A Reasonable C++ Wrappered Java Native （一个合理的c++封装Java本机）.pdfVIP

A Reasonable C++ Wrappered Java Native Interface Craig Bordelon Telcordia Technologies, Piscataway, NJ 08854 USA E-mail: cbordelon@ SUMMARY A reasonable C++ Java Native Interface (JNI) technique termed C++ Wrappered JNI (C++WJ) is presented. The technique simplifies current error-prone JNI development by wrappering JNI calls. Provided development is done with the aid of a C++ compiler, C++WJ offers type checking and behind the scenes caching. A tool (jH) patterned on javah automates the creation of C++WJ classes. The paper presents the rationale behind the choices that led to C++WJ. Handling of Java class and interface hierarchy including Java type downcasts is discussed. Efficiency considerations in the C++WJ lead to two flavors of C++ classes: jtypes and Jtypes. A jtype is a lightweight less than full wrapper of a JNI object reference. A Jtype is a heavyweight full wrapper of a JNI object reference. KEY WORDS: Java; JNI; C++; native caching; wrapper classes, templates Introduction Java has emerged as an implementation language of choice for a variety of software applications. Still, at times there is a need to leverage pre-existing C/C++ software or to use low level system specific C/C++ software with Java software. Java and JDK 1.1/1.2 provide the Java nativemodifier and the Java Native Interface6 (JNI) to allow C/C++ use with Java. The JNI, while powerful, lacks some things to make native C/C++ easy to write. This paper rationalizes a technique to create C++ classes as needed to allow for simpler and at the same time efficient native C++ software. The created C++ classes encapsulate JNI calls in an inlinemanner and can sacrifice almost no performance. The