• 定義java測試類

package com.example;

public class StringDeal {
    
    public native static String resolveString(String str);
    
    static{
        System.loadLibrary("StringDeal");
    }
    public static void main(String[] args) {
        System.out.println(resolveString(""));
    }

}

• 實現(xiàn)c代碼

/*
* Class:     com_example_StringDeal
* Method:    resolveString
* Signature: (Ljava/lang/String;)V
*/
JNIEXPORT jstring JNICALL Java_com_example_StringDeal_resolveString
(JNIEnv *env, jclass jcls, jstring jstr){
    char *c_str = "我是來自c的字符串,現(xiàn)在要返回給java端使用";
    printf("%s \n", c_str);
    //查找class
    jclass jclz = (*env)->FindClass(env, "java/lang/String");
    if (jclz == NULL)
    {
        return NULL;
    }
    //獲取構(gòu)造函數(shù)
    jmethodID jmid = (*env)->GetMethodID(env, jclz, "<init>", "([BLjava/lang/String;)V");
    if (jmid == NULL)
    {
        return NULL;
    }
    //獲取字符串長度
    jsize size = strlen(c_str);
    //構(gòu)建一個新的jbyteArray
    jbyteArray jbytes =(*env)->NewByteArray(env, size);
    //將c_str的值賦給jbytes
    (*env)->SetByteArrayRegion(env, jbytes, 0, size, c_str);
    //構(gòu)建字符編碼
    jstring js = (*env)->NewStringUTF(env, "GB2312");
    //創(chuàng)建一個String對象 通過構(gòu)造函數(shù)String(byte [] bytes ,String charset);
    return (*env)->NewObject(env, jclz, jmid, jbytes, js);;

}

運(yùn)行結(jié)果.png