodeEquals("0: aload_0", cmds[0]);
            assertOpCodeEquals("1: invokespecial #12", cmds[1]);
            assertOpCodeEquals("4: aload_0", cmds[2]);
            assertOpCodeEquals("5: aload_1", cmds[3]);
            assertOpCodeEquals("6: putfield #15", cmds[4]);
            assertOpCodeEquals("9: aload_0", cmds[5]);
            assertOpCodeEquals("10: iload_2", cmds[6]);
            assertOpCodeEquals("11: putfield #17", cmds[7]);
            assertOpCodeEquals("14: return", cmds[8]);
        }

        {
            Method setNameMethod = this.clzFile.getMethod("setName", "(Ljava/lang/String;)V");
            ByteCodeCommand[] cmds = setNameMethod.getCmds();

            assertOpCodeEquals("0: aload_0", cmds[0]);
            assertOpCodeEquals("1: aload_1", cmds[1]);
            assertOpCodeEquals("2: putfield #15", cmds[2]);
            assertOpCodeEquals("5: return", cmds[3]);

        }

        {
            Method sayHelloMethod = this.clzFile.getMethod("sayHello", "()V");
            ByteCodeCommand[] cmds = sayHelloMethod.getCmds();

            assertOpCodeEquals("0: getstatic #28", cmds[0]);
            assertOpCodeEquals("3: ldc #34", cmds[1]);
            assertOpCodeEquals("5: invokevirtual #36", cmds[2]);
            assertOpCodeEquals("8: return", cmds[3]);

        }

        {
            Method mainMethod = this.clzFile.getMainMethod();

            ByteCodeCommand[] cmds = mainMethod.getCmds();

            assertOpCodeEquals("0: new #1", cmds[0]);
            assertOpCodeEquals("3: dup", cmds[1]);
            assertOpCodeEquals("4: ldc #43", cmds[2]);
            assertOpCodeEquals("6: bipush 29", cmds[3]);
            assertOpCodeEquals("8: invokespecial #45", cmds[4]);
            assertOpCodeEquals("11: astore_1", cmds[5]);
            assertOpCodeEquals("12: aload_1", cmds[6]);
            assertOpCodeEquals("13: invokevirtual #47", cmds[7]);
            assertOpCodeEquals("16: return", cmds[8]);
        }

    }

    private void assertOpCodeEquals(String expected, ByteCodeCommand cmd) {

        String acctual = cmd.getOffset() + ": " + cmd.getReadableCodeText();

        if (cmd instanceof OneOperandCmd) {
            if (cmd instanceof BiPushCmd) {
                acctual += " " + ((OneOperandCmd) cmd).getOperand();
            } else {
                acctual += " #" + ((OneOperandCmd) cmd).getOperand();
            }
        }
        if (cmd instanceof TwoOperandCmd) {
            acctual += " #" + ((TwoOperandCmd) cmd).getIndex();
        }
        Assert.assertEquals(expected, acctual);
    }

}