### Run Sample Bot with application.yml

Source: https://github.com/line/line-bot-sdk-java/blob/master/samples/sample-spring-boot-echo-kotlin/README.md

If you have configured the `application.yml` file, you can start the web server using this Gradle command. This method assumes configuration is already set up.

```bash
../gradlew bootRun
```

--------------------------------

### Build Project with Gradle

Source: https://github.com/line/line-bot-sdk-java/blob/master/CONTRIBUTING.md

Run this command to download dependencies, check the build, and compile the project. Ensure JDK 17 or later is installed.

```bash
./gradlew build
```

--------------------------------

### Full Echo Bot Application Example

Source: https://github.com/line/line-bot-sdk-java/blob/master/spring-boot/line-bot-spring-boot-client/README.md

This is a complete example of an echo bot using Spring Boot and the LINE Messaging API. It demonstrates setting up the application, handling text messages, and replying with the same text. Ensure you have the necessary LINE SDK dependencies.

```java
package com.example.bot.spring.echo;

import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import com.linecorp.bot.messaging.client.MessagingApiClient;
import com.linecorp.bot.messaging.model.ReplyMessageRequest;
import com.linecorp.bot.messaging.model.TextMessage;
import com.linecorp.bot.spring.boot.handler.annotation.EventMapping;
import com.linecorp.bot.spring.boot.handler.annotation.LineMessageHandler;
import com.linecorp.bot.webhook.model.Event;
import com.linecorp.bot.webhook.model.MessageEvent;
import com.linecorp.bot.webhook.model.TextMessageContent;

@SpringBootApplication
@LineMessageHandler
public class EchoApplication {
    private final Logger log = LoggerFactory.getLogger(EchoApplication.class);
    private final MessagingApiClient messagingApiClient;

    public static void main(String[] args) {
        SpringApplication.run(EchoApplication.class, args);
    }

    public EchoApplication(MessagingApiClient messagingApiClient) {
        this.messagingApiClient = messagingApiClient;
    }

    @EventMapping
    public void handleTextMessageEvent(MessageEvent event) {
        log.info("event: " + event);
        if (event.message() instanceof TextMessageContent) {
            TextMessageContent message = (TextMessageContent) event.message();
            final String originalMessageText = message.text();
            messagingApiClient.replyMessage(new ReplyMessageRequest(
                event.replyToken(),
                List.of(new TextMessage(originalMessageText)),
                false));
        }
    }

    @EventMapping
    public void handleDefaultMessageEvent(Event event) {
        System.out.println("event: " + event);
    }
}
```

--------------------------------

### Handling FollowEvent

Source: https://github.com/line/line-bot-sdk-java/blob/master/spring-boot/line-bot-spring-boot-client/README.md

This example shows how to handle a FollowEvent, which is triggered when a user follows your LINE bot. It returns a simple text message indicating the follow action. Ensure the class is annotated with @LineMessageHandler.

```java
@LineMessageHandler
public class EchoApplication {
    @EventMapping
    public TextMessage handleFollowEvent(FollowEvent event) {
        System.out.println("event: " + event);
        return new TextMessage("Folllowed");
    }
}
```

--------------------------------

### Handling Any Event Type

Source: https://github.com/line/line-bot-sdk-java/blob/master/spring-boot/line-bot-spring-boot-client/README.md

This example demonstrates how to create a general event handler that catches any type of Event. Use this when you need to log or perform a default action for events not specifically handled by other methods. The class must be annotated with @LineMessageHandler.

```java
@LineMessageHandler
public class EchoApplication {
    @EventMapping
    public void handleDefaultMessageEvent(Event event) {
        System.out.println("event: " + event);
    }
}
```

--------------------------------

### Get x-line-request-id from API Response

Source: https://github.com/line/line-bot-sdk-java/blob/master/README.md

Retrieve the `x-line-request-id` header from an API response by accessing the `requestId()` method of the `Result<T>` object. This is useful for tracking requests across different LINE APIs.

```java
Result<Object> apiResponse = messagingApiClient
    .narrowcast(retryKey, new NarrowcastRequest.Builder(messages).build())
    .get();
System.out.println("x-line-request-id: " + apiResponse.requestId());
```

--------------------------------

### Run Sample Bot with Gradle

Source: https://github.com/line/line-bot-sdk-java/blob/master/samples/sample-spring-boot-echo/README.md

Execute the sample bot using Gradle. You need to provide your Channel access token and Channel secret as command-line arguments.

```bash
../gradlew bootRun -Dline.bot.channelToken=YOUR_CHANNEL_TOKEN \
                       -Dline.bot.channelSecret=YOUR_CHANNEL_SECRET
```

```bash
../gradlew bootRun
```

--------------------------------

### Run Sample Bot with Gradle

Source: https://github.com/line/line-bot-sdk-java/blob/master/samples/sample-spring-boot-echo-kotlin/README.md

Use this command to run the sample bot with specific channel access token and secret. Ensure these values are replaced with your actual credentials.

```bash
../gradlew bootRun -Dline.bot.channelToken=YOUR_CHANNEL_TOKEN \
                       -Dline.bot.channelSecret=YOUR_CHANNEL_SECRET
```

--------------------------------

### Run Sample Spring Boot Echo Bot

Source: https://github.com/line/line-bot-sdk-java/blob/master/CONTRIBUTING.md

Use this Gradle command to run the sample Spring Boot echo bot project locally for testing.

```bash
./gradlew :samples:sample-spring-boot-echo:bootRun
```

--------------------------------

### Generate JavaDoc Documentation

Source: https://github.com/line/line-bot-sdk-java/blob/master/CONTRIBUTING.md

Execute this Gradle command to generate JavaDoc for the project. Ensure all new or modified code includes proper JavaDoc comments.

```bash
./gradlew javadoc
```

--------------------------------

### Spring Boot Echo Bot Implementation

Source: https://github.com/line/line-bot-sdk-java/blob/master/README.md

This Java code demonstrates a basic Spring Boot application for a LINE echo bot. It handles incoming text messages and replies with the same text. Ensure you have the necessary Spring Boot and LINE SDK dependencies.

```java
package com.example.bot.spring.echo;

import java.util.List;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import com.linecorp.bot.messaging.client.MessagingApiClient;
import com.linecorp.bot.messaging.model.ReplyMessageRequest;
import com.linecorp.bot.messaging.model.TextMessage;
import com.linecorp.bot.spring.boot.handler.annotation.EventMapping;
import com.linecorp.bot.spring.boot.handler.annotation.LineMessageHandler;
import com.linecorp.bot.webhook.model.Event;
import com.linecorp.bot.webhook.model.MessageEvent;
import com.linecorp.bot.webhook.model.TextMessageContent;

@SpringBootApplication
@LineMessageHandler
public class EchoApplication {
    private final MessagingApiClient messagingApiClient;

    public static void main(String[] args) {
        SpringApplication.run(EchoApplication.class, args);
    }

    public EchoApplication(MessagingApiClient messagingApiClient) {
        this.messagingApiClient = messagingApiClient;
    }

    @EventMapping
    public void handleTextMessageEvent(MessageEvent<TextMessageContent> event) {
        System.out.println("event: " + event);
        final String originalMessageText = ((TextMessageContent) event.message()).text();
        messagingApiClient.replyMessage(
            new ReplyMessageRequest.Builder(event.replyToken(), List.of(new TextMessage(originalMessageText)))
                .build()
        );
    }

    @EventMapping
    public void handleDefaultMessageEvent(Event event) {
        System.out.println("event: " + event);
    }
}
```

--------------------------------

### Gradle Dependencies for LINE Messaging API SDK

Source: https://github.com/line/line-bot-sdk-java/blob/master/README.md

Add these dependencies to your Gradle build file to include the LINE Messaging API SDK modules. Replace <VERSION> with the desired version. Some modules are not required for explicit dependency.

```kotlin
implementation("com.linecorp.bot:line-bot-messaging-api-client:<VERSION>")
implementation("com.linecorp.bot:line-bot-insight-client:<VERSION>")
implementation("com.linecorp.bot:line-bot-manage-audience-client:<VERSION>")
implementation("com.linecorp.bot:line-bot-module-attach-client:<VERSION>")
implementation("com.linecorp.bot:line-bot-module-client:<VERSION>")
implementation("com.linecorp.bot:line-bot-shop-client:<VERSION>")
implementation("com.linecorp.bot:line-channel-access-token-client:<VERSION>")
implementation("com.linecorp.bot:line-liff-client:<VERSION>")

implementation("com.linecorp.bot:line-bot-webhook:<VERSION>")
implementation("com.linecorp.bot:line-bot-parser:<VERSION>") // You don't need to depend on this explicitly.

implementation("com.linecorp.bot:line-bot-spring-boot-webmvc:<VERSION>")
implementation("com.linecorp.bot:line-bot-spring-boot-client:<VERSION>") // If you want to write spring-boot API client
implementation("com.linecorp.bot:line-bot-spring-boot-handler:<VERSION>") // You don't need to depend on this explicitly.
implementation("com.linecorp.bot:line-bot-spring-boot-web:<VERSION>") // You don't need to depend on this explicitly.
```

--------------------------------

### Handle Text Message Event with Destination

Source: https://github.com/line/line-bot-sdk-java/blob/master/spring-boot/line-bot-spring-boot-client/README.md

Use @LineBotDestination as the first parameter in an event handler to receive the destination field. The event object should be the second parameter. This is useful for identifying the source of the message.

```java
import com.linecorp.bot.spring.boot.annotation.EventMapping;
import com.linecorp.bot.spring.boot.annotation.LineMessageHandler;
import com.linecorp.bot.spring.boot.annotation.LineBotDestination;
import com.linecorp.bot.model.event.MessageEvent;
import com.linecorp.bot.model.event.message.TextMessageContent;
import com.linecorp.bot.model.message.TextMessage;

@LineMessageHandler
public class EchoApplication {
    @EventMapping
    public TextMessage handleTextMessageEvent(@LineBotDestination String destination,
                                              MessageEvent<TextMessageContent> event) {
        System.out.println("event: " + event);
        return new TextMessage(event.getMessage().getText());
    }
}
```

--------------------------------

### Configuring Proxy for Messaging API Client

Source: https://github.com/line/line-bot-sdk-java/blob/master/README.md

This Java code snippet shows how to configure the MessagingApiClient to use an HTTP proxy server. This is useful when your application needs to connect to the LINE Messaging API through a proxy.

```java
api = MessagingApiClient.builder("MY_OWN_TOKEN")
        .apiEndPoint(URI.create("https://api.line.me/"))
        .proxy(new Proxy(Proxy.Type.HTTP,
                new InetSocketAddress("proxy.example.com", 8080)
        ))
        .build();
```

--------------------------------

### Echo Bot with TextMessage Return Type

Source: https://github.com/line/line-bot-sdk-java/blob/master/spring-boot/line-bot-spring-boot-client/README.md

This snippet shows a simplified echo bot handler that directly returns a TextMessage. It's suitable when you only need to echo text messages and don't require explicit client calls for replying. Ensure the class is annotated with @LineMessageHandler.

```java
@LineMessageHandler
public class EchoApplication {
    @EventMapping
    public TextMessage handleTextMessageEvent(MessageEvent event, TextMessageContent content) {
        System.out.println("event: " + event);
        return new TextMessage(content.getText());
    }
}
```

--------------------------------

### Retrieve x-line-accepted-request-id from Error Response

Source: https://github.com/line/line-bot-sdk-java/blob/master/README.md

Access specific headers, such as `x-line-accepted-request-id`, from an error response by using the `getHeader()` method on the `MessagingApiClientException` object.

```java
exception.getHeader("x-line-accepted-request-id")
```

--------------------------------

### Handle MessagingApiClientException in Java

Source: https://github.com/line/line-bot-sdk-java/blob/master/README.md

Catch `MessagingApiClientException` to handle errors when using the `MessagingApiClient`. This allows you to access detailed error information such as the HTTP status code, response body, and a general error message. Ensure you are catching `ExecutionException` to access the underlying `MessagingApiClientException`.

```java
try {
    messagingApiClient.replyMessage(new ReplyMessage(replyToken, messages));
} catch (ExecutionException e) {
    if (e.getCause() instanceof MessagingApiClientException){
        MessagingApiClientException exception=(MessagingApiClientException)e.getCause();
        System.out.println("Error http status code: " + exception.getCode());
        System.out.println("Error response: " + exception.getDetails());
        System.out.println("Error message: " + exception.getMessage());
    }
}
```

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