Java ClassFile.read方法代码示例

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
void checkClassFile(final File cfile, String methodToFind, int[][] expectedLNT) throws Exception {
    ClassFile classFile = ClassFile.read(cfile);
    boolean methodFound = false;
    for (Method method : classFile.methods) {
        if (method.getName(classFile.constant_pool).equals(methodToFind)) {
            methodFound = true;
            Code_attribute code = (Code_attribute) method.attributes.get("Code");
            LineNumberTable_attribute lnt =
                    (LineNumberTable_attribute) code.attributes.get("LineNumberTable");
            Assert.check(lnt.line_number_table_length == expectedLNT.length,
                    "The LineNumberTable found has a length different to the expected one");
            int i = 0;
            for (LineNumberTable_attribute.Entry entry: lnt.line_number_table) {
                Assert.check(entry.line_number == expectedLNT[i][0] &&
                        entry.start_pc == expectedLNT[i][1],
                        "LNT entry at pos " + i + " differ from expected." +
                        "Found " + entry.line_number + ":" + entry.start_pc +
                        ". Expected " + expectedLNT[i][0] + ":" + expectedLNT[i][1]);
                i++;
            }
        }
    }
    Assert.check(methodFound, "The seek method was not found");
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
void verifyDefaultBody(String classFile) {
    String workDir = System.getProperty("test.classes");
    File file = new File(workDir, classFile);
    try {
        final ClassFile cf = ClassFile.read(file);
        for (Method m : cf.methods) {
            Code_attribute codeAttr = (Code_attribute)m.attributes.get(Attribute.Code);
            for (Instruction instr : codeAttr.getInstructions()) {
                if (instr.getOpcode() == Opcode.INVOKESPECIAL) {
                    int pc_index = instr.getShort(1);
                    CPRefInfo ref = (CPRefInfo)cf.constant_pool.get(pc_index);
                    String className = ref.getClassName();
                    if (className.equals("BaseInterface"))
                        throw new IllegalStateException("Must not directly refer to TestedInterface");
                }
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
        throw new Error("error reading " + file +": " + e);
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
static void verifyInvokerBytecodeGenerator() throws Exception {
    int count = 0;
    int mcount = 0;
    try (DirectoryStream<Path> ds = newDirectoryStream(new File(".").toPath(),
            // filter in lambda proxy classes
            "A$I$$Lambda$*.class")) {
        for (Path p : ds) {
            System.out.println(p.toFile());
            ClassFile cf = ClassFile.read(p.toFile());
            // Check those methods implementing Supplier.get
            mcount += checkMethod(cf, "get");
            count++;
        }
    }
    if (count < 3) {
        throw new RuntimeException("unexpected number of files, "
                + "expected atleast 3 files, but got only " + count);
    }
    if (mcount < 3) {
        throw new RuntimeException("unexpected number of methods, "
                + "expected atleast 3 methods, but got only " + mcount);
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
private void checkDebugAttributes(byte[] strippedClassFile) throws IOException, ConstantPoolException {
    ClassFile classFile = ClassFile.read(new ByteArrayInputStream(strippedClassFile));
    String[] debugAttributes = new String[]{
            Attribute.LineNumberTable,
            Attribute.LocalVariableTable,
            Attribute.LocalVariableTypeTable
    };
    for (Method method : classFile.methods) {
        String methodName = method.getName(classFile.constant_pool);
        Code_attribute code = (Code_attribute) method.attributes.get(Attribute.Code);
        for (String attr : debugAttributes) {
            if (code.attributes.get(attr) != null) {
                throw new AssertionError("Debug attribute was not removed: " + attr +
                        " from method " + classFile.getName() + "#" + methodName);
            }
        }
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
void checkClassFile(final Path path) throws Exception {
    ClassFile classFile = ClassFile.read(
            new BufferedInputStream(Files.newInputStream(path)));
    constantPool = classFile.constant_pool;
    utf8Index = constantPool.getUTF8Index("STR_TO_LOOK_FOR");
    for (Method method: classFile.methods) {
        if (method.getName(constantPool).equals("methodToLookFor")) {
            Code_attribute codeAtt = (Code_attribute)method.attributes.get(Attribute.Code);
            for (Instruction inst: codeAtt.getInstructions()) {
                inst.accept(codeVisitor, null);
            }
        }
    }
    Assert.check(numberOfRefToStr == 1,
            "There should only be one reference to a CONSTANT_String_info structure in the generated code");
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
public Element readFrom(InputStream in) throws IOException {
    try {
        this.in = in;
        ClassFile c = ClassFile.read(in);
        // read the file header
        if (c.magic != 0xCAFEBABE) {
            throw new RuntimeException("bad magic number " +
                    Integer.toHexString(c.magic));
        }
        cfile.setAttr("magic", "" + c.magic);
        int minver = c.minor_version;
        int majver = c.major_version;
        cfile.setAttr("minver", "" + minver);
        cfile.setAttr("majver", "" + majver);
        readCP(c);
        readClass(c);
        return result();
    } catch (InvalidDescriptor | ConstantPoolException ex) {
        throw new IOException("Fatal error", ex);
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
static void verifyASM() throws Exception {
    ClassWriter cw = new ClassWriter(0);
    cw.visit(V1_8, ACC_PUBLIC, "X", null, "java/lang/Object", null);
    MethodVisitor mv = cw.visitMethod(ACC_STATIC, "foo",
            "()V", null, null);
    mv.visitMaxs(2, 1);
    mv.visitMethodInsn(INVOKESTATIC,
            "java/util/function/Function.class",
            "identity", "()Ljava/util/function/Function;", true);
    mv.visitInsn(RETURN);
    cw.visitEnd();
    byte[] carray = cw.toByteArray();
    // for debugging
    // write((new File("X.class")).toPath(), carray, CREATE, TRUNCATE_EXISTING);

    // verify using javap/classfile reader
    ClassFile cf = ClassFile.read(new ByteArrayInputStream(carray));
    int mcount = checkMethod(cf, "foo");
    if (mcount < 1) {
        throw new RuntimeException("unexpected method count, expected 1" +
                "but got " + mcount);
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
@Test
public void testSimpleAnnotation(Path base) throws Exception {
    Path moduleSrc = base.resolve("module-src");
    Path m1 = moduleSrc.resolve("m1x");

    tb.writeJavaFiles(m1,
                      "@Deprecated module m1x { }");

    Path modulePath = base.resolve("module-path");

    Files.createDirectories(modulePath);

    new JavacTask(tb)
            .options("--module-source-path", moduleSrc.toString())
            .outdir(modulePath)
            .files(findJavaFiles(m1))
            .run()
            .writeAll();

    ClassFile cf = ClassFile.read(modulePath.resolve("m1x").resolve("module-info.class"));
    RuntimeVisibleAnnotations_attribute annotations = (RuntimeVisibleAnnotations_attribute) cf.attributes.map.get(Attribute.RuntimeVisibleAnnotations);

    if (annotations == null || annotations.annotations.length != 1) {
        throw new AssertionError("Annotations not correct!");
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
void checkReference() throws IOException, ConstantPoolException {
    File file = new File("A.class");
    ClassFile classFile = ClassFile.read(file);
    for (int i = 1;
            i < classFile.constant_pool.size() - 1;
            i += classFile.constant_pool.get(i).size()) {
        for (int j = i + classFile.constant_pool.get(i).size();
                j < classFile.constant_pool.size();
                j += classFile.constant_pool.get(j).size()) {
            if (classFile.constant_pool.get(i).toString().
                    equals(classFile.constant_pool.get(j).toString())) {
                throw new AssertionError(
                        "Duplicate entries in the constant pool at positions " +
                        i + " and " + j);
            }
        }
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
static Entry[] findEntries() throws IOException, ConstantPoolException {
    ClassFile self = ClassFile.read(FinallyLineNumberTest.class.getResourceAsStream("FinallyLineNumberTest.class"));
    for (Method m : self.methods) {
        if ("method".equals(m.getName(self.constant_pool))) {
            Code_attribute code_attribute = (Code_attribute)m.attributes.get(Attribute.Code);
            for (Attribute at : code_attribute.attributes) {
                if (Attribute.LineNumberTable.equals(at.getName(self.constant_pool))) {
                    return ((LineNumberTable_attribute)at).line_number_table;
                }
            }
        }
    }
    return null;
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
protected ClassFile readClassFile(JarFile jarfile, JarEntry e) throws IOException {
    InputStream is = null;
    try {
        is = jarfile.getInputStream(e);
        return ClassFile.read(is);
    } catch (ConstantPoolException ex) {
        throw new ClassFileError(ex);
    } finally {
        if (is != null)
            is.close();
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
/**
 * Analyze the dependencies of all classes in the given JAR file. The
 * method updates knownTypes and unknownRefs as part of the analysis.
 */
static void analyzeDependencies(Path jarpath) throws Exception {
    System.out.format("Analyzing %s%n", jarpath);
    try (JarFile jf = new JarFile(jarpath.toFile())) {
        Enumeration<JarEntry> entries = jf.entries();
        while (entries.hasMoreElements()) {
            JarEntry e = entries.nextElement();
            String name = e.getName();
            if (name.endsWith(".class")) {
                ClassFile cf = ClassFile.read(jf.getInputStream(e));
                for (Dependency d : finder.findDependencies(cf)) {
                    String origin = toClassName(d.getOrigin().getName());
                    String target = toClassName(d.getTarget().getName());

                    // origin is now known
                    unknownRefs.remove(origin);
                    knownTypes.add(origin);

                    // if the target is not known then record the reference
                    if (!knownTypes.contains(target)) {
                        Set<String> refs = unknownRefs.get(target);
                        if (refs == null) {
                            // first time seeing this unknown type
                            refs = new HashSet<>();
                            unknownRefs.put(target, refs);
                        }
                        refs.add(origin);
                    }
                }
            }
        }
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
void analyzeClassFile(File path) throws Exception {
    ClassFile classFile = ClassFile.read(path);
    InnerClasses_attribute innerClasses =
            (InnerClasses_attribute) classFile.attributes.get(Attribute.InnerClasses);
    for (Info classInfo : innerClasses.classes) {
        Assert.check(!classInfo.inner_class_access_flags.is(AccessFlags.ACC_STRICT),
                "Inner classes attribute must not have the ACC_STRICT flag set");
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
/** Check the SourceFileAttribute is the simple name of the original source file. */
void verifySourceFileAttribute(File f) {
    System.err.println("verify: " + f);
    try {
        ClassFile cf = ClassFile.read(f);
        SourceFile_attribute sfa = (SourceFile_attribute) cf.getAttribute(Attribute.SourceFile);
        String found = sfa.getSourceFile(cf.constant_pool);
        String expect = f.getName().replaceAll("([$.].*)?\\.class", ".java");
        if (!expect.equals(found)) {
            error("bad value found: " + found + ", expected: " + expect);
        }
    } catch (Exception e) {
        error("error reading " + f +": " + e);
    }
}
 

import com.sun.tools.classfile.ClassFile; //导入方法依赖的package包/类
void checkNoBridgeOnDefaults(File f) {
    System.err.println("check: " + f);
    try {
        ClassFile cf = ClassFile.read(f);
        for (Method m : cf.methods) {
            String mname = m.getName(cf.constant_pool);
            if (mname.equals(TEST_METHOD_NAME)) {
                throw new Error("unexpected bridge method found " + m);
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
        throw new Error("error reading " + f +": " + e);
    }
}