JNI学习1--传递java对象 demo

1.首先创建HelloWorld.java文件：

class Person {public String name;public int age;public boolean student;Person(String name, int age, boolean student){this.name = name;this.age = age;this.student = student;}public String getName(){return this.name;}public void setName(String name){this.name = name;}public int getAge(){return this.age;}public void setAge(int age){this.age = age;}public boolean getStudent(){return this.student;}public void setStudent(boolean student){this.student = student;}}public class HelloWorld {public native void displayHelloWorld();public native void displayPerson(Person p);static{System.loadLibrary("hello");}public static void main(String[] args){new HelloWorld().displayHelloWorld();Person p = new Person("hc", 19, true);p.setAge(23);new HelloWorld().displayPerson(p);}} 

2.在命令行中编译java文件：

javac HelloWorld.java

编译生成.h文件：

javah HelloWorld

生成HelloWorld.h文件。

3.在vc++6.0或者vs中创建dll工程，并将生成的HelloWorld.h文件引入。

4.创建c++的Person类

Person.h：

#include <string>using namespace std;class Person{public:string name;int age;bool student;public:Person();Person(string name, int age, bool student);string toString();virtual ~Person();}; 

Person.cpp

#include "Person.h"Person::Person(){}Person::Person(string name, int age, bool student):name(name), age(age), student(student){}string Person::toString(){string str = "name:" + this->name;return str;}Person::~Person(){} 

5.实现HelloWorld.cpp：

#include "jni.h"#include "HelloWorld.h"#include "Person.h"#include <iostream>using namespace std;JNIEXPORT void JNICALL Java_HelloWorld_displayHelloWorld(JNIEnv *env, jobject obj){cout << "Hello World!" << endl;}JNIEXPORT void JNICALL Java_HelloWorld_displayPerson(JNIEnv *env, jobject obj1, jobject obj){Person *p = new Person();jclass cls = (env)->GetObjectClass(obj);jfieldID name = env->GetFieldID(cls, "name", "Ljava/lang/String;");jstring str1 = (jstring)env->GetObjectField(obj, name);jboolean c = '1';string str = env->GetStringUTFChars(str1, &c);jfieldID age = env->GetFieldID(cls, "age", "I");p->name = str;p->age = env->GetIntField(obj, age);//p->student = obj.student;cout << p->toString() << " age:" << p->age << endl;} 

6.在工程中导入“JDKpath”/include中的“jni.h”以及“JDKpath”/include/win32中的“jni_md.h”

7.生成dll，并将dll放入java工程的目录里

8.运行java

java HelloWorld

总结：传递java对象，对象的各个属性需要与jni提供的类型进行转换然后再赋值给c++的对象，还是比较麻烦的，不知道有没有更好的方法。。。