Javassist：在catch块的开头插入一个方法

Question

我有代码：

ControlFlow cf = new ControlFlow(method);

for (ControlFlow.Block block : cf.basicBlocks()) {
   ControlFlow.Catcher catchBlocks[] = block.catchers();
   for (int i = 0;i < catchBlocks.length;i++) {
      int position = catchBlocks[i].block().position();
      method.insertAt(position, "System.out.println(\"catch block\")")
   }    
}

此代码片段在方法的开头插入打印语句，这不是我想要的。我希望代码像这样放置：

void foo() {
    try {
        a();
    } catch(Exception e) {
        System.out.println("catch block");//inserted by javassist
        b();
    }
}

知道我的代码哪里出错了吗？

更优雅的处理方式

 CtBehavior.instrument(new ExprEditor() {
            @Override
            public void edit(Handler h) throws CannotCompileException {
                if( !h.isFinally()) {
                    h.insertBefore("System.out.println(\"catch block\")");
                }
            }
        });

参考：http://www.javassist.org/tutorial/tutorial2.html#intro

Answer 1

您应该尝试获取您要查找的块的源代码中的行号。

试试这样的东西：

ControlFlow cf = new ControlFlow(method); for (ControlFlow.Block block : cf.basicBlocks()) { ControlFlow.Catcher catchBlocks[] = block.catchers(); for (int i = 0;i < catchBlocks.length;i++) { int position = catchBlocks[i].block().position(); // Get source code line position int lineNumber = method.getMethodInfo().getLineNumber(position ); method.insertAt(lineNumber+1 , "System.out.println(\"catch block\")") } }

Javassist：在catch块的开头插入一个方法

Javassist: insert a method at the beginning of catch block

bytecode

try-catch

javassist