我的任务是为我的一个编程任务创建一个简单的Java服务器。这个，我没有遇到麻烦。服务器本质上是一个存储有关音乐数据的点唱机。 （它实际上并不存储任何音乐用于分配）客户端应该能够与此服务器交互以添加歌曲，查看歌曲列表，并增加歌曲流行度。执行其中一项操作后，客户端将断开连接。这个，我没有遇到任何问题。我制作了一个带套接字和服务器套接字的简单多线程服务器。我在telnet上测试了它，所有所需的功能都完美无缺。我的问题来自于我们必须做的一些测试。为了正式测试服务器，我们要创建一个只创建一堆客户端套接字并让它们与服务器交互的java类。这是一个例子。
public class LikeTunesServerTest {
public static void main(String[] args) {
try {
Socket client = new Socket("localhost", 12010);
BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
PrintWriter out = new PrintWriter(new OutputStreamWriter(client.getOutputStream()));
out.println("0"); // add tune
out.println("The Beatles");
out.println("Yellow Submarine");
out.flush();
client.close();
client = new Socket("localhost", 12010);
in = new BufferedReader(new InputStreamReader(client.getInputStream()));
out = new PrintWriter(new OutputStreamWriter(client.getOutputStream()));
out.println("2"); // request all tunes in alphabetical order
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
client.close();
}
catch (IOException e) {
System.out.println("e");
}
}
}
据我所知，第一个客户端成功完成其交互并退出。然后，第二个客户端连接，但程序然后挂起。该程序应打印披头士/ nYellow潜艇/ n0。我猜这与我的BufferedReader的while循环有关，但老实说我不知道，我不是最了解我学到的JAVA IO。如果有人能帮助我推断导致挂起的原因以及为什么没有打印出来，我将不胜感激。作为参考，这里是服务器程序的片段，显示服务器处理客户端的操作。
try {
// Open I/O
in = new BufferedReader(new InputStreamReader(incomingConnection.getInputStream()));
out = new PrintStream(incomingConnection.getOutputStream());
// Ask for input (For Telnet Testing)
//out.println("Welcome to the LikeTunes Server!.");
//out.println("Type 0 to add a tune to the list.");
//out.println("Type 1 to like an existing Tune.");
//out.println("Type 2 to view the list of Tunes in alphabetical order.");
//out.println("Type 3 to view the list of Tunes in order of popularity.");
try {
final int temp = Integer.parseInt(in.readLine());
// Add a Tune to the TuneLst
if (temp == 0) {
// Get Tune to be added
// TuneList method is synchronised to prevent duplicates
//out.println("Please input the name of the artist.");
String artistName = new String(in.readLine());
//out.println("Please input the name of the Tune.");
String title = new String(in.readLine());
// If the client leaves an artist's name or title blank
if (artistName.equals("") || title.equals("")) {
out.println("5");
}
// Otherwise, add the Tune
else {
successCheck = LikeTunesServer.tl.addTune(artistName,title);
// Tune was added successfully
if (successCheck == 1)
out.println("Request Completed, closing server");
// Tune was a duplicate
else
out.println("Tune was a duplicate, closing server");
}
}
// Like a Tune on the TuneList
else if (temp == 1) {
// Get Tune to be liked
// TuneList method is synchronised to prevent incorrect Tune likes
//out.println("Please input the name of the artist.");
String artistName = new String(in.readLine());
//out.println("Please input the name of the Tune.");
String title = new String(in.readLine());
// If the client leaves an artist's name or title blank
if (artistName.equals("") || title.equals("")) {
out.println("5");
}
// Otherwise, like the Tune
else {
successCheck = LikeTunesServer.tl.likeTune(artistName,title);
// Tune was liked successfully
if (successCheck == 1)
out.println("Request Completed, closing server");
// Tune was not there to like
else
out.println("Could not like Tune, it does not exist on the server yet!");
}
}
// List Tunes Alphabetically
else if (temp == 2) {
String result = new String(LikeTunesServer.tl.listAlphabetically());
out.println(result);
out.println("Request Completed, closing server");
}
// List Tunes by Popularity
else if (temp == 3) {
String result = new String(LikeTunesServer.tl.listByLikes());
out.println(result);
out.println("Request Completed, closing server");
}
// Client made an unrecognised request
else {
out.println("7");
}
}
来自Tunelist.java的方法
public String listAlphabetically() {
String result = new String();
Tune currentTune = theListAlph;
// Loops through the alphabetical list concatenating the Tune's info to the result string
for (int i = 0; i < length(); i++) {
if (i == 0) {
result = currentTune.returnTune();
}
else {
result = result.concat(currentTune.returnTune());
}
currentTune = currentTune.nextAlph;
}
return result;
}
public synchronized int addTune(String artistName, String title) {
// If the list is empty, add the first Tune
int temp = 0;
if (theListAlph == null) {
Tune newNode = new Tune(artistName, title);
theListAlph = newNode;
theListPop = newNode;
temp = 1;
}
// Otherwise, begin searching this List for the new Tune's correct lexicographical position in the Linked List
else {
Tune currentTune = theListAlph;
while (temp == 0) {
String testArtist = currentTune.artistName;
String newArtist = artistName;
int compare = newArtist.compareTo(testArtist);
// This artist of the new Tune comes before the tested artist alphabetically
if (compare < 0) {
Tune newNode = new Tune(artistName, title);
// If the tested Tune was the first Tune in the alphabetical List, insert the new Tune as the new beginning of the alphabetical Linked List
if (theListAlph == currentTune) {
insertNewFirst(newNode, currentTune, theListPop);
}
// Inserting the new Tune in all other locations in the alphabetical Linked List
else {
insertBeforeNotFirst(newNode, currentTune, theListPop);
}
temp = 1;
}
// The new artist is the same as the tested artist, begin testing the titles of the Tunes lexicographically
if (compare == 0) {
String testTitle = currentTune.title;
String newTitle = title;
int compareTitle = newTitle.compareTo(testTitle);
// The new title comes before the tested title lexicographically
if (compareTitle < 0) {
Tune newNode = new Tune(artistName, title);
// If the tested Tune was the first Tune in the alphabetical List, insert the new Tune as the new beginning of the alphabetical Linked List
if (theListAlph == currentTune) {
insertNewFirst(newNode, currentTune, theListPop);
}
// Inserting the new Tune in all other locations in the alphabetical Linked List
else {
insertBeforeNotFirst(newNode, currentTune, theListPop);
}
temp = 1;
}
//The titles are the same
//The same tune cannot be entered twice
if (compareTitle == 0) {
temp = 2;
}
}
// The new tune comes last alphabetically, it will be added to the end of the List
if (currentTune.nextAlph == null && temp == 0) {
Tune newNode = new Tune(artistName, title);
currentTune.nextAlph = newNode;
newNode.prevAlph = currentTune;
currentTune = theListPop;
while (currentTune.nextPop != null) {
currentTune = currentTune.nextPop;
}
currentTune.nextPop = newNode;
newNode.prevPop = currentTune;
temp = 1;
}
currentTune = currentTune.nextAlph;
}
}
return temp;
}
答案 0 :(得分：0)
尝试在out.flush();之后添加out.println("2");。