java玩转区块链-基础篇-solidity语法-基础类型

• • java环境配置
  • 代码准备
  • • • maven
      • • 完整solidity
      • 执行步骤
  • 基础类型
  • • 布尔类型
    • • • 类型标识:
        • 字面常量值:
        • 运算符:
        • 短路规则:
        • • example
    • 整形
    • • • 类型标识:
        • 字面常量值：
        • 除法截断
        • 代码
    • 浮点类型
    • 地址类型
    • • • 类型标识:
        • 字面常量值：

可以不让搞，但是不允许你不会

1. jdk版本，jdk1.8+；
2. IDE环境，ideas；
3. 依赖包，web3；
4. 区块链网路，开发网，Ganache；

以下是本章所有实例的代码

        8
        8
    

    

        
            org.web3j
            core
            5.0.0
        
        
            org.web3j
            contracts
            5.0.0
        
        
            org.apache.commons
            commons-lang3
            3.12.0
        
        
        
            org.web3j
            web3j-unit
            4.8.1
        
        
            com.google.guava
            guava
            23.0
        
    
    
        
            
                org.web3j
                web3j-maven-plugin
                4.6.5
                
                    
                
            
        
    
    
        
            central
            central
            https://maven.aliyun.com/repository/central
            
                true
            
            
                false
            
        
        
            jcenter
            jcenter
            http://jcenter.bintray.com/
            
                true
            
            
                false
            
        
        
            maven-net-cn
            Maven China Mirror
            https://dl.bintray.com/ethereum/maven
            
                true
            
            
                false
            
        
    

pragma solidity ^0.5.0;

contract TypeDescContract {

    constructor() public {

    }

    function boolTrunc() public view returns (uint){
        uint a = 12;
        a < 13 || a++ < 14;
        return a;
    }

    function boolTrunc2() public view returns (uint){
        uint a = 12;
        a < 13 && a++ < 14;
        return a;
    }

    function uintDivTrunc() public view returns (uint) {
        uint a = 5/2.5;
        return a;
    }

    function getSelfAddress() public view returns (address){
        return msg.sender;
    }
}

(1) 启动ganache
(2) 在项目目录resources中编写合约脚本

(3) 执行脚本转化java类

双击执行插件命令，生成java类。
(4) 部署合约到ganache本地开发链

package com.lession.type;

import org.web3j.crypto.Credentials;
import org.web3j.model.ArrayContract;
import org.web3j.model.TypeDescContract;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.http.HttpService;
import org.web3j.tx.gas.StaticGasProvider;

import java.math.BigInteger;

public class TypeDescMain {
    public static void main(String[] args) throws Exception {
        Web3j web3j = Web3j.build(new HttpService("HTTP://127.0.0.1:7545"));
        String pk = "d8673b8d4c7a9345c7cd8bb91574389d29b1e69cdbe0be9ac8fdf10f43e69c55";//(1)
        Credentials credentials = Credentials.create(pk);//(2)
        System.out.println("Account address: " + credentials.getAddress());
        System.out.println("Account ak: " + credentials.getEcKeyPair().getPrivateKey().toString(16));
        System.out.println("Account pk: " + credentials.getEcKeyPair().getPublicKey().toString(16));
        StaticGasProvider provider = new StaticGasProvider(new BigInteger("20000000000"),new BigInteger("6721975"));
        TypeDescContract contract = TypeDescContract.deploy(web3j,credentials,provider).send();//(3)
        System.out.println("contractAddress:" + contract.getContractAddress());//(4)
    }
}

代码解释:
(1) 从ganache中找一个账户的私钥
(2) 通过私钥生成鉴权信息
(3) 部署合约
(4) 打印生成链上合约地址

(5) rpc调用合约

package com.lession.type;

import org.web3j.crypto.Credentials;
import org.web3j.model.TypeDescContract;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.http.HttpService;
import org.web3j.tx.gas.StaticGasProvider;

import java.math.BigInteger;

public class TypeDescClient {
    public static void main(String[] args) throws Exception {
        Web3j web3j = Web3j.build(new HttpService("HTTP://127.0.0.1:7545"));
        String pk = "d8673b8d4c7a9345c7cd8bb91574389d29b1e69cdbe0be9ac8fdf10f43e69c55";
        Credentials credentials = Credentials.create(pk);
        System.out.println("Account address: " + credentials.getAddress());//(1)
        System.out.println("Account ak: " + credentials.getEcKeyPair().getPrivateKey().toString(16));
        System.out.println("Account pk: " + credentials.getEcKeyPair().getPublicKey().toString(16));
        StaticGasProvider provider = new StaticGasProvider(new BigInteger("20000000000"),new BigInteger("6721975"));
        TypeDescContract contract = TypeDescContract.load("0x64de7ed9f8a2fe5c6303cc980c7d15ccac873f85",web3j,credentials,provider);//(2)
        System.out.println("boolTrunc:" + contract.boolTrunc().send().toString()); //(3)
        System.out.println("boolTrunc2:" + contract.boolTrunc2().send().toString());
        System.out.println("uintDivTrunc:" + contract.uintDivTrunc().send().toString());
    }
}

代码解释:
(1) 通过私钥生成鉴权
(2) 通过合约地址，加载合约
(3) rpc调用合约函数

bool

true 或 false

!(逻辑非) ,&&(逻辑与),||(逻辑或),==(等于),!=(不等于),<=(小于等于),<(小于),>=(大于等于),>(大于)

||和&&遵循短路规则，f(x)||g(y)如果f(x)为true，则g(y)不会执行，f(x)&&g(y),如果f(x)为false，则g(y)不会执行。

合约代码

function boolTrunc() public view returns (uint){
        uint a = 12;
        a < 13 || a++ < 14;
        return a;
    }

    function boolTrunc2() public view returns (uint){
        uint a = 12;
        a < 13 && a++ < 14;
        return a;
    }

java代码

System.out.println("boolTrunc:" + contract.boolTrunc().send().toString()); 
        System.out.println("boolTrunc2:" + contract.boolTrunc2().send().toString());

执行结果:

boolTrunc:12
boolTrunc2:13

boolTrunc中的a++并未执行，boolTrunc2中的a++执行了变成了13

uint,uint8~uint256

12 --> 为uint256

5/3=1

solidity

function uintDivTrunc() public view returns (uint) {
        uint a = 5/2.5;
        return a;
    }

java

System.out.println("uintDivTrunc:" + contract.uintDivTrunc().send().toString());

执行结果

uintDivTrunc:2

不支持

address

0x45b6d967bd2962ebb232c2a8065ce9e4abc93aab
地址类型存储一个 20 字节的值

java玩转区块链-基础篇-账户