Android 开发中 JAVA 调用 C++,androidc++
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Android 开发中 JAVA 调用 C++,androidc++
<无详细内容>1.步骤 #1:使用ANT编译项目 NativeAdd.java
package org.apache; import Android.util.Log; public class NativeAdd { static { try { Log.i("JNI", "Trying to load libNativeAdd.so"); System.loadLibrary("NativeAdd"); } catch (UnsatisfiedLinkError ule) { Log.e("JNI", "WARNING: Could not load libNativeAdd.so"); } } public static native long add(long a, long b); }
2.下面片断给出主activity中如何调用这个类/方法
public void onClick(View view) { Log.i(LOG_TAG, "onClick"); EditText a = (EditText) findViewById(R.id.a); EditText b = (EditText) findViewById(R.id.b); EditText c = (EditText) findViewById(R.id.c); Log.i(LOG_TAG, "calling native method"); long sum = NativeAdd.add( Long.parseLong(a.getText().toString()), Long.parseLong(b.getText().toString())); Log.i(LOG_TAG, "back from native method"); String text = Long.toString(sum); c.setText("Native add returns = " + text.subSequence(0, text.length())); }
3.步骤#2:运行下面的命令产生头文件
javah -classpath ../../Android.jar;../bin/classes; org.apache.NativeAdd
4.新产生的头文件“(org_apache_CallNative.h”内容如下
/* DO NOT EDIT THIS FILE - it is machine generated */ #include /* Header for class org_apache_NativeAdd */ #ifndef _Included_org_apache_NativeAdd #define _Included_org_apache_NativeAdd #ifdef __cplusplus extern "C" { #endif /* * Class: org_apache_NativeAdd * Method: add * Signature: (JJ)J */ JNIEXPORT jlong JNICALL Java_org_apache_NativeAdd_add (JNIEnv *, jclass, jlong, jlong); #ifdef __cplusplus } #endif #endif
5.步骤#3: 编写C文件如下“org_apache_NativeAdd.c”
#include "org_apache_NativeAdd.h" JNIEXPORT jlong JNICALL Java_org_apache_NativeAdd_add (JNIEnv *env, jclass c, jlong a, jlong b) { return a + b; }
6.步骤#5: 编译和连接 org_apache_NativeAdd.c/org_apache_NativeAdd.h为一个共享库.
arm-none-linux-gnueabi-gcc -I/usr/lib/jvm/java-1.5.0-sun/include -I/usr/lib/jvm/java-1.5.0-sun/include/linux -fpic -c org_apache_NativeAdd.c arm-none-linux-gnueabi-ld -T armelf_linux_eabi.xsc -shared -o libNativeAdd.so org_apache_NativeAdd.o
7.步骤 #6: 复制编译文件到模拟器中. 同时安装APK程序.
adb push native/libNativeAdd.so /system/lib adb install bin/CallNative.apk
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