1、创建布局：
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2、创建页面
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51/** * @描述 TODO * @项目名称 App_imooc * @包名 com.android.imooc.jni * @类名 JniActivity *@author chenlin *@date 5月24日 上午6:58:39 *@version 1.0 */
public class JniActivity extends Activity {
private EditText mEtPwd;
static{
//加载类库
System.loadLibrary("hello");
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_jni);
mEtPwd = (EditText) findViewById(R.id.et_pwd);
Log.i("tag", helloFromC());
}
public void encode(View view){
String text = mEtPwd.getText().toString();
if (!TextUtils.isEmpty(text)) {
String pwd = encodePwd(text, text.length());
System.out.println("加密密码=" + pwd);
mEtPwd.setText(pwd);
}
}
public void decode(View view){
String text = mEtPwd.getText().toString();
if (!TextUtils.isEmpty(text)) {
System.out.println("解密密码=" + decodePwd(text, text.length()));
}
}
public native String helloFromC();
public native int sum(int x, int y);
public native String encodePwd(String pass, int len);
public native String decodePwd(String pass, int len);
}
3、进入项目的src目录下 按住shift+右键，打开cmd窗口
在窗口里输入
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1javah com.android.imooc.jni.JniActivity
此时会生成文件com_android_imooc_jni_JniActivity 打开 拷贝里面的两个方法到hello.c文件里
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6JNIEXPORT jstring JNICALL Java_com_android_imooc_jni_JniActivity_encodePwd
(JNIEnv *, jobject, jstring, jint);
JNIEXPORT jstring JNICALL Java_com_android_imooc_jni_JniActivity_decodePwd
(JNIEnv *, jobject, jstring, jint);
4、改写hello.c里的这两个方法
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39//把java的字符串转换成c的字符串
char* Jstring2CStr(JNIEnv* env, jstring jstr) {
char* rtn = NULL;
jclass clsstring = (*env)->FindClass(env, "java/lang/String");
jstring strencode = (*env)->NewStringUTF(env, "GB2312");
jmethodID mid = (*env)->GetMethodID(env, clsstring, "getBytes",
"(Ljava/lang/String;)[B");
jbyteArray barr = (jbyteArray) (*env)->CallObjectMethod(env, jstr, mid,
strencode); // String .getByte("GB2312");
jsize alen = (*env)->GetArrayLength(env, barr);
jbyte* ba = (*env)->GetByteArrayElements(env, barr, JNI_FALSE);
if (alen > 0) {
rtn = (char*) malloc(alen + 1); //"\0"
memcpy(rtn, ba, alen);
rtn[alen] = 0;
}
(*env)->ReleaseByteArrayElements(env, barr, ba, 0); //
return rtn;
}
//加密
JNIEXPORT jstring JNICALL Java_com_android_imooc_jni_JniActivity_encodePwd(
JNIEnv * env, jobject obj, jstring jstr, jint len) {
char * cstr = Jstring2CStr(env, jstr);
for (int i = 0; i < len; i++) {
*(cstr + i) += 1;
}
return (*env)->NewStringUTF(env, cstr);
}
//解密
JNIEXPORT jstring JNICALL Java_com_android_imooc_jni_JniActivity_decodePwd(
JNIEnv * env, jobject obj, jstring jstr, jint len) {
char * cstr = Jstring2CStr(env, jstr);
for (int i = 0; i < len; i++) {
*(cstr + i) -= 1;
}
return (*env)->NewStringUTF(env, cstr);
}
5、运行，如图
6、输入字母”abc” 得到结果 06-06 14:09:55.561: I/System.out(3956): 加密密码=cde 06-06 14:09:58.437: I/System.out(3956): 解密密码=bcd
