编译后的Java类文件很容易被反编译，在Java应用上会产生源代码的安全问题。该文对传统的Java类文件保护方法进行分析，在类加载器（ClassLoader）加密技术的基础上，提出一种使用JNI技术调用本地解密接13的改进方法。解密接口在设计上保证了JNI技术调用本地解密接口时的通信安全，从而提升了Java类文件的安全性。实验结果表明，该方法是有效的。-Compiled Java class files can easily be decompiled, in the Java application will produce the source code security issues. In this paper, the traditional method of Java class file protection analysis in the class loader (ClassLoader) encryption technology, based on the use of JNI technology presents a call to a local pick 13 of the improved method decryption. Decryption interface is designed to ensure the JNI interface technology, called a local decryption of communications security, thus enhancing the security of Java class files. The experimental results show that the method is effective.