jni相关

封装 jni 的 java 层 Integer、Long 对象使用时必须用 new 对象的形式,防止修改 128>x x>-128 之间缓存的对象,一定要谨记

配置

在 eclipse 环境下开发 jni
1. 导入 ndk Window->Preferences->Android->NDK,点击 Browse 引入 ndk 的目录
2. 创建 java 类 , 声明一个 private native String CBBT_getVersionString();

JNIEXPORT jstring JNICALL Java_com_raiing_ABBTSurface_getVersionString(JNIEnv *env,

jobject obj)
3. 使用 javah 生成 jni 头文件.

3-a. run - external tools - external tools configuration - program - new lanch configuration 3-b. name:javah

location:jdk 安装目录中的 javah.exe 所在目录javah.exe FilesJavajdk1.7.0_02injavah.exe

working directory: ${workspace_loc}

arguments: -v -classpath "${project_loc}/bin/classes" ${java_type_name}

common - Display in favorites menu - 选中 External tools 中显示 javah。
3-c. apply , close
3-d. 点中 src- com.raiing - CTMProcess.java 文件

3-e. run - external tools - javah 将生成 jni 的头文件在 jni 目录下。按 F5 刷新 project explorer 的 jni 目录。

4. 添加 Android.mk 和 Application.mk 文件到 jni 目录。 android.mk 内容:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

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

LOCAL_MODULE := child 自己起的库名字

LOCAL_SRC_FILES := com_raiing_childmodule_ChildModule.cpp utilities.c include $(BUILD_SHARED_LIBRARY)

ifeq ($(TARGET_ARCH_ABI),armeabi-v7a)
LOCAL_LDFLAGS := $(LOCAL_PATH)ccodearmeabi-v7alibCBBT.a LOCAL_LDFLAGS += $(LOCAL_PATH)ccodearmeabi-v7alibutilities.a 两者有顺序

比如:C:Program "${project_loc}/jni"

-d
以便在 run - external tools

#LOCAL_STATIC_LIBRARIES := utilities

endif

需要修改上述内容的 LOCAL_MODULE:= 为希望的库名称。生成的库名将在这个名称前增加 lib 前缀。
需要修改 LOCAL_SRC_FILES:= 将 jni 目录下的所有 cpp c 添加到后面,空格分隔。

Application.mk 内容:
APP_ABI := all 生成所有平台的目录文件,我们一般只需要三个

APP_ABI := armeabi armeabi-v7a arm64-v8a
APP_CFLAGS += -Wno-error=format-security -D_ENV_ANDROID_=1

5. 添加 ndk 编译命令到项目。
5-a. run - external tools - external tools configuration - program - new lanch configuration

main- name: ndk_build

main-location: ndk 安装目录 dk-build.cmd 比如:S:work_dirandroid-ndk-r9d dk-build.cmd

main- working directory: ${workspace_loc}/${project_name}/jni common - Display in favorites menu - 选中 External tools

5-b. 选中 CTMProcess 项目名,project - properties - builders - import - ndk_build 5-d. 在 builders 中选中 ndk_build ,点击 UP,将 ndk_build 调整到最高。

基本数据类型

Java Type Native Type Description

boolean jboolean

byte jbyte

char jchar

double jdouble

float jfloat

int jint

long jlong

short jshort

void void

8 bits, unsigned 8 bits, signed
16 bits, unsigned 64 bits

32 bits
32 bits, signed 64 bits, signed 16 bits, signed N/A

Java Type

Signature

boolean Z

byte B

char C double D

float F

int I

long J

void V

object Lfully-qualified-class; type[] [type
method signature ( arg-types) ret-type

Method	Signature
void f1()	()V
int f2(int, long)	(IJ)I
boolean f3(int[])	([I)B
double f4(String, int)	(Ljava/lang/String;I)D
void f5(int, String [], char)	(I[Ljava/lang/String;C)V

数据交互

基本类型不需要转换,navtive 层直接可以使用,赋值到 c 里面需要强转,如 int uciT->cycleDays = (uint16) cycle_days;
uint16 表示有符号,正数 int16 无符号正负都可以

String 转换
const char *= CBBT_getVersionString();

char*转String
jstring jstrBuf = env->NewStringUTF();
String 转 char*
char *filePath = (char *)(env->GetStringUTFChars(path, NULL)); 不用时需要释放
ReleaseStringUTFChars(buf, jstrBuf);

对象
有 jobject 对象

jclass cls = env->GetObjectClass(javaUCI);

创建某个类对象

jclass cls_acr = env->FindClass("com/raiing/cbbtjni/entity_jni/ACR_T"); jmethodID construct_acr = env->GetMethodID(cls_acr, "<init>", "()V"); jobject obj_acr = env->NewObject(cls_acr, construct_acr, "");

给对象某个字段赋值,首先获取字段 id,再给字段赋值 jfieldID originFieldID = env->GetFieldID(cls_acr, "origin", "I"); env->SetIntField(obj_acr, originFieldID, (jint) acrT->origin); jfieldID extraDataFieldID = env->GetFieldID(cls, "extraData", "[B");

对象集合 ArrayList<Entity>,给集合添加对象
jclass cls_ArrayList = env->GetObjectClass(jobject);
jmethodID arrayList_add = env->GetMethodID(cls_ArrayList, "add", "(Ljava/lang/Object;)Z");

env->CallBooleanMethod(jobject, arrayList_add, obj_cbbt); env->DeleteLocalRef(obj_cbbt);

获取集合里面的对象

jmethodID arraylist_get = env->GetMethodID(cls_arraylist, "get", "(I)Ljava/lang/Object;"); jobject obj_uci = env->CallObjectMethod(jobject, arraylist_get, i); env->DeleteLocalRef(obj_uci);

循环操作里面一定要删除引用,否则会有 512 的限制,如:jbytearray jstring jclass jobject

数组类型数据赋值给 c 层
jbyteArray extraData = (jbyteArray) env->GetObjectField(obj,

extraDataFieldID);
int size = env->GetArrayLength(extraData);

jbyte *ed = (jbyte *) cbbt.extraData; env->GetByteArrayRegion(, 0, size, ed); env->DeleteLocalRef(extraData);

c 层数组赋值给 java
jbyteArray jbarray = env->NewByteArray(len); jbyte *jb = env->GetByteArrayElements(jbarray, 0); memcpy(jb, cbbt->extraData, len); env->SetByteArrayRegion(jbarray, 0, len, jb);

输入输出

c
int8 ABBT_getExpectedDataRange(uint32 currentTime, int32 timeZone, uint32 *startTime, uint32 *endTime);
java
private native int getExpectedDataRange(long currentTime, long timeZone, Long startTime, Long endTime);

cpp
JNIEXPORT jint JNICALL Java_com_raiing_ABBTSurface_getExpectedDataRange(

JNIEnv *env, jobject obj, jlong curTime, jlong timeZone,

jobject startTime, jobject endTime)
jclass cls = env->GetObjectClass(retObject);
jmethodID codeMethodID = env->GetMethodID(cls, "<init>", "(J)V"); env->CallVoidMethod(startTime, codeMethodID, retLong);

java 层错误的写法
Integer startTime = 0;
Integer endTime = 0;
两者指向的同一个内存地址,再 c 层输出修改的时候,本来输出两个值,就变为了一个

查看 ndk 崩溃 log
需要的 So 文件在 objlocalarm64-v8alibCBBT.so

S:Android_SDK dk-bundle oolchains Eclipse jni 提示

异常问题
建的工程没有 c/c++ build 支持,工程右键 android tools

Log 占位符

C 语言中输入输出函数占位符介绍 : 占位符数据类型

%d int
%ld long int

%c char

%f float

&lf double

%x 十六进制

%O 八进制

%s 字符串

--> Add native Support

Project Properties -> C/C++ General -> Path and Symbols

选择 include 标签,

Add -> $Android_NDK_HOME/platforms/android-14/arch-arm/usr/include 任意版本

选中 All languages.

最后 Apply -> OK

Log 测试不能输出 long uint64,需要分解为 uint32 LOGV("java2SYMPTOM->UEI_SYMPTOM_T 结构体 111: symptomTypeH jj

h:%u,l:%u", (uint32)(symptomTypeH>>32),(uint32)(symptomTypeH));

学习网址

http://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/functions.html http://home.pacifier.com/~mmead/jni/cs510ajp/index.html#JNI Data Types

http://blog.csdn.net/woshinia/article/details/25132353

http://blog.csdn.net/u012690435/article/details/38612461 参数传递 http://mysuperbaby.iteye.com/blog/1603817 DeleteLocalRef 问题

http://www.oschina.net/question/2241352_213433 addr2line 定位 jni 问题行号