JNI将字符串从java传递到c++;然后通过c++;字符串到字符串数组
我用java声明了本机方法JNI将字符串从java传递到c++;然后通过c++;字符串到字符串数组,java,android,c++,java-native-interface,Java,Android,C++,Java Native Interface,我用java声明了本机方法 static { // Replace "Myfile" with the name of your Native File System.loadLibrary("JohnnyX"); } // Declare your native methods here public static native String string(StringBuffer sb); 并将字符串缓冲区传递给它 System.out.println(string(sb
static
{
// Replace "Myfile" with the name of your Native File
System.loadLibrary("JohnnyX");
}
// Declare your native methods here
public static native String string(StringBuffer sb);
并将字符串缓冲区传递给它
System.out.println(string(sb));
和在我的JNYNX.CPP中,我使用以下方法将java字符串转换成C++字符串。
std::string jstring2string(JNIEnv *env, jstring jStr)
{
if (!jStr)
return "";
const jclass stringClass = env->GetObjectClass(jStr);
const jmethodID getBytes = env->GetMethodID(stringClass, "getBytes", "(Ljava/lang/String;)[B");
const jbyteArray stringJbytes = (jbyteArray) env->CallObjectMethod(jStr, getBytes,
env->NewStringUTF("UTF-8"));
size_t length = (size_t) env->GetArrayLength(stringJbytes);
jbyte *pBytes = env->GetByteArrayElements(stringJbytes, NULL);
std::string ret = std::string((char *) pBytes, length);
env->ReleaseByteArrayElements(stringJbytes, pBytes, JNI_ABORT);
env->DeleteLocalRef(stringJbytes);
env->DeleteLocalRef(stringClass);
return ret;
}
extern "C" JNIEXPORT jstring JNICALL Java_com_example_rsolver_Solver_string(JNIEnv *env, jobject object,jstring string) {
// Converting Java String into C++ String and calling a "solution" method and passing c++ string
return solution(jstring2string(env,string));
}
我的解决方法是:
string solution (string argv[]) {
// this will return a string
}
我的问题是,如何在解决方案中传递C++字符串到字符串数组(字符串ARVV[])? 一个简单的解决方案是临时字符串对象
extern "C" JNIEXPORT jstring JNICALL
Java_com_example_rsolver_Solver_string(JNIEnv *env, jobject object,jstring string) {
// Converting Java String into C++ String and
// calling a "solution" method and passing c++ string
std::string tmp{jstring2string(env,string)};
return solution(&tmp);
}
这为解决方案
提供了一个由1个元素组成的数组。但是solution()
不知道这个数组有多少个元素,所以您也必须添加数组大小
std::string solution (int size, std::string argv[]) {
// this will return a string
}
// ...
std::string tmp{jstring2string(env, string)};
return solution(1, &tmp);
更好的是,跳过原始数组,并传递
std::string
s的std::vector
std::string solution (const std::vector<std::string> &argv) {
// this will return a string
}
// ...
std::vector<std::string> tmp = { jstring2string(env, string) };
return solution(tmp);
std::string解决方案(const std::vector和argv){
//这将返回一个字符串
}
// ...
std::vector tmp={jstring2string(env,string)};
返回溶液(tmp);