JNI有两种基本数据类型基本数据类型和引用数据类型
基本数据类型在jnt.h中可以找到
//如果没在jni_md.中定义好的话
#ifndef JNI_TYPES_ALREADY_DEFINED_IN_JNI_MD_H
//就使用下面的定义
typedef unsigned char jboolean;
typedef unsigned short jchar;
typedef short jshort;
typedef float jfloat;
typedef double jdouble;
typedef jint jsize;
找到jnt_md.h中的数据定义
在jnt_md.h中找到如上定义,根据环境选择数据类型,根据X86架构找到jni_x86.h文件
#ifndef _JAVASOFT_JNI_MD_H_
#define _JAVASOFT_JNI_MD_H_
#if defined(SOLARIS) || defined(LINUX) || defined(_ALLBSD_SOURCE)
// Note: please do not class="superseo">change these without also changing jni_md.h in the JDK
// repository
#ifndef __has_attribute
#define __has_attribute(x) 0
#endif
#if (defined(__GNUC__) && ((__GNUC__ > 4) || (__GNUC__ == 4) && (__GNUC_MINOR__ > 2))) || __has_attribute(visibility)
#define JNIEXPORT __attribute__((visibility("default")))
#define JNIIMPORT __attribute__((visibility("default")))
#else
#define JNIEXPORT
#define JNIIMPORT
#endif
#define JNICALL
typedef int jint;
#if defined(_LP64)
typedef long jlong;
#else
typedef long long jlong;
#endif
#else
#define JNIEXPORT __declspec(dllexport)
#define JNIIMPORT __declspec(dllimport)
#define JNICALL __stdcall
typedef int jint;
typedef __int64 jlong;
#endif
typedef signed char jbyte;
#endif /* !_JAVASOFT_JNI_MD_H_ */
引用数据类型
方法签名时用到的公共体类型
typedef union jvalue {
jboolean z;
jbyte b;
jchar c;
jshort s;
jint i;
jlong j;
jfloat f;
jdouble d;
jobject l;
} jvalue;
属性ID和方法ID的定义
struct _jfieldID;
typedef struct _jfieldID *jfieldID;
struct _jmethodID;
typedef struct _jmethodID *jmethodID;
四种不同引用类型的定义
/* Return values from jobjectRefType */
typedef enum _jobjectType {
JNIInvalidRefType = 0,
JNILocalRefType = 1,
JNIGlobalRefType = 2,
JNIWeakGlobalRefType = 3
} jobjectRefType;
分别为JNIInvalidRefType(无效引用)、JNILocalRefType(本地引用)、JNIWeakGlobalRefType(弱全局引用)和JNIGlobalRefType(全局引用)的枚举类型
JNI错误类型的定义/*
* jboolean constants
*/
#define JNI_FALSE 0
#define JNI_TRUE 1
/*
* possible return values for JNI functions.
*/
#define JNI_OK 0 /* success */
#define JNI_ERR (-1) /* unknown error */
#define JNI_EDETACHED (-2) /* thread detached from the VM */
#define JNI_EVERSION (-3) /* JNI version error */
#define JNI_ENOMEM (-4) /* not enough memory */
#define JNI_EEXIST (-5) /* VM already created */
#define JNI_EINVAL (-6) /* invalid arguments */
/*
* used in ReleaseScalarArrayElements
*/
#define JNI_COMMIT 1
#define JNI_ABORT 2
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