JNI调用Java构造方法，父类方法

本文基于此项目Hello JNI

本文用到的函数：Call< Type>Method, CallNonvirtual< Type>Method

JNIDemo.java创建两个native方法

    //访问构造方法
    public native void accessConstructMethod();

    //访问父类方法
    public native void accessParentMethod();

创建一个父类：Person和一个子类：Student

Person.java

package com.test.git.jnidemo.JniUtil;

import android.util.Log;

/**
 * Created by lk on 16/9/26.
 */

public class Person {
     
    private static final String TAG = "Person";
    protected String name;
    protected int age;

    public Person(){

    }


    public Person(String name, int age){
        this.name = name;
        this.age = age;
    }


    @Override
    public String toString() {
        return "name:" + name + "  age:" + age;
    }

    public void printPerson(){
        Log.i(TAG, "printPerson: " + toString());
    }

    public void eat(){
        Log.i(TAG, "eat: Person");
    }
}

Student.java

package com.test.git.jnidemo.JniUtil;

import android.util.Log;

/**
 * Created by lk on 16/9/26.
 */

public class Student extends Person{
     
    private static final String TAG = "Student";

    public Student(String name, int age){
        this.name = name;
        this.age = age;
    }

    @Override
    public void eat() {
        super.eat();
        Log.i(TAG, "eat: Student");
    }
}

com_test_git_jnidemo_JniUtil_JniDemo.h添加相应头文件方法

JNIEXPORT void JNICALL Java_com_test_git_jnidemo_JniUtil_JniDemo_accessConstructMethod
  (JNIEnv *, jobject);

JNIEXPORT void JNICALL Java_com_test_git_jnidemo_JniUtil_JniDemo_accessParentMethod
  (JNIEnv *, jobject);

JniDemo.cpp

调用Java构造方法，并执行相应对象的实例方法

此处初始化的是有参数的构造方法，然后通过生成的Person对象，调用相应的printPerson方法。

JNIEXPORT void JNICALL Java_com_test_git_jnidemo_JniUtil_JniDemo_accessConstructMethod
        (JNIEnv *env, jobject jobj){
     
    //1.获取package com.test.git.jnidemo.JniUtil目录下Person的jclass
    jclass  cls = env->FindClass("com/test/git/jnidemo/JniUtil/Person");
    //2.获取Person的构造函数ID
    jmethodID mid = env->GetMethodID(cls, "", "(Ljava/lang/String;I)V");
//    jobject jniDemo = env->NewObject(cls, mid);
    //3.初始化构造函数(此处传递了参数)
    jobject jniDemo = env->NewObject(cls, mid, env->NewStringUTF("小明"), 10);
    //4.获取Person的printPerson方法ID
    jmethodID pritid = env->GetMethodID(cls, "printPerson", "()V");
    //5.调用Person的printPerson方法
    env->CallVoidMethod(jniDemo, pritid);
};

调用父类的方法

JNIEXPORT void JNICALL Java_com_test_git_jnidemo_JniUtil_JniDemo_accessParentMethod
        (JNIEnv *env, jobject jobj){
     
    //1.获取Student的jclass
    jclass jcls = env->FindClass("com/test/git/jnidemo/JniUtil/Student");
    //2.获取Student的构造方法ID
    jmethodID mid = env->GetMethodID(jcls, "", "(Ljava/lang/String;I)V");
    //3.实例化Student并传递参数
    jobject jcobj = env->NewObject(jcls, mid, env->NewStringUTF("小学生"), 5);
    //4.获取父类的jclass
    jclass jpcls = env->FindClass("com/test/git/jnidemo/JniUtil/Person");
    //5.获取子类的eat方法ID
    jmethodID peatID = env->GetMethodID(jcls, "eat", "()V");
    //直接调用子类方法
//    env->CallVoidMethod(jcobj, peatID);
    //6.调用父类方法
    env->CallNonvirtualVoidMethod(jcobj, jpcls, peatID);
};

MainActivity

        jd.accessConstructMethod();
        jd.accessParentMethod();

运行结果：

09-26 16:00:08.124 10098-10098/? I/Person: printPerson: name:小明  age:10
09-26 16:00:08.124 10098-10098/? I/Person: eat: Person