JNI——结构体（即java中的类）的传入与设置——NativeMethod映射表
时间：2014-05-09 00:10:19
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参考：http://www.cnblogs.com/skywang12345/archive/2013/05/26/3093593.html
java 类:
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package
com.skywang.ndk;public class MyInfo { private
String mName; private
int mAge; private
float mHeight; public
String toString(){ return
"mName:"+mName+", mAge:"+mAge+", mHeight:"+mHeight; }}============================================Person.java: package
com.skywang.ndk;public
class Person { private
String mName; private
int mAge; private
float mHeight; public
String toString(){ return
"mName:"+mName+", mAge:"+mAge+", mHeight:"+mHeight; }} |
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package
com.skywang.ndk;import android.app.Activity;import android.os.Bundle;import android.util.Log;public class NdkParam extends
Activity { public
static final String TAG="skywang--NdkParam"; public
static final String TAG_MY="MY_skywang--NdkParam"; /** Called when the activity is first created. */ private
Person person=null; private
MyInfo myinfo = null; @Override public
void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Log.d(TAG, "on create."); person = new
Person(); for
(int i=0; i<3; i++) { getPersonInfoByIndex(person, i); Log.d(TAG, "person["+i+"] -- "+person); } Log.d(TAG, "==============================》MyInfo.《=================================="); myinfo = new
MyInfo(); for
(int i=0; i<3; i++) { getMyInfoByIndex(myinfo, i); Log.d(TAG, "myinfo["+i+"] -- "+myinfo); } } // jni private
native int getPersonInfoByIndex(Person person, int
index); private
native int getMyInfoByIndex(MyInfo myinfo, int
index); static
{ //System.loadLibrary("ndk_param"); System.loadLibrary("ndk_param"); }} |
JNI:
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头文件：#include <stdlib.h>#include <string.h>#include <stdio.h>#include <jni.h>#include <assert.h>// 获取数组的大小# define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))// 指定要注册的类，对应完整的java类名#define JNIREG_CLASS "com/skywang/ndk/NdkParam"#define JNIPAR_CLASS "com/skywang/ndk/Person"#define JNIPAR_CLASS_MYINFO "com/skywang/ndk/MyInfo"// 引入log头文件#include <android/log.h> // log标签#define TAG "hello_param"// 定义info信息#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,TAG,__VA_ARGS__)// 定义debug信息#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__)// 定义error信息#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,TAG,__VA_ARGS__)// jfieldID结构体，用于保存类“Person.java”的filedIDstruct
PersonOffsets{ jfieldID name; jfieldID age; jfieldID height;} gPersonOffsets;struct
MyInfoOffsets{ jfieldID name; jfieldID age; jfieldID height;} gMyInfoOffsets;// 与“Person.java”对应的结构体，用于保存数据，并将数据赋值给Person.java的成员typedef
struct tagPerson{ char
mName[10]; int
mAge; float
mHeight;}Person;typedef
struct tagMyInfo{ char
mName[10]; int
mAge; float
mHeight;}MyInfo;// 定义了3个Personstatic
Person gPersons[] = { {"skywang", 25, 175}, {"eman"
, 30, 166}, {"Dan"
, 51, 172},};static
MyInfo gMyInfos[] = { {"liu", 25, 175}, {"gang"
, 30, 166}, {"hong"
, 51, 172},};#define GPERSON_NUM NELEM(gPersons)#define GMYINFO_NUM NELEM(gMyInfos) |
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c文件：#include "ndk_param.h"/* * 根据index获取Person信息。 * 参数说明： * env : JNI 接口指针。 * claszz : Java 类对象。 * person : 输入参数，java对象 * index : 输入参数，序列号。 */JNIEXPORT jint JNICALL getPersonInfoByIndex(JNIEnv *env, jobject clazz, jobject person, jint index){ // 若index无效，则直接返回-1。 if
((int)index<0 || (int)index>=GPERSON_NUM) return
-1; // 将Person数组(gPersons)中的第index个成员赋值给pPerson指针 Person *pPerson = &gPersons[index]; // 设置java对象person的mName jstring name = (*env)->NewStringUTF(env, pPerson->mName); (*env)->SetObjectField(env, person, gPersonOffsets.name, name); // 设置java对象person的mAge (*env)->SetIntField(env, person, gPersonOffsets.age, pPerson->mAge); // 设置java对象person的mHeight (*env)->SetFloatField(env, person, gPersonOffsets.height, pPerson->mHeight); LOGD("%s index-%d mName:%s, mAge:%d, mHeight:%f\n", __func__, index, pPerson->mName, pPerson->mAge, pPerson->mHeight); return
0;}JNIEXPORT jint JNICALL getMyInfoByIndex(JNIEnv *env, jobject clazz, jobject myinfo, jint index){ // 若index无效，则直接返回-1。 if
((int)index<0 || (int)index>=GMYINFO_NUM) return
-1; // 将Person数组(gPersons)中的第index个成员赋值给pPerson指针 MyInfo *pMyInfo = &gMyInfos[index]; // 设置java对象person的mName jstring name = (*env)->NewStringUTF(env, pMyInfo->mName); (*env)->SetObjectField(env, myinfo, gMyInfoOffsets.name, name); // 设置java对象person的mAge (*env)->SetIntField(env, myinfo, gMyInfoOffsets.age, pMyInfo->mAge); // 设置java对象person的mHeight (*env)->SetFloatField(env, myinfo, gMyInfoOffsets.height, pMyInfo->mHeight); LOGD("%s index-%d mName:%s, mAge:%d, mHeight:%f\n", __func__, index, pMyInfo->mName, pMyInfo->mAge, pMyInfo->mHeight); return
0;}// 初始化函数，用于获取Java中各个成员对应的fieldID。static
void nativeClassInit (JNIEnv *env){ jclass personClass = (*env)->FindClass(env, JNIPAR_CLASS); jclass myinfoClass = (*env)->FindClass(env, JNIPAR_CLASS_MYINFO); // 获取Person的mName成员对应的FieldID，并保存到gPersonOffsets中 gPersonOffsets.name = (*env)->GetFieldID(env, personClass, "mName"
, "Ljava/lang/String;"); gMyInfoOffsets.name = (*env)->GetFieldID(env, myinfoClass, "mName"
, "Ljava/lang/String;"); // 获取Person的mAge成员对应的FieldID，并保存到gPersonOffsets中 gPersonOffsets.age = (*env)->GetFieldID(env, personClass, "mAge"
, "I"); gMyInfoOffsets.age = (*env)->GetFieldID(env, myinfoClass, "mAge"
, "I"); // 获取Person的mHeight成员对应的FieldID，并保存到gPersonOffsets中 gPersonOffsets.height = (*env)->GetFieldID(env, personClass, "mHeight", "F"); gMyInfoOffsets.height = (*env)->GetFieldID(env, myinfoClass, "mHeight", "F");}// Java和JNI函数的绑定表static
JNINativeMethod method_table[] = { { "getPersonInfoByIndex", "(Lcom/skywang/ndk/Person;I)I", (void*)getPersonInfoByIndex },//绑定 { "getMyInfoByIndex", "(Lcom/skywang/ndk/MyInfo;I)I", (void*)getMyInfoByIndex },//绑定 };// 注册native方法到java中static
int registerNativeMethods(JNIEnv* env, const
char* className, JNINativeMethod* gMethods, int
numMethods){ jclass clazz; clazz = (*env)->FindClass(env, className); if
(clazz == NULL) { return
JNI_FALSE; } if
((*env)->RegisterNatives(env, clazz, gMethods, numMethods) < 0) { return
JNI_FALSE; } return
JNI_TRUE;}int
register_ndk_param(JNIEnv *env){ nativeClassInit(env); // 调用注册方法 return
registerNativeMethods(env, JNIREG_CLASS, method_table, NELEM(method_table));}// JNI_OnLoad在jni注册时，会被回调执行。JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved){ JNIEnv* env = NULL; jint result = -1; if
((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_4) != JNI_OK) { return
result; } register_ndk_param(env); // 返回jni的版本 return
JNI_VERSION_1_4;} |
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