jni中的簽名引數是一個很麻煩的東西，稍不注意，應用就gg了。

1.基本型別

另外：typedef jint jsize;

2.引用型別

3.成員變數描述符

4.方法描述符

5.引數簽名.基本格式

(引數1型別標示;引數2型別標示;...引數n型別標示)返回值型別標示。

表1-2  函式簽名小例子

6.Demo

package com.victor.hello;
import java.io.Serializable;
public class People implements Serializable {
    public int age;
    public String name;
    public int getAge() {
        return age
 
;
}

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

    public void setAge(int age) {
        this.age = age;
}

    public String getName() {
        return name;
}

    public void setName(String name) {
        this.name = name;
}

    public 
 
People getInstance() {
        return this;
}
}

JNIEXPORT jint JNICALL Java_com_victor_hello_HelloWorld_getPeopleToStr
        (JNIEnv *env, jobject clazz, jobject peopleObj)
{
    //先找到com/victor/hello/People類在JNI層中對應的jclass例項。
jclass peopleInterface = env->FindClass("com/victor/hello/People");
jmethodID setAgeMethodID = env->GetMethodID(peopleInterface, "setAge", "(I)V");
env->CallIntMethod(peopleObj, setAgeMethodID, 110);
jmethodID getAgeMethodID = env->GetMethodID(peopleInterface, "getAge", "()I");
jint age = env->CallIntMethod(peopleObj, getAgeMethodID);
return age;
}

最後呼叫方法：

getPeopleToStr(new People());

返回：110

多個引數的呼叫：

JNIEXPORT void JNICALL Java_com_victor_hello_HelloWorld_setPeopleParams
        (JNIEnv *env, jobject clazz, jobject clientObj, jstring name, jint age)
{
    jclass peopleInterface = env->FindClass("com/victor/hello/People");
jmethodID setAgeMethodID = env->GetMethodID(peopleInterface, "setNameAndAge", "(Ljava/lang/String;I)V");
env->CallIntMethod(clientObj, setAgeMethodID, name, age);
}