在android jni中运用log

开发环境：

ubuntu 10.10 + eclipse + adt +android ndk + ?android sdk

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1、新建简单项目：JNIDemo，

设计jni到java类：

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package com.lt.jni

public class JNI {	/**	 * call the native printf method to print	 */	public native void print();		public native String sayHello();}

2、在android到bin目录下，执行命令：

javah -jni com.lt.jni.JNI 来生成头文件：com_lt_jni_JNI.h

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/* DO NOT EDIT THIS FILE - it is machine generated */#include <jni.h>/* Header for class com_lt_jni_JNI */#ifndef _Included_com_lt_jni_JNI#define _Included_com_lt_jni_JNI#ifdef __cplusplusextern "C" {#endif/* * Class:     com_lt_jni_JNI * Method:    print * Signature: ()V */JNIEXPORT void JNICALL Java_com_lt_jni_JNI_print  (JNIEnv *, jobject);/* * Class:     com_lt_jni_JNI * Method:    sayHello * Signature: ()Ljava/lang/String; */JNIEXPORT jstring JNICALL Java_com_lt_jni_JNI_sayHello  (JNIEnv *, jobject);#ifdef __cplusplus}#endif#endif

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3、在项目目录下，新建jni目录，并新建c源文件com_lt_jni_JNI.c：

#include <jni.h>#include <stdio.h>#include <string.h>#include <android/log.h>#include "com_lt_jni_JNI.h"/* * Class:     com_lt_jni_JNI * Method:    print * Signature: ()V */JNIEXPORT void JNICALL Java_com_lt_jni_JNI_print  (JNIEnv *env, jobject obj){	__android_log_print(ANDROID_LOG_INFO,"JNI","Java_com_lt_jni_JNI_print");	printf("Hello world!\n");	return ;}JNIEXPORT jstring JNICALL Java_com_lt_jni_JNI_sayHello  (JNIEnv *env, jobject obj){	__android_log_print(ANDROID_LOG_INFO,"JNI","Java_com_lt_jni_JNI_sayHello");	return (*env)->NewStringUTF(env,"Hello JNI");}?

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关键代码：#include <android/log.h>

__android_log_print(ANDROID_LOG_INFO,"TAG","log info");

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4、在jni目录下新建Android.mk文件：

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LOCAL_PATH:= $(call my-dir)

include $(CLEAR_VARS)

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LOCAL_SRC_FILES:=\

com_lt_jni_JNI.c

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LOCAL_CFLAGS := -O2 -g

#LOCAL_CFLAGS += -D__FAVOR_BSD

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#LOCAL_C_INCLUDES += \

# bionic/libc/include\

# external/libpcap

LOCAL_C_INCLUDES := \

? ? $(JNI_H_INCLUDE)

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#LOCAL_STATIC_LIBRARIES += libpcap

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#LOCAL_SHARED_LIBRARIES += libssl libcrypto

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LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog

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LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)

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#LOCAL_MODULE_TAGS := eng

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LOCAL_MODULE := helloworld

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include $(BUILD_SHARED_LIBRARY)

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