摘要：與通信一就是基于的遠(yuǎn)程過(guò)程調(diào)用，這么解釋比較抽象。在運(yùn)行某些合約方法比如時(shí)要先用戶(hù)發(fā)送交易之后一定要在服務(wù)器端啟動(dòng)挖礦這樣交易才會(huì)真的寫(xiě)入到區(qū)塊比如你調(diào)用之后，卻發(fā)現(xiàn)對(duì)方?jīng)]有到賬，先別吃驚，啟動(dòng)挖礦試試。

Json RPC就是基于json的遠(yuǎn)程過(guò)程調(diào)用，這么解釋比較抽象。簡(jiǎn)單來(lái)說(shuō)，就是post一個(gè)json格式的數(shù)據(jù)調(diào)用rpc server中的方法. 而這個(gè)json格式是固定的, 總的來(lái)說(shuō)有這么幾項(xiàng):

{
    "method": "",
    "params": [],
    "id": idNumber
}

method: 方法名

params: 參數(shù)列表

id: 對(duì)過(guò)程調(diào)用的唯一標(biāo)識(shí)號(hào)

url = $url;
        // proxy
        empty($proxy) ? $this->proxy = "" : $this->proxy = $proxy;
        // debug state
        empty($debug) ? $this->debug = false : $this->debug = true;
        // message id
        $this->id = 1;
    }
    
    /**
     * Sets the notification state of the object. In this state, notifications are performed, instead of requests.
     *
     * @param boolean $notification
     */
    public function setRPCNotification($notification) {
        empty($notification) ?
                            $this->notification = false
                            :
                            $this->notification = true;
    }
    
    /**
     * Performs a jsonRCP request and gets the results as an array
     *
     * @param string $method
     * @param array $params
     * @return array
     */
    public function __call($method,$params) {
        
        // check
        if (!is_scalar($method)) {
            throw new Exception("Method name has no scalar value");
        }
        
        // check
        if (is_array($params)) {
            // no keys
            $params = $params[0];
        } else {
            throw new Exception("Params must be given as array");
        }
        
        // sets notification or request task
        if ($this->notification) {
            $currentId = NULL;
        } else {
            $currentId = $this->id;
        }
        
        // prepares the request
        $request = array(
                        "method" => $method,
                        "params" => $params,
                        "id" => $currentId
                        );
        $request = json_encode($request);
        $this->debug && $this->debug.="***** Request *****"."
".$request."
"."***** End Of request *****"."

";

        // performs the HTTP POST
        $opts = array ("http" => array (
                            "method"  => "POST",
                            "header"  => "Content-type: application/json",
                            "content" => $request
                            ));
        $context  = stream_context_create($opts);
        if ($fp = fopen($this->url, "r", false, $context)) {
            $response = "";
            while($row = fgets($fp)) {
                $response.= trim($row)."
";
            }
            $this->debug && $this->debug.="***** Server response *****"."
".$response."***** End of server response *****"."
";
            $response = json_decode($response,true);
        } else {
            throw new Exception("Unable to connect to ".$this->url);
        }
        
        // debug output
        if ($this->debug) {
            echo nl2br($debug);
        }
        
        // final checks and return
        if (!$this->notification) {
            // check
            if ($response["id"] != $currentId) {
                throw new Exception("Incorrect response id (request id: ".$currentId.", response id: ".$response["id"].")");
            }
            if (!is_null($response["error"])) {
                throw new Exception("Request error: ". var_export($response["error"], true));
            }
            
            return $response["result"];
            
        } else {
            return true;
        }
    }
}
?>

比較簡(jiǎn)單的代碼，如果比較懶，拿過(guò)去用就行了。也可以上packagist.org自己找一個(gè)rpc client.

有兩類(lèi)方法需要調(diào)用. 一類(lèi)是RPC server自帶方法，另一類(lèi)就是合約方法.

{
    "method": "eth_accounts",
    "params": [],
    "id": 1
}

RPC Server自帶方法的列表

調(diào)用自帶方法比較簡(jiǎn)單，參考上述鏈接，大部分都有示例.

調(diào)用合約方法必須使用自帶方法中的eth_call. 而合約方法名稱(chēng)和合約方法參數(shù)列表則使用params進(jìn)行體現(xiàn), 比如: 我們要調(diào)用合約中的balanceOf方法, 則json數(shù)據(jù)應(yīng)該如何構(gòu)造呢?

首先看看getBalanace的函數(shù)實(shí)現(xiàn):

function balanceOf(address _owner) public view returns (uint256 balance)

提煉出函數(shù)原型:

balanceOf(address)

在geth控制臺(tái)下運(yùn)行命令:

web3.sha3("balanceOf(address)").substring(0, 10)

得到函數(shù)hash "0x70a08231"

假設(shè)待查詢(xún)的地址 address _owner = "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", 則去掉前面的"0x", 并在左邊補(bǔ)24個(gè)零(一般地址長(zhǎng)度為42位, 去掉"0x"后為40位)，構(gòu)成64位十六進(jìn)制參數(shù).

最終得到的參數(shù)為 "0x70a0823100000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750"

假設(shè)我們的合約地址為 "0xaeab4084194B2a425096fb583Fbcd67385210ac3".

則得到最終的json數(shù)據(jù)為:

{
    "method": "eth_call",
    "params": [{"from": "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", "to": "0xaeab4084194B2a425096fb583Fbcd67385210ac3", "data": "0x70a0823100000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750"}, "latest"],
    "id": 1
}

把以上json數(shù)據(jù)以post方式發(fā)送給服務(wù)器，就可以調(diào)用合約方法"balanceOf", 查詢(xún)給定的地址中的代幣余額.

調(diào)用合約中的其他方法也要新遵循上面的方式, 我們?cè)俜治鲆幌?b>transfer方法, 加深印象:

首先, 看看代碼中的函數(shù)實(shí)現(xiàn):

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

其次, 提煉出函數(shù)原型:

transfer(address,uint256)  //注意逗號(hào)后面不能有空格

再次, 在控制臺(tái)運(yùn)行sha3函數(shù):

web3.sha3("transfer(address,uint256)").substring(0, 10)

得到函數(shù)hash "0xa9059cbb"

第一個(gè)參數(shù)假設(shè) address _to = "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", 則去"0x", 補(bǔ)零到64位.
第二個(gè)參數(shù)假設(shè) uint256 _value = 43776, 則化為十六進(jìn)制"0xab00"后, 去"0x", 補(bǔ)零到64位.

連接起來(lái) "0xa9059cbb00000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750000000000000000000000000000000000000000000000000000000000000ab00"

構(gòu)建json數(shù)據(jù):

{
    "method": "eth_call",
    "params": [{"from": "0x38aabef4cd283ccd5091298dedc88d27c5ec5750", "to": "0xaeab4084194B2a425096fb583Fbcd67385210ac3", "data": "0xa9059cbb00000000000000000000000038aabef4cd283ccd5091298dedc88d27c5ec5750000000000000000000000000000000000000000000000000000000000000ab00"}, "latest"],
    "id": 1
}

from 轉(zhuǎn)出者地址

to 合約地址

data 上述操作得到的十六進(jìn)制數(shù)

把以上的步驟轉(zhuǎn)化為代碼.

getMessage();
        }

        return call_user_func([self::$client, $method], $params);

    }

    public static function getBalance($address)
    {
        $method_hash = "0x70a08231";
        $method_param1_hex = str_pad(substr($address, 2), 64, "0", STR_PAD_LEFT);
        $data = $method_hash . $method_param1_hex;

        $params = ["from" => $address, "to" => self::CONTRACT, "data" => $data];

        $total_balance = self::eth_call([$params, "latest"]);

        return hexdec($total_balance) / (pow(10, 18));
    }

    public static function transfer($to, $value)
    {
        self::personal_unlockAccount([self::COINBASE, "123456", 3600]);

        $value = bcpow(10, 18) * $value;

        $method_hash = "0xa9059cbb";
        $method_param1_hex =str_pad(substr($to, 2), 64, "0", STR_PAD_LEFT);    
        $method_param2_hex = str_pad(strval(bc_dechex($value)), 64, "0", STR_PAD_LEFT);

        $data = $method_hash . $method_param1_hex . $method_param2_hex;
        $params = ["from" => self::COINBASE, "to" => self::CONTRACT, "data" => $data];

        return self::eth_sendTransaction([$params]);

    }

}

代碼比較簡(jiǎn)單, 要注意幾點(diǎn):

transfer函數(shù)的value單位很小, 是 10 ^ -18, 所以如果你想轉(zhuǎn)1000個(gè)，其實(shí)是要乘于 10的18次方, 這里的18是decimals.

由于第1點(diǎn), 應(yīng)該使用bcpow代替pow函數(shù).

不能使用php自帶的dechex函數(shù). 因?yàn)?b>dechex要求整型不能大于 PHP_INT_MAX, 而這個(gè)數(shù)在32位機(jī)上為4294967295。由于第1 點(diǎn), 所有的數(shù)都要乘于10的18次方, 所以得到的數(shù)要遠(yuǎn)遠(yuǎn)大于PHP_INT_MAX. 建議自己實(shí)現(xiàn)10進(jìn)制轉(zhuǎn)16進(jìn)制，如果你不知道如何實(shí)現(xiàn)，參考上述代碼。

在運(yùn)行某些合約方法, 比如transfer時(shí), 要先unlock用戶(hù).

發(fā)送交易之后, 一定要在服務(wù)器端啟動(dòng)挖礦, 這樣交易才會(huì)真的寫(xiě)入到區(qū)塊, 比如你調(diào)用transfer之后，卻發(fā)現(xiàn)對(duì)方?jīng)]有到賬，先別吃驚，啟動(dòng)挖礦試試。如果想啟用自動(dòng)挖碼, 在geth --rpc ...最后加上 --mine.

測(cè)試: