jni返回结构体数组

jni返回结构体数组.这个卡了我两天.好郁闷.从网上找了好多的办法都不成功. 可能是人品问题,呵呵呵好在现在搞定了.把源码贴出来让大家也看看,希望能帮到那些和我人品不好的人嘿嘿..其实回想起来.挺简单的. 返回结构体数组有如下步骤./** 返回一个结构体数组步骤* 1.通过FindClass找到要返回的android中定义的class.* 2.通过NewObjectArray创建一个要返回的结构体数组.* 3.通过GetMethodID得到你要返回的class的默认构造方法* 4.通过GetFieldID得到定义的class里面所有的成员* 5.通过NewObject创建一个对应的class对象* 6.通过SetObjectField为5创建的class对象赋值(如果字段为int,那么就用SetIntField这个方法)* 7.通过SetObjectArrayElement把创建的class对象放到创建的objectArray里面去* 8.返回这个objectArray对象.* 9.完成. 就这么简单.* */是不是简单啊. 嘿嘿嘿嘿.好.现在看是放源码.android 代码.这个代码是activity 代码

package com.example.jnitest2;import android.os.Bundle;import android.app.Activity;import android.util.Log;import android.view.Menu;public class MainActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);MX2 changeJni = new MX2();changeJni.displayParms("Hello World!", 100, true);int ret = changeJni.add(12, 20);Log.e("logZ", "相加结果为:"+ret);boolean[] blList = new boolean[] { true, false, true };changeJni.setArray(blList);String[] strList = changeJni.getStringArray();for (int i = 0; i < strList.length; i++){Log.e("logZ", "第"+i+"string为:"+ strList[i]);}//返回一个结构mx2Data data = changeJni.getStruct();Log.e("logZ", "名称为"+data.name+"序列为"+data.index);//返回一个结构数组mx2Data[] dataList = changeJni.getStructArray();for (int i = 0; i < dataList.length; i++){Log.e("logZ", "第"+i+"个:"+"名称为"+data.name+"序列为"+data.index);}}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.activity_main, menu);return true;}}

这个是调用jni代码

package com.example.jnitest2;public class MX2 {static {System.loadLibrary("myjni");}public native void displayParms(String showText, int i, boolean bl);// 返回两个int相加public native int add(int a, int b);// 输入一个数组public native void setArray(boolean[] blList);// 返回一个字符串数组public native String[] getStringArray();// 返回一个结构public native mx2Data getStruct();// 返回一个结构数组public native mx2Data[] getStructArray();}

这个是要返回的结构体(在java中好像叫类  嘿嘿)

package com.example.jnitest2;public class  mx2Data{public  String name;public  int   index;}

这里还是放jni源码

#include "jni.h"#include <stdio.h>#include <math.h>#include <stdio.h>#include "stdlib.h"#include "string.h"/*作用为:传入的参数为:string, int, boolean返回是处理后的s.*/JNIEXPORT void JNICALL jni_displayParms(JNIEnv *env, jobject obj, jstring s, jint i, jboolean b){const char* szStr = (env)->GetStringUTFChars(s, 0 );printf( "String = [%s]\n", szStr );printf( "int = %d\n", i );printf( "boolean = %s\n", (b==JNI_TRUE ? "true" : "false") );(env)->ReleaseStringUTFChars(s, szStr );}/*返回两个整数相加.*/JNIEXPORT jint JNICALL jni_add(JNIEnv *env, jobject, jint a, jint b){int rtn = (int) (a + b);return (jint) rtn;}/*处理一个bool数组.*/JNIEXPORT void JNICALL jni_setArray(JNIEnv *env, jobject, jbooleanArray ba){jboolean* pba = (env)->GetBooleanArrayElements(ba, 0 );jsize len = (env)->GetArrayLength(ba);int i=0;for( i=0; i < len; i+=2 ){pba[i] = JNI_FALSE;printf( "boolean = %s\n", (pba[i]==JNI_TRUE ? "true" : "false") );}(env)->ReleaseBooleanArrayElements(ba, pba, 0 );}/*返回一个string数组.*/JNIEXPORT jobjectArray JNICALL jni_getStringArray(JNIEnv *env, jobject){jstring str;jobjectArray args = 0;jsize len = 5;const char* sa[] = { "Hello,", "world!", "mx2", "is", "good" };int i = 0;args = (env)->NewObjectArray(len, (env)->FindClass("java/lang/String"), 0);for (i = 0; i < len; i++){str = (env)->NewStringUTF(sa[i]);(env)->SetObjectArrayElement(args, i, str);}return args;}/*返回一个java object对象.*/JNIEXPORT jobject JNICALL jni_getStruct(JNIEnv *env, jobject obj){//获取Java中的mx2Data类jclass objectClass = (env)->FindClass("com/example/jnitest2/mx2Data");//得到这个类的构造方法id.  //得到类的默认构造方法的id.都这样写.jmethodID consID = (env)->GetMethodID(objectClass, "<init>", "()V");//获取类中每一个变量的定义//namejfieldID str = (env)->GetFieldID(objectClass, "name", "Ljava/lang/String;");//indexjfieldID idex = (env)->GetFieldID(objectClass, "index", "I");//创建一个jobject对象.jobject myReturn = (env)->NewObject(objectClass, consID);//给每一个实例的变量赋值(env)->SetObjectField(myReturn, str, (env)->NewStringUTF("mei xiang 2"));(env)->SetIntField(myReturn, idex, 10);return myReturn;}/*返回一个jobject数组. 这里放回的是 mx2Data类的数组.*/JNIEXPORT jobjectArray JNICALL jni_getStructArray(JNIEnv *env, jobject _obj){jobjectArray MXArray = NULL;       // jobjectArray 为指针类型jclass clsMX = NULL;         // jclass 为指针类型jobject obj;jint len = 5;  //设置这个数组的长度.//知道要返回的class.clsMX = env->FindClass("com/example/jnitest2/mx2Data");//创建一个MXAray的数组对象.MXArray = env->NewObjectArray(len, clsMX, NULL);//获取类中每一个变量的定义//namejfieldID str = (env)->GetFieldID(clsMX, "name", "Ljava/lang/String;");//indexjfieldID idex = (env)->GetFieldID(clsMX, "index", "I");//得到这个类的构造方法id.  //得到类的默认构造方法的id.都这样写.jmethodID consID = (env)->GetMethodID(clsMX, "<init>", "()V");for (jint i = 0; i < len; i++){obj = env->NewObject(clsMX, consID);env->SetObjectField(obj, str, env->NewStringUTF("mx is mingxiang"));env->SetIntField(obj, idex, (jint) i);env->SetObjectArrayElement(MXArray, i, obj);}return MXArray;}/*创建调用的方法数组.{ "displayParms", "(Ljava/lang/String;IZ)V",     (void*)jni_displayParms },java里面调用的方法  , (java调用时传入的参数类型)返回的类型  , 对应的jni里面的函数.*/static JNINativeMethod const gMethods[] ={{ "displayParms", "(Ljava/lang/String;IZ)V", (void*)jni_displayParms },{ "add", "(II)I", (void*)jni_add },{ "setArray", "([Z)V",(void*)jni_setArray },{ "getStringArray", "()[Ljava/lang/String;",(void*) jni_getStringArray },{ "getStruct", "()Lcom/example/jnitest2/mx2Data;",(void*) jni_getStruct },{ "getStructArray", "()[Lcom/example/jnitest2/mx2Data;",(void*) jni_getStructArray },};/*jni_Onload方法.照着写就行了.*/jint JNI_OnLoad(JavaVM *jvm, void *reserved){JNIEnv* env = NULL;if (jvm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK){return -1;}jclass clazz = (env)->FindClass("com/example/jnitest2/MX2");  //这里是唯一的要注意的. 这里的mx2是在java中引用jni类的类名.(env)->RegisterNatives(clazz, gMethods, sizeof(gMethods) / sizeof(gMethods[0]));return JNI_VERSION_1_4;}void JNI_OnUnload(JavaVM *jvm, void *reserved){return;}