Java Bytecode.addReturn方法代码示例

import scouter.javassist.bytecode.Bytecode; //导入方法依赖的package包/类
/**
 * Creates a public getter method.  The getter method returns the value
 * of the specified field in the class to which this method is added.
 * The created method is initially not static even if the field is
 * static.  Change the modifiers if the method should be static.
 *
 * @param methodName        the name of the getter
 * @param field             the field accessed.
 */
public static CtMethod getter(String methodName, CtField field)
    throws CannotCompileException
{
    FieldInfo finfo = field.getFieldInfo2();
    String fieldType = finfo.getDescriptor();
    String desc = "()" + fieldType;
    ConstPool cp = finfo.getConstPool();
    MethodInfo minfo = new MethodInfo(cp, methodName, desc);
    minfo.setAccessFlags(AccessFlag.PUBLIC);

    Bytecode code = new Bytecode(cp, 2, 1);
    try {
        String fieldName = finfo.getName();
        if ((finfo.getAccessFlags() & AccessFlag.STATIC) == 0) {
            code.addAload(0);
            code.addGetfield(Bytecode.THIS, fieldName, fieldType);
        }
        else
            code.addGetstatic(Bytecode.THIS, fieldName, fieldType);

        code.addReturn(field.getType());
    }
    catch (NotFoundException e) {
        throw new CannotCompileException(e);
    }

    minfo.setCodeAttribute(code.toCodeAttribute());
    CtClass cc = field.getDeclaringClass();
    // a stack map is not needed.
    return new CtMethod(minfo, cc);
}
 

import scouter.javassist.bytecode.Bytecode; //导入方法依赖的package包/类
/**
 * Creates a public setter method.  The setter method assigns the
 * value of the first parameter to the specified field
 * in the class to which this method is added.
 * The created method is not static even if the field is
 * static.  You may not change it to be static
 * by <code>setModifiers()</code> in <code>CtBehavior</code>.
 *
 * @param methodName        the name of the setter
 * @param field             the field accessed.
 */
public static CtMethod setter(String methodName, CtField field)
    throws CannotCompileException
{
    FieldInfo finfo = field.getFieldInfo2();
    String fieldType = finfo.getDescriptor();
    String desc = "(" + fieldType + ")V";
    ConstPool cp = finfo.getConstPool();
    MethodInfo minfo = new MethodInfo(cp, methodName, desc);
    minfo.setAccessFlags(AccessFlag.PUBLIC);

    Bytecode code = new Bytecode(cp, 3, 3);
    try {
        String fieldName = finfo.getName();
        if ((finfo.getAccessFlags() & AccessFlag.STATIC) == 0) {
            code.addAload(0);
            code.addLoad(1, field.getType());
            code.addPutfield(Bytecode.THIS, fieldName, fieldType);
        }
        else {
            code.addLoad(1, field.getType());
            code.addPutstatic(Bytecode.THIS, fieldName, fieldType);
        }

        code.addReturn(null);
    }
    catch (NotFoundException e) {
        throw new CannotCompileException(e);
    }

    minfo.setCodeAttribute(code.toCodeAttribute());
    CtClass cc = field.getDeclaringClass();
    // a stack map is not needed.
    return new CtMethod(minfo, cc);
}
 

import scouter.javassist.bytecode.Bytecode; //导入方法依赖的package包/类
private static CtMethod delegator0(CtMethod delegate, CtClass declaring)
    throws CannotCompileException, NotFoundException
{
    MethodInfo deleInfo = delegate.getMethodInfo2();
    String methodName = deleInfo.getName();
    String desc = deleInfo.getDescriptor();
    ConstPool cp = declaring.getClassFile2().getConstPool();
    MethodInfo minfo = new MethodInfo(cp, methodName, desc);
    minfo.setAccessFlags(deleInfo.getAccessFlags());

    ExceptionsAttribute eattr = deleInfo.getExceptionsAttribute();
    if (eattr != null)
        minfo.setExceptionsAttribute(
                            (ExceptionsAttribute)eattr.copy(cp, null));

    Bytecode code = new Bytecode(cp, 0, 0);
    boolean isStatic = Modifier.isStatic(delegate.getModifiers());
    CtClass deleClass = delegate.getDeclaringClass();
    CtClass[] params = delegate.getParameterTypes();
    int s;
    if (isStatic) {
        s = code.addLoadParameters(params, 0);
        code.addInvokestatic(deleClass, methodName, desc);
    }
    else {
        code.addLoad(0, deleClass);
        s = code.addLoadParameters(params, 1);
        code.addInvokespecial(deleClass, methodName, desc);
    }

    code.addReturn(delegate.getReturnType());
    code.setMaxLocals(++s);
    code.setMaxStack(s < 2 ? 2 : s); // for a 2-word return value
    minfo.setCodeAttribute(code.toCodeAttribute());
    // a stack map is not needed. 
    return new CtMethod(minfo, declaring);
}