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JMockit is a Java toolkit for automated developer testing.
It contains mocking/faking APIs and a code coverage tool, supporting both JUnit and TestNG.
The mocking APIs allow all kinds of Java code, without testability restrictions, to be tested
in isolation from selected dependencies.
package mockit.asm;
import javax.annotation.*;
/**
* A Java class parser to make a {@link ClassVisitor} visit an existing class.
* This class parses a byte array conforming to the Java class file format and calls the appropriate visit methods of a
* given class visitor for each field, method and bytecode instruction encountered.
*/
public final class ClassReader extends AnnotatedReader
{
public interface Flags {
/**
* Flag to skip method code. If this class is set CODE attribute won't be visited.
* This can be used, for example, to retrieve annotations for methods and method parameters.
*/
int SKIP_CODE = 1;
/**
* Flag to skip the debug information in the class. If this flag is set the debug information of the class is not
* visited, i.e. the {@link MethodVisitor#visitLocalVariable} and {@link MethodVisitor#visitLineNumber} methods
* will not be called.
*/
int SKIP_DEBUG = 2;
int SKIP_CODE_DEBUG = SKIP_CODE + SKIP_DEBUG;
int SKIP_INNER_CLASSES = 4;
}
private static final String[] NO_INTERFACES = {};
/**
* Start index of the class header information (access, name...) in {@link #code}.
*/
@Nonnegative final int header;
ClassVisitor cv;
@Nonnegative int flags;
@Nonnull private String[] interfaces = NO_INTERFACES;
@Nullable private String sourceFileName;
@Nullable private EnclosingMethod enclosingMethod;
@Nonnegative private int innerClassesCodeIndex;
@Nonnegative private int attributesCodeIndex;
/**
* The start index of each bootstrap method.
*/
@Nullable int[] bootstrapMethods;
/**
* Initializes a new class reader with the given bytecode array for a classfile.
*/
public ClassReader(@Nonnull byte[] code) {
super(code);
header = codeIndex; // the class header information starts just after the constant pool
}
/**
* Returns the classfile version of the class being read (see {@link ClassVersion}).
*/
public int getVersion() {
codeIndex = 6;
return readShort();
}
/**
* Returns the class's access flags (see {@link Access}).
*/
public int getAccess() {
codeIndex = header;
return readUnsignedShort();
}
/**
* Returns the internal of name of the super class. For interfaces, the super class is {@link Object}.
*/
@Nonnull
public String getSuperName() {
codeIndex = header + 4;
return readNonnullClass();
}
/**
* Returns the bytecode array of the Java classfile that was read.
*/
@Nonnull
public byte[] getBytecode() { return code; }
/**
* Makes the given visitor visit the Java class of this Class Reader, all attributes included.
*/
public void accept(ClassVisitor cv) {
accept(cv, 0);
}
/**
* Makes the given visitor visit the Java class of this Class Reader.
*
* @param cv the visitor that must visit this class.
* @param flags option flags that can be used to modify the default behavior of this class. See {@link Flags}.
*/
public void accept(@Nonnull ClassVisitor cv, @Nonnegative int flags) {
this.cv = cv;
this.flags = flags;
int version = getVersion();
codeIndex = header;
access = readUnsignedShort();
String classDesc = readNonnullClass();
String superClassDesc = readClass();
readInterfaces();
readClassAttributes();
cv.visit(version, access, classDesc, signature, superClassDesc, interfaces);
visitSourceFileName();
visitOuterClass();
readAnnotations(cv);
readInnerClasses();
readFieldsAndMethods();
cv.visitEnd();
}
private void readInterfaces() {
int interfaceCount = readUnsignedShort();
if (interfaceCount > 0) {
interfaces = new String[interfaceCount];
for (int i = 0; i < interfaceCount; i++) {
interfaces[i] = readNonnullClass();
}
}
}
private void readClassAttributes() {
sourceFileName = null;
enclosingMethod = null;
innerClassesCodeIndex = 0;
codeIndex = getAttributesStartIndex();
readAttributes();
}
@Nullable @Override
Boolean readAttribute(@Nonnull String attributeName) {
if ("SourceFile".equals(attributeName)) {
sourceFileName = readNonnullUTF8();
return true;
}
if ("EnclosingMethod".equals(attributeName)) {
enclosingMethod = new EnclosingMethod(this);
return true;
}
if ("BootstrapMethods".equals(attributeName)) {
readBootstrapMethods();
return true;
}
if ("InnerClasses".equals(attributeName)) {
if ((flags & Flags.SKIP_INNER_CLASSES) == 0) {
innerClassesCodeIndex = codeIndex;
}
return false;
}
return null;
}
private void readBootstrapMethods() {
int bsmCount = readUnsignedShort();
bootstrapMethods = new int[bsmCount];
for (int i = 0; i < bsmCount; i++) {
bootstrapMethods[i] = codeIndex;
codeIndex += 2;
int codeOffset = readUnsignedShort();
codeIndex += codeOffset << 1;
}
}
private void visitSourceFileName() {
if ((flags & Flags.SKIP_DEBUG) == 0) {
cv.visitSource(sourceFileName);
}
}
private void visitOuterClass() {
if (enclosingMethod != null) {
cv.visitOuterClass(enclosingMethod.owner, enclosingMethod.name, enclosingMethod.desc);
}
}
private void readInnerClasses() {
int startIndex = innerClassesCodeIndex;
if (startIndex != 0) {
codeIndex = startIndex;
for (int innerClassCount = readUnsignedShort(); innerClassCount > 0; innerClassCount--) {
String name = readNonnullClass();
String outerName = readClass();
String innerName = readUTF8();
int access = readUnsignedShort();
cv.visitInnerClass(name, outerName, innerName, access);
}
}
}
private void readFieldsAndMethods() {
codeIndex = getCodeIndexAfterInterfaces(interfaces.length);
FieldReader fieldReader = new FieldReader(this);
codeIndex = fieldReader.readFields();
MethodReader methodReader = new MethodReader(this);
codeIndex = methodReader.readMethods();
}
@Nonnegative
private int getCodeIndexAfterInterfaces(@Nonnegative int interfaceCount) { return header + 8 + 2 * interfaceCount; }
/**
* Returns the start index of the attribute_info structure of this class.
*/
@Nonnegative
private int getAttributesStartIndex() {
if (attributesCodeIndex == 0) {
skipHeader();
skipClassMembers(); // fields
skipClassMembers(); // methods
attributesCodeIndex = codeIndex;
}
return attributesCodeIndex;
}
private void skipHeader() {
int interfaceCount = readUnsignedShort(header + 6);
codeIndex = getCodeIndexAfterInterfaces(interfaceCount);
}
private void skipClassMembers() {
for (int memberCount = readUnsignedShort(); memberCount > 0; memberCount--) {
codeIndex += 6; // skips access, name and desc
skipMemberAttributes();
}
}
private void skipMemberAttributes() {
for (int attributeCount = readUnsignedShort(); attributeCount > 0; attributeCount--) {
codeIndex += 2; // skips attribute name
int codeOffsetToNextAttribute = readInt();
codeIndex += codeOffsetToNextAttribute;
}
}
boolean positionAtBootstrapMethodsAttribute() {
codeIndex = getAttributesStartIndex();
for (int attributeCount = readUnsignedShort(); attributeCount > 0; attributeCount--) {
String attrName = readNonnullUTF8();
if ("BootstrapMethods".equals(attrName)) {
return true;
}
int codeOffsetToNextAttribute = readInt();
codeIndex += codeOffsetToNextAttribute;
}
return false;
}
}