写一段Java调用webservice代码
时间: 2023-03-14 09:15:28 浏览: 82
要写一段Java调用webservice代码,首先需要创建一个Service对象,然后使用Service对象调用Webservice的相关方法,例如:Service service = new Service();
Call call = (Call) service.createCall();
call.setTargetEndpointAddress("http://webservice.example.com/webservice");
call.setOperationName(new QName("http://webservice.example.com/webservice", "operationName"));
Object result = call.invoke(new Object[]{"param1", "param2"});
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写一段 Java 静态函数代码
我可以回答这个问题。以下是一段 Java 静态函数代码:
public static int add(int a, int b) {
return a + b;
}
这个函数接收两个整数参数,将它们相加并返回它们的和。由于这是一个静态函数,可以直接通过类名调用,而不需要创建类的实例。
用java写一段mqtt调用代码
### 回答1:
这是一段基本的Java代码,用于调用MQTT服务:
```
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
public class MqttPublisher {
public static void main(String[] args) {
String topic = "test";
String content = "Hello MQTT";
int qos = 2;
String broker = "tcp://localhost:1883";
String clientId = "JavaPublisher";
MemoryPersistence persistence = new MemoryPersistence();
try {
MqttClient client = new MqttClient(broker, clientId, persistence);
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setCleanSession(true);
System.out.println("Connecting to broker: " + broker);
client.connect(connOpts);
System.out.println("Connected");
System.out.println("Publishing message: " + content);
MqttMessage message = new MqttMessage(content.getBytes());
message.setQos(qos);
client.publish(topic, message);
System.out.println("Message published");
client.disconnect();
System.out.println("Disconnected");
System.exit(0);
} catch (MqttException me) {
System.out.println("reason " + me.getReasonCode());
System.out.println("msg " + me.getMessage());
System.out.println("loc " + me.getLocalizedMessage());
System.out.println("cause " + me.getCause());
System.out.println("excep " + me);
me.printStackTrace();
}
}
}
```
请注意,在使用该代码之前,您需要将其导入Eclipse Paho MQTT客户端库。
### 回答2:
以下是一个使用Java编写的MQTT调用代码示例:
```java
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
public class MQTTClient {
// 定义MQTT服务器地址和端口号
private static final String BROKER = "tcp://mqtt.example.com:1883";
// 定义客户端ID
private static final String CLIENT_ID = "mqtt_client_example";
public static void main(String[] args) {
try {
// 创建MqttClient实例
MqttClient mqttClient = new MqttClient(BROKER, CLIENT_ID, new MemoryPersistence());
// 配置MqttConnectOptions
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setCleanSession(true); // 设置为非持久化会话
connOpts.setAutomaticReconnect(true); // 设置自动重新连接
// 设置回调函数
mqttClient.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
System.out.println("连接丢失!");
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
System.out.println("收到消息: " + new String(message.getPayload()));
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
// 消息发送成功后的回调
}
});
// 连接到MQTT服务器
mqttClient.connect(connOpts);
// 订阅主题
mqttClient.subscribe("topic/example");
// 发布消息
String messageContent = "Hello, MQTT!";
MqttMessage message = new MqttMessage(messageContent.getBytes());
message.setQos(1); // 设置消息质量为1(最多一次)
mqttClient.publish("topic/example", message);
// 断开与MQTT服务器的连接
mqttClient.disconnect();
} catch (MqttException e) {
e.printStackTrace();
}
}
}
```
上述代码使用Eclipse Paho MQTT库实现了一个简单的MQTT客户端。在代码中创建了一个MqttClient实例,并设置连接选项,包括服务器地址和客户端ID。然后,通过设置MqttCallback来处理连接丢失、收到消息和消息发送成功后的回调。接着,通过调用mqttClient.connect()方法连接到MQTT服务器,并使用mqttClient.subscribe()方法订阅主题。然后,创建一个MqttMessage实例并使用mqttClient.publish()方法发布消息。最后,通过mqttClient.disconnect()方法断开与MQTT服务器的连接。请注意,上述代码是一个简单示例,实际应用中可能会根据需求进行进一步的处理和错误处理。
### 回答3:
以下是用Java写的一个简单的MQTT调用代码:
```java
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
public class MQTTClient {
private static final String BROKER = "tcp://localhost:1883";
private static final String TOPIC = "test/topic";
private static final String CLIENT_ID = "mqtt-client";
public static void main(String[] args) {
MemoryPersistence persistence = new MemoryPersistence();
try {
MqttClient mqttClient = new MqttClient(BROKER, CLIENT_ID, persistence);
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setCleanSession(true);
mqttClient.connect(connOpts);
mqttClient.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
System.out.println("Connection Lost!");
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
System.out.println("Received message: " + message.toString());
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println("Message Delivered!");
}
});
mqttClient.subscribe(TOPIC);
String payload = "Hello, MQTT!";
MqttMessage mqttMessage = new MqttMessage(payload.getBytes());
mqttClient.publish(TOPIC, mqttMessage);
mqttClient.disconnect();
} catch (MqttException e) {
e.printStackTrace();
}
}
}
```
这段代码使用了Eclipse Paho MQTT客户端库,首先创建一个`MqttClient`对象,指定了MQTT代理地址和客户端ID。然后设置连接选项,包括设置`CleanSession`为`true`,以及连接回调函数。
接下来,连接到MQTT代理并设置回调函数,当连接断开、收到消息或消息发送完成时,回调函数会被调用。
然后,订阅主题`test/topic`,并发布一条消息到主题上。
最后,断开与MQTT代理的连接。
以上是一个简单的MQTT调用代码,主要包括连接、订阅、发布等操作。根据实际需求,你可以根据这个例子进行修改和扩展。