作者：芈橙
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本文解析的为比原提供的币币合约 模板如下：
contract TradeOffer(assetRequested: Asset, amountRequested: Amount, seller: Program, cancelKey: PublicKey) locks offered { clause trade() requires payment: amountRequested of assetRequested { lock payment with seller unlock offered } clause cancel(sellerSig: Signature) { verify checkTxSig(cancelKey, sellerSig) unlock offered }} 导读： 初次接触比原只能合约的请点击 和 学习，方便更好的理解该文档
锁定合约
第一步：调用create-account-receiver 生成 control_program
以下是相关代码片段：
sendHttpPost("{\"account_id\":\"0IJVD7MNG0A02\"}","create-account-receiver","http://127.0.0.1:9888",""); 第二步调用list-pubkeys 获取 pubkey
以下是相关代码片段：
sendHttpPost("{\"account_id\":\"0IJVD7MNG0A02\"}","list-pubkeys","http://127.0.0.1:9888",""); 第三步： 将1 2步获取的值调用compile接口编译合约获得program 合约程序
以下是相关代码片段：
JSONObject param=new JSONObject(); JSONArray agrs=new JSONArray(); //合约的四个参数值 JSONObject assetParam=new JSONObject(); assetParam.put("string","81d097312645696daea84b761d2898d950d8fba0de06c9267d8513b16663dd3a"); agrs.put(assetParam); JSONObject amountParam=new JSONObject(); amountParam.put("integer",200000000l); agrs.put(amountParam); JSONObject programParam=new JSONObject(); programParam.put("string",control_program); agrs.put(programParam); JSONObject publicKeyParam=new JSONObject(); publicKeyParam.put("string",pubkey); agrs.put(publicKeyParam); param.put("agrs",agrs); param.put("contract","contract TradeOffer(assetRequested: Asset, amountRequested: Amount, seller: Program, cancelKey: PublicKey) locks offered { clause trade() requires payment: amountRequested of assetRequested { lock payment with seller unlock offered } clause cancel(sellerSig: Signature) { verify checkTxSig(cancelKey, sellerSig) unlock offered } }"); //调用编译合约 sendHttpPost(param.toString(),"list-pubkeys","http://127.0.0.1:9888",""); 第四步：将program 传入build-transaction接口去build一个交易的到data
以下是相关代码片段：
param=new JSONObject(); agrs=new JSONArray(); JSONObject spendAccount=new JSONObject(); spendAccount.put("account_id","0H757LPD00A02"); spendAccount.put("amount",9909099090000l); spendAccount.put("asset_id","161b9767b664df907fa926a31f9e835236e57f3e9ccc5f80c12bd97723322652"); spendAccount.put("type","spend_account"); agrs.put(spendAccount); JSONObject controlAccount=new JSONObject(); controlAccount.put("control_program",program); controlAccount.put("amount",9909099090000l); controlAccount.put("asset_id","161b9767b664df907fa926a31f9e835236e57f3e9ccc5f80c12bd97723322652"); controlAccount.put("type","control_program"); agrs.put(controlAccount); JSONObject spendAccount2=new JSONObject(); spendAccount2.put("account_id","0H757LPD00A02"); spendAccount2.put("amount",6000000l); spendAccount2.put("asset_id","ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"); spendAccount2.put("type","spend_account"); agrs.put(spendAccount2); param.put("actions",agrs); param.put("ttl",0); sendHttpPost(param.toString(),"build-transaction","http://127.0.0.1:9888",""); 第五步：输入密码调用sign-transaction签名第四步build的data 得到raw_transaction
以下是相关代码片段：
param=new JSONObject(); param.put("password","xxx"); param.put("transaction",data); sendHttpPost(param.toString(),"sign-transaction","http://127.0.0.1:9888",""); 第六步：调用submit-transactions提交交易
以下是相关代码片段：
param=new JSONObject(); param.put("raw_transaction",raw_transaction); sendHttpPost(param.toString(),"submit-transactions","http://127.0.0.1:9888",""); 解锁/取消合约
首先需要decode出生成合约时候的参数
调用list-unspent-outputs 获取生成的合约信息获取program
以下是相关代码片段：
param=new JSONObject(); param.put("id",outputid); param.put("smart_contract",true); sendHttpPost(param.toString(),"list-unspent-outputs","http://127.0.0.1:9888",""); 调用decode-program 传入获取生成的合约参数信息
以下是相关代码片段：
param=new JSONObject(); param.put("program",program); sendHttpPost(param.toString(),"decode-program","http://127.0.0.1:9888",""); 需要注意的是decode出来的为值是逆序的(后续会有文章详细介绍)
解锁/取消其实就是把生成合约的步骤中的第三步去掉,替换调用生成合约第四步的参数即可
取消合约的构造参数如下： 
spendAccountUnspentOutput = arguments: [{ type: 'raw_tx_signature', // 生成合约第二步的pubkeylist 详情 raw_data: { derivation_path: pubkeylist.pubkey_infos[0].derivation_path, xpub: pubkeylist.root_xpub } }, { type: 'data', raw_data: { // 参数偏移量 在一个合约里是固定的 value: '13000000' } }], output_id: output_id, type: 'spend_account_unspent_output' } const controlAction = { type: 'control_program', amount: 100000000, asset_id: asset_id, control_program:control_program } const gasAction = { type: 'spend_account', account_id:account_id, asset_alias: 'BTM', amount: 50000000 } 执行合约的参数构造如下： 
const spendAccountUnspentOutput = { arguments: [{ type: 'data', raw_data: { // 00000000 指的是第一个 clause，表示直接执行，无需跳转 value: '00000000' } }], output_id: output_id, type: 'spend_account_unspent_output' } // 合约执行提供的资产 const issueControlAction = { control_program: control_program, amount: 100000000, asset_id: asset_id, type: 'control_program' } // 合约执行提供的资产 const issueSpendAction = { account_id: account_id, amount: 100000000, asset_id: asset_id, type: 'spend_account' } // 矿工费 const gasAction = { type: 'spend_account', account_id: account_id, asset_alias: 'BTM', amount: 50000000 } // 合约执行获得资产对象 const controlAction = { type: 'control_program', amount: 100000000, asset_id: asset_id, control_program: compileData.control_program } build 操作其实就是指定输入输出的过程,详情请查看 和
备注
调用比原基于okhttp接口javautil 如下：
public static String sendHttpPost(String bodyStr,String method,String bytomApiserverUrl,String bytomApiserverToken) throws IOException { OkHttpClient client = new OkHttpClient(); MediaType mediaType = MediaType.parse("application/json"); RequestBody body = RequestBody.create(mediaType, bodyStr); Request request = new Request.Builder() .url(bytomApiserverUrl+"/"+method) .post(body) .addHeader("cache-control", "no-cache") .addHeader("Connection", "close") .build(); if (bytomApiserverUrl==null || bytomApiserverUrl.contains("127.0.0.1") || bytomApiserverUrl.contains("localhost")){ }else { byte[] encodedAuth = Base64.encodeBase64(bytomApiserverToken.getBytes(Charset.forName("US-ASCII"))); String authHeader = "Basic " + new String(encodedAuth); request = new Request.Builder() .url(bytomApiserverUrl+"/"+method) .post(body) .addHeader("authorization", authHeader) .addHeader("cache-control", "no-cache") .addHeader("Connection", "close") .build(); } Response response = client.newCall(request).execute(); return response.body().string(); }