jni string 转换

参考：https://github.com/wangzuxing/MyFFmpegH264H265YUVOpenGL/blob/master/MyFFmpegH264H265YUVOpenGL/jni/streamer.cpp

#include <jni.h>

#include <android/log.h>
#include <liveMedia.hh>
#include <BasicUsageEnvironment.hh>
#include <GroupsockHelper.hh>
#include <pthread.h>
#include "DynamicRTSPServer.hh"
#include "version.hh"
#include "RTSPStream.h"
#include "H264VideoSource.h"
#include "H264VideoServerMediaSubsession.h"

#ifdef __cplusplus
extern "C" {
#endif

#define LOG_TAG "streamer"
#define LOGW(a )  __android_log_write(ANDROID_LOG_WARN,LOG_TAG,a)
#define LOGI(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGD(...)  __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)
#define LOGE(...)  __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)
void play();
void afterPlaying(void* /*clientData*/);
//}

UsageEnvironment* uEnv;
H264VideoStreamFramer* videoSource;
RTPSink* videoSink;
char quit;
char* url;
int port_number;
FILE *file;
char const *inputFilename;
Boolean reuseFirstSource  = False;
Boolean reuseFirstSource0 = True;
pthread_mutex_t   mutex;

//将const char类型转换成jstring类型
jstring CStr2Jstring0(JNIEnv* env, const char* pat )
{
    // 定义java String类 strClass
    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 * Jstring2CStr0( 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;
}

jstring CharTojstring0(JNIEnv* env, char* str)
{
    jsize len = strlen(str);
    jclass  clsstring = env->FindClass("java/lang/String");
    jstring  strencode = env->NewStringUTF("GB2312");
    jmethodID  mid = env->GetMethodID(clsstring,"<init>","([BLjava/lang/String;)V");
    jbyteArray  barr = env-> NewByteArray(len);
    env-> SetByteArrayRegion(barr,0,len,(jbyte*)str);
    return (jstring)env-> NewObject(clsstring,mid,barr,strencode);
}

void doExecuteVideoViewShow0(JNIEnv * env, jobject obj, jstring sdp) {
    // 1.找到java的MainActivity的class
    jclass clazz = env->FindClass("com/example/mylive55servermediacodec2/StreamerActivity2");
    if (clazz == 0) {
        LOGI("can't find clazz");
    }
    LOGI(" find clazz");

    //2 找到class 里面的方法定义
    jmethodID methodid = env->GetMethodID(clazz, "PlayRtspStream", "(Ljava/lang/String;)V");
    if (methodid == 0) {
        LOGI("can't find methodid");
    }
    LOGI(" find methodid");

    //3 .调用方法
    env->CallVoidMethod(clazz, methodid, sdp);
}

static void announceStream0(RTSPServer* rtspServer, ServerMediaSession* sms,
        char const* streamName, char const* inputFileName)
{
    char* url = rtspServer->rtspURL(sms);
    char buf[255] = { 0 };
    UsageEnvironment& env = rtspServer->envir();
    sprintf(buf,
            "%s-->stream, from the file-->%s,Play this stream using the URL:%s",
            streamName, inputFileName, url);
    LOGW(buf);
    delete[] url;
}