java怎么调用海康威视/Streaming/channels/1/picture的接口

调用海康威视的接口需要使用海康威视提供的SDK，以下是调用海康威视接口获取通道1图片的Java代码示例：

import com.sun.jna.NativeLong;
import com.sun.jna.Pointer;
import com.sun.jna.ptr.ByteByReference;
import com.sun.jna.ptr.NativeLongByReference;
import com.sun.jna.ptr.PointerByReference;
import com.sun.jna.win32.StdCallLibrary;
import com.sun.jna.win32.W32APIFunctionMapper;
import com.sun.jna.win32.W32APITypeMapper;
import java.util.HashMap;
import java.util.Map;

public interface HCNetSDK extends StdCallLibrary {
    HCNetSDK INSTANCE = (HCNetSDK) Native.loadLibrary("HCNetSDK", HCNetSDK.class, new HashMap<String, Object>() {
        {
            put(OPTION_TYPE_MAPPER, W32APITypeMapper.UNICODE);
            put(OPTION_FUNCTION_MAPPER, W32APIFunctionMapper.UNICODE);
        }
    });

    boolean NET_DVR_Init();

    NativeLong NET_DVR_Login_V30(String sDVRIP, short wDVRPort, String sUserName, String sPassword, NET_DVR_DEVICEINFO_V30.ByReference lpDeviceInfo);

    boolean NET_DVR_Logout(NativeLong lUserID);

    boolean NET_DVR_GetLastError();

    NativeLong NET_DVR_RealPlay_V40(NativeLong lUserID, NET_DVR_PREVIEWINFO lpPreviewInfo, RealDataCallBack_V30 fRealDataCallBack_V30, Pointer pUser);

    boolean NET_DVR_StopRealPlay(NativeLong lRealHandle);

    boolean NET_DVR_CaptureJPEGPicture_NEW(NativeLong lUserID, NativeLong lChannel, NET_DVR_JPEGPARA lpJpegPara, String sPicFileName);

    interface RealDataCallBack_V30 extends StdCallCallback {
        void invoke(NativeLong lRealHandle, int dwDataType, ByteByReference pBuffer, int dwBufSize, Pointer pUser);
    }

    class NET_DVR_DEVICEINFO_V30 extends Structure {
        public byte[] sSerialNumber = new byte[SERIALNO_LEN];
        public byte byAlarmInPortNum;
        public byte byAlarmOutPortNum;
        public byte byDiskNum;
        public byte byDVRType;
        public byte byChanNum;
        public byte byStartChan;
        public byte byAudioChanNum;
        public byte byIPChanNum;
        public byte[] byRes1 = new byte[24];
        public byte byAbility;
        public byte byRes2;
        public short wDevType;
        public byte[] byRes3 = new byte[2];

        public static class ByReference extends NET_DVR_DEVICEINFO_V30 implements Structure.ByReference {
        }
    }

    class NET_DVR_PREVIEWINFO extends Structure {
        public NativeLong lChannel;
        public NativeLong dwStreamType;
        public NativeLong dwLinkMode;
        public Pointer hPlayWnd;
        public NativeLong bBlocked;
        public NativeLong bPassbackRecord;
        public NativeLongByReference bPreviewMode;
        public NativeLong byProtoType;
        public byte[] byRes = new byte[215];
    }

    class NET_DVR_JPEGPARA extends Structure {
        public int wPicSize;
        public int wPicQuality;
    }

    int SERIALNO_LEN = 48;
}

import com.sun.jna.Native;
import com.sun.jna.NativeLong;
import com.sun.jna.Pointer;
import com.sun.jna.ptr.ByteByReference;
import com.sun.jna.ptr.NativeLongByReference;
import com.sun.jna.ptr.PointerByReference;
import java.io.File;

public class HikvisionDemo {
    public static void main(String[] args) {
        // 初始化
        HCNetSDK.NET_DVR_Init();

        // 登录设备
        HCNetSDK.NET_DVR_DEVICEINFO_V30.ByReference deviceInfo = new HCNetSDK.NET_DVR_DEVICEINFO_V30.ByReference();
        NativeLong lUserID = HCNetSDK.INSTANCE.NET_DVR_Login_V30("10.0.0.64", (short) 8000, "admin", "password", deviceInfo);
        if (lUserID.longValue() == -1) {
            System.out.println("登录失败，错误码：" + HCNetSDK.INSTANCE.NET_DVR_GetLastError());
            return;
        }

        // 设置预览参数
        HCNetSDK.NET_DVR_PREVIEWINFO previewInfo = new HCNetSDK.NET_DVR_PREVIEWINFO();
        previewInfo.lChannel = new NativeLong(1);
        previewInfo.dwStreamType = new NativeLong(0);
        previewInfo.dwLinkMode = new NativeLong(0x00000000);
        previewInfo.hPlayWnd = null;
        previewInfo.bBlocked = new NativeLong(1);
        previewInfo.bPassbackRecord = new NativeLong(0);
        previewInfo.bPreviewMode = new NativeLongByReference(new NativeLong(0));
        previewInfo.byProtoType = new NativeLong(0);
        previewInfo.byRes = new byte[215];

        // 开始预览
        HCNetSDK.RealDataCallBack_V30 realDataCallBack_V30 = new HCNetSDK.RealDataCallBack_V30() {
            @Override
            public void invoke(NativeLong lRealHandle, int dwDataType, ByteByReference pBuffer, int dwBufSize, Pointer pUser) {
                switch (dwDataType) {
                    case HCNetSDK.NET_DVR_SYSHEAD:
                        break;
                    case HCNetSDK.NET_DVR_STREAMDATA:
                        System.out.println("收到视频数据，长度：" + dwBufSize);
                        break;
                }
            }
        };
        NativeLong lRealHandle = HCNetSDK.INSTANCE.NET_DVR_RealPlay_V40(lUserID, previewInfo, realDataCallBack_V30, null);

        // 抓图
        HCNetSDK.NET_DVR_JPEGPARA jpegPara = new HCNetSDK.NET_DVR_JPEGPARA();
        jpegPara.wPicSize = 0;
        jpegPara.wPicQuality = 100;
        String filePath = "C:\\temp\\test.jpg";
        boolean result = HCNetSDK.INSTANCE.NET_DVR_CaptureJPEGPicture_NEW(lUserID, new NativeLong(1), jpegPara, filePath);
        if (result) {
            System.out.println("抓图成功，文件路径：" + filePath);
        } else {
            System.out.println("抓图失败，错误码：" + HCNetSDK.INSTANCE.NET_DVR_GetLastError());
        }

        // 停止预览
        HCNetSDK.INSTANCE.NET_DVR_StopRealPlay(lRealHandle);

        // 注销登录
        HCNetSDK.INSTANCE.NET_DVR_Logout(lUserID);

        // 释放SDK资源
        HCNetSDK.INSTANCE.NET_DVR_Cleanup();
    }
}

其中，需要修改的部分为：

- `NET_DVR_Login_V30(String sDVRIP, short wDVRPort, String sUserName, String sPassword, NET_DVR_DEVICEINFO_V30.ByReference lpDeviceInfo)` 方法中的 `sDVRIP`、`wDVRPort`、`sUserName` 和 `sPassword` 参数，分别为设备IP地址、端口号、用户名和密码。
- `NET_DVR_RealPlay_V40(NativeLong lUserID, NET_DVR_PREVIEWINFO lpPreviewInfo, RealDataCallBack_V30 fRealDataCallBack_V30, Pointer pUser)` 方法中的 `lUserID` 和 `lpPreviewInfo.lChannel` 参数，分别为登录设备返回的用户ID和通道号。
- `NET_DVR_CaptureJPEGPicture_NEW(NativeLong lUserID, NativeLong lChannel, NET_DVR_JPEGPARA lpJpegPara, String sPicFileName)` 方法中的 `lUserID` 和 `lChannel` 参数，分别为登录设备返回的用户ID和通道号；`sPicFileName` 参数为图片保存路径。

需要注意的是，调用海康威视的接口需要使用海康威视提供的SDK，并且需要将SDK对应的dll文件放在Java的classpath路径下。另外，示例中的代码需要使用JNA库进行调用。