我正在尝试在android中实现聊天应用程序。客户端（智能手机）将通过安装在计算机中的服务器进行通信。我不知道客户端 - 服务器通信，所以我很需要你的帮助。我已经阅读了很多关于我的结论，我必须使用HTTP（请求/响应），这是对的吗？在HTTP中，客户端/服务器分别发送请求和服务器/客户端发送响应，这是否有效？套接字是另一种强制方式，我的意思是我不需要HTTP的任何套接字？对不起，我问所有这些，但我真的很困惑。我还需要任何第三方软件吗？我把客户端（android应用程序）和服务器（java应用程序）放在完全不同的项目包中。我还使用以下代码登录表单：
public void tryLogin（）{
//The Android logging system provides a mechanism for collecting and viewing system debug output. Logcat dumps a log of system messages, which include things such as stack traces when the emulator throws an error and messages that you have written from your application by using the Log class.
Log.v(TAG, "Trying to Login");//TAG used to identify the source of a log message. It usually identifies the class or activity where the log call occurs./second param The message you would like logged.
EditText etxt_user = (EditText) findViewById(R.id.username);//finds the username TextView
EditText etxt_pass = (EditText) findViewById(R.id.password);//finds the pasword TextView
String username1 = etxt_user.getText().toString();//gets the text that the user has typed as his/her username
String password1 = etxt_pass.getText().toString();//gets the text that the user haw typed as his/her password
DefaultHttpClient client = new DefaultHttpClient();//creates a DefaultHttpClient object
HttpPost httppost = new HttpPost("http://.......");
//add your Data
List< BasicNameValuePair > nvps = new ArrayList< BasicNameValuePair >();
nvps.add(new BasicNameValuePair("username", username1));
nvps.add(new BasicNameValuePair("password", password1));
try {
UrlEncodedFormEntity p_entity = new UrlEncodedFormEntity(nvps, HTTP.UTF_8);//The message-body (if any) of an HTTP message is used to carry the entity-body associated with the request or response. The message-body differs from the entity-body only when a transfer-coding has been applied, as indicated by the Transfer-Encoding header field
httppost.setEntity(p_entity);
//Execute HTTP Post Request
HttpResponse response = client.execute(httppost);
Log.v(TAG, response.getStatusLine().toString());//HTTP/1.1 200 OK --> see DDMS //HTTP has been in use by the World-Wide Web global information initiative since 1990. This specification defines the protocol referred to as "HTTP/1.1", and is an update to RFC 2068 [33].//OK 200-->The request was fulfilled.
//The message-body (if any) of an HTTP message is used to carry the entity-body associated with the request or response.
HttpEntity responseEntity = response.getEntity();
Log.v(TAG, "Set response to responseEntity" + EntityUtils.toString(responseEntity));
//SAXParserFactory --> defines a factory API that enables applications to configure and obtain a SAX based parser to parse XML documents.
SAXParserFactory spf = SAXParserFactory.newInstance();//obtain a new instance of a SAXParserFactory
SAXParser sp = spf.newSAXParser();//creates a new instance of a SAXParser using the currently configured factory parameters.
XMLReader xr = sp.getXMLReader();//interface for reading an xml document using callbacks
LoginHandler myLoginHandler = new LoginHandler();
xr.setContentHandler(myLoginHandler);
xr.parse(retrieveInputStream(responseEntity));//retrieves the response of the server
ParsedLoginDataSet parsedLoginDataSet = myLoginHandler.getParsedLoginData();
if (parsedLoginDataSet.getExtractedString().equals("SUCCESS")) {
// Store the username and password in SharedPreferences after the successful login
SharedPreferences.Editor editor=mPreferences.edit();
editor.putString("UserName", username1);
editor.putString("PassWord", password1);
editor.commit();
Message myMessage=new Message();
myMessage.obj="SUCCESS";
handler.sendMessage(myMessage);
} else if(parsedLoginDataSet.getExtractedString().equals("ERROR")) {
Intent intent = new Intent(getApplicationContext(), LoginError.class);
intent.putExtra("LoginMessage", parsedLoginDataSet.getMessage());
startActivity(intent);
removeDialog(0);
}
} catch (Exception e)
{
/** InetAddress xxxx;//this code returns the localhost
try {//this code returns the localhost
xxxx = InetAddress.getLocalHost()to.String();*///this code returns the localhost
Intent intent = new Intent(getApplicationContext(), LoginError.class);//calls the activity LoginError.java
intent.putExtra("LoginMessage", "Unable to login");//sends information with intent.putExtra. The information that will be sent is the text which we would like to appear in the TextView of the LoginError activity.(putextra(name, value????))
startActivity(intent);//starts the LoginError.java activity.
removeDialog(0);//closes the dialog box with the message "please wait while connecting...
// e.printStackTrace();//It's a method of the Throwable class. All exceptions are a subclass of that class. The trace prints exactly where the program was at the moment the exception was throw.
/**} catch (UnknownHostException e1) {//this code returns the localhost
e1.printStackTrace();//this code returns the localhost
}*///this code returns the localhost
}
}
它似乎工作到行xr.setContentHandler（myLoginHandler）;对于其余的代码，我必须构建服务器。服务器如何从客户端获取请求然后发回响应？在HTTP邮件中，这是我必须放的地址？当我把我的IP地址它不起作用，但当我使用默认geteway它似乎工作。至少，我可以让客户端和服务器在同一台计算机上测试通信，或者我必须有两台计算机（一台用于客户端，一台用于服务器）？ 我知道很多问题，但请至少回答一些问题。我真的是个新手。
提前谢谢！
答案 0 :(得分：0)
我建议调查REST服务。基本结构是让你的Android应用程序预先向服务器发出HTTP请求（最好是在一个单独的线程中），让服务器用xml或json进行响应。
这是我经常使用的线程http post类。
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.util.EntityUtils;
import android.os.Handler;
import android.os.Message;
public class HttpPostThread extends Thread {
public static final int FAILURE = 0;
public static final int SUCCESS = 1;
public static final String VKEY = "FINDURB#V0";
private final Handler handler;
private String url;
ArrayList<NameValuePair> pairs;
public HttpPostThread(String Url, ArrayList<NameValuePair> pairs, final Handler handler)
{
this.url =Url;
this.handler = handler;
this.pairs = pairs;
if(pairs==null){
this.pairs = new ArrayList<NameValuePair>();
}
}
@Override
public void run()
{
try {
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(url);
HttpParams httpParameters = new BasicHttpParams();
int timeoutConnection = 3000;
HttpConnectionParams.setConnectionTimeout(httpParameters,
timeoutConnection);
if(pairs!=null)
post.setEntity(new UrlEncodedFormEntity(pairs));
HttpResponse response = client.execute(post);
HttpEntity entity = response.getEntity();
String answer = EntityUtils.toString(entity);
Message message = new Message();
message.obj = answer;
message.what = HttpPostThread.SUCCESS;
handler.sendMessage(message);
} catch (Exception e) {
e.printStackTrace();
handler.sendEmptyMessage(HttpPostThread.FAILURE);
}
}
}
每当您需要与服务器通信时，您都会执行此类操作。
Handler handler = new Handler()
{
@Override
public void handleMessage(Message msg)
{
removeDialog(0);
switch (msg.what)
{
case HttpPostThread.SUCCESS:
String answer = (String)msg.obj;
if (answer != null)
{
//do something with the return string
}
break;
case HttpPostThread.FAILURE:
// do some error handeling
break;
default:
break;
}
}
}
ArrayList<NameValuePair> pairs = new ArrayList<NameValuePair>();
pairs.add(new BasicNameValuePair("key", "value"));
HttpPostThread thread = new HttpPostThread("http://serviceURL",pairs, handler);
thread.start();
要回答下面的问题，可以使用任意数量的技术实施该服务。下面是一个简单的php服务示例，它从上面的示例中获取键/值对。
简单PHP服务的示例
<?php
$value = $_POST['key'];
echo "The value".$value. "was received by the service!";
?>
当服务器响应时，将调用handleMessage并且answer内的值将等于此行
echo "The value".$value. "was received by the service!";