你可以在web3j库的帮助下使用java轻松监听以太坊交易，但此库无法监听Erc20 Token交易。

要监听Erc20Token交易，你必须使用在合约（token）创建时的token封装类。我假设你已经使用最少的功能部署了合约，因此你的封装类看起来像这样：

package com.bolenum.util;import java.io.IOException;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util...;import org.web3j.abi.EventEncoder;
import org.web3j.abi...
import org.web3j.crypto.Credentials;
import org.web3j.protocol.Web3j;
import org.web3j.protocol...;
import org.web3j.tx.Contract;
import org.web3j.tx.TransactionManager;import rx.Observable;
import rx.functions.Func1;...public final class Erc20TokenWrapper extends Contract {private static final String BINARY = "contract binary key";private Erc20TokenWrapper(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {super(BINARY, contractAddress, web3j, credentials, gasPrice, gasLimit);}private Erc20TokenWrapper(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {super(BINARY, contractAddress, web3j, transactionManager, gasPrice, gasLimit);}public List<TransferEventResponse> getTransferEvents(TransactionReceipt transactionReceipt) {...return responses;}public Observable<TransferEventResponse> transferEventObservable(DefaultBlockParameter startBlock, DefaultBlockParameter endBlock) {...}...public Uint256 balanceOf(Address _owner) throws IOException {Function function = new Function("balanceOf", Arrays.<Type>asList(_owner), Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));return executeCallSingleValueReturn(function);}...public TransactionReceipt transfer(Address _to, Uint256 _amount) throws IOException, TransactionException {Function function = new Function("transfer", Arrays.<Type>asList(_to, _amount), Collections.<TypeReference<?>>emptyList());return executeTransaction(function);}...public static Erc20TokenWrapper load(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {return new Erc20TokenWrapper(contractAddress, web3j, transactionManager, gasPrice, gasLimit);}public static class TransferEventResponse {public Address _from;public Address _to;public Uint256 _value;public String _transactionHash;}...
}

现在你必须使用这个类函数来加载合约然后监听交易。使用下面的代码加载和监听交易：

Web3j web3j = Web3j.build(new HttpService("url of your ethereum blockchain"))
ClientTransactionManager transactionManager = new ClientTransactionManager(web3j,"your deployed contract addess");Erc20TokenWrapper token = Erc20TokenWrapper.load("your deployed contract addess", web3j, transactionManager,Contract.GAS_PRICE, Contract.GAS_LIMIT);token.transferEventObservable(DefaultBlockParameterName.EARLIEST, DefaultBlockParameterName.LATEST).subscribe(tx -> {String toAddress = tx._to.getValue();String fromAddress = tx._from.getValue();String txHash = tx._transactionHash.getValue();}

如果你已经部署了合约，它由第三人部署，那么你可以直接使用我的包装类，只需更改你可以从https://etherscan.io/tokens很容易获得的二进制密钥。

结论：因此你可以将此代码用于任何token的监听交易。此代码为你提供address，fromAddress和transactionHash。所以这些东西你可以根据你的要求使用，你可以将它们保存在你的数据库中，或者你只保存地址是你的钱包地址的交易。

谢谢，我希望这会有所帮助。

如果希望快速进行web3j、java、以太坊开发，那请看我们精心打造的教程： java以太坊开发教程，主要是针对java和android程序员进行区块链以太坊开发的web3j详解。

这里是原文

完整代码如下：

package com.bolenum.util;import java.io.IOException;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.Future;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.protocol.exceptions.TransactionException;
import org.web3j.tx.Contract;
import org.web3j.tx.TransactionManager;import rx.Observable;
import rx.functions.Func1;/*** Auto generated code.<br>* <strong>Do not modify!</strong><br>* Please use the <a href="https://docs.web3j.io/command_line.html">web3j command line tools</a>, or {@link org.web3j.codegen.SolidityFunctionWrapperGenerator} to update.** <p>Generated with web3j version 2.3.1.*/
public final class Erc20TokenWrapper extends Contract {private static final String BINARY = "contract binary key";private Erc20TokenWrapper(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {super(BINARY, contractAddress, web3j, credentials, gasPrice, gasLimit);}private Erc20TokenWrapper(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {super(BINARY, contractAddress, web3j, transactionManager, gasPrice, gasLimit);}public List<TransferEventResponse> getTransferEvents(TransactionReceipt transactionReceipt) {final Event event = new Event("Transfer", Arrays.<TypeReference<?>>asList(new TypeReference<Address>() {}, new TypeReference<Address>() {}),Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));List<EventValues> valueList = extractEventParameters(event, transactionReceipt);ArrayList<TransferEventResponse> responses = new ArrayList<TransferEventResponse>(valueList.size());for (EventValues eventValues : valueList) {TransferEventResponse typedResponse = new TransferEventResponse();typedResponse._from = (Address) eventValues.getIndexedValues().get(0);typedResponse._to = (Address) eventValues.getIndexedValues().get(1);typedResponse._value = (Uint256) eventValues.getNonIndexedValues().get(0);responses.add(typedResponse);}return responses;}public Observable<TransferEventResponse> transferEventObservable(DefaultBlockParameter startBlock, DefaultBlockParameter endBlock) {final Event event = new Event("Transfer", Arrays.<TypeReference<?>>asList(new TypeReference<Address>() {}, new TypeReference<Address>() {}),Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));EthFilter filter = new EthFilter(startBlock, endBlock, getContractAddress());filter.addSingleTopic(EventEncoder.encode(event));return web3j.ethLogObservable(filter).map(new Func1<Log, TransferEventResponse>() {@Overridepublic TransferEventResponse call(Log log) {EventValues eventValues = extractEventParameters(event, log);TransferEventResponse typedResponse = new TransferEventResponse();typedResponse._from = (Address) eventValues.getIndexedValues().get(0);typedResponse._to = (Address) eventValues.getIndexedValues().get(1);typedResponse._value = (Uint256) eventValues.getNonIndexedValues().get(0);typedResponse._transactionHash = log.getTransactionHash();return typedResponse;}});}public List<ApprovalEventResponse> getApprovalEvents(TransactionReceipt transactionReceipt) {final Event event = new Event("Approval", Arrays.<TypeReference<?>>asList(new TypeReference<Address>() {}, new TypeReference<Address>() {}),Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));List<EventValues> valueList = extractEventParameters(event, transactionReceipt);ArrayList<ApprovalEventResponse> responses = new ArrayList<ApprovalEventResponse>(valueList.size());for (EventValues eventValues : valueList) {ApprovalEventResponse typedResponse = new ApprovalEventResponse();typedResponse._owner = (Address) eventValues.getIndexedValues().get(0);typedResponse._spender = (Address) eventValues.getIndexedValues().get(1);typedResponse._value = (Uint256) eventValues.getNonIndexedValues().get(0);responses.add(typedResponse);}return responses;}public Observable<ApprovalEventResponse> approvalEventObservable(DefaultBlockParameter startBlock, DefaultBlockParameter endBlock) {final Event event = new Event("Approval", Arrays.<TypeReference<?>>asList(new TypeReference<Address>() {}, new TypeReference<Address>() {}),Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));EthFilter filter = new EthFilter(startBlock, endBlock, getContractAddress());filter.addSingleTopic(EventEncoder.encode(event));return web3j.ethLogObservable(filter).map(new Func1<Log, ApprovalEventResponse>() {@Overridepublic ApprovalEventResponse call(Log log) {EventValues eventValues = extractEventParameters(event, log);ApprovalEventResponse typedResponse = new ApprovalEventResponse();typedResponse._owner = (Address) eventValues.getIndexedValues().get(0);typedResponse._spender = (Address) eventValues.getIndexedValues().get(1);typedResponse._value = (Uint256) eventValues.getNonIndexedValues().get(0);typedResponse._transactionHash = log.getTransactionHash();return typedResponse;}});}public Future<Utf8String> name() throws IOException {Function function = new Function("name", Arrays.<Type>asList(), Arrays.<TypeReference<?>>asList(new TypeReference<Utf8String>() {}));return executeCallSingleValueReturn(function);}public TransactionReceipt approve(Address _spender, Uint256 _amount) throws IOException, TransactionException {Function function = new Function("approve", Arrays.<Type>asList(_spender, _amount), Collections.<TypeReference<?>>emptyList());return executeTransaction(function);}public Future<Uint256> totalSupply() throws IOException {Function function = new Function("totalSupply", Arrays.<Type>asList(), Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));return executeCallSingleValueReturn(function);}public TransactionReceipt transferFrom(Address _from, Address _to, Uint256 _amount) throws IOException, TransactionException {Function function = new Function("transferFrom", Arrays.<Type>asList(_from, _to, _amount), Collections.<TypeReference<?>>emptyList());return  executeTransaction(function);}public Uint8 decimals() throws IOException {Function function = new Function("decimals", Arrays.<Type>asList(), Arrays.<TypeReference<?>>asList(new TypeReference<Uint8>() {}));return executeCallSingleValueReturn(function);}public Uint256 balanceOf(Address _owner) throws IOException {Function function = new Function("balanceOf", Arrays.<Type>asList(_owner), Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));return executeCallSingleValueReturn(function);}public Future<Address> owner() throws IOException {Function function = new Function("owner", Arrays.<Type>asList(), Arrays.<TypeReference<?>>asList(new TypeReference<Address>() {}));return executeCallSingleValueReturn(function);}public Future<Utf8String> symbol() throws IOException {Function function = new Function("symbol", Arrays.<Type>asList(), Arrays.<TypeReference<?>>asList(new TypeReference<Utf8String>() {}));return executeCallSingleValueReturn(function);}public TransactionReceipt transfer(Address _to, Uint256 _amount) throws IOException, TransactionException {Function function = new Function("transfer", Arrays.<Type>asList(_to, _amount), Collections.<TypeReference<?>>emptyList());return executeTransaction(function);}public Future<Uint256> allowance(Address _owner, Address _spender) throws IOException {Function function = new Function("allowance", Arrays.<Type>asList(_owner, _spender), Arrays.<TypeReference<?>>asList(new TypeReference<Uint256>() {}));return executeCallSingleValueReturn(function);}public static RemoteCall<Erc20TokenWrapper> deploy(Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit, BigInteger initialWeiValue, Uint256 totalSupply, Utf8String tokenName, Uint8 decimalUnits, Utf8String tokenSymbol) {String encodedConstructor = FunctionEncoder.encodeConstructor(Arrays.<Type>asList(totalSupply, tokenName, decimalUnits, tokenSymbol));return deployRemoteCall(Erc20TokenWrapper.class, web3j, credentials, gasPrice, gasLimit, BINARY, encodedConstructor, initialWeiValue);}public static RemoteCall<Erc20TokenWrapper> deploy(Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit, BigInteger initialWeiValue, Uint256 totalSupply, Utf8String tokenName, Uint8 decimalUnits, Utf8String tokenSymbol) {String encodedConstructor = FunctionEncoder.encodeConstructor(Arrays.<Type>asList(totalSupply, tokenName, decimalUnits, tokenSymbol));return deployRemoteCall(Erc20TokenWrapper.class, web3j, transactionManager, gasPrice, gasLimit, BINARY, encodedConstructor, initialWeiValue);}public static Erc20TokenWrapper load(String contractAddress, Web3j web3j, Credentials credentials, BigInteger gasPrice, BigInteger gasLimit) {return new Erc20TokenWrapper(contractAddress, web3j, credentials, gasPrice, gasLimit);}public static Erc20TokenWrapper load(String contractAddress, Web3j web3j, TransactionManager transactionManager, BigInteger gasPrice, BigInteger gasLimit) {return new Erc20TokenWrapper(contractAddress, web3j, transactionManager, gasPrice, gasLimit);}public static class TransferEventResponse {public Address _from;public Address _to;public Uint256 _value;public String _transactionHash;}public static class ApprovalEventResponse {public Address _owner;public Address _spender;public Uint256 _value;public String _transactionHash;}
}