Gateway Java Demo

This section provides a demo based on Fabric Gateway for Java. Fabric Gateway Java encapsulates the Java SDK, which reduces the code amount and helps users develop Java client applications.

Common APIs

When you use Fabric-Gateway-Java to initiate transactions and query data, the Network and Contract interfaces are used. For more interfaces, see the Fabric official website.

Network

The common interfaces are as follows:

API	Description	Setting	Returned Values
getContract	Gets an instance of a contract.	String chaincodeId	Contract
addBlockListener	Adds a listener to listen to block events.	Consumer<org.hyperledger.fabric.sdk.BlockEvent> listener	Consumer<org.hyperledger.fabric.sdk.BlockEvent>
getChannel	Gets the channel associated with the network.	/	org.hyperledger.fabric.sdk.Channel
removeBlockListener	Removes a listener.	Consumer<org.hyperledger.fabric.sdk.BlockEvent> listener	void

Contract

The common interfaces are as follows:

API	Description	Setting	Returned Values
submitTransaction	Submits a transaction. The invocation method and parameters need to be entered.	String name, String... args	byte[]
evaluateTransaction	Evaluates a transaction. The invocation method and parameters need to be entered.	String name, String... args	byte[]
createTransaction	Creates a transaction. The transaction needs to be submitted.	String name	Transaction
addContractListener	Adds a listener to listen to events emitted by committed transactions.	Consumer<ContractEvent> listener	Consumer<ContractEvent> listener
removeContractListener	Removes a listener.	Consumer<ContractEvent> listener	void