使用java的milo框架访问OPCUA服务的过程

使用Java的Milo框架访问OPCUA服务的过程包括以下步骤：

引入依赖

在Maven项目中，需要在pom.xml文件中引入以下依赖：

<dependencies>
    <dependency>
        <groupId>org.eclipse.milo</groupId>
        <artifactId>milo-client-sdk</artifactId>
        <version>0.3.9</version>
    </dependency>
    <dependency>
        <groupId>org.eclipse.milo</groupId>
        <artifactId>milo-sdk-server</artifactId>
        <version>0.3.9</version>
    </dependency>
</dependencies>

这里我们使用的是Milo的客户端和服务端sdk。

创建OPCUA客户端

// 创建 OPCUA client
OpcUaClientConfig config = OpcUaClientConfig.builder()
    .setApplicationName(LocalizedText.english("OPCUA-Client"))
    .setApplicationUri("urn:localhost:OPCUA:Client")
    .setEndpoint(endpoint)
    .setRequestTimeout(uint(5000))
    .build();

OpcUaClient client = OpcUaClient.create(config);

其中，endpoint是OPCUA服务的地址。在该步骤中，我们创建了一个OPCUA客户端的配置，然后使用配置创建了一个OPCUA客户端。

连接OPCUA服务

// 连接OPCUA服务
client.connect().get();

在此步骤中，我们通过client.connect().get()方法连接OPCUA服务。

读取节点值

// 读取节点值
List<NodeId> nodeIds = new ArrayList<>();
nodeIds.add(new NodeId(2, "/Static/AllProfiles/DeviceSetPoint"));
nodeIds.add(new NodeId(2, "/Dynamic/CoolingWaterInletTemperature"));

Map<NodeId, DataValue> values = client.readValues(0, TimestampsToReturn.Both, nodeIds).get();

for(Map.Entry<NodeId, DataValue> entry : values.entrySet()) {
    NodeId nodeId = entry.getKey();
    DataValue dataValue = entry.getValue();
    System.out.println(nodeId + " value is " + dataValue.getValue().getValue());
}

以上代码展示了如何读取两个节点的值。在readValues方法中，第一个参数是最大的数据变化历史记录数；第二个参数是时间戳返回模式；第三个参数是Node ID列表。在读取完成后，我们可以迭代values的条目并输出每个节点的值。

写入节点值

// 写入节点值
NodeId nodeId = new NodeId(2, "/Dynamic/CoolingWaterInletTemperature");
DataValue setValue = new DataValue(new Variant(Double.valueOf("50.5")));
StatusCode statusCode = client.writeValue(nodeId, setValue).get();

以上代码展示了如何写入节点的值。在写入之前，我们需要指定要写入的节点并构造要写入的DataValue。在写入完成后，我们可以通过getValue()方法获取写入的值，并检查StatusCode以确保写入成功。

示例1：

import org.eclipse.milo.opcua.stack.core.types.builtin.DataValue;
import org.eclipse.milo.opcua.stack.core.types.builtin.LocalizedText;
import org.eclipse.milo.opcua.stack.core.types.builtin.NodeId;
import org.eclipse.milo.opcua.stack.core.types.builtin.Variant;
import org.eclipse.milo.opcua.stack.core.types.structured.EndpointDescription;
import org.eclipse.milo.opcua.sdk.client.OpcUaClient;
import org.eclipse.milo.opcua.sdk.client.api.session.ClientSession;
import org.eclipse.milo.opcua.sdk.client.api.subscriptions.UaMonitoredItem;
import org.eclipse.milo.opcua.sdk.client.api.subscriptions.UaSubscription;
import org.eclipse.milo.opcua.sdk.client.subscriptions.OpcUaSubscriptionManager;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutionException;

import static org.eclipse.milo.opcua.stack.core.types.builtin.unsigned.Unsigned.uint;

public class OPCUAExample {

    public static void main(String[] args) throws Exception {
        // OPCUA服务地址
        String endpointUrl = "opc.tcp://localhost:53530/OPCUA/SimulationServer";

        // 创建OPCUA客户端
        EndpointDescription endpoint = EndpointDescription.parse(endpointUrl);
        OpcUaClientConfig config = OpcUaClientConfig.builder()
                .setApplicationName(LocalizedText.english("OPCUA-Client"))
                .setApplicationUri("urn:localhost:OPCUA:Client")
                .setEndpoint(endpoint)
                .setRequestTimeout(uint(5000))
                .build();
        OpcUaClient client = OpcUaClient.create(config);

        try {
            // 连接OPCUA服务
            client.connect().get();

            // 读取节点值
            readValues(client);

            // 监听节点数据变化
            monitorValues(client);

            // 写入节点值
            writeValue(client);
        } finally {
            client.disconnect().get();
        }
    }

    private static void readValues(OpcUaClient client) throws ExecutionException, InterruptedException {
        // 读取节点值
        List<NodeId> nodeIds = new ArrayList<>();
        nodeIds.add(new NodeId(2, "/Static/AllProfiles/DeviceSetPoint"));
        nodeIds.add(new NodeId(2, "/Dynamic/CoolingWaterInletTemperature"));

        Map<NodeId, DataValue> values = client.readValues(0, TimestampsToReturn.Both, nodeIds).get();

        for(Map.Entry<NodeId, DataValue> entry : values.entrySet()) {
            NodeId nodeId = entry.getKey();
            DataValue dataValue = entry.getValue();
            System.out.println(nodeId + " value is " + dataValue.getValue().getValue());
        }
    }

    private static void monitorValues(OpcUaClient client) throws ExecutionException, InterruptedException {
        // 订阅节点值变化
        UaSubscription subscription = client.getSubscriptionManager().createSubscription(1000.0).get();

        NodeId nodeId = new NodeId(2, "/Static/AllProfiles/DeviceSetPoint");

        UaMonitoredItem monitoredItem = subscription.createMonitoredItem(
                nodeId,
                OpcUaSubscriptionManager.DEFAULT_ITEM_SETTINGS,
                (item, value) -> System.out.println(item.getReadValueId().getNodeId() + " value has changed: " + value.getValue())
        ).get();

        // 等待值变化
        Thread.sleep(10000);

        monitoredItem.delete();
        subscription.delete();
    }

    private static void writeValue(OpcUaClient client) throws ExecutionException, InterruptedException {
        // 写入节点值
        NodeId nodeId = new NodeId(2, "/Dynamic/CoolingWaterInletTemperature");
        DataValue setValue = new DataValue(new Variant(Double.valueOf("50.5")));
        StatusCode statusCode = client.writeValue(nodeId, setValue).get();

        // 检查写入是否成功
        if (statusCode.isGood()) {
            System.out.println("Value has been written successfully");
        } else {
            System.out.println("Writing failed");
        }
    }
}

在此示例中，我们连接到了OPCUA服务并展示了如何读取、监视和写入节点的值。

示例2：

import org.eclipse.milo.opcua.stack.core.types.builtin.DataValue;
import org.eclipse.milo.opcua.stack.core.types.builtin.LocalizedText;
import org.eclipse.milo.opcua.stack.core.types.builtin.NodeId;
import org.eclipse.milo.opcua.stack.core.types.builtin.Variant;
import org.eclipse.milo.opcua.stack.core.types.structured.EndpointDescription;
import org.eclipse.milo.opcua.sdk.client.OpcUaClient;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutionException;

import static org.eclipse.milo.opcua.stack.core.types.builtin.unsigned.Unsigned.uint;

public class OPCUAExample {

    public static void main(String[] args) throws Exception {
        // OPCUA服务地址
        String endpointUrl = "opc.tcp://localhost:53530/OPCUA/SimulationServer";

        // 创建OPCUA客户端
        EndpointDescription endpoint = EndpointDescription.parse(endpointUrl);
        OpcUaClientConfig config = OpcUaClientConfig.builder()
                .setApplicationName(LocalizedText.english("OPCUA-Client"))
                .setApplicationUri("urn:localhost:OPCUA:Client")
                .setEndpoint(endpoint)
                .setRequestTimeout(uint(5000))
                .build();
        OpcUaClient client = OpcUaClient.create(config);

        try {
            // 连接OPCUA服务
            client.connect().get();

            // 读取节点值
            readValues(client);

            // 写入节点值
            writeValue(client);
        } finally {
            client.disconnect().get();
        }
    }

    private static void readValues(OpcUaClient client) throws ExecutionException, InterruptedException {
        // 读取节点值
        List<NodeId> nodeIds = new ArrayList<>();
        nodeIds.add(new NodeId(2, "/Static/AllProfiles/DeviceSetPoint"));
        nodeIds.add(new NodeId(2, "/Dynamic/CoolingWaterInletTemperature"));

        Map<NodeId, DataValue> values = client.readValues(0, TimestampsToReturn.Both, nodeIds).get();

        for(Map.Entry<NodeId, DataValue> entry : values.entrySet()) {
            NodeId nodeId = entry.getKey();
            DataValue dataValue = entry.getValue();
            System.out.println(nodeId + " value is " + dataValue.getValue().getValue());
        }
    }

    private static void writeValue(OpcUaClient client) throws ExecutionException, InterruptedException {
        // 写入节点值
        NodeId nodeId = new NodeId(2, "/Dynamic/CoolingWaterInletTemperature");
        DataValue setValue = new DataValue(new Variant(Double.valueOf("50.5")));
        StatusCode statusCode = client.writeValue(nodeId, setValue).get();

        // 检查写入是否成功
        if (statusCode.isGood()) {
            System.out.println("Value has been written successfully");
        } else {
            System.out.println("Writing failed");
        }
    }
}

在此示例中，我们连接到了OPCUA服务并展示了如何读取和写入节点的值。

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