ReaderBuilder (Pulsar Client

All Superinterfaces:

Cloneable
```
public interface ReaderBuilder<T>
extends Cloneable
```
ReaderBuilder is used to configure and create instances of Reader.

Since:

2.0.0

See Also:

PulsarClient.newReader()

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`ReaderBuilder<T>`	`clone()` Create a copy of the current `ReaderBuilder`.
`Reader<T>`	`create()` Finalize the creation of the `Reader` instance.
`CompletableFuture<Reader<T>>`	`createAsync()` Finalize the creation of the `Reader` instance in asynchronous mode.
`ReaderBuilder<T>`	`cryptoFailureAction(ConsumerCryptoFailureAction action)` Sets the `ConsumerCryptoFailureAction` to specify
`ReaderBuilder<T>`	`cryptoKeyReader(CryptoKeyReader cryptoKeyReader)` Sets a `CryptoKeyReader` to decrypt the message payloads.
`ReaderBuilder<T>`	`loadConf(Map<String,Object> config)` Load the configuration from provided `config` map.
`ReaderBuilder<T>`	`readCompacted(boolean readCompacted)` If enabled, the reader will read messages from the compacted topic rather than reading the full message backlog of the topic.
`ReaderBuilder<T>`	`readerListener(ReaderListener<T> readerListener)` Sets a `ReaderListener` for the reader
`ReaderBuilder<T>`	`readerName(String readerName)` Specify a reader name.
`ReaderBuilder<T>`	`receiverQueueSize(int receiverQueueSize)` Sets the size of the consumer receive queue.
`ReaderBuilder<T>`	`startMessageId(MessageId startMessageId)` The initial reader positioning is done by specifying a message id.
`ReaderBuilder<T>`	`subscriptionRolePrefix(String subscriptionRolePrefix)` Set the subscription role prefix.
`ReaderBuilder<T>`	`topic(String topicName)` Specify the topic this reader will read from.

- Method Detail
  - create
```
Reader<T> create()
          throws PulsarClientException
```
    Finalize the creation of the Reader instance.
    This method will block until the reader is created successfully or an exception is thrown.
    
    Returns:
    
    the reader instance
    
    Throws:
    
    PulsarClientException - if the reader creation fails
  - createAsync
```
CompletableFuture<Reader<T>> createAsync()
```
    Finalize the creation of the Reader instance in asynchronous mode.
    This method will return a CompletableFuture that can be used to access the instance when it's ready.
    
    Returns:
    
    the reader instance
    
    Throws:
    
    PulsarClientException - if the reader creation fails
  - loadConf
```
ReaderBuilder<T> loadConf(Map<String,Object> config)
```
    Load the configuration from provided config map.
    Example:
```
 Map<String, Object> config = new HashMap<>();
 config.put("topicName", "test-topic");
 config.put("receiverQueueSize", 2000);

 ReaderBuilder<byte[]> builder = ...;
 builder = builder.loadConf(config);

 Reader<byte[]> reader = builder.create();
 
```
    Parameters:
    
    config - configuration to load
    
    Returns:
    
    the reader builder instance
  - clone
```
ReaderBuilder<T> clone()
```
    Create a copy of the current ReaderBuilder.
    Cloning the builder can be used to share an incomplete configuration and specialize it multiple times. For example:
```
 ReaderBuilder<String> builder = client.newReader(Schema.STRING)
             .readerName("my-reader")
             .receiverQueueSize(10);

 Reader<String> reader1 = builder.clone().topic("topic-1").create();
 Reader<String> reader2 = builder.clone().topic("topic-2").create();
 
```
    Returns:
    
    a clone of the reader builder instance
  - topic
```
ReaderBuilder<T> topic(String topicName)
```
    Specify the topic this reader will read from.
    This argument is required when constructing the reader.
    
    Parameters:
    
    topicName - the name of the topic
    
    Returns:
    
    the reader builder instance
  - startMessageId
```
ReaderBuilder<T> startMessageId(MessageId startMessageId)
```
    The initial reader positioning is done by specifying a message id. The options are:
    - MessageId.earliest: Start reading from the earliest message available in the topic
    - MessageId.latest: Start reading from end of the topic. The first message read will be the one published *after* the creation of the builder
    - MessageId: Position the reader on a particular message. The first message read will be the one immediately *after* the specified message
    Parameters:
    
    startMessageId - the message id where the reader will be initially positioned on
    
    Returns:
    
    the reader builder instance
  - readerListener
```
ReaderBuilder<T> readerListener(ReaderListener<T> readerListener)
```
    Sets a ReaderListener for the reader
    When a ReaderListener is set, application will receive messages through it. Calls to Reader.readNext() will not be allowed.
    
    Parameters:
    
    readerListener - the listener object
    
    Returns:
    
    the reader builder instance
  - cryptoKeyReader
```
ReaderBuilder<T> cryptoKeyReader(CryptoKeyReader cryptoKeyReader)
```
    Sets a CryptoKeyReader to decrypt the message payloads.
    
    Parameters:
    
    cryptoKeyReader - CryptoKeyReader object
    
    Returns:
    
    the reader builder instance
  - cryptoFailureAction
```
ReaderBuilder<T> cryptoFailureAction(ConsumerCryptoFailureAction action)
```
    Sets the ConsumerCryptoFailureAction to specify
    
    Parameters:
    
    action - The action to take when the decoding fails
    
    Returns:
    
    the reader builder instance
  - receiverQueueSize
```
ReaderBuilder<T> receiverQueueSize(int receiverQueueSize)
```
    Sets the size of the consumer receive queue.
    The consumer receive queue controls how many messages can be accumulated by the Consumer before the application calls Consumer.receive(). Using a higher value could potentially increase the consumer throughput at the expense of bigger memory utilization.
    Default value is 1000 messages and should be good for most use cases.
    
    Parameters:
    
    receiverQueueSize - the new receiver queue size value
    
    Returns:
    
    the reader builder instance
  - readerName
```
ReaderBuilder<T> readerName(String readerName)
```
    Specify a reader name.
    The reader name is purely informational and can used to track a particular reader in the reported stats. By default a randomly generated name is used.
    
    Parameters:
    
    readerName - the name to use for the reader
    
    Returns:
    
    the reader builder instance
  - subscriptionRolePrefix
```
ReaderBuilder<T> subscriptionRolePrefix(String subscriptionRolePrefix)
```
    Set the subscription role prefix. The default prefix is "reader".
    
    Parameters:
    
    subscriptionRolePrefix -
    
    Returns:
    
    the reader builder instance
  - readCompacted
```
ReaderBuilder<T> readCompacted(boolean readCompacted)
```
    If enabled, the reader will read messages from the compacted topic rather than reading the full message backlog of the topic. This means that, if the topic has been compacted, the reader will only see the latest value for each key in the topic, up until the point in the topic message backlog that has been compacted. Beyond that point, the messages will be sent as normal.
    readCompacted can only be enabled when reading from a persistent topic. Attempting to enable it on non-persistent topics will lead to the reader create call throwing a PulsarClientException.
    
    Parameters:
    
    readCompacted - whether to read from the compacted topic
    
    Returns:
    
    the reader builder instance

Interface ReaderBuilder<T>

Method Summary

Method Detail

create

createAsync

loadConf

clone

topic

startMessageId

readerListener

cryptoKeyReader

cryptoFailureAction

receiverQueueSize

readerName

subscriptionRolePrefix

readCompacted