我正在尝试使我的应用程序与主机 PC 通信（在真实手机上运行时仍然是这种情况）。我的 PC 本身与远程服务器通信：我编写了发送 HTTP 请求并侦听传入 HTTP 通知的 Java 类。这些课程在我的电脑上完美运行。
我在我的 Android 应用程序中对它们进行了一些调整。但不幸的是，应用程序无法访问互联网：所有请求都超时。我仔细检查了授权：我的清单文件中允许 Internet 访问，并且有效地出现在参数菜单的应用程序信息中。我的模拟器有完整的互联网访问权限：我可以浏览互联网，包括主机 PC 上的网站。
为了消除 PC 的问题，我首先尝试获取“ http://www.google.fr/index.html ”：它在我的具有相同类的 PC 上完美运行，但不适用于模拟器。然后，我尝试按照此处的建议在模拟器的界面上对流量进行 tcpdump ：我没有任何 HTTP 请求。
我想不通为什么...
我的模拟器运行的是 Android 2.3.3（API 级别 10）。
这是我的连接类（我用 HTTPClient 尝试过并且遇到了同样的问题）：（我知道日志语句“请求发送”不是最好的地方，它将被纠正:)
package com.example.myApp;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.security.InvalidParameterException;
import android.util.Log;
public class ServerConnection {
private String url;
private String method;
private String body;
private String response;
private int responseCode;
private int DEFAULT_TIMEOUT = 4 * 1000;
private int READ_TIMEOUT = 6 * 1000;
private static String TAG = "ServerConnection";
/**
* Create a new HTTP connection in order to send requests, retrieve responses, delete resources or receive notifications
* method MUST BE GET, POST or DELETE.
* @param url
* @param port
* @param method
* @param body
* @throws InvalidParameterException
*/
public ServerConnection(String url, String method, String body) throws InvalidParameterException{
this.url = url;
this.method = method;
this.body = body;
Log.d(TAG,"ServerConnection instantiated with parameters");
if(this.method == "POST")
this.sendPost();
else if (this.method =="GET")
this.sendGet();
else if (this.method == "DELETE")
this.sendDelete();
else
throw new InvalidParameterException("Invalid HTTP method");
}
/**
* Sends a HTTP request that does not require any body : for example a GET or DELETE
* @param url
* @param method
* @throws InvalidParameterException
*/
public ServerConnection(String url, String method) throws InvalidParameterException{
this.url = url;
this.method = method;
Log.d(TAG,"HTTP Request instantiated without body");
if (this.method =="GET")
this.sendGet();
else if (this.method == "DELETE")
this.sendDelete();
else
throw new InvalidParameterException("Invalid HTTP method");
}
/**
* Send a POST request with the specified url, port, body arguments.
*
* @return
*/
public void sendPost(){
new Thread(new Runnable() {
public void run() {
HttpURLConnection connection = null;
Log.d(TAG,"Sending HTTP POST Request...");
try{
URL serverUrl = new URL(ServerConnection.this.url);
connection = (HttpURLConnection) serverUrl.openConnection();
InputStream is;
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/xml");
connection.setRequestProperty("Accept", "application/xml");
connection.setRequestProperty("Content-Length","" + Integer.toString(ServerConnection.this.body.getBytes().length));
connection.setUseCaches(false);
connection.setInstanceFollowRedirects(false);
connection.setConnectTimeout(DEFAULT_TIMEOUT);
connection.setReadTimeout(READ_TIMEOUT);
connection.connect();
OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
writer.write(ServerConnection.this.body);
writer.flush();
writer.close();
// Get the response
is = connection.getInputStream();
ServerConnection.this.response = getStringFromInputStream(is);
ServerConnection.this.responseCode = connection.getResponseCode();
} catch(SocketTimeoutException ex) {
ex.printStackTrace();
Log.d(TAG,"SocketTimeoutException");
ServerConnection.this.response = null;
return;
}catch(MalformedURLException ex) {
ex.printStackTrace();
Log.e(TAG,"MalformedURLException");
} catch (IOException ex) {
ex.printStackTrace();
Log.e(TAG,"IOException");
} finally {
connection.disconnect();
Log.d(TAG,"Request sent.");
}
}
}).start();
}
public void sendDelete(){
new Thread(new Runnable() {
public void run() {
HttpURLConnection connection = null;
Log.d(TAG,"Sending HTTP DELETE Request...");
try{
URL serverUrl = new URL(ServerConnection.this.url);
connection = (HttpURLConnection) serverUrl.openConnection();
InputStream is;
connection.setDoOutput(true);
connection.setRequestMethod("DELETE");
connection.setRequestProperty("Accept", "application/xml");
connection.setRequestProperty("Host", ServerConnection.this.url);
connection.setConnectTimeout(DEFAULT_TIMEOUT);
connection.setReadTimeout(READ_TIMEOUT);
connection.connect();
Log.d(TAG,"Connected");
// Get the response
is = connection.getInputStream();
ServerConnection.this.response = getStringFromInputStream(is);
ServerConnection.this.responseCode = connection.getResponseCode();
} catch(SocketTimeoutException ex) {
ex.printStackTrace();
Log.d(TAG,"SocketTimeoutException");
ServerConnection.this.response = null;
return;
}catch(MalformedURLException ex) {
ex.printStackTrace();
Log.d(TAG,"MalformedURLException");
} catch (IOException ex) {
ex.printStackTrace();
Log.d(TAG,"IOException");
} finally {
connection.disconnect();
Log.d(TAG,"Request sent.");
}
}
});
}
public void sendGet(){
new Thread(new Runnable() {
public void run() {
HttpURLConnection connection = null;
Log.d(TAG,"Sending HTTP GET Request...");
try{
InputStream is;
URL serverUrl = new URL(ServerConnection.this.url);
connection = (HttpURLConnection) serverUrl.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("GET");
connection.setRequestProperty("Accept", "application/xml");
connection.setRequestProperty("Host", ServerConnection.this.url);
connection.setConnectTimeout(DEFAULT_TIMEOUT);
connection.setInstanceFollowRedirects(false);
connection.connect();
Log.d(TAG,"Connecting for GET request");
// Get the response
ServerConnection.this.responseCode = connection.getResponseCode();
is = connection.getInputStream();
ServerConnection.this.response = getStringFromInputStream(is);
Log.d(TAG,"page received: " + ServerConnection.this.response);
} catch(SocketTimeoutException ex) {
ex.printStackTrace();
Log.d(TAG,"SocketTimeoutException while sending GET request");
ServerConnection.this.response = null;
}catch(MalformedURLException ex) {
ex.printStackTrace();
Log.e(TAG,"MalformedURLException");
} catch (IOException ex) {
ex.printStackTrace();
Log.e(TAG,"IOException");
} finally {
connection.disconnect();
Log.d(TAG,"Request sent.");
}
}
}).start();
}
private static String getStringFromInputStream(InputStream is) {
Log.d(TAG,"Converting InputStream to response String...");
BufferedReader br = null;
StringBuilder sxb = new StringBuilder();
String line;
try {
br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
sxb.append(line);
}
} catch (IOException e) {
Log.e(TAG,"IOException");
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
Log.e(TAG,"IOException");
}
}
}
return sxb.toString();
}
public int getResponseCode(){
return this.responseCode;
}
public String getResponse(){
return this.response;
}
@Override
public String toString() {
return "CTSConnection [url=" + url + ", method=" + method + ", body="
+ body + ", response=" + response + ", responseCode="
+ responseCode + "]";
}
}
当我启动时ServerConnection cnx = new ServerConnection("http://www.google.fr/index.html","GET");，我得到以下日志：
08-30 14:42:43.072: D/ServerConnection(581): Sending HTTP GET Request...
08-30 14:42:43.203: D/ServerConnection(581): Connecting for GET request
08-30 14:42:43.252: W/System.err(581): java.io.FileNotFoundException: http://www.google.fr/index.html
08-30 14:42:43.252: W/System.err(581): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:521)
08-30 14:42:43.252: W/System.err(581): at com.example.myApp.ServerConnection$3.run(ServerConnection.java:205)
08-30 14:42:43.252: W/System.err(581): at java.lang.Thread.run(Thread.java:1019)
08-30 14:42:43.252: E/ServerConnection(581): IOException
08-30 14:42:43.252: D/ServerConnection(581): Request sent.
对于 POST 请求（具有有效正文），例如ServerConnection cnx = new SertverConnection(10.0.2.2:65005,"POST","xml_document_to_string")：
08-30 14:42:43.299: D/ServerConnection(581): Sending HTTP POST Request...
08-30 14:42:47.348: W/System.err(581): java.net.SocketTimeoutException: Connection timed out
08-30 14:42:47.365: W/System.err(581): java.net.SocketTimeoutException: Connection timed out
08-30 14:42:47.365: W/System.err(581): at org.apache.harmony.luni.platform.OSNetworkSystem.connect(Native Method)
08-30 14:42:47.365: W/System.err(581): at dalvik.system.BlockGuard$WrappedNetworkSystem.connect(BlockGuard.java:357)
08-30 14:42:47.365: W/System.err(581): at org.apache.harmony.luni.net.PlainSocketImpl.connect(PlainSocketImpl.java:204)
08-30 14:42:47.365: W/System.err(581): at org.apache.harmony.luni.net.PlainSocketImpl.connect(PlainSocketImpl.java:437)
08-30 14:42:47.365: W/System.err(581): at java.net.Socket.connect(Socket.java:983)
08-30 14:42:47.365: W/System.err(581): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection.<init>(HttpConnection.java:75)
08-30 14:42:47.365: W/System.err(581): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection.<init>(HttpConnection.java:48)
08-30 14:42:47.365: W/System.err(581): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnection$Address.connect(HttpConnection.java:322)
08-30 14:42:47.365: W/System.err(581): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpConnectionPool.get(HttpConnectionPool.java:89)
08-30 14:42:47.365: W/System.err(581): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.getHttpConnection(HttpURLConnectionImpl.java:285)
08-30 14:42:47.372: W/System.err(581): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.makeConnection(HttpURLConnectionImpl.java:267)
08-30 14:42:47.372: W/System.err(581): at org.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:205)
08-30 14:42:47.372: W/System.err(581): at com.example.myApp.ServerConnection$1.run(ServerConnection.java:102)
08-30 14:42:47.382: W/System.err(581): at java.lang.Thread.run(Thread.java:1019)
08-30 14:42:47.382: D/ServerConnection(581): SocketTimeoutException
08-30 14:42:47.382: D/ServerConnection(581): Request sent.
好吧，我真的不知道这个问题是从哪里来的……有什么提示吗？
提前致谢 ！