Java Web应用中常见的错误和异常问题处理

Java Web指的是基于Java技术解决互联网Web端的技术，Web由服务器和客户端两部分组成。由于Java Web采用分层思想，在降低软件耦合性的同时增强了其内聚性，但是另一方面却使整个软件开发工作显得复杂并容易出现运行错误。所以错误和异常问题处理是Java语言的重要机制，正确、合理地处理对电脑有着极为重要的作用。进行相应的错误和异常问题处理架构模型的构建式很重要的，本文围绕Java Web应用中错误和异常问题处理，通过对其架构、处理原则、异常处理与实现进行分析和说明。     

Distance-based outliers: algorithms and applications

This paper deals with finding outliers (exceptions) in large, multidimensional datasets. The identification of outliers can lead to the discovery of truly unexpected knowledge in areas such as electronic commerce, credit card fraud, and even the analysis of performance statistics of professional athletes. Existing methods that we have seen for finding outliers can only deal efficiently with two dimensions/attributes of a dataset. In this paper, we study the notion of DB (distance-based) outliers. Specifically, we show that (i) outlier detection can be done efficiently for large datasets, and for k-dimensional datasets with large values of k (e.g., ); and (ii), outlier detection is a meaningful and important knowledge discovery task. First, we present two simple algorithms, both having a complexity of , k being the dimensionality and N being the number of objects in the dataset. These algorithms readily support datasets with many more than two attributes. Second, we present an optimized cell-based algorithm that has a complexity that is linear with respect to N, but exponential with respect to k. We provide experimental results indicating that this algorithm significantly outperforms the two simple algorithms for . Third, for datasets that are mainly disk-resident, we present another version of the cell-based algorithm that guarantees at most three passes over a dataset. Again, experimental results show that this algorithm is by far the best for . Finally, we discuss our work on three real-life applications, including one on spatio-temporal data (e.g., a video surveillance application), in order to confirm the relevance and broad applicability of DB outliers. Received February 15, 1999 / Accepted August 1, 1999     

API文档缺陷自动检测和修复方法

在为了完善应用程序编程接口（application programming interface,API）文档,提出了基于程序静态分析和自然语言处理的自动检测和修复API文档缺陷的方法。该方法能够自动检测和修复API文档缺陷。实验中缺陷检测结果的准确率和召回率分别达到74.6%和81.4%,能够较为准确地检测到Java API的文档缺陷。在进一步的实验中还对API文档的修复功能进行了评估,结果表明生成的文档正确且简洁,可以有效地修复API文档缺陷。     

Unchecked Exceptions Can Be Strictly More Powerful Than Call/CC

We demonstrate that in the context of statically-typed purely-functional lambda calculi without recursion, unchecked exceptions (e.g., SML exceptions) can be strictly more powerful than call/cc. More precisely, we prove that a natural extension of the simply-typed lambda calculus with unchecked exceptions is strictly more powerful than all known sound extensions of Girard's F (a superset of the simply-typed lambda calculus) with call/cc.This result is established by showing that the first language is Turing complete while the later languages permit only a subset of the recursive functions to be written. We show that our natural extension of the simply-typed lambda calculus with unchecked exceptions is Turing complete by reducing the untyped lambda calculus to it by means of a novel method for simulating recursive types using unchecked-exception–returning functions. The result concerning extensions of F with call/cc stems from previous work of the author and Robert Harper.