Java JNI full instance from the beginning

Java Call DLL

Preparation stage: 1). Java Environment JDK (in fact this ...)

2). MyEclipse or eclipse (this is your own choice)

3). C language IDE Microsoft Visual c++6.0 (This can also be your own choice)

The tools used in the following steps are used in my own case

First step: Open Eclipse Build Project: generate a communication contract interface between Java and C

Step two: Find the Eclipse directory space where the project is located, view in properties (Eclipse presses shortcut key Alt+enter)

Then open cmd to switch directories to the Helloworld.java directory, for example, my directory is "E:\workspace\JavadllDemo\src\" and then use the Javah name to generate the header file to be used when C is compiled:

Step three: Write our DLL file, open Microsoft Visual c++6.0

After the establishment, in the E:\WORKSPACE\JAVADLLDEMO\SRC directory just below the generated HelloWorld.h file copied to the C workspace, However, because the compiler can be called by the Java program can also be called by the C program DLL time also need two header files, one is jni.h one is jni_md.h

These two files are located in the Include folder in your JDK installation directory java_home\jdk1.6.0_17\include\jni.h, java_home\jdk1.6.0_17\include\win32\jni_md.h

To copy these two files and HelloWorld.h altogether three files into the workspace of the C project, and after copying to the C project workspace, you need to change the HelloWorld header file Introduction method to change # include <jni.h> to #include "Jni.h" finally:

Fourth step: Write the DLL inside the function to be called by Java

HelloWorld.cpp:Defines the entry point for the DLL application.//#include "HelloWorld.h"/* * Class:     HelloWorld * Method:    init * Signature: (i) I */jniexport jint jnicall java_helloworld_init (jnienv *env, Jobject job, Jint Lport) {in T number=10; Number+=lport; return number;} /* Class:     HelloWorld * Method:    print * Signature: (ljava/lang/string;) V */jniexport void Jnicall java_helloworl D_print (jnienv *env, Jobject job, jstring str) {printf ("%d\n", str);}

As shown in the following:

The final build compiles our DLLs (first reorganized, compiled) such as:

This error may occur during the compilation process: Unexpected end of file while looking for precompiled header directive workaround such as:

As set after the compilation, if the prompt is not wrong, it means that the compilation is successful!

After compiling, we will find HelloWorld.dll in our C Project Workspace Debug folder, when we copy this HelloWorld.dll to the Lib file in our Java project.

Java JNI full instance from the beginning