JNI jstring char* 类型转换

#include<jni.h>
#include<stdlib.h>
#include<stdio.h>
#include<fcntl.h>
#include "common.h"

//jstring to char*
char* jstringTostring(JNIEnv* env, jstring jstr) {
    char* rtn = NULL;
    //jclass clsstring = env->FindClass("java/lang/String");
    jclass clsstring = (env)->FindClass("java/lang/String");
    jstring strencode = env->NewStringUTF("utf-8");
    jmethodID mid = env->GetMethodID(clsstring, "getBytes",
            "(Ljava/lang/String;)[B");
    jbyteArray barr = (jbyteArray) env->CallObjectMethod(jstr, mid, strencode);
    jsize alen = env->GetArrayLength(barr);
    jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE);
    if (alen > 0) {
        rtn = (char*) malloc(alen + 1);
        memcpy(rtn, ba, alen);
        rtn[alen] = 0;
    }
    env->ReleaseByteArrayElements(barr, ba, 0);
    return rtn;
}

//char* to jstring
jstring stoJstring(JNIEnv* env, const char* pat) {
    jclass strClass = env->FindClass("Ljava/lang/String;");
    jmethodID ctorID = env->GetMethodID(strClass, "<init>",
            "([BLjava/lang/String;)V");
    jbyteArray bytes = env->NewByteArray(strlen(pat));
    env->SetByteArrayRegion(bytes, 0, strlen(pat), (jbyte*) pat);
    jstring encoding = env->NewStringUTF("utf-8");
    return (jstring) env->NewObject(strClass, ctorID, bytes, encoding);
}

jstring CStr2Jstring(JNIEnv* env, const char* pat) {
    //定义java String类 strClass
    //jclass strClass = (env)->FindClass("Ljava/lang/String;");
    jclass strClass = (env)->FindClass("java/lang/String");
    //获取java String类方法String(byte[],String)的构造器,用于将本地byte[]数组转换为一个新String
    jmethodID ctorID = (env)->GetMethodID(strClass, "<init>",
            "([BLjava/lang/String;)V");
    //建立byte数组
    jbyteArray bytes = (env)->NewByteArray((jsize) strlen(pat));
    //将char* 转换为byte数组
    (env)->SetByteArrayRegion(bytes, 0, (jsize) strlen(pat), (jbyte*) pat);
    //设置String, 保存语言类型,用于byte数组转换至String时的参数
    jstring encoding = (env)->NewStringUTF("GB2312");
    //将byte数组转换为java String,并输出
    return (jstring)(env)->NewObject(strClass, ctorID, bytes, encoding);

}

char* Jstring2CStr(JNIEnv* env, jstring jstr) {

    char* rtn = NULL;
    jclass clsstring = env->FindClass("java/lang/String");
    jstring strencode = env->NewStringUTF("GB2312");
    jmethodID mid = env->GetMethodID(clsstring, "getBytes",
            "(Ljava/lang/String;)[B");
    jbyteArray barr = (jbyteArray) env->CallObjectMethod(jstr, mid, strencode);
    jsize alen = env->GetArrayLength(barr);
    jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE);
    if (alen > 0) {
        rtn = (char*) malloc(alen + 1);         //new   char[alen+1];
        memcpy(rtn, ba, alen);
        rtn[alen] = 0;
    }
    env->ReleaseByteArrayElements(barr, ba, 0);
    return rtn;

}

发出来,看了网上的有一个地方FindClass("Ljava/lang/String")好像是错误的,至少我没有build通过.

注意上面修改:

jclass objClass = env->FindClass("java/lang/String");//定义数组中元素类型

而不是FindClass("Ljava/lang/String;");