JNI方法签名规则

本文讲解不使用javah命令怎么将.java文件生成相对应的.h文件

首先看看签名表

例子（主要为同名函数的类型签名）

java代码

public class TestJni
{
    /*验证同名函数*/
    public native long print(byte b,int i);
    public native long print(long l, double d);
    
    /*验证下划线*/
    public native void print_m();
    public native void print_m(long m);
    
    /*验证"/"和";"*/
    public native int print();
    public native short print(String s);
}

生成的h头文件（代码中有注释说明）

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class TestJni */

#ifndef _Included_TestJni
#define _Included_TestJni
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     TestJni
 * Method:    print
 * Signature: (BI)J
 */
/*BI分别表示参数byte,int的签名*/
JNIEXPORT jlong JNICALL Java_TestJni_print__BI 
  (JNIEnv *, jobject, jbyte, jint);

/*
 * Class:     TestJni
 * Method:    print
 * Signature: (JD)J
 */
/*JD分别表示参数long,double的签名*/
JNIEXPORT jlong JNICALL Java_TestJni_print__JD
  (JNIEnv *, jobject, jlong, jdouble);

/*
 * Class:     TestJni
 * Method:    print_m
 * Signature: ()V
 */
/*_1表示_的签名*/
JNIEXPORT void JNICALL Java_TestJni_print_1m__
  (JNIEnv *, jobject);

/*
 * Class:     TestJni
 * Method:    print_m
 * Signature: (J)V
 */
JNIEXPORT void JNICALL Java_TestJni_print_1m__J
  (JNIEnv *, jobject, jlong);

/*
 * Class:     TestJni
 * Method:    print
 * Signature: ()I
 */
JNIEXPORT jint JNICALL Java_TestJni_print__
  (JNIEnv *, jobject);

/*
 * Class:     TestJni
 * Method:    print
 * Signature: (Ljava/lang/String;)S
 */
/*Ljava/lang/String;表示String的签名，然后在函数中"/"变成"_"，";"变成"_2"*/
JNIEXPORT jshort JNICALL Java_TestJni_print__Ljava_lang_String_2
  (JNIEnv *, jobject, jstring);

#ifdef __cplusplus
}
#endif
#endif

在知道规则后，那么代码的生成只不过是字符串的拼接了，剩下的交给你们自己练手吧