不啰嗦直接上代碼（在這里貼一部分代碼，如果要源碼，點擊最后的連接去下載）
1.eclipse使用.dll庫調用
/*
返回字符給java層
*/
JNIEXPORT jstring JNICALL Java_com_zack_jni_JniDemo_getStringJniOne
(JNIEnv * env, jclass jclz){
return (*env)->NewStringUTF(env, "hello Wrold");
}
/* 返回一個不是static 的*/
JNIEXPORT jstring JNICALL Java_com_zack_jni_JniDemo_getNoStaticString
(JNIEnv * env, jobject jobj){
return (*env)->NewStringUTF(env, "no static ");
}
/* 通過 方法來改變 里面的的值*/
JNIEXPORT jstring JNICALL Java_com_zack_jni_JniDemo_accessField
(JNIEnv * env, jobject jobj){
jclass jcl = (*env)->GetObjectClass(env, jobj);
jfieldID fid = (*env)->GetFieldID(env, jcl, "key", "Ljava/lang/String;");
// 得到key 對應的值
// GetXXXField
jstring jstr=(*env)->GetObjectField(env, jobj, fid);
// jni -> c
char * c_str = (*env)->GetStringUTFChars(env, jstr, NULL);
char tempString[30] = "zack";
strcat(tempString, c_str);
jstring newString = (*env)->NewStringUTF(env, tempString);
(*env)->SetObjectField(env, jobj, fid, newString);
(*env)->ReleaseStringUTFChars(env, newString, c_str);
return newString;
//// jclass
//jclass jclz = (*env)->GetObjectClass(env, jobj);
//// fieldId 屬性名稱，屬性簽名
//jfieldID fid = (*env)->GetFieldID(env, jclz, "key", "Ljava/lang/String;");
//// key -> dongNao key
//// 得到key 對應的值
//// GetXXXField
//jstring jstr = (*env)->GetObjectField(env, jobj, fid);
//// jni -> c
//char * c_str = (*env)->GetStringUTFChars(env, jstr, NULL);
//char text[30] = "dongNao";
//// 生成新的字符串 dongNao key
//strcat(text, c_str);
//// C -> jni
//jstring new_str = (*env)->NewStringUTF(env, text);
////setXXXField
//(*env)->SetObjectField(env, jobj, fid, new_str);
//(*env)->ReleaseStringChars(env, new_str, c_str);
//return new_str;
}
/* 改變 java 成的靜態值 */
JNIEXPORT void JNICALL Java_com_zack_jni_JniDemo_accessStaticField
(JNIEnv * env, jobject jobj){
jclass jcl = (*env)->GetObjectClass(env, jobj);
jfieldID fid=(*env)->GetStaticFieldID(env, jcl, "count", "I");
jint count = (*env)->GetStaticIntField(env, jobj, fid);
count++;
(*env)->SetStaticIntField(env, jcl, fid, count);
}
// 中文的處理
JNIEXPORT jobject JNICALL Java_com_zack_jni_JniDemo_chineseChars
(JNIEnv * env, jobject jobj,jstring in){
}
AS 動態注冊：
static? const JNINativeMethod getMethod[]= {
{
"diff", "(Ljava/lang/String;Ljava/lang/String;I)V", (void *) native_zack_diff
}
,{
"getString","()Ljava/lang/String;",(void*)native_java_str
}
,{
"getNoStaticString","()Ljava/lang/String;",(void*)native_no_static
},
{
"accessField","()Ljava/lang/String;",(void*)change_zack_key
},
{
"chineseChars","(Ljava/lang/String;)Ljava/lang/String;",(void*)getchineseChars
},
{
"acceessConstructor","()Ljava/util/Date;",(void*)zack_getDate
},
{
"getStudentName","()Ljava/lang/String;",(void*)zack_getStudentName
}
};
static int registerNatives(JNIEnv* engv)
{
LOGI("registerNatives begin");
jclass? clazz;
clazz = (*engv) -> FindClass(engv, "com/zack/banner/FileUtils");
if (clazz == NULL) {
LOGI("clazz is null");
return JNI_FALSE;
}
if ((*engv) ->RegisterNatives(engv, clazz, getMethod, NELEM(getMethod)) < 0) {
LOGI("RegisterNatives error");
return JNI_FALSE;
}
return JNI_TRUE;
}
//JNI_OnLoad
JNIEXPORT jint JNI_OnLoad(JavaVM *vm,void* reserved){
LOGI("jni_OnLoad begin");
JNIEnv* env = NULL;
if ((*vm)->GetEnv(vm,(void**) &env, JNI_VERSION_1_4) != JNI_OK) {
LOGI("ERROR: GetEnv failed\n");
return -1;
}
assert(env != NULL);
registerNatives(env);
return? JNI_VERSION_1_4;
}
#include "com_zack_banner_FileUtils.h"#include#include#include "assert.h"#include#define? TAG "zack"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__)
# define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))
//ava_com_zack_banner_FileUtils_diff
JNIEXPORT void JNICALL native_zack_diff
(JNIEnv * env, jclass jcl, jstring path, jstring pattern_Path, jint file_num) {
LOGI("jni begin");
}
JNIEXPORT jstring JNICALL native_java_str(JNIEnv * env,jclass jcl){
return? (*env)->NewStringUTF(env,"hello zack? static Method");
}
JNIEXPORT jstring JNICALL native_no_static(JNIEnv * env,jobject jobj){
return? (*env)->NewStringUTF(env,"hello zack? not static Method");
}
/* 通過 方法來改變 里面的的值*/
JNIEXPORT jstring JNICALL change_zack_key
(JNIEnv * env, jobject jobj) {
jclass jcl = (*env)->GetObjectClass(env, jobj);
jfieldID fid = (*env)->GetFieldID(env, jcl, "key", "Ljava/lang/String;");
// 得到key 對應的值
// GetXXXField
jstring jstr = (*env)->GetObjectField(env, jobj, fid);
// jni -> c
char *c_str = (*env)->GetStringUTFChars(env, jstr, NULL);
char tempString[30] = "zack";
strcat(tempString, c_str);
jstring newString = (*env)->NewStringUTF(env, tempString);
(*env)->SetObjectField(env, jobj, fid, newString);
(*env)->ReleaseStringUTFChars(env, newString, c_str);
return newString;
}
