我是Android新手。首先，我用Java编写了一个Chat_Client和Server。它很棒。
然后我尝试将其转换为有效的Android应用程序，我总是收到消息＆＃34;无法连接到服务器！再试一次！＆＃34;所以Socket连接尝试显然有问题，但我无法弄清楚它是什么。
背景知识：
- 我连接到我的根服务器，看看chat_server进程。它正在运行！
- 我试图从我的PC上的其他chat_client连接到chat_server。它有效！
- 主机和端口是正确的。检查了几次
- 权限设置<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
- 我可以在我的Nexus 5上运行应用程序
- LogCat或控制台中没有列出错误，它似乎正常运行..
我的chat_client代码：
package de.Voldemord.chatter;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.*;
import java.io.*;
import java.net.*;
import java.util.*;
public class MainActivity extends Activity implements OnClickListener{
private Button btn;
private EditText et_send;
private EditText et_chat;
private String s_username = "Voldemord", s_host = "www.example.com"; // !Example host!
private int s_port = 2222; // !Example port!
private Socket socket = null;
private BufferedReader in;
private PrintWriter out;
@SuppressWarnings({ "unchecked", "rawtypes" })
ArrayList<String> users = new ArrayList();
boolean isConnected = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_send = (EditText) findViewById(R.id.sendTextView);
et_chat = (EditText) findViewById(R.id.chatTextView);
btn = (Button) findViewById(R.id.btn);
btn.setOnClickListener(this);
if (isConnected == false){
try{
socket = new Socket(InetAddress.getByName(s_host), s_port);
InputStreamReader streamreader = new InputStreamReader(socket.getInputStream());
in = new BufferedReader(streamreader);
out = new PrintWriter(socket.getOutputStream());
out.println(s_username + ":has connected.:Connect");
out.flush();
isConnected = true;
}catch (Exception ex){
et_chat.append("Cannot Connect! Try Again. \n"+ socket);
}
ListenThread();
}else if (isConnected == true){
et_chat.append("You are already connected. \n");
}
}
protected void onDestroy(){
super.onDestroy();
sendDisconnect();
Disconnect();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onClick(View v) {
String nothing = "";
if ((et_send.getText()).equals(nothing)) {
et_send.setText("");
et_send.requestFocus();
} else {
try {
out.println(s_username + ":" + et_send.getText() + ":" + "Chat");
out.flush(); // flushes the buffer
} catch (Exception ex) {
et_chat.append("Message was not sent. \n");
}
et_send.setText("");
et_send.requestFocus();
}
et_send.setText("");
et_send.requestFocus();
}
public void sendDisconnect(){
String bye = (s_username + ": :Disconnect");
try{
out.println(bye);
out.flush();
}catch (Exception e){
et_chat.append("Could not send Disconnect message.\n");
}
}
public void Disconnect(){
try{
et_chat.append("Disconnected.\n");
socket.close();
}catch (Exception e){
et_chat.append("Failed to disconnect.\n");
}
isConnected = false;
}
public void ListenThread(){
Thread IncomingReader = new Thread(new IncomingReader());
IncomingReader.start();
}
public void userAdd(String user){
users.add(user);
}
public void userRemove(String user){
et_chat.append(user + " is now Offline.\n");
}
public class IncomingReader implements Runnable{
@Override
public void run(){
String[] data;
String stream, done = "Done", connect = "Connect", disconnect = "Disconnect", chat = "Chat", shutdown = "Shutdown";
try{
while ((stream = in.readLine()) != null){
data = stream.split(":");
if(data[data.length-1].equals(shutdown)){
if(data[0].equals("Server")){
et_chat.append("Server: The Server is Shutting down!\n");
}
sendDisconnect();
Disconnect();
}else if (data[data.length-1].equals(chat)){
et_chat.append(data[0] + ": " + extract(stream) + "\n");
// et_chat.setCaretPosition(et_chat.getDocument().getLength());
}else if (data[data.length-1].equals(connect)){
userAdd(data[0]);
}else if (data[data.length-1].equals(disconnect)){
userRemove(data[0]);
}else if (data[data.length-1].equals(done)){
users.clear();
}
}
}catch(Exception ex){
}
}
private String extract(String input) {
for(int i=0;i<input.length();i++){
if(input.charAt(i) == ':'){
input = input.substring(i+1,input.length()-5);
break;
}
}
return input;
}
}
}
我的root_chat_server代码：
import java.awt.EventQueue;
import java.io.*;
import java.net.*;
import java.util.*;
public class root_Chat_Server{
private ServerStart serverStart;
private boolean isStarted = false;
private Thread starter;
@SuppressWarnings("rawtypes")
ArrayList clientOutputStreams;
@SuppressWarnings("rawtypes")
ArrayList clientHandler;
ArrayList<String> users;
/**
* Create the application.
*/
public class ClientHandler implements Runnable{
BufferedReader reader;
Socket sock;
PrintWriter client;
public ClientHandler(Socket clientSocket, PrintWriter user){
client = user;
try{
sock = clientSocket;
InputStreamReader isReader = new InputStreamReader(sock.getInputStream());
reader = new BufferedReader(isReader);
}
catch (Exception ex){
System.out.print("Unexpected error... \n");
}
}
@Override
public void run(){
String message, connect = "Connect", disconnect = "Disconnect", chat = "Chat" ;
String[] data;
try{
while ((message = reader.readLine()) != null){
System.out.print("Received: " + message + "\n");
data = message.split(":");
for (String token:data){
System.out.print(token + "\n");
}
if (data[data.length-1].equals(connect)){
tellEveryone((data[0] + ":" + data[1] + ":" + chat));
userAdd(data[0]);
}else if (data[data.length-1].equals(disconnect)){
tellEveryone((data[0] + ":has disconnected." + ":" + chat));
userRemove(data[0]);
}else if (data[data.length-1].equals(chat)){
System.out.print("\n\n"+ message +"\n\n");
tellEveryone(message);
}else{
System.out.print("No Conditions were met. \n");
}
}
}catch (Exception ex){
System.out.print("Lost a connection. \n");
ex.printStackTrace();
clientOutputStreams.remove(client);
}
}
public void stop() throws IOException{
sock.close();
}
}
public root_Chat_Server() {
}
private void start(){
if(!isStarted){
starter = new Thread(serverStart = new ServerStart());
starter.start();
System.out.print("Server started...\n");
isStarted = true;
}
}
private void stop(){
try{
tellEveryone("Server:Shutdown");
Thread.sleep(2000);
serverStart.stop();
isStarted = false;
}catch (InterruptedException | IOException ex){
Thread.currentThread().interrupt();
}
System.out.print("Server is stopping...\n\n\n");
}
private void users(){
System.out.print("\nOnline Users:\n");
for(String current_users : users){
System.out.print("-" + current_users + "\n");
}
}
public class ServerStart implements Runnable{
ServerSocket serverSock;
Socket clientSock;
@SuppressWarnings({ "rawtypes", "unchecked" })
@Override
public void run(){
clientOutputStreams = new ArrayList();
users = new ArrayList();
clientHandler = new ArrayList();
ClientHandler clientHand;
try{
serverSock = new ServerSocket(2222);
while (true){
clientSock = serverSock.accept();
PrintWriter writer = new PrintWriter(clientSock.getOutputStream());
clientOutputStreams.add(writer);
Thread listener = new Thread(clientHand = new ClientHandler(clientSock, writer));
clientHandler.add(clientHand);
listener.start();
System.out.print("Got a connection. \n");
}
}catch (Exception ex){
System.out.print("Error making a connection. \n");
}
}
private void stop() throws IOException{
if(serverSock != null && clientSock != null){
serverSock.close();
clientSock.close();
}else if(serverSock != null){
serverSock.close();
}
}
}
public void userAdd (String data){
String message, add = ": :Connect", done = "Server: :Done", name = data;
if(!users.contains(name)){
System.out.print("Before " + name + " added. \n");
users.add(name);
System.out.print("After " + name + " added. \n");
String[] tempList = new String[(users.size())];
users.toArray(tempList);
for (String token:tempList){
message = (token + add);
tellEveryone(message);
}
tellEveryone(done);
}else{
PrintWriter writer = (PrintWriter)clientOutputStreams.get(clientOutputStreams.size()-1);
ClientHandler clientHand = (ClientHandler)clientHandler.get(clientHandler.size()-1);
writer.println("Disconnect:Shutdown");
writer.flush();
try {
clientHand.stop();
} catch (IOException e) {
e.printStackTrace();
}
clientHandler.remove(clientHandler.size()-1);
clientOutputStreams.remove(clientOutputStreams.size()-1);
}
}
public void userRemove (String data){
String message, add = ": :Connect", done = "Server: :Done", name = data;
users.remove(name);
String[] tempList = new String[(users.size())];
users.toArray(tempList);
for (String token:tempList){
message = (token + add);
tellEveryone(message);
}
tellEveryone(done);
}
@SuppressWarnings("rawtypes")
public void tellEveryone(String message){
Iterator it = clientOutputStreams.iterator();
while (it.hasNext()){
try{
PrintWriter writer = (PrintWriter) it.next();
writer.println(message);
System.out.print("Sending: " + message + "\n");
writer.flush();
}catch (Exception ex){
System.out.print("Error telling everyone. \n");
}
}
}
/**
* Launch the application.
*/
public static void main(String[] args){
EventQueue.invokeLater(new Runnable(){
public void run(){
if(args.length == 1){
root_Chat_Server server = new root_Chat_Server();
if(args[0].equals("start")){
server.start();
}else if(args[0].equals("stop")){
server.stop();
}else if(args[0].equals("users")){
server.users();
}
}else{
System.out.println("java root_Chat_Server start|stop|users");
}
}
});
}
}
谢谢你的每一个答案！
答案 0 :(得分：1)
没有错误，因为您正在捕获异常并打印＆＃34;无法连接到服务器！再试一次！＆＃34;。您应该打印异常消息以发现正在发生的事情。
In Android, you have to run asynchronous network operations on a thread other than the main one.您当前正在主线程上运行套接字操作，这将导致异常。
答案 1 :(得分：0)
如果您在项目中使用本机异步时遇到问题。看看这个link。您可以将它用于您的项目。它在带有android客户端的后端Node.js上运行。