我使用以下代码从Applet客户端连接java socket。我将客户端的IP地址和一些随机数存储在以下代码中addNewClient()函数中发生的每个新连接中。我将此信息存储在HashMap中。我在此ArrayList的{{1}}中添加了更多客户信息。
如果HashMap中已有一些客户信息，我需要仔细阅读。我正在使用ArrayList在SocketConnection课程中尝试这一点。
我看到的问题是，我在Iterator中添加了3个客户端信息。但是，当我使用ArrayList读取它时，它只能获得最后添加的客户端信息，而其他KEYS只是变空。但是，与此同时，它正确地将ArrayList大小赋予Iterator
有些专家可以参考我下面的完整代码，并告诉我那里可能出现什么问题？
3更新：根据Amrish建议，更改了以下代码，它解决了问题。
public class DataSharingSocketListner {
public static void main(String[] args) {
System.out.println("client trying to connect before thread creation");
Thread thr = new Thread(new SocketThread());
thr.start();
}
}
class SocketThread implements Runnable {
HashMap<String, ClientInfo> clientInfo = new HashMap<String, ClientInfo>();
ArrayList<HashMap<String, ClientInfo>> myList = new ArrayList<HashMap<String, ClientInfo>>();
@Override
public void run() {
try {
System.out.println("client trying to connect after thread creation");
ServerSocket server = new ServerSocket(8080);
while (true) {
SocketConnection client = new SocketConnection(server.accept(), clientInfo, myList);
client.start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
class SocketConnection extends Thread {
InputStream input;
PrintWriter output;
Socket socket;
ObjectOutputStream out = null;
OutputStream clientOutput;
Scanner scannerObj;
HashMap<String, byte[]> hm;
InetAddress addr;
HashMap<String, ClientInfo> clientinfo;
ArrayList<HashMap<String, ClientInfo>> clientList;
public SocketConnection(Socket socket, HashMap<String, ClientInfo> clientInfo, ArrayList<HashMap<String, ClientInfo>> myList) {
super("Thread 1");
this.socket = socket;
//this.hm = dataHashMap;
this.clientinfo = clientInfo;
this.clientList = myList;
try {
// IT IS PRINTING TOTAL SIZE 3 SUCCESSFULLY HERE
int totalClientList = clientList.size();
System.out.println("totalClientList: " + totalClientList);
if ( totalClientList>0 )
{
for (int i=0; i<totalClientList; i++)
{
System.out.println("client list reading " + i);
HashMap<String, ClientInfo> tmpData = (HashMap<String, ClientInfo>) clientList.get(i);
// IT IS GETTING ONLY THE LAST KEY, OTHER KEYS ARE SHOWING EMPTY
Set<String> key = tmpData.keySet();
Iterator it = key.iterator();
while (it.hasNext()) {
System.out.println("hasNexthasNext");
String hmKey = (String)it.next();
ClientInfo hmData = (ClientInfo) tmpData.get(hmKey);
System.out.println("Key: "+hmKey +" & Data: "+hmData.getRandomNo());
it.remove(); // avoids a ConcurrentModificationException
}
}
// TO ADD NEW CLIENT EVERY TIME
addNewClient();
}
else {
System.out.println("Client List shows empty");
// TO ADD NEW CLIENT EVERY TIME
addNewClient();
}
// Not used yet, will be used
input = socket.getInputStream();
scannerObj = new Scanner(socket.getInputStream());
clientOutput = socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
}
public int genRandomNumber() {
Random r = new Random( System.currentTimeMillis() );
return 10000 + r.nextInt(20000);
}
String getLocalIP () {
InetAddress inetAddress = null;
String ipAddress = null;
try {
inetAddress = InetAddress.getLocalHost();
ipAddress = inetAddress.getHostAddress();
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("ipAddress : " + ipAddress);
return ipAddress;
}
void addNewClient () {
String ipAddress = getLocalIP();
if ( ipAddress!=null )
{
ClientInfo clientobj = new ClientInfo();
clientobj.setIPAdd(ipAddress);
int randno = genRandomNumber();
System.out.println("genRandomNumber() : " + randno);
clientobj.setRandomNo(randno);
String key = String.valueOf(randno);
clientinfo.put(key, clientobj);
clientList.add(clientinfo);
}
}
@Override
public void run() {
System.out.println("Going to Read client data");
//do something
{
String hostIP = addr.getHostAddress() ;
System.out.println("hostIP: " + hostIP);
//do something
}
}
}
class ClientInfo {
private String IPAddress;
private long RandomNumber;
private byte[] data;
public static void main(String []args) {
System.out.println("Client info Main");
}
//Setter
void setIPAdd (String ip) {
System.out.println("setIPAdd called");
IPAddress = ip;
}
void setRandomNo (long randomno) {
RandomNumber = randomno;
}
void setImageData (byte[] imgData) {
data = imgData;
}
//Getter
String getIPAdd () {
return IPAddress;
}
long getRandomNo () {
return RandomNumber;
}
byte[] getImageData () {
return data;
}
}
答案 0 :(得分：1)
你的Arraylist有3个hashmap，但每个hashmap只有一个对象。因此，您将大小设置为3，但是当您遍历hashmap时，只返回一个对象。
答案 1 :(得分：0)
这里的问题是你在比较两件事：
int totalClientList = clientList.size();
这将为您提供列表中的客户数量：
HashMap<String, ClientInfo> tmpData = (HashMap<String, ClientInfo>) clientList.get(i);
Set<String> key = tmpData.keySet();
这将为您提供i'th client的密钥。这与total clients.
您应该做的是drop List of hashmaps，只需使用single HashMap来跟踪所有客户。
希望这有帮助。
将您的SocketThread更改为删除列表
class SocketThread implements Runnable {
HashMap<String, ClientInfo> clientInfo = new HashMap<String, ClientInfo>();
@Override
public void run() {
try {
System.out.println("client trying to connect after thread creation");
ServerSocket server = new ServerSocket(8080);
while (true) {
SocketConnection client = new SocketConnection(server.accept(), clientInfo);
client.start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
更改您的SockectConnection以删除列表
HashMap<String, ClientInfo> clientinfo;
public SocketConnection(Socket socket, HashMap<String, ClientInfo> clientInfo) {
super("Thread 1");
this.socket = socket;
//this.hm = dataHashMap;
this.clientinfo = clientInfo;
try {
// IT IS PRINTING TOTAL SIZE 3 SUCCESSFULLY HERE
int totalClientList = clientInfo.size();
System.out.println("totalClientList: " + totalClientList);
if ( totalClientList>0 )
{
// IT IS GETTING ONLY THE LAST KEY, OTHER KEYS ARE SHOWING EMPTY
Set<String> key = clientInfo.keySet()
Iterator it = key.iterator();
while (it.hasNext()) {
System.out.println("hasNexthasNext");
String hmKey = (String)it.next();
ClientInfo hmData = (ClientInfo) tmpData.get(hmKey);
System.out.println("Key: "+hmKey +" & Data: "+hmData.getRandomNo());
it.remove(); // avoids a ConcurrentModificationException
}
// TO ADD NEW CLIENT EVERY TIME
addNewClient();
}
else {
System.out.println("Client List shows empty");
// TO ADD NEW CLIENT EVERY TIME
addNewClient();
}
// Not used yet, will be used
input = socket.getInputStream();
scannerObj = new Scanner(socket.getInputStream());
clientOutput = socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
}
更改添加新客户：
void addNewClient () {
String ipAddress = getLocalIP();
if ( ipAddress!=null )
{
ClientInfo clientobj = new ClientInfo();
clientobj.setIPAdd(ipAddress);
int randno = genRandomNumber();
System.out.println("genRandomNumber() : " + randno);
clientobj.setRandomNo(randno);
String key = String.valueOf(randno);
clientinfo.put(key, clientobj);
}
}
我刚编辑了你的代码，它应该给你一个开始。希望这会有所帮助。
答案 2 :(得分：0)
你在谈论两件不同的事情。一个是列表的大小，另一个是hashMap的大小。 试试这个：
int mapSize = tmpData.size();
您可以获取地图的大小并检查它是否正确。