Java中的客户机-服务器应用程序
我有一个用Java编写的服务器应用程序,其中包含一个Student对象列表(实现可序列化)。客户端应用程序发送一条消息,其中包含要获取的Student对象的整数索引。然后将所选学生发送到客户端,客户端修改其值并发回。然而,应用程序在某个时候会冻结,这可能是我在下面代码中强调的行的问题 服务器:Java中的客户机-服务器应用程序,java,sockets,serialization,client,server,Java,Sockets,Serialization,Client,Server,我有一个用Java编写的服务器应用程序,其中包含一个Student对象列表(实现可序列化)。客户端应用程序发送一条消息,其中包含要获取的Student对象的整数索引。然后将所选学生发送到客户端,客户端修改其值并发回。然而,应用程序在某个时候会冻结,这可能是我在下面代码中强调的行的问题 服务器: public class Server { public static void main(String[] arg) { ArrayList <Student> s
public class Server {
public static void main(String[] arg) {
ArrayList <Student> studentList = new ArrayList <Student> ();
studentList.add(new Student(170435, "justyna", "kaluzka", new ArrayList <Float>()));
studentList.add(new Student(170438, "michal", "szydlowski", new ArrayList <Float>()));
studentList.add(new Student(170436, "marek", "polewczyk", new ArrayList <Float>()));
studentList.add(new Student(170439, "jakub", "szydlowski", new ArrayList <Float>()));
studentList.add(new Student(170430, "anna", "majchrzak", new ArrayList <Float>()));
studentList.add(new Student(170425, "krzysztof", "krawczyk", new ArrayList <Float>()));
studentList.add(new Student(170445, "adam", "szydlowski", new ArrayList <Float>()));
studentList.add(new Student(170415, "karol", "chodkiewicz", new ArrayList <Float>()));
studentList.add(new Student(170465, "artur", "schopenhauer", new ArrayList <Float>()));
ServerSocket socketConnection = null;
ObjectInputStream serverInputStream = null;
ObjectOutputStream serverOutputStream = null;
try {
socketConnection = new ServerSocket(11111);
System.out.println("Server Waiting");
Socket pipe = socketConnection.accept();
serverOutputStream = new ObjectOutputStream( pipe.getOutputStream());
serverInputStream = new ObjectInputStream( pipe.getInputStream());
int index = serverInputStream.readInt();
System.out.println(index);
// HERE'S WHEN THE PROBLEM STARTS
serverOutputStream.writeObject(studentList.get(index));
Student student = (Student) serverInputStream.readObject();
System.out.println(student.toString());
} catch (IOException e) {
System.out.println(e);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
serverInputStream.close();
serverOutputStream.close();
socketConnection.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
我对客户机-服务器套接字的了解很模糊,所以这很可能是一个简单的错误。有什么想法吗
编辑:
学生班
public class Student implements Serializable {
private static final long serialVersionUID = -5169551431906499332L;
private int indexNumber;
private String name;
private String familyName;
private ArrayList<Float> marks;
private float average;
public Student(int indexNumber, String name, String familyName,
ArrayList<Float> marks) {
this.indexNumber = indexNumber;
this.name = name;
this.familyName = familyName;
this.marks = marks;
this.average = 0;
generateMarks();
calculateAverage();
}
public int getIndexNumber() {
return indexNumber;
}
public void setIndexNumber(int indexNumber) {
this.indexNumber = indexNumber;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getFamilyName() {
return familyName;
}
public void setFamilyName(String familyName) {
this.familyName = familyName;
}
public float getAverage() {
return average;
}
public void setAverage(float average) {
this.average = average;
}
/**
* Calculates average of all Student's marks.
*/
public void calculateAverage() {
float sum = 0;
for (int i = 0; i < marks.size(); i++) {
sum += marks.get(i);
}
this.average = sum / marks.size();
}
/**
* Generates a random set of marks for the student.
*/
public void generateMarks() {
for (int i = 0; i < 10; i++) {
addMark(new Random().nextFloat() * 5);
}
}
/**
* Mark getter
*
* @return String representation of marks
*/
public String getMarks() {
String marksstr = "";
for (int i = 0; i < marks.size(); i++) {
marksstr += marks.get(i).toString() + " ";
}
return marksstr;
}
/**
* Adds a mark to the list.
*
* @param mark
*/
public void addMark(float mark) {
marks.add(mark);
}
@Override
public String toString() {
return "Index number:" + indexNumber + "\tName:" + name
+ "\tFamily name:" + familyName + "\t\tAverage:" + getAverage()
+ "\n";
}
}
公共类学生实现可序列化{
私有静态最终长serialVersionUID=-5169551431906499332L;
私有整数指数;
私有字符串名称;
私有字符串familyName;
私有数组列表标记;
私人浮动平均线;
公立学生(int索引编号、字符串名称、字符串家庭名称、,
ArrayList标记){
this.indexNumber=indexNumber;
this.name=名称;
this.familyName=familyName;
这个。标记=标记;
这个平均值=0;
生成标记();
计算频率();
}
public int getIndexNumber(){
返回索引编号;
}
公共无效setIndexNumber(int indexNumber){
this.indexNumber=indexNumber;
}
公共字符串getName(){
返回名称;
}
公共void集合名(字符串名){
this.name=名称;
}
公共字符串getFamilyName(){
返回家庭名称;
}
public void setFamilyName(字符串familyName){
this.familyName=familyName;
}
公共浮动平均值(){
收益率平均值;
}
公共平均值(浮动平均值){
这个平均数=平均数;
}
/**
*计算所有学生分数的平均值。
*/
公众假期{
浮点数和=0;
对于(int i=0;i
在服务器上的ObjectInputSteam
之前初始化ObjectOutputStream
初始化ObjectInputStream
时,它会等待“header”数据。您的服务器正在等待该标头数据。您需要首先初始化ObjectOutputStream
(发送头数据),然后初始化ObjectInputStream
您可以在中找到更多关于此的信息
写入int后,必须刷新
ObjectOutputStream
。将数据写入流时,它会写入缓冲区。只有当流的缓冲区已满时,才会发送来自该缓冲区的数据。int不能填充它,因此您必须flush()
它才能从缓冲区手动发送数据。在服务器上的objectinputstream
之前初始化ObjectOutputStream
初始化ObjectInputStream
时,它会等待“header”数据。您的服务器正在等待该标头数据。您需要首先初始化ObjectOutputStream
(发送头数据),然后初始化ObjectInputStream
您可以在中找到更多关于此的信息
写入int后,必须刷新
ObjectOutputStream
。将数据写入流时,它会写入缓冲区。只有当流的缓冲区已满时,才会发送来自该缓冲区的数据。int不能填充它,因此您必须flush()
it才能从缓冲区手动发送数据。我假设您的对象是可序列化的?在之后“问题开始了”
您能走多远?到下面的println
两行?不,我只在服务器端得到“服务器等待”,在客户端没有得到任何结果。ofc是可序列化的。在这一行之前,它工作正常:student=(student)clientInputStream.readObject();这就是它开始不响应的时候了。我假设您的对象是可序列化的?在之后“问题就从这里开始”
您走了多远?到下面的println
两行?不,我只在服务器端得到“服务器等待”,在客户端没有得到任何结果。ofc是可序列化的。在这一行之前,它工作正常:student=(student)clientInputStream.readObject();这就是它开始不响应的时候。@markspace假设您没有遵守严格的协议。此外,即使在使用不同线程进行读/写操作时,有些人也喜欢将初始化保持在中心位置,以便于管理。最好是以正确的方式进行,了解问题的原因。但你是对的;在不同线程上初始化也可以解决这个问题好的,诀窍是:我想从客户端到服务器发送一个整数,然后从服务器到客户端发送一个对象,让客户端修改它,然后将它发送回服务器。只需创建两个可运行文件(一个用于读取,一个用于写入)并启动两个线程就可以了吗?@user4359659是的,但您需要两个线程吗?我不这么认为,我也不建议这样做(如果可能的话,尽量避免并发,这样你就不必担心了)
public class Student implements Serializable {
private static final long serialVersionUID = -5169551431906499332L;
private int indexNumber;
private String name;
private String familyName;
private ArrayList<Float> marks;
private float average;
public Student(int indexNumber, String name, String familyName,
ArrayList<Float> marks) {
this.indexNumber = indexNumber;
this.name = name;
this.familyName = familyName;
this.marks = marks;
this.average = 0;
generateMarks();
calculateAverage();
}
public int getIndexNumber() {
return indexNumber;
}
public void setIndexNumber(int indexNumber) {
this.indexNumber = indexNumber;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getFamilyName() {
return familyName;
}
public void setFamilyName(String familyName) {
this.familyName = familyName;
}
public float getAverage() {
return average;
}
public void setAverage(float average) {
this.average = average;
}
/**
* Calculates average of all Student's marks.
*/
public void calculateAverage() {
float sum = 0;
for (int i = 0; i < marks.size(); i++) {
sum += marks.get(i);
}
this.average = sum / marks.size();
}
/**
* Generates a random set of marks for the student.
*/
public void generateMarks() {
for (int i = 0; i < 10; i++) {
addMark(new Random().nextFloat() * 5);
}
}
/**
* Mark getter
*
* @return String representation of marks
*/
public String getMarks() {
String marksstr = "";
for (int i = 0; i < marks.size(); i++) {
marksstr += marks.get(i).toString() + " ";
}
return marksstr;
}
/**
* Adds a mark to the list.
*
* @param mark
*/
public void addMark(float mark) {
marks.add(mark);
}
@Override
public String toString() {
return "Index number:" + indexNumber + "\tName:" + name
+ "\tFamily name:" + familyName + "\t\tAverage:" + getAverage()
+ "\n";
}
}