高级语言调用C接口(二)回调函数(2)Java

先看这样一个C接口

    typedef struct _stPayResult
    {
        enPlace place = SD_D_PLACE_BUTT; //收单机构
        const char* errCode = NULL; //错误码
        const char* errInfo = NULL; //错误信息
        const char* seqId = NULL; //平台流水号
        const char* merOrderId = NULL; //商户订单号
        const char* srcReserve = NULL; //请求系统预留字段
        const char* attachedData = NULL; //商户附加数据
        const char* totalAmount = NULL; //订单金额
        const char* couponAmount = NULL; //优惠金额
        const char* payAmount = NULL; //实付金额
        const char* payTime = NULL; //支付时间
        const char* orderCreateTime = NULL; //订单创建时间
        const char* status = NULL; //交易状态
    }stPayResult;

    typedef void(*OnPayResult)(stPayResult* pstPayResult);
    
    size_t SDPALMPAYPOSAPI Init(const char* pcPayDeviceIP, unsigned short usTlsPort, OnPayResult onPayResult)

接口用于初始化SDK并设置了回调函数。回调函数的参数是一个结构体的指针，首先，我们来看一下C中如何调用该接口

void PayResult(stPayResult* pstPayResult)
{
    printf("errCode:%s, errInfo:%s\n", pstPayResult->errCode, pstPayResult->errInfo);
}

int main(int argc, char**argv)
{
    Init("127.0.0.1", 443, PayResult);
}

调用方法非常的简单粗暴，接下来，我们看一下JAVA中JNA是如何实现调用的。

接口定义

    long  Init(String pcPayDeviceIP, int usTlsPort, OnPayResult onPayResult);

结构体定义

package com.saintdeem;

import java.util.Arrays;
import java.util.List;

import com.sun.jna.Structure;

public class stPayResult extends Structure {
	public int place = enPlace.SD_D_PLACE_BUTT.getValue(); //收单机构
	public String errCode; //错误码
	public String errInfo; //错误信息
	public String seqId; //平台流水号
	public String merOrderId; //商户订单号
	public String srcReserve; //请求系统预留字段
	public String attachedData; //商户附加数据
	public String totalAmount; //订单金额
	public String couponAmount; //优惠金额
	public String payAmount; //实付金额
	public String payTime; //支付时间
	public String orderCreateTime; //订单创建时间
	public String status; //交易状态
	
	public static class ByReference extends stPayResult implements
	Structure. ByReference {
	}
	public static class ByValue extends stPayResult implements
	Structure. ByValue {
	}
	
    /**
     * 重写getFieldOrder获取字段列表
     * @return
     */
    @Override
    protected List<String> getFieldOrder() {
        return Arrays.asList("place", "errCode", "errInfo", "seqId", "merOrderId", "srcReserve", "attachedData", "totalAmount", "couponAmount", "payAmount", "payTime", "orderCreateTime", "status");
    }

}

回调接口定义

import com.sun.jna.Callback;

public interface OnPayResult extends Callback {
	void onPayResult(stPayResult.ByReference payResult);
}

回调实现类定义

	private class OnPayResultImpl implements OnPayResult {
		@Override
		public void onPayResult(stPayResult.ByReference payResult) {
			PayResult(payResult);
		}
	}

回调接口实现

	@Override
	final protected void PayResult(stPayResult.ByReference pstPayResult) {
		System.out.printf("errCode:%s, errInfo:%s\n", pstPayResult.errCode, pstPayResult.errInfo);
	}

调用

private OnPayResult onPayResult = new OnPayResultImpl();
SDPalmPayDevicePosSDKApi.instanceDll.Init("127.0.0.1", 443, onPayResult);

下一篇将介绍C#的调用方式