如何從 Java 呼叫合約的函式？

有 BizzleTokenSale 合約。

pragma solidity ^0.4.2;

import "./BizzleToken.sol";

contract BizzleTokenSale {

address admin;

BizzleToken public tokenContract;
uint256 public tokenPrice;
uint256 public tokensSold;


event Sell(address _buyer, uint256 _amount);

function BizzleTokenSale(BizzleToken _tokenContract, uint256 _tokenPrice) public {
   admin = msg.sender;
   tokenContract = _tokenContract;
   tokenPrice = _tokenPrice;


}

function multiply(uint x, uint y) internal pure returns (uint z) {

   require(y == 0 || (z = x * y) / y == x);

}

function buyTokens(uint256 _numberOfTokens) public payable {

   // Require that value is equal
   require(msg.value == multiply(_numberOfTokens, tokenPrice));

   // Require token contract has enough tokens
   require(tokenContract.balanceOf(this) >= _numberOfTokens);

   // Require transfer is successfull
   require(tokenContract.transfer(msg.sender, _numberOfTokens));

   // Keep track tokensSold
   tokensSold += _numberOfTokens;

   // track Sell event
   Sell(msg.sender, _numberOfTokens);
}

function endSale() public {
   require(msg.sender == admin);
   require(tokenContract.transfer(admin, tokenContract.balanceOf(this)));
   admin.transfer(address(this).balance);
}
}

還有 BizzleToken.sol

pragma solidity ^0.4.2;


contract BizzleToken {

string public name = "Bizzle Token";
string public symbol = "BIZ";
string public standart = "Bizzle Token v1.0";
uint256 public totalSupply;

mapping(address => uint256) public balanceOf;
mapping(address => mapping(address => uint256)) public allowance;


event Transfer(
   address indexed _from,
   address indexed _to,
   uint256 _value
);

event Approval(
   address indexed _owner,
   address indexed _spender,
   uint256 _value
);

function BizzleToken(uint256 _initialSupply) public {
   balanceOf[msg.sender] = _initialSupply;
   totalSupply = _initialSupply;

}

function transfer(address _to , uint256 _value) public returns (bool success){

   // Exception does not have enough tokens
   require(balanceOf[msg.sender] >= _value);

   balanceOf[msg.sender] -= _value;

   balanceOf[_to] += _value;

   Transfer(msg.sender, _to, _value);


   return true;

}


function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {

    // check _from token balance
   require(_value <= balanceOf[_from]);
    // check allowance is big enough
   require(_value <= allowance[_from][msg.sender]);

   balanceOf[_from] -= _value;
   balanceOf[_to] += _value;

   allowance[_from][msg.sender] -= _value;

   Transfer(_from,_to,_value);

   return true;

}


function approve(address _spender, uint256 _value) public returns (bool success) {

   allowance[msg.sender][_spender] = _value;

   Approval(msg.sender,_spender, _value);

   return true;


}

function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
   return allowance[_owner][_spender];
}

}

我已經用 JavaScript 測試過它可以工作。

App = {
web3Provider: null,
contracts: {},
account: '0x0',
loading: false,
tokenPrice: 1000000000000000,
tokensSold: 0,
tokensAvailable: 750000,

init: function() {
console.log("App initialized...")
return App.initWeb3();
},

**/// Buy tokens Function**

buyTokens: function() {
$('#content').hide();
$('#loader').show();
var numberOfTokens = $('#numberOfTokens').val();
App.contracts.BizzleTokenSale.deployed().then(function(instance) {
 return instance.buyTokens(numberOfTokens, {
   from: App.account,
   value: numberOfTokens * App.tokenPrice,
   gas: 500000 // Gas limit
 });
}).then(function(result) {
 console.log("Tokens bought...")
 $('form').trigger('reset') // reset number of tokens in form
 // Wait for Sell event
});

}

我的問題是如何使用 Java 引入智能合約？

這是我的java類。

   public TransactionReceipt buyTokens(Uint256 _amount) throws IOException, TransactionException {
   Function function = new Function("buyTokens", Arrays.<Type>asList(_amount), Collections.<TypeReference<?>>emptyList());
   return executeTransaction(function);
   }

乙太幣沒有發送到智能合約。

因為函式是payable; 您也可以傳輸該值。

沒有價值，功能似乎在這一行恢復：

function buyTokens(uint256 _numberOfTokens) public payable {

   // Require that value is equal
   require(msg.value == multiply(_numberOfTokens, tokenPrice));

（值為 0 或 null）

在 Java 中試試這個：

//Calculate "value" like it is done in JS code that you mentioned. And provide that as parameter.
public TransactionReceipt buyTokens(Uint256 _amount, BigInteger value) throws IOException, TransactionException {
   Function function = new Function("buyTokens", Arrays.<Type>asList(_amount), Collections.<TypeReference<?>>emptyList());
   return executeTransaction(function, value);
   }

引用自：https://ethereum.stackexchange.com/questions/63085