Substrate 的 RPC 客户端之 Subxt 入门篇

    hide/  
    ├── error.rs  
    ├── events.rs  
    ├── extrinsic.rs  
    ├── frame  
    │   ├── balances.rs  
    │   ├── contracts.rs  
    │   ├── mod.rs  
    │   └── system.rs  
    ├── lib.rs  
    ├── metadata.rs  
    ├── rpc.rs  
    └── runtimes.rs  

    use subxt::{  
        balances::{  
            self,  
            BalancesStore,  
        },  
        DefaultNodeRuntime as Runtime,  
        ClientBuilder,  
    };  
    use sp_keyring::AccountKeyring;  

    fn main() {  

        // 整个 client 需要由 tokio 驱动。首先创建一个适配  
        // DefaultNodeRuntime 的客户端  
        let mut rt = tokio::runtime::Runtime::new().unwrap();  
        let client_future = ClientBuilder::::new().build();  
        let client = rt.block_on(client_future).unwrap();  

        // 为 Alice 创建一个 transaction builder  
        let signer = AccountKeyring::Alice.pair();  
        let xt = rt.block_on(client.xt(signer, None)).unwrap();  

        let bob = AccountKeyring::Bob.to_account_id();  
        // 从 Alice 向 Bob 发起转账  
        let transfer =  
            xt.submit(balances::transfer::(bob.clone().into(), 10_000_000));  
        rt.block_on(transfer).unwrap();  

        // 查询 Bob 的余额  
        // 需要注意的是，由于上一步只能确保转账已经被提交  
        // 这里的余额一般还没来得及发生改变  
        println!("{:?}", rt.block_on(client.free_balance(bob.into())).unwrap());  
    }  

    [dependencies]  
    tokio = "0.1"  
    sp-keyring = { git = "https://github.com/paritytech/substrate/", package = "sp-keyring" }  
    subxt = { git = "https://github.com/paritytech/substrate-subxt", package = "substrate-subxt" }