在上几篇内容中我们已经成功的编写、编译、部署和通过控制台调用执行了智能合约。那么，如何将智能合约与具体的业务相结合使用呢？就是前面介绍过的 JSON-RPC 接口。本篇内容将基于以太坊提供的这套接口，通过 Java 方法来对智能合约进行调用操作，该篇幅将以代码的形式展现，并在操作上加以讲解说明，至于具体的细节没办法逐一讲解，大家在完成相应的操作步骤之后，可进行深入的研究。
基础项目依赖及准备工作
还记得我们在第04课搭建的那套项目调用基本 JSON-RPC 接口的内容么？这里完全在此基础上进行研发，依赖的 jar 包依旧需要：
<dependency>
<groupId>org.web3jgroupId>
<artifactId>coreartifactId>
<version>3.2.0version>
dependency>
<dependency>
<groupId>org.web3jgroupId>
<artifactId>gethartifactId>
<version>3.2.0version>
dependency>
而本套依赖的源代码是在 GitHub 上开源的，感兴趣的深入研究一下，请单击这里查看。本篇的内容就是围绕此套开源代码来实现我们自己的代币的调用。
Web3j 提供了直接生成代币包装类的工具，我们可以直接通过命令行来生成对应的代码，但在生产之前需要准备两样内容，就是智能合约的 ABI（Application Binary Interface）和编译之后生成的 bin 文件。
上篇在部署智能合约的时候 var acContract = web3.eth.contract(...) 中省略号内的内容就是 abi 的信息。bin 文件的内容就是 var ac = acContract.new(...) 方法中 data 对应的内容，分别获取其中的内容，创建两个文本文件，后缀名分别改为 abi 和 bin，比如 ac.abi 和 ac.bin。
如果智能合约已经发布，可以直接在 Etherscan 上查到对应的智能合约，拿到相应的信息，下图中第一部分为 abi 信息，第二部分为 bin 文件内容，也可以从这里获得。
生成 Java 包装类
此包装类就在上面介绍的 Web3j 开源框架中提供对应的方法，官方网站也有介绍，通过 Web3j 命令来生成：
web3j solidity generate /path/to/.bin /path/to/.abi -o /path/to/src/main/java -p com.your.organisation.name
将上面找到的 abi 和 bin 文件分别替换上面命令中的参数，然后执行命令即可，当然前提条件是需要在电脑上安装 Web3j。
本篇重点介绍此方法在 Web3j 中对应的类。其实上面那条命令在 Jar 包中有对应的类存在，那就是 org.web3j.codegen.SolidityFunctionWrapperGenerator。来看一下此类的内容：
package org.web3j.codegen;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.web3j.protocol.ObjectMapperFactory;
import org.web3j.protocol.core.methods.response.AbiDefinition;
import org.web3j.utils.Files;
import org.web3j.utils.Strings;
import static org.web3j.codegen.Console.exitError;
import static org.web3j.utils.Collection.tail;
/**
* Java wrapper source code generator for Solidity ABI format.
*/
public class SolidityFunctionWrapperGenerator extends FunctionWrapperGenerator {
private static final String USAGE = "solidity generate "
+ "[--javaTypes|--solidityTypes] "
+ ".bin .abi "
+ "-p|--package " ;
private final String binaryFileLocation;
private final String absFileLocation;
private SolidityFunctionWrapperGenerator(
String binaryFileLocation,
String absFileLocation,
String destinationDirLocation,
String basePackageName,
boolean useJavaNativeTypes) {
super(destinationDirLocation, basePackageName, useJavaNativeTypes);
this.binaryFileLocation = binaryFileLocation;
this.absFileLocation = absFileLocation;
}
public static void run(String[] args) throws Exception {
if (args.length < 1 || !args[0].equals("generate")) {
exitError(USAGE);
} else {
main(tail(args));
}
}
public static void main(String[] args) throws Exception {
String[] fullArgs;
if (args.length == 6) {
fullArgs = new String[args.length + 1];
fullArgs[0] = JAVA_TYPES_ARG;
System.arraycopy(args, 0, fullArgs, 1, args.length);
} else {
fullArgs = args;
}
if (fullArgs.length != 7) {
exitError(USAGE);
}
boolean useJavaNativeTypes = useJavaNativeTypes(fullArgs[0], USAGE);
String binaryFileLocation = parsePositionalArg(fullArgs, 1);
String absFileLocation = parsePositionalArg(fullArgs, 2);
String destinationDirLocation = parseParameterArgument(fullArgs, "-o", "--outputDir");
String basePackageName = parseParameterArgument(fullArgs, "-p", "--package");
if (binaryFileLocation.equals("")
|| absFileLocation.equals("")
|| destinationDirLocation.equals("")
|| basePackageName.equals("")) {
exitError(USAGE);
}
new SolidityFunctionWrapperGenerator(
binaryFileLocation,
absFileLocation,
destinationDirLocation,
basePackageName,
useJavaNativeTypes)
.generate();
}
static List loadContractDefinition(File absFile)
throws IOException {
ObjectMapper objectMapper = ObjectMapperFactory.getObjectMapper();
AbiDefinition[] abiDefinition = objectMapper.readValue(absFile, AbiDefinition[].class);
return Arrays.asList(abiDefinition);
}
private void generate() throws IOException, ClassNotFoundException {
File binaryFile = new File(binaryFileLocation);
if (!binaryFile.exists()) {
exitError("Invalid input binary file specified: " + binaryFileLocation);
}
byte[] bytes = Files.readBytes(new File(binaryFile.toURI()));
String binary = new String(bytes);
File absFile = new File(absFileLocation);
if (!absFile.exists() || !absFile.canRead()) {
exitError("Invalid input ABI file specified: " + absFileLocation);
}
String fileName = absFile.getName();
String contractName = getFileNameNoExtension(fileName);
bytes = Files.readBytes(new File(absFile.toURI()));
String abi = new String(bytes);
List functionDefinitions = loadContractDefinition(absFile);
if (functionDefinitions.isEmpty()) {
exitError("Unable to parse input ABI file");
} else {
String className = Strings.capitaliseFirstLetter(contractName);
System.out.printf("Generating " + basePackageName + "." + className + " ... ");
new SolidityFunctionWrapper(useJavaNativeTypes).generateJavaFiles(
contractName, binary, abi, destinationDirLocation.toString(), basePackageName);
System.out.println("File written to " + destinationDirLocation.toString() + "\n");
}
}
}
看了上面的参数描述，对照一下 Web3j 的命令，是不是一下子就豁然开朗了？由上面的包名得知生成包装类的工具在 codegen 中，对应的 pom 依赖为：
<dependency>
<groupId>org.web3jgroupId>
<artifactId>codegenartifactId>
<version>3.2.0version>
dependency>
经验分享
上面类就是一个 main 方法，执行对应的 main 方法，传递对应的参数就可以生成代码。曾经作者就将此依赖引入项目中，然后创建一个自己的生成类，同样继承 FunctionWrapperGenerator 类，并把 SolidityFunctionWrapperGenerator 中通过参数输入的信息改为常量的方式来生成属于包装类。感兴趣的读者可以尝试一下。
包装类
通过上面的命令执行之后，在对应的目录得到了下面的类：
package com.secbro.eth;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import org.web3j.abi.EventEncoder;
import org.web3j.abi.EventValues;
import org.web3j.abi.FunctionEncoder;
import org.web3j.abi.TypeReference;
import org.web3j.abi.datatypes.Address;
import org.web3j.abi.datatypes.Event;
import org.web3j.abi.datatypes.Function;
import org.web3j.abi.datatypes.Type;
import org.web3j.abi.datatypes.Utf8String;
import org.web3j.abi.datatypes.generated.Uint256;
import org.web3j.abi.datatypes.generated.Uint8;
import org.web3j.crypto.Credentials;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.core.DefaultBlockParameter;
import org.web3j.protocol.core.RemoteCall;
import org.web3j.protocol.core.methods.request.EthFilter;
import org.web3j.protocol.core.methods.response.Log;
import org.web3j.protocol.core.methods.response.TransactionReceipt;
import org.web3j.tx.Contract;
import org.web3j.tx.TransactionManager;
import rx.Observable;
import rx.functions.Func1;
/**
* Auto generated code.
*
Do not modify!
*
Please use the web3j command line tools,
* or the org.web3j.codegen.SolidityFunctionWrapperGenerator in the
* codegen module to update.
*
*
Generated with web3j version 3.1.1.
*/
public final class Ac extends Contract {
private static final String BINARY = "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\n";
private Ac(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {
super(BINARY, contractAddress, web3j, credentials, gasPrice, gasLimit);
}
private Ac(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {
super(BINARY, contractAddress, web3j, transactionManager, gasPrice, gasLimit);
}
public List getTransferEvents(TransactionReceipt transactionReceipt) {
final Event event = new Event("Transfer",
Arrays.>>asList(new TypeReference() {}, new TypeReference() {}),
Arrays.>>asList(new TypeReference() {}));
List valueList = extractEventParameters(event, transactionReceipt);
ArrayList responses = new ArrayList(valueList.size());
for (EventValues eventValues : valueList) {
TransferEventResponse typedResponse = new TransferEventResponse();
typedResponse.from = (String) eventValues.getIndexedValues().get(0).getValue();
typedResponse.to = (String) eventValues.getIndexedValues().get(1).getValue();
typedResponse.value = (BigInteger) eventValues.getNonIndexedValues().get(0).getValue();
responses.add(typedResponse);
}
return responses;
}
public Observable transferEventObservable(DefaultBlockParameter startBlock, DefaultBlockParameter endBlock) {
final Event event = new Event("Transfer",
Arrays.>>asList(new TypeReference() {}, new TypeReference() {}),
Arrays.>>asList(new TypeReference() {}));
EthFilter filter = new EthFilter(startBlock, endBlock, getContractAddress());
filter.addSingleTopic(EventEncoder.encode(event));
return web3j.ethLogObservable(filter).map(new Func1() {
@Override
public TransferEventResponse call(Log log) {
EventValues eventValues = extractEventParameters(event, log);
TransferEventResponse typedResponse = new TransferEventResponse();
typedResponse.from = (String) eventValues.getIndexedValues().get(0).getValue();
typedResponse.to = (String) eventValues.getIndexedValues().get(1).getValue();
typedResponse.value = (BigInteger) eventValues.getNonIndexedValues().get(0).getValue();
return typedResponse;
}
});
}
public List getBurnEvents(TransactionReceipt transactionReceipt) {
final Event event = new Event("Burn",
Arrays.>>asList(new TypeReference() {}),
Arrays.>>asList(new TypeReference() {}));
List valueList = extractEventParameters(event, transactionReceipt);
ArrayList responses = new ArrayList(valueList.size());
for (EventValues eventValues : valueList) {
BurnEventResponse typedResponse = new BurnEventResponse();
typedResponse.from = (String) eventValues.getIndexedValues().get(0).getValue();
typedResponse.value = (BigInteger) eventValues.getNonIndexedValues().get(0).getValue();
responses.add(typedResponse);
}
return responses;
}
public Observable burnEventObservable(DefaultBlockParameter startBlock, DefaultBlockParameter endBlock) {
final Event event = new Event("Burn",
Arrays.>>asList(new TypeReference() {}),
Arrays.>>asList(new TypeReference() {}));
EthFilter filter = new EthFilter(startBlock, endBlock, getContractAddress());
filter.addSingleTopic(EventEncoder.encode(event));
return web3j.ethLogObservable(filter).map(new Func1() {
@Override
public BurnEventResponse call(Log log) {
EventValues eventValues = extractEventParameters(event, log);
BurnEventResponse typedResponse = new BurnEventResponse();
typedResponse.from = (String) eventValues.getIndexedValues().get(0).getValue();
typedResponse.value = (BigInteger) eventValues.getNonIndexedValues().get(0).getValue();
return typedResponse;
}
});
}
public List getFreezeEvents(TransactionReceipt transactionReceipt) {
final Event event = new Event("Freeze",
Arrays.>>asList(new TypeReference() {}),
Arrays.>>asList(new TypeReference() {}));
List valueList = extractEventParameters(event, transactionReceipt);
ArrayList responses = new ArrayList(valueList.size());
for (EventValues eventValues : valueList) {
FreezeEventResponse typedResponse = new FreezeEventResponse();
typedResponse.from = (String) eventValues.getIndexedValues().get(0).getValue();
typedResponse.value = (BigInteger) eventValues.getNonIndexedValues().get(0).getValue();
responses.add(typedResponse);
}
return responses;
}
public Observable freezeEventObservable(DefaultBlockParameter startBlock, DefaultBlockParameter endBlock) {
final Event event = new Event("Freeze",
Arrays.>>asList(new TypeReference() {}),
Arrays.>>asList(new TypeReference() {}));
EthFilter filter = new EthFilter(startBlock, endBlock, getContractAddress());
filter.addSingleTopic(EventEncoder.encode(event));
return web3j.ethLogObservable(filter).map(new Func1() {
@Override
public FreezeEventResponse call(Log log) {
EventValues eventValues = extractEventParameters(event, log);
FreezeEventResponse typedResponse = new FreezeEventResponse();
typedResponse.from = (String) eventValues.getIndexedValues().get(0).getValue();
typedResponse.value = (BigInteger) eventValues.getNonIndexedValues().get(0).getValue();
return typedResponse;
}
});
}
public List getUnfreezeEvents(TransactionReceipt transactionReceipt) {
final Event event = new Event("Unfreeze",
Arrays.>>asList(new TypeReference() {}),
Arrays.>>asList(new TypeReference() {}));
List valueList = extractEventParameters(event, transactionReceipt);
ArrayList responses = new ArrayList(valueList.size());
for (EventValues eventValues : valueList) {
UnfreezeEventResponse typedResponse = new UnfreezeEventResponse();
typedResponse.from = (String) eventValues.getIndexedValues().get(0).getValue();
typedResponse.value = (BigInteger) eventValues.getNonIndexedValues().get(0).getValue();
responses.add(typedResponse);
}
return responses;
}
public Observable unfreezeEventObservable(DefaultBlockParameter startBlock, DefaultBlockParameter endBlock) {
final Event event = new Event("Unfreeze",
Arrays.>>asList(new TypeReference() {}),
Arrays.>>asList(new TypeReference() {}));
EthFilter filter = new EthFilter(startBlock, endBlock, getContractAddress());
filter.addSingleTopic(EventEncoder.encode(event));
return web3j.ethLogObservable(filter).map(new Func1() {
@Override
public UnfreezeEventResponse call(Log log) {
EventValues eventValues = extractEventParameters(event, log);
UnfreezeEventResponse typedResponse = new UnfreezeEventResponse();
typedResponse.from = (String) eventValues.getIndexedValues().get(0).getValue();
typedResponse.value = (BigInteger) eventValues.getNonIndexedValues().get(0).getValue();
return typedResponse;
}
});
}
public RemoteCall name() {
Function function = new Function("name",
Arrays.asList(),
Arrays.>asList(new TypeReference() {}) ) ;
return executeRemoteCallSingleValueReturn(function, String.class);
}
public RemoteCall approve(String _spender, BigInteger _value) {
Function function = new Function(
"approve",
Arrays.asList(new Address(_spender),
new Uint256(_value)),
Collections.>emptyList()) ;
return executeRemoteCallTransaction(function);
}
public RemoteCall totalSupply() {
Function function = new Function("totalSupply",
Arrays.asList(),
Arrays.>asList(new TypeReference() {}) ) ;
return executeRemoteCallSingleValueReturn(function, BigInteger.class);
}
public RemoteCall transferFrom(String _from, String _to, BigInteger _value) {
Function function = new Function(
"transferFrom",
Arrays.asList(new Address(_from),
new Address(_to),
new Uint256(_value)),
Collections.>emptyList()) ;
return executeRemoteCallTransaction(function);
}
public RemoteCall decimals() {
Function function = new Function("decimals",
Arrays.asList(),
Arrays.>asList(new TypeReference() {}) ) ;
return executeRemoteCallSingleValueReturn(function, BigInteger.class);
}
public RemoteCall burn(BigInteger _value) {
Function function = new Function(
"burn",
Arrays.asList(new Uint256(_value)),
Collections.>emptyList()) ;
return executeRemoteCallTransaction(function);
}
public RemoteCall unfreeze(BigInteger _value) {
Function function = new Function(
"unfreeze",
Arrays.asList(new Uint256(_value)),
Collections.>emptyList()) ;
return executeRemoteCallTransaction(function);
}
public RemoteCall balanceOf(String param0) {
Function function = new Function("balanceOf",
Arrays.asList(new Address(param0)),
Arrays.>asList(new TypeReference() {}) ) ;
return executeRemoteCallSingleValueReturn(function, BigInteger.class);
}
public RemoteCall owner() {
Function function = new Function("owner",
Arrays.asList(),
Arrays.>asList(new TypeReference() {})) ;
return executeRemoteCallSingleValueReturn(function, String.class);
}
public RemoteCall symbol() {
Function function = new Function("symbol",
Arrays.asList(),
Arrays.>asList(new TypeReference() {}) ) ;
return executeRemoteCallSingleValueReturn(function, String.class);
}
public RemoteCall transfer(String _to, BigInteger _value) {
Function function = new Function(
"transfer",
Arrays.asList(new Address(_to),
new Uint256(_value)),
Collections.>emptyList()) ;
return executeRemoteCallTransaction(function);
}
public RemoteCall freezeOf(String param0) {
Function function = new Function("freezeOf",
Arrays.asList(new Address(param0)),
Arrays.>asList(new TypeReference() {}) ) ;
return executeRemoteCallSingleValueReturn(function, BigInteger.class);
}
public RemoteCall freeze(BigInteger _value) {
Function function = new Function(
"freeze",
Arrays.asList(new Uint256(_value)),
Collections.>emptyList()) ;
return executeRemoteCallTransaction(function);
}
public RemoteCall allowance(String param0, String param1) {
Function function = new Function("allowance",
Arrays.asList(new Address(param0),
new Address(param1)),
Arrays.>asList(new TypeReference() {}) ) ;
return executeRemoteCallSingleValueReturn(function, BigInteger.class);
}
public static RemoteCall deploy(Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit, BigInteger initialSupply, String tokenName, String tokenSymbol, String holder) {
String encodedConstructor = FunctionEncoder.encodeConstructor(Arrays.asList(new Uint256(initialSupply),
new Utf8String(tokenName),
new Utf8String(tokenSymbol),
new Address(holder)));
return deployRemoteCall(Ac.class, web3j, credentials, gasPrice, gasLimit, BINARY, encodedConstructor);
}
public static RemoteCall deploy(Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit, BigInteger initialSupply, String tokenName, String tokenSymbol, String holder) {
String encodedConstructor = FunctionEncoder.encodeConstructor(Arrays.asList(new Uint256(initialSupply),
new Utf8String(tokenName),
new Utf8String(tokenSymbol),
new Address(holder)));
return deployRemoteCall(Ac.class, web3j, transactionManager, gasPrice, gasLimit, BINARY, encodedConstructor);
}
public static Ac load(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {
return new Ac(contractAddress, web3j, credentials, gasPrice, gasLimit);
}
public static Ac load(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {
return new Ac(contractAddress, web3j, transactionManager, gasPrice, gasLimit);
}
public static class TransferEventResponse {
public String from;
public String to;
public BigInteger value;
}
public static class BurnEventResponse {
public String from;
public BigInteger value;
}
public static class FreezeEventResponse {
public String from;
public BigInteger value;
}
public static class UnfreezeEventResponse {
public String from;
public BigInteger value;
}
}
仔细对照会发现，智能合约中的方法对应的存在了一个包装类，当进行相应的操作时调用对应的方法即可。
方法调用
下面介绍怎么调用此类的方法：
public class Main {
public static void observer(String contractAddress) throws IOException, CipherException {
new Thread(new Runnable() {
@Override
public void run() {
Web3j web3j = initWeb3j();
Credentials credentials = null;
try {
credentials = WalletUtils.loadCredentials("123456", "/Users/zzs/develop/eth/geth/tmp/UTC--2017-12-05T01-18-36.275000000Z--ce90c7a044be4da928e04f19e7a67ad8096c988d.json");
} catch (IOException e) {
e.printStackTrace();
} catch (CipherException e) {
e.printStackTrace();
}
Ac contract = Ac.load(contractAddress, web3j, credentials, new BigInteger("21000"), new BigInteger("90000"));
Observable observable = contract.transferEventObservable(new DefaultBlockParameterNumber(new BigInteger("0")), DefaultBlockParameterName.LATEST);
observable.subscribe(transferEventResponse -> {
// 代币交易发起方地址
String foAddress = transferEventResponse.from;
System.out.println("foAddress = " + foAddress);
// 代币交易接受方地址
String toAddress = transferEventResponse.to;
System.out.println("toAddress = " + toAddress);
// 发送代币金额
BigInteger value = transferEventResponse.value;
System.out.println("value = " + value);
// 匹配交易是否为本地地址交易，如果是则进行相应的交易记录或业务流转（比如汇总等操作）
},error->{
System.out.println(error);
});
}
}).start();
System.out.println("监听已经启动");
}
public static void main(String[] args) throws IOException, CipherException, InvalidAlgorithmParameterException, NoSuchAlgorithmException, NoSuchProviderException {
// 监听合约地址并
observer("0x4efcbf4c53158808fd067f58e1c67d496ef6c9ff");
}
}
上面的方法实现了针对以太坊节点注册了一个监听器，当此代币有交易发生时此监听器会获得相应的代币交易信息。此处需注意的是：一旦节点重启，此监听器也需要重启，否则将无法获得相应的数据，其他细节就不再赘述，官方文档已经说的比较清楚了。
实战经验
在上面注册的监听器启动时，某些场景下我们可能需要更多的参数，而不仅仅是代币的 from、to 和 value，这时怎么再会调用中拿到相应的交易信息呢，那就需要修改生成的代码类型，首先在 TransferEventResponse 添加需要的属性值，然后在 transferEventObservable 方法的 return 部分中的 call 方法内容给 TransferEventResponse 的属性赋值。这些值来自何处呢？来自 call 方法的参数 Log 对象，此对象里面封装了很多交易相关的信息。
小结
截止今天读者应该已经可以完成一列以太坊的基本操作，从环境的搭建、接口的调用、代币的编写发行，以及 Token Java 版本的调用。按照本篇内容的提示，深入研究之后基本能完成以太坊大多数的操作了。基于这些内容，下篇为大家带来应用层面的讲解和经验分享。感谢大家的支持。