JNI性能测试一—JNI调用C与Java调用java性能比较

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PerformanceTest.java

package com.jni;import android.app.Activity;import android.os.Bundle;import android.util.Log;public class PerformanceTest extends Activity {static{try {System.loadLibrary("PerformanceTest");} catch (UnsatisfiedLinkError ule) {System.err.println("WARNING: Could not load library!");}}private final String PerformanceTestTAG ="PerformanceTest:performanceTestFunc :";/* JNI 测试函数 */private native void emptyJniFunction();/* JAVA测试函数 */private void emptyJavaFunction(){} /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); performanceTestFunc(); } /* 性能测试函数 */ public void performanceTestFunc() { /* 测试数量级为100万次 */int mLoopCount = 1000000;int i = 0;int base = 1000000; String timeStr_ms;/* 毫秒对应String*//* 精确度为纳秒级 */long startTime = System.nanoTime();/* JNI 调用 */for(i = 0;i <= mLoopCount; ++ i){emptyJniFunction();}long endTime = System.nanoTime();timeStr_ms = String.valueOf((endTime-startTime)/base);Log.v(PerformanceTestTAG+"In Jni:", timeStr_ms+"ms");startTime = System.nanoTime();/* JAVA 调用 */for(i = 0;i <= mLoopCount; ++ i){emptyJavaFunction();}endTime = System.nanoTime();timeStr_ms = String.valueOf((endTime-startTime)/base);Log.v(PerformanceTestTAG+"In JAVA:", timeStr_ms+"ms"); }}

com_jni_PerformanceTest.c

/* DO NOT EDIT THIS FILE - it is machine generated */#include <jni.h>/* Header for class com_jni_PerformanceTest */#ifndef _Included_com_jni_PerformanceTest#define _Included_com_jni_PerformanceTest#ifdef __cplusplusextern "C" {#endif/* * Class: com_jni_PerformanceTest * Method: emptyJniFunction * Signature: ()V */JNIEXPORT void JNICALL Java_com_jni_PerformanceTest_emptyJniFunction (JNIEnv *env, jobject obj){ }JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved){JNIEnv *env;int result;result = JNI_VERSION_1_4;return result;}#ifdef __cplusplus}#endif#endif

Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := PerformanceTest

LOCAL_SRC_FILES := src/com_jni_PerformanceTest.c

include $(BUILD_SHARED_LIBRARY)

如上图所示，通过Jni调用c的空实现函数，调用100万次，用时41747ms，而使用java调用java的空实现函数100万次，用时25378ms。以上测试数量级为100万次，系统android 2.2,测试于android模拟器上，jdk1.6.0_17。