jni string 转换

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

返回字符串：

      string result="aaaaa";
      char *p = const_cast<char*>(result.c_str());
       jstring jres = env->NewStringUTF(p);
      return jres;
  
 

string转换

      #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;
      }
  
 

文章来源: blog.csdn.net，作者：网奇，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/jacke121/article/details/72911460