"Block Chain" Ethernet Square web3j for Java use-deployment and invocation contracts <3>__mysql

WEB3J Deployment Contract

Environment: Mac OS & Android Studio

Official website: here

Ethernet square web3j for Java configuration and use <1>: here

Ethernet square web3j for Java use-Create a voucher for a user credentials <2>:here One, compile a contract

Solc <contract>.sol--bin--abi--optimize-o <output-dir>/

====> production. Abi and. bin files

For example, in the Hello.sol file directory, enter:
solc hello.sol--bin--abi--optimize-o/users/pro/desktop

second, generate. java Files

WEB3J solidity generate [--javatypes|--soliditytypes]/path/to/<smart-contract>.bin/path/to/< Smart-contract>.abi-o/path/to/src/main/java-p Com.your.organisation.name

For example:

The generated. java file is then imported into an Android project.

III. Deployment of contracts

Yoursmartcontract contract = Yoursmartcontract.deploy (<web3j>, <credentials>, Gas_price, GAS_LIMIT,
    [<initialvalue>,]
    <param1>,.., <paramN>). Send ();

Or you can load a contract that has been deployed on a private chain:

Yoursmartcontract contract = Yoursmartcontract.load (
    "0x<address>|<ensname>", web3j, credentials, Gas_price, Gas_limit);

For example:

allbikeshared contract = Allbikeshared.load ("0x055a864a5f39f9eecd17e729e2cfc4fb6b12c19b", web3, credentials, Gas_ Price, gas_limit);

Iv. invoking the contract

1.call way, without changing the status of the smart contract

    Type result = Contract.somemethod (<param1>, ...). Send ();

For example:

    BigInteger result = Contract.getusercount (). Send ();