java - 使用 Socket 发送和接收对象

Question

我正在编写一个用于创建拍卖的小型客户端服务器应用程序。它适用于套接字，客户端应用程序和服务器应用程序交换两种对象 - 拍卖对象和客户端对象。客户端工作正常，但拍卖存在问题。当应用程序第一次发送特定拍卖时，效果很好，我们假设一等奖是 100.00。其他客户收到此拍卖。但当有人出价时，奇迹就会发生。我已调试连接，客户端应用程序正在发送新奖品 (110.00) 的拍卖，但服务器收到旧奖品 (100.00) 的拍卖。什么可能导致这个问题？

这是拍卖类:

public class Auction implements Comparable<Auction>, Serializable{

private Double prize;
private Item item;
private Client winner;
private Client owner;

public Auction(double prize, Item item, Client owner){
    this.prize = prize;
    this.item = item;
    this.owner = owner;
    this.winner = owner;
}

public Auction(double prize, Item item, Client owner, Client winner){
    this.prize = prize;
    this.item = item;
    this.owner = owner;
    this.winner = winner;
}

public void placeBid(double bidValue, Client winner){
    double newPrize = prize + bidValue;
    setWinner(winner);
    setPrize(newPrize);
}

@Override
public int compareTo(Auction auction) {
    int compare = prize.compareTo(auction.getPrize());
    return compare;
}

public String toString(){
    String value = String.format(item + " : %1$.2f | winner: " + winner, prize);
    return value;
}

public double getPrize(){
    return prize;
}

public Client getWinner(){
    return winner;
}

public Client getOwner(){
    return owner;
}

public Item getItem(){
    return item;
}

public boolean equals(Object anAuction){
    Auction auction = (Auction) anAuction;
    Client testOwner = auction.getOwner();
    Item testItem = auction.getItem();
    String testItemName = testItem.getName();
    String itemName = item.getName();
    double testPrize = auction.getPrize();
    return owner.equals(testOwner) && itemName.equals(testItemName);
}

private void setPrize(double prize){
    this.prize = prize;
}

private void setWinner(Client winner){
    this.winner = winner;
}
}

在客户端发送此拍卖的方法:

private void sendAuctions() throws IOException {
    for(Auction auction : auctionList){
        outputStream.writeObject("AUCTIONS");
        outputStream.flush();
        outputStream.writeObject(auction);
        outputStream.flush();
    }
}

以及在服务器端接收拍卖的方法:

private void receiveData() {
    String receivedDataLabel = "";
    try {
        while (!receivedDataLabel.equals("END")) {
            receivedDataLabel = (String) inputStream.readObject();
            if (receivedDataLabel.equals("CLIENTS")) {
                receiveClients();
            } else if (receivedDataLabel.equals("AUCTIONS")) {
                receiveAuctions();
            } else if (receivedDataLabel.equals("CONNECTION_END")){
                isConnected = false;
            }
        }
    } catch (ClassNotFoundException | IOException e) {
        e.printStackTrace();
    }
}

private void receiveAuctions() throws ClassNotFoundException, IOException {
    Auction auction = (Auction) inputStream.readObject();
    dataContainer.registerAuction(auction);
}

Answer 1

Java 序列化保留了对象图的完整性，但代价是不重新传输已发送的对象，这可能会造成困惑。您需要查看 ObjectOutputStream.reset() 或 ObjectOutputStream.writeUnshared() 以及它们存在的原因。