Android(安卓)从 JNI 中传入 UTF8 的字符到 Java
由于env->NewStringUTF支持的是 Modified UTF-8，所以这个API不能用来从JNI
中传入标准的UTF8字符到Java。
我们有两种解决方法：
Java代码
ReturnUTF8.java
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public class ReturnUTF8 {
static {
System.loadLibrary("ReturnUTF8Jni");
}
public static native byte[] method1();
public static native Object method2();
public static void main(String[] args) {
try {
byte[] buffer = ReturnUTF8.method1();
String s1 = new String(buffer, "UTF-8");
System.out.println("s1 = " + s1);
String s2 = ReturnUTF8.method2().toString();
System.out.println("s2 = " + s2);
} catch (java.io.UnsupportedEncodingException e) {
e.printStackTrace();
}
}
}
public class
ReturnUTF8 {
static {
System.loadLibrary("ReturnUTF8Jni");
}
public static native byte[] method1();
public static native Object method2();
public static void main(String[] args) {
try {
byte[] buffer = ReturnUTF8.method1();
String s1 = new String(buffer, "UTF-8");
System.out.println("s1 = " + s1);
String s2 = ReturnUTF8.method2().toString();
System.out.println("s2 = " + s2);
} catch (java.io.UnsupportedEncodingException e) {
e.printStackTrace();
}
}
}
# javac ReturnUTF8.java
# javah ReturnUTF8
-> 这里会生成一个ReturnUTF8.h头文件
C++代码
ReturnUTF8.cpp
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#include "ReturnUTF8.h"
JNIEXPORT jbyteArray JNICALL Java_ReturnUTF8_method1
(JNIEnv *env, jclass cls)
{
jbyte buffer[] = /* UTF8 encoding buffer */
jbyteArray bytes = env->NewByteArray(sizeof(buffer));
env->SetByteArrayRegion(bytes, 0, sizeof(buffer), buffer);
return bytes;
}
JNIEXPORT jbyteArray JNICALL Java_ReturnUTF8_method2
(JNIEnv *env, jclass cls)
{
jbyte buffer[] = /* UTF8 encoding buffer */
jbyteArray bytes = env->NewByteArray(sizeof(buffer));
env->SetByteArrayRegion(bytes, 0, sizeof(buffer), buffer);
jchar encoding_name[] = { 'U', 'T', 'F', '-', '8', '' };
jstring encoding = env->NewString(encoding_name, 5);
jclass theStringClass = env->FindClass("Ljava/lang/String;");
jmethodID mid = env->GetMethodID(theStringClass, "", "([BLjava/lang/String;)V");
jobject result = env->NewObject(theStringClass, mid, bytes, encoding);
return result;
}
#include
"ReturnUTF8.h"
JNIEXPORT jbyteArray JNICALL Java_ReturnUTF8_method1
(JNIEnv *env, jclass cls)
{
jbyte buffer[] = /* UTF8 encoding buffer */
jbyteArray bytes = env->NewByteArray(sizeof(buffer));
env->SetByteArrayRegion(bytes, 0, sizeof(buffer), buffer);
return bytes;
}
JNIEXPORT jbyteArray JNICALL Java_ReturnUTF8_method2
(JNIEnv *env, jclass cls)
{
jbyte buffer[] = /* UTF8 encoding buffer */
jbyteArray bytes = env->NewByteArray(sizeof(buffer));
env->SetByteArrayRegion(bytes, 0, sizeof(buffer), buffer);
jchar encoding_name[] = { 'U', 'T', 'F', '-', '8', '' };
jstring encoding = env->NewString(encoding_name, 5);
jclass theStringClass = env->FindClass("Ljava/lang/String;");
jmethodID mid = env->GetMethodID(theStringClass, "",
"([BLjava/lang/String;)V");
jobject result = env->NewObject(theStringClass, mid, bytes,
encoding);
return result;
}
# g++ -shared -I /usr/lib/jvm/java-1.5.0-sun/include -I /usr/lib/jvm/java-1.5.0-sun/include/linux ReturnUTF8.cpp -o libReturnUTF8Jni.so
# export LD_LIBRARY=.
# java ReturnUTF8
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