org.objectweb.asm

Class ClassWriter

public class ClassWriter extends Object implements ClassVisitor

A {@link ClassVisitor ClassVisitor} that generates Java class files. More precisely this visitor generates a byte array conforming to the Java class file format. It can be used alone, to generate a Java class "from scratch", or with one or more {@link ClassReader ClassReader} and adapter class visitor to generate a modified class from one or more existing Java classes.

Author: Eric Bruneton

Constructor Summary
ClassWriter(boolean computeMaxs)
Constructs a new {@link ClassWriter ClassWriter} object.
ClassWriter(boolean computeMaxs, boolean skipUnknownAttributes)
Constructs a new {@link ClassWriter ClassWriter} object.
Method Summary
intnewClass(String value)
Adds a class reference to the constant pool of the class being build.
intnewConst(Object cst)
Adds a number or string constant to the constant pool of the class being build.
intnewConstDouble(double d)
intnewConstFloat(float f)
intnewConstInt(int i)
intnewConstLong(long l)
intnewField(String owner, String name, String desc)
Adds a field reference to the constant pool of the class being build.
intnewMethod(String owner, String name, String desc, boolean itf)
Adds a method reference to the constant pool of the class being build.
intnewNameType(String name, String desc)
Adds a name and type to the constant pool of the class being build.
intnewUTF8(String value)
Adds an UTF8 string to the constant pool of the class being build.
byte[]toByteArray()
Returns the bytecode of the class that was build with this class writer.
voidvisit(int version, int access, String name, String superName, String[] interfaces, String sourceFile)
voidvisitAttribute(Attribute attr)
voidvisitEnd()
voidvisitField(int access, String name, String desc, Object value, Attribute attrs)
voidvisitInnerClass(String name, String outerName, String innerName, int access)
CodeVisitorvisitMethod(int access, String name, String desc, String[] exceptions, Attribute attrs)

Constructor Detail

ClassWriter

public ClassWriter(boolean computeMaxs)
Constructs a new {@link ClassWriter ClassWriter} object.

Parameters: computeMaxs true if the maximum stack size and the maximum number of local variables must be automatically computed. If this flag is true, then the arguments of the {@link CodeVisitor#visitMaxs visitMaxs} method of the {@link CodeVisitor CodeVisitor} returned by the {@link #visitMethod visitMethod} method will be ignored, and computed automatically from the signature and the bytecode of each method.

ClassWriter

public ClassWriter(boolean computeMaxs, boolean skipUnknownAttributes)
Constructs a new {@link ClassWriter ClassWriter} object.

Parameters: computeMaxs true if the maximum stack size and the maximum number of local variables must be automatically computed. If this flag is true, then the arguments of the {@link CodeVisitor#visitMaxs visitMaxs} method of the {@link CodeVisitor CodeVisitor} returned by the {@link #visitMethod visitMethod} method will be ignored, and computed automatically from the signature and the bytecode of each method. skipUnknownAttributes true to silently ignore unknown attributes, or false to throw an exception if an unknown attribute is found.

Method Detail

newClass

public int newClass(String value)
Adds a class reference to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for {@link Attribute} sub classes, and is normally not needed by class generators or adapters.

Parameters: value the internal name of the class.

Returns: the index of a new or already existing class reference item.

newConst

public int newConst(Object cst)
Adds a number or string constant to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for {@link Attribute} sub classes, and is normally not needed by class generators or adapters.

Parameters: cst the value of the constant to be added to the constant pool. This parameter must be an {@link java.lang.Integer Integer}, a {@link java.lang.Float Float}, a {@link java.lang.Long Long}, a {@link java.lang.Double Double} or a {@link String String}.

Returns: the index of a new or already existing constant item with the given value.

newConstDouble

public int newConstDouble(double d)

newConstFloat

public int newConstFloat(float f)

newConstInt

public int newConstInt(int i)

newConstLong

public int newConstLong(long l)

newField

public int newField(String owner, String name, String desc)
Adds a field reference to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for {@link Attribute} sub classes, and is normally not needed by class generators or adapters.

Parameters: owner the internal name of the field's owner class. name the field's name. desc the field's descriptor.

Returns: the index of a new or already existing field reference item.

newMethod

public int newMethod(String owner, String name, String desc, boolean itf)
Adds a method reference to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for {@link Attribute} sub classes, and is normally not needed by class generators or adapters.

Parameters: owner the internal name of the method's owner class. name the method's name. desc the method's descriptor. itf true if owner is an interface.

Returns: the index of a new or already existing method reference item.

newNameType

public int newNameType(String name, String desc)
Adds a name and type to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for {@link Attribute} sub classes, and is normally not needed by class generators or adapters.

Parameters: name a name. desc a type descriptor.

Returns: the index of a new or already existing name and type item.

newUTF8

public int newUTF8(String value)
Adds an UTF8 string to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for {@link Attribute} sub classes, and is normally not needed by class generators or adapters.

Parameters: value the String value.

Returns: the index of a new or already existing UTF8 item.

toByteArray

public byte[] toByteArray()
Returns the bytecode of the class that was build with this class writer.

Returns: the bytecode of the class that was build with this class writer.

visit

public void visit(int version, int access, String name, String superName, String[] interfaces, String sourceFile)

visitAttribute

public void visitAttribute(Attribute attr)

visitEnd

public void visitEnd()

visitField

public void visitField(int access, String name, String desc, Object value, Attribute attrs)

visitInnerClass

public void visitInnerClass(String name, String outerName, String innerName, int access)

visitMethod

public CodeVisitor visitMethod(int access, String name, String desc, String[] exceptions, Attribute attrs)