我正在开发一个连接到服务器并来回讲话的程序。
服务器最初发送String然后我发送第一个字母回服务器发送第二个，我发送第三个，依此类推。
谁不发送字符串的最后一个字母发送“完成！”。
我的程序正在努力获取字符串并分解为字符，但是它似乎不会进入while循环，我无法弄清楚原因。
下面是我的代码和我试图传递的测试用例。
有人可以解释为什么我的代码不起作用（我认为它与while循环有关），以及我需要做些什么来修复它？
我的代码
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;
public class Program2 {
static String rec;
public static void goClient(){
try{
String server = "localhost";
int port = 4321;
Socket socket = new Socket(server, port);
InputStream inStream = socket.getInputStream();
OutputStream outStream = socket.getOutputStream();
Scanner scan = new Scanner(inStream);
PrintWriter out = new PrintWriter(outStream);
rec = scan.nextLine();
System.out.println(rec);
char[] array = new char[rec.length()];
for(int i = 0; i < rec.length(); i++){
array[i] = rec.charAt(i);
System.out.println(array[i]);
}
if(array.length % 2 == 0){
while(scan.hasNext()){
for(int x = 0; x < array.length; x+=2){
String str;
str = Character.toString(array[x]);
System.out.print(str);
out.println(str);
str = scan.nextLine();
System.out.print(str);
}
}
}
if(array.length % 2 != 0){
while(scan.hasNext()){
for(int x = 0; x < array.length - 1; x+=2){
String str;
str = Character.toString(array[x]);
System.out.print(str);
out.println(str);
str = scan.nextLine();
System.out.print(str);
}
}
out.println("done!");
}
scan.close();
socket.close();
} catch (IOException e) {}
}
}
Junit测试用例
import static org.junit.Assert.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.CountDownLatch;
import org.junit.Before;
import org.junit.Test;
public class Program2Test {
@Before
public void wait2SecondsBeforeEachTest() {
try {
Thread.sleep( 2000 );
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
@Test
public void test0() {
Runnable client = new Runnable() {
@Override
public void run() {
Program2.goClient();
}
};
final CountDownLatch gate = new CountDownLatch( 1 );
Runnable server = new Runnable() {
@Override
public void run() {
ServerSocket server = null;
try {
server = new ServerSocket( 4321 );
Socket client = server.accept();
PrintWriter out = new PrintWriter( client.getOutputStream(), true );
Scanner in = new Scanner ( client.getInputStream() );
out.println( "Lorem" );
String actual = in.nextLine();
assertEquals( "Incorrect result", "L", actual );
out.println( "o" );
actual = in.nextLine();
assertEquals( "Incorrect result", "r", actual );
out.println( "e" );
actual = in.nextLine();
assertEquals( "Incorrect result", "m", actual );
out.println( "done!" );
assertFalse( "Client hasn't closed its socket", in.hasNext() );
client.close();
gate.countDown();
}
catch (IOException e) {
e.printStackTrace();
}
finally {
try {
if (server != null) {
server.close();
}
}
catch (IOException e) {
e.printStackTrace();
}
}
}
};
Thread serverThread = new Thread( server );
serverThread.start();
Thread clientThread = new Thread( client );
clientThread.start();
int count = 0;
while (serverThread.isAlive() && count++ < 300) {
try {
Thread.sleep( 10 );
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
assertTrue( "Client did not arrive or did not finish correctly", gate.getCount() == 0 );
}
@Test
public void test1() {
Runnable client = new Runnable() {
@Override
public void run() {
Program2.goClient();
}
};
final CountDownLatch gate = new CountDownLatch( 1 );
Runnable server = new Runnable() {
@Override
public void run() {
ServerSocket server = null;
try {
server = new ServerSocket( 4321 );
Socket client = server.accept();
PrintWriter out = new PrintWriter( client.getOutputStream(), true );
Scanner in = new Scanner ( client.getInputStream() );
out.println( "Let it be." );
String actual = in.nextLine();
assertEquals( "Incorrect result", "L", actual );
out.println( "e" );
actual = in.nextLine();
assertEquals( "Incorrect result", "t", actual );
out.println( " " );
actual = in.nextLine();
assertEquals( "Incorrect result", "i", actual );
out.println( "t" );
actual = in.nextLine();
assertEquals( "Incorrect result", " ", actual );
out.println( "b" );
actual = in.nextLine();
assertEquals( "Incorrect result", "e", actual );
out.println( "." );
actual = in.nextLine();
assertEquals( "Incorrect result", "done!", actual );
assertFalse( "Client hasn't closed its socket", in.hasNext() );
client.close();
gate.countDown();
}
catch (IOException e) {
e.printStackTrace();
}
finally {
try {
if (server != null) {
server.close();
}
}
catch (IOException e) {
e.printStackTrace();
}
}
}
};
Thread serverThread = new Thread( server );
serverThread.start();
Thread clientThread = new Thread( client );
clientThread.start();
int count = 0;
while (serverThread.isAlive() && count++ < 300) {
try {
Thread.sleep( 10 );
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
assertTrue( "Client did not arrive or did not finish correctly", gate.getCount() == 0 );
}
@Test
public void test2() {
Runnable client = new Runnable() {
@Override
public void run() {
Program2.goClient();
}
};
final CountDownLatch gate = new CountDownLatch( 1 );
Runnable server = new Runnable() {
@Override
public void run() {
ServerSocket server = null;
try {
server = new ServerSocket( 4321 );
Socket client = server.accept();
PrintWriter out = new PrintWriter( client.getOutputStream(), true );
Scanner in = new Scanner ( client.getInputStream() );
out.println( "Upside Down" );
String actual = in.nextLine();
assertEquals( "Incorrect result", "U", actual );
out.println( "p" );
actual = in.nextLine();
assertEquals( "Incorrect result", "s", actual );
out.println( "i" );
actual = in.nextLine();
assertEquals( "Incorrect result", "d", actual );
out.println( "e" );
actual = in.nextLine();
assertEquals( "Incorrect result", " ", actual );
out.println( "D" );
actual = in.nextLine();
assertEquals( "Incorrect result", "o", actual );
out.println( "w" );
actual = in.nextLine();
assertEquals( "Incorrect result", "n", actual );
out.println( "done!" );
assertFalse( "Client hasn't closed its socket", in.hasNext() );
client.close();
gate.countDown();
}
catch (IOException e) {
e.printStackTrace();
}
finally {
try {
if (server != null) {
server.close();
}
}
catch (IOException e) {
e.printStackTrace();
}
}
}
};
Thread serverThread = new Thread( server );
serverThread.start();
Thread clientThread = new Thread( client );
clientThread.start();
int count = 0;
while (serverThread.isAlive() && count++ < 300) {
try {
Thread.sleep( 10 );
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
assertTrue( "Client did not arrive or did not finish correctly", gate.getCount() == 0 );
}
}
控制台输出
Lorem
L
o
r
e
m
java.net.BindException: Address already in use: JVM_Bind
at java.net.DualStackPlainSocketImpl.bind0(Native Method)
at java.net.DualStackPlainSocketImpl.socketBind(Unknown Source)
at java.net.AbstractPlainSocketImpl.bind(Unknown Source)
at java.net.PlainSocketImpl.bind(Unknown Source)
at java.net.ServerSocket.bind(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at Program2Test$4.run(Program2Test.java:112)
at java.lang.Thread.run(Unknown Source)
java.net.BindException: Address already in use: JVM_Bind
at java.net.DualStackPlainSocketImpl.bind0(Native Method)
at java.net.DualStackPlainSocketImpl.socketBind(Unknown Source)
at java.net.AbstractPlainSocketImpl.bind(Unknown Source)
at java.net.PlainSocketImpl.bind(Unknown Source)
at java.net.ServerSocket.bind(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at Program2Test$6.run(Program2Test.java:199)
at java.lang.Thread.run(Unknown Source)
答案 0 :(得分：0)
从堆栈跟踪中，您的程序似乎尝试绑定（保留）已使用的端口，可能是因为运行Program2Test的语句
server = new ServerSocket( 4321 );
您还使用端口4321作为Program2的套接字定义，即在语句
Socket socket = new Socket(server, port);
检查是否在客户端或服务器端产生冲突，或JUnit是否运行test2()方法的1倍以上。