Android移植---JNI中HelloWorld的C和C++实现

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MainActivity.java

package com.example.jniload;import android.os.Bundle;import android.app.Activity;import android.view.Menu;import android.widget.TextView;public class MainActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);TextView  tv = new TextView(this);        tv.setText( stringFromJNI() );        setContentView(tv);//setContentView(R.layout.activity_main);}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}native String stringFromJNI();static{System.loadLibrary("jniload");}}

test-jni.c

#include <jni.h>#include <stdio.h>#include <string.h>#include <assert.h># define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))#define JNIREG_CLASS "com/example/test/Test"JNIEXPORT jstring JNICALL stringFromJNI(JNIEnv *env, jclass clazzi){    return (*env)->NewStringUTF(env, "hello Android3.");}static JNINativeMethod method_table[] = {    { "stringFromJNI", "()Ljava/lang/String;", (void*)stringFromJNI },//绑定};static int registerNativeMethods(JNIEnv* env, const char* className,        JNINativeMethod* gMethods, int numMethods){    jclass clazz;    clazz = (*env)->FindClass(env, className);    if (clazz == NULL) {        return JNI_FALSE;    }    if ((*env)->RegisterNatives(env, clazz, gMethods, numMethods) < 0) {        return JNI_FALSE;    }    return JNI_TRUE;}int register_ndk_load(JNIEnv *env){    return registerNativeMethods(env, JNIREG_CLASS,            method_table, NELEM(method_table));}JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved){    JNIEnv* env = NULL;    jint result = -1;    if ((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_4) != JNI_OK) {        return result;    }    register_ndk_load(env);    return JNI_VERSION_1_4;}

jni-load.cpp

#include <jni.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <assert.h>#define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))#define JNIREG_CLASS "com/example/jniload/MainActivity"extern "C"/*jstring Java_com_example_jniload_MainActivity_stringFromJNI( JNIEnv* env,jobject thiz ){char* str="Hello from JNI.";return (env)->NewStringUTF(str);}*/JNIEXPORT jstring JNICALL stringFromJNI( JNIEnv* env,jobject thiz ){char* str="Hello from JNI.";return (env)->NewStringUTF(str);}static JNINativeMethod method_table[] = {    { "stringFromJNI", "()Ljava/lang/String;", (void*)stringFromJNI },};static int registerNativeMethods(JNIEnv* env, const char* className,        JNINativeMethod* gMethods, int numMethods){    jclass clazz;    clazz = env->FindClass(className);    if (clazz == NULL) {        return JNI_FALSE;    }    if (env->RegisterNatives(clazz, gMethods, numMethods) < 0) {        return JNI_FALSE;    }    return JNI_TRUE;}int register_ndk_load(JNIEnv *env){   return registerNativeMethods(env, JNIREG_CLASS, method_table, NELEM(method_table));}jint JNI_OnLoad(JavaVM* vm, void* reserved){    JNIEnv* env = NULL;    jint result = -1;    if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {    return result;}    //result=register_ndk_load(env);    if ( register_ndk_load(env) < 0){    goto bail;    }    result = JNI_VERSION_1_4;bail:    return result;}

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