合约的调用

// Log represents a contract log event. These events are generated by the LOG opcode and
// stored/indexed by the node.
type Log struct {
	// Consensus fields:
	// address of the contract that generated the event
	Address common.Address `json:"address" gencodec:"required"`
	// list of topics provided by the contract.
	Topics []common.Hash `json:"topics" gencodec:"required"`
	// supplied by the contract, usually ABI-encoded
	Data []byte `json:"data" gencodec:"required"`

	// Derived fields. These fields are filled in by the node
	// but not secured by consensus.
	// block in which the transaction was included
	BlockNumber uint64 `json:"blockNumber"`
	// hash of the transaction
	TxHash common.Hash `json:"transactionHash" gencodec:"required"`
	// index of the transaction in the block
	TxIndex uint `json:"transactionIndex" gencodec:"required"`
	// hash of the block in which the transaction was included
	BlockHash common.Hash `json:"blockHash"`
	// index of the log in the block
	Index uint `json:"logIndex" gencodec:"required"`

	// The Removed field is true if this log was reverted due to a chain reorganisation.
	// You must pay attention to this field if you receive logs through a filter query.
	Removed bool `json:"removed"`
}

实现一个简单的 ERC20 代币水龙头

/*
author: yqq
data: 2019-09-06 12:33
desc: call erc20 contranct to transfer
*/

contract ERC20 {
    function totalSupply() public constant returns (uint);
    function balanceOf(address tokenOwner) public constant returns (uint balance);
    function allowance(address tokenOwner, address spender) public constant returns (uint remaining);
    function transfer(address to, uint tokens) public returns (bool success);
    function approve(address spender, uint tokens) public returns (bool success);
    function transferFrom(address from, address to, uint tokens) public returns (bool success);
    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}



contract ERC20Faucet{
  address token_addr = 0xe30d2B6F144e6eAD802414C09a3F519B72Ff12F3; 

  function ERC20Faucet() public{
  }

  function getTokens(address to, uint256 value ) public {
    ERC20(token_addr).transfer(to, value );
  }
}