Java与C的相互调用
java:
package com.nan.callback; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.widget.Button; import android.widget.TextView; public class MyCallbackActivity extends Activity { private Button intButton = null; private Button stringButton = null; private Button arrayButton = null; private TextView intTextView = null; private TextView stringTextView = null; private TextView arrayTextView = null; private Handler mHandler = null; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); intButton = (Button)this.findViewById(R.id.intbutton); //注册按钮监听 intButton.setOnClickListener(new ClickListener()); stringButton = (Button)this.findViewById(R.id.stringbutton); //注册按钮监听 stringButton.setOnClickListener(new ClickListener()); arrayButton = (Button)this.findViewById(R.id.arraybutton); //注册按钮监听 arrayButton.setOnClickListener(new ClickListener()); intTextView = (TextView)this.findViewById(R.id.inttextview); stringTextView = (TextView)this.findViewById(R.id.stringtextview); arrayTextView = (TextView)this.findViewById(R.id.arraytextview); //消息处理 mHandler = new Handler() { @Override public void handleMessage(Message msg) { switch(msg.what) { //整型 case 0: { intTextView.setText(msg.obj.toString()); break; } //字符串 case 1: { stringTextView.setText(msg.obj.toString()); break; } //数组 case 2: { byte[] b = (byte[])msg.obj; arrayTextView.setText(Byte.toString(b[0])+Byte.toString(b[1])+Byte.toString(b[2])+Byte.toString(b[3])+Byte.toString(b[4])); break; } } } }; } //按钮监听实现 public class ClickListener implements View.OnClickListener { @Override public void onClick(View v) { // TODO Auto-generated method stub switch(v.getId()) { case R.id.intbutton: { //调用JNI中的函数 callJNIInt(1); break; } case R.id.stringbutton: { //调用JNI中的函数 callJNIString("你好A"); break; } case R.id.arraybutton: { //调用JNI中的函数 callJNIByte(new byte[]{1,2,3,4,5}); break; } } } } //被JNI调用，参数由JNI传入 private void callbackInt(int i) { Message msg = new Message(); //消息类型 msg.what = 0; //消息内容 msg.obj = i; //发送消息 mHandler.sendMessage(msg); } //被JNI调用，参数由JNI传入 private void callbackString(String s) { Message msg = new Message(); //消息类型 msg.what = 1; //消息内容 msg.obj = s; //发送消息 mHandler.sendMessage(msg); } //被JNI调用，参数由JNI传入 private void callbackByte(byte[] b) { Message msg = new Message(); //消息类型 msg.what = 2; //消息内容 msg.obj = b; //发送消息 mHandler.sendMessage(msg); } //本地方法，由java调用 private native void callJNIInt(int i); private native void callJNIString(String s); private native void callJNIByte(byte[] b); static { //加载本地库 System.loadLibrary("myjni"); } }
C:
#include <string.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <jni.h> #include <android/log.h> #define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO, "native-activity", __VA_ARGS__)) #define LOGW(...) ((void)__android_log_print(ANDROID_LOG_WARN, "native-activity", __VA_ARGS__)) /**********传输整数************* */ JNIEXPORT void JNICALL Java_com_nan_callback_MyCallbackActivity_callJNIInt( JNIEnv* env, jobject obj , jint i) { //找到java中的类 jclass cls = (*env)->FindClass(env, "com/nan/callback/MyCallbackActivity"); //再找类中的方法 jmethodID mid = (*env)->GetMethodID(env, cls, "callbackInt", "(I)V"); if (mid == NULL) { LOGI("int error"); return; } //打印接收到的数据 LOGI("from java int: %d",i); //回调java中的方法 (*env)->CallVoidMethod(env, obj, mid ,i); } /********传输字符串************* */ JNIEXPORT void JNICALL Java_com_nan_callback_MyCallbackActivity_callJNIString( JNIEnv* env, jobject obj , jstring s) { //找到java中的类 jclass cls = (*env)->FindClass(env, "com/nan/callback/MyCallbackActivity"); //再找类中的方法 jmethodID mid = (*env)->GetMethodID(env, cls, "callbackString", "(Ljava/lang/String;)V"); if (mid == NULL) { LOGI("string error"); return; } const char *ch; //获取由java传过来的字符串 ch = (*env)->GetStringUTFChars(env, s, NULL); //打印 LOGI("from java string: %s",ch); (*env)->ReleaseStringUTFChars(env, s, ch); //回调java中的方法 (*env)->CallVoidMethod(env, obj, mid ,(*env)->NewStringUTF(env,"你好haha")); } /********传输数组(byte[])************* */ JNIEXPORT void JNICALL Java_com_nan_callback_MyCallbackActivity_callJNIByte( JNIEnv* env, jobject obj , jbyteArray b) { //找到java中的类 jclass cls = (*env)->FindClass(env, "com/nan/callback/MyCallbackActivity"); //再找类中的方法 jmethodID mid = (*env)->GetMethodID(env, cls, "callbackByte", "([B)V"); if (mid == NULL) { LOGI("byte[] error"); return; } //获取数组长度 jsize length = (*env)->GetArrayLength(env,b); LOGI("length: %d",length); //获取接收到的数据 int i; jbyte* p = (*env)->GetByteArrayElements(env,b,NULL); //打印 for(i=0;i<length;i++) { LOGI("%d",p[i]); } char c[5]; c[0] = 1;c[1] = 2;c[2] = 3;c[3] = 4;c[4] = 5; //构造数组 jbyteArray carr = (*env)->NewByteArray(env,length); (*env)->SetByteArrayRegion(env,carr,0,length,c); //回调java中的方法 (*env)->CallVoidMethod(env, obj, mid ,carr); }
Reprinted from:http://blog.csdn.net/vincent_czz/article/details/7688882