• 深入理解JNINativeInterface函数＜二＞

        该篇文章一起学习类的属性和方法。类的属性和方法一般分为静态和非静态，所以JNINativeInterface关于类的属性操作也分为对于静态和非静态的获取和设置。

    一、静态属性

    1、获取静态属性ID

    jfieldID    (*GetStaticFieldID)(JNIEnv*, jclass, const char*,const char*);

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    2、 获取静态属性值

        jobject     (*GetStaticObjectField)(JNIEnv*, jclass, jfieldID);
    jboolean    (*GetStaticBooleanField)(JNIEnv*, jclass, jfieldID);
    jbyte       (*GetStaticByteField)(JNIEnv*, jclass, jfieldID);
    jchar       (*GetStaticCharField)(JNIEnv*, jclass, jfieldID);
    jshort      (*GetStaticShortField)(JNIEnv*, jclass, jfieldID);
    jint        (*GetStaticIntField)(JNIEnv*, jclass, jfieldID);
    jlong       (*GetStaticLongField)(JNIEnv*, jclass, jfieldID);
    jfloat      (*GetStaticFloatField)(JNIEnv*, jclass, jfieldID);
    jdouble     (*GetStaticDoubleField)(JNIEnv*, jclass, jfieldID);

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    3、设置静态属性的值

        void        (*SetStaticObjectField)(JNIEnv*, jclass, jfieldID, jobject);
    void        (*SetStaticBooleanField)(JNIEnv*, jclass, jfieldID, jboolean);
    void        (*SetStaticByteField)(JNIEnv*, jclass, jfieldID, jbyte);
    void        (*SetStaticCharField)(JNIEnv*, jclass, jfieldID, jchar);
    void        (*SetStaticShortField)(JNIEnv*, jclass, jfieldID, jshort);
    void        (*SetStaticIntField)(JNIEnv*, jclass, jfieldID, jint);
    void        (*SetStaticLongField)(JNIEnv*, jclass, jfieldID, jlong);
    void        (*SetStaticFloatField)(JNIEnv*, jclass, jfieldID, jfloat);
    void        (*SetStaticDoubleField)(JNIEnv*, jclass, jfieldID, jdouble);

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    4、示例

    StaticFieldClass.java

    package com.anniljing.jnidemo;

public class StaticFieldClass {
    public static String name;
}

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    ClassStaticFieldOperator.java

    package com.anniljing.jnidemo.ClassFieldOperator;

import com.anniljing.jnidemo.StaticFieldClass;

public class ClassStaticFieldOperator {

    public static native void setClassStaticField(StaticFieldClass staticFieldClass);
    public static native String getClassStaticField(StaticFieldClass staticFieldClass);
}

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    ClassStaticFieldOperator.cpp

    #include 


extern "C"
JNIEXPORT void JNICALL
Java_com_anniljing_jnidemo_ClassFieldOperator_ClassStaticFieldOperator_setClassStaticField(
        JNIEnv *env, jclass clazz, jobject static_field_class) {
    jclass staticField = env->GetObjectClass(static_field_class);
    jfieldID staticFieldId = env->GetStaticFieldID(staticField, "name", "Ljava/lang/String;");
    env->SetStaticObjectField(staticField, staticFieldId, env->NewStringUTF("我是静态属性"));
}
extern "C"
JNIEXPORT jstring JNICALL
Java_com_anniljing_jnidemo_ClassFieldOperator_ClassStaticFieldOperator_getClassStaticField(
        JNIEnv *env, jclass clazz, jobject static_field_class) {
    jclass staticClass = env->GetObjectClass(static_field_class);
    jfieldID nameField = env->GetStaticFieldID(staticClass, "name", "Ljava/lang/String;");
    return static_cast<jstring>(env->GetStaticObjectField(staticClass, nameField));
}

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    MainActivity.java

        public void setStaticField(View view) {
        StaticFieldClass staticFieldClass = new StaticFieldClass();
        ClassStaticFieldOperator.setClassStaticField(staticFieldClass);
        Log.d(TAG, "getStaticField:" + ClassStaticFieldOperator.getClassStaticField(staticFieldClass));
    }

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    JNI层设置static属性值并返回

    二、非静态属性

    1、获取非静态属性ID

    jfieldID    (*GetFieldID)(JNIEnv*, jclass, const char*, const char*);

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    2、获取属性

        jobject GetObjectField(jobject obj, jfieldID fieldID)
    { return functions->GetObjectField(this, obj, fieldID); }
    jboolean GetBooleanField(jobject obj, jfieldID fieldID)
    { return functions->GetBooleanField(this, obj, fieldID); }
    jbyte GetByteField(jobject obj, jfieldID fieldID)
    { return functions->GetByteField(this, obj, fieldID); }
    jchar GetCharField(jobject obj, jfieldID fieldID)
    { return functions->GetCharField(this, obj, fieldID); }
    jshort GetShortField(jobject obj, jfieldID fieldID)
    { return functions->GetShortField(this, obj, fieldID); }
    jint GetIntField(jobject obj, jfieldID fieldID)
    { return functions->GetIntField(this, obj, fieldID); }
    jlong GetLongField(jobject obj, jfieldID fieldID)
    { return functions->GetLongField(this, obj, fieldID); }
    jfloat GetFloatField(jobject obj, jfieldID fieldID)
    { return functions->GetFloatField(this, obj, fieldID); }
    jdouble GetDoubleField(jobject obj, jfieldID fieldID)
    { return functions->GetDoubleField(this, obj, fieldID); }

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    3、设置属性值

        void        (*SetObjectField)(JNIEnv*, jobject, jfieldID, jobject);
    void        (*SetBooleanField)(JNIEnv*, jobject, jfieldID, jboolean);
    void        (*SetByteField)(JNIEnv*, jobject, jfieldID, jbyte);
    void        (*SetCharField)(JNIEnv*, jobject, jfieldID, jchar);
    void        (*SetShortField)(JNIEnv*, jobject, jfieldID, jshort);
    void        (*SetIntField)(JNIEnv*, jobject, jfieldID, jint);
    void        (*SetLongField)(JNIEnv*, jobject, jfieldID, jlong);
    void        (*SetFloatField)(JNIEnv*, jobject, jfieldID, jfloat);
    void        (*SetDoubleField)(JNIEnv*, jobject, jfieldID, jdouble);

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    4、示例

    JavaClass.java

    package com.anniljing.jnidemo;

import android.util.Log;

public class JavaClass {
    public static String name;
    private String version="hello";
    private static int sCode;

    public JavaClass() {
        Log.d("MainActivity","Init JavaClass");
    }

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }

    public static void setCode(int code){
        sCode=code;
    }

    @Override
    public String toString() {
        return "JavaClass{" +
                "version='" + version + '\''+"Code="+sCode+'\'' +
                '}';
    }
}


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    ClassFieldOperator.java

    package com.anniljing.jnidemo.ClassFieldOperator;

import com.anniljing.jnidemo.JavaClass;

public class ClassFieldOperator {
    public  native JavaClass classFieldOperator();
}


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    ClassFieldOperator.cpp

    #include 
#include 

extern "C"
JNIEXPORT jobject JNICALL
Java_com_anniljing_jnidemo_ClassFieldOperator_ClassFieldOperator_classFieldOperator(JNIEnv *env,
                                                                                    jobject thiz) {
    jclass javaClass = env->FindClass("com/anniljing/jnidemo/JavaClass");
    jmethodID constructor = env->GetMethodID(javaClass, "", "()V");
    jobject obj = env->NewObject(javaClass, constructor);
    jfieldID versionId = env->GetFieldID(javaClass, "version", "Ljava/lang/String;");
    jobject versionValue = env->GetObjectField(obj, versionId);
    jstring value=((jstring) versionValue);
    //不能使用%s打印jstring，需要做一下处理
    const char *c_str = NULL;
    char buff[128] = {0};
    jboolean isCopy;    // 返回JNI_TRUE表示原字符串的拷贝，返回JNI_FALSE表示返回原字符串的指针
    c_str = env->GetStringUTFChars(value, &isCopy);
    LOGD("Current version value: %s", c_str);
    env->SetObjectField(obj, versionId, env->NewStringUTF("Version:1.00.00"));
    return obj;
}



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    MainActivity.java

      public void setNormalField(View view) {
        ClassFieldOperator classFieldOperator = new ClassFieldOperator();
        JavaClass javaClass = classFieldOperator.classFieldOperator();
        Log.d(TAG, javaClass.toString());
    }

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    在这里插入图片描述

    三、静态方法

    1、获取静态方法ID

    jmethodID   (*GetStaticMethodID)(JNIEnv*, jclass, const char*, const char*);

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    2、调用静态方法

        jobject     (*CallStaticObjectMethod)(JNIEnv*, jclass, jmethodID, ...);
    jobject     (*CallStaticObjectMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    jobject     (*CallStaticObjectMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    jboolean    (*CallStaticBooleanMethod)(JNIEnv*, jclass, jmethodID, ...);
    jboolean    (*CallStaticBooleanMethodV)(JNIEnv*, jclass, jmethodID,
                        va_list);
    jboolean    (*CallStaticBooleanMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    jbyte       (*CallStaticByteMethod)(JNIEnv*, jclass, jmethodID, ...);
    jbyte       (*CallStaticByteMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    jbyte       (*CallStaticByteMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    jchar       (*CallStaticCharMethod)(JNIEnv*, jclass, jmethodID, ...);
    jchar       (*CallStaticCharMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    jchar       (*CallStaticCharMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    jshort      (*CallStaticShortMethod)(JNIEnv*, jclass, jmethodID, ...);
    jshort      (*CallStaticShortMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    jshort      (*CallStaticShortMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    jint        (*CallStaticIntMethod)(JNIEnv*, jclass, jmethodID, ...);
    jint        (*CallStaticIntMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    jint        (*CallStaticIntMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    jlong       (*CallStaticLongMethod)(JNIEnv*, jclass, jmethodID, ...);
    jlong       (*CallStaticLongMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    jlong       (*CallStaticLongMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    jfloat      (*CallStaticFloatMethod)(JNIEnv*, jclass, jmethodID, ...);
    jfloat      (*CallStaticFloatMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    jfloat      (*CallStaticFloatMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    jdouble     (*CallStaticDoubleMethod)(JNIEnv*, jclass, jmethodID, ...);
    jdouble     (*CallStaticDoubleMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    jdouble     (*CallStaticDoubleMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);
    void        (*CallStaticVoidMethod)(JNIEnv*, jclass, jmethodID, ...);
    void        (*CallStaticVoidMethodV)(JNIEnv*, jclass, jmethodID, va_list);
    void        (*CallStaticVoidMethodA)(JNIEnv*, jclass, jmethodID, const jvalue*);

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    3、示例

    JavaClass.java

    package com.anniljing.jnidemo;

import android.util.Log;

public class JavaClass {
    public static String name;
    private String version="hello";
    private static int sCode;

    public JavaClass() {
        Log.d("MainActivity","Init JavaClass");
    }

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }

    public static void setCode(int code){
        sCode=code;
    }

    @Override
    public String toString() {
        return "JavaClass{" +
                "version='" + version + '\''+"Code="+sCode+'\'' +
                '}';
    }
}


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    ClassMethodOperator.java

    package com.anniljing.jnidemo.classMethodOperator;

import com.anniljing.jnidemo.JavaClass;

public class ClassMethodOperator {
    public static native JavaClass operatorClassStaticMethod();
}


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    ClassMethodOPerator.cpp

    #include 

extern "C"
JNIEXPORT jobject JNICALL
Java_com_anniljing_jnidemo_classMethodOperator_ClassMethodOperator_operatorClassStaticMethod(
        JNIEnv *env, jclass clazz) {
    jclass javaClass = env->FindClass("com/anniljing/jnidemo/JavaClass");
    jmethodID constrcture = env->GetMethodID(javaClass, "", "()V");
    jobject javaClassObj = env->NewObject(javaClass, constrcture);
    jmethodID staticCode=env->GetStaticMethodID(javaClass,"setCode", "(I)V");
    env->CallStaticVoidMethod(javaClass,staticCode,11);
    return javaClassObj;
}

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    四、非静态方法

    1、获取非静态方法ID

    jmethodID   (*GetMethodID)(JNIEnv*, jclass, const char*, const char*);

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    2、调用非静态方法

        jobject     (*CallObjectMethod)(JNIEnv*, jobject, jmethodID, ...);
    jobject     (*CallObjectMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jobject     (*CallObjectMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    jboolean    (*CallBooleanMethod)(JNIEnv*, jobject, jmethodID, ...);
    jboolean    (*CallBooleanMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jboolean    (*CallBooleanMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    jbyte       (*CallByteMethod)(JNIEnv*, jobject, jmethodID, ...);
    jbyte       (*CallByteMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jbyte       (*CallByteMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    jchar       (*CallCharMethod)(JNIEnv*, jobject, jmethodID, ...);
    jchar       (*CallCharMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jchar       (*CallCharMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    jshort      (*CallShortMethod)(JNIEnv*, jobject, jmethodID, ...);
    jshort      (*CallShortMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jshort      (*CallShortMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    jint        (*CallIntMethod)(JNIEnv*, jobject, jmethodID, ...);
    jint        (*CallIntMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jint        (*CallIntMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    jlong       (*CallLongMethod)(JNIEnv*, jobject, jmethodID, ...);
    jlong       (*CallLongMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jlong       (*CallLongMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    jfloat      (*CallFloatMethod)(JNIEnv*, jobject, jmethodID, ...);
    jfloat      (*CallFloatMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jfloat      (*CallFloatMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    jdouble     (*CallDoubleMethod)(JNIEnv*, jobject, jmethodID, ...);
    jdouble     (*CallDoubleMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    jdouble     (*CallDoubleMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);
    void        (*CallVoidMethod)(JNIEnv*, jobject, jmethodID, ...);
    void        (*CallVoidMethodV)(JNIEnv*, jobject, jmethodID, va_list);
    void        (*CallVoidMethodA)(JNIEnv*, jobject, jmethodID, const jvalue*);

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    3、示例

    JavaClass.java

    package com.anniljing.jnidemo;

import android.util.Log;

public class JavaClass {
    public static String name;
    private String version="hello";
    private static int sCode;

    public JavaClass() {
        Log.d("MainActivity","Init JavaClass");
    }

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }

    public static void setCode(int code){
        sCode=code;
    }

    @Override
    public String toString() {
        return "JavaClass{" +
                "version='" + version + '\''+"Code="+sCode+'\'' +
                '}';
    }
}


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    ClassMethodOperator.java

    package com.anniljing.jnidemo.classMethodOperator;

import com.anniljing.jnidemo.JavaClass;

public class ClassMethodOperator {
    public static native JavaClass operatorClassMethod();
}


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    ClassMethodOPerator.cpp

    #include 


extern "C"
JNIEXPORT jobject JNICALL
Java_com_anniljing_jnidemo_classMethodOperator_ClassMethodOperator_operatorClassMethod(JNIEnv *env,
                                                                                       jclass clazz) {
    jclass javaClass = env->FindClass("com/anniljing/jnidemo/JavaClass");
    jmethodID constrcture = env->GetMethodID(javaClass, "", "()V");
    jobject javaClassObj = env->NewObject(javaClass, constrcture);
    jmethodID setVersion = env->GetMethodID(javaClass, "setVersion", "(Ljava/lang/String;)V");
    env->CallVoidMethod(javaClassObj, setVersion, env->NewStringUTF("1.1.1"));
    return javaClassObj;
}

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    代码已同步GitHub

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  • 原文地址：https://blog.csdn.net/u011557841/article/details/126338702