当在较低的api级别（例如15或19）（在模拟器和真实设备上）上尝试我的应用时，我得到特定URL的UnknownHostException：http://jotihunt-api_v2.mysite123.nl/login mysite123是虚构的。但我没有得到谷歌等其他网址的UnknownHostException。所以我似乎URL是错误的，但在API级别22，例如我没有得到这个例外。我有一个Internet连接，我有所需的权限：
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
我使用此代码执行对Web API的发布/获取请求：
@Override
protected List<WebResponse> doInBackground(WebRequest... params) {
ArrayList<WebResponse> responses = new ArrayList<>();
WebRequest current;
for(int i = 0; i < params.length; i++)
{
current = params[i];
try {
InetAddress address = InetAddress.getByName(current.getUrl().getHost());
Log.i("WebRequestTask", address.toString());
} catch (UnknownHostException exception) {
Log.e("WebRequestTask", exception.toString(), exception);
}
TRYCATCH:
try
{
if(current.getUrl() == null) break TRYCATCH;
HttpURLConnection connection = (HttpURLConnection)current.getUrl().openConnection();
switch (current.getMethod())
{
case WebRequestMethod.POST:
if(current.hasData())
{
connection.setDoOutput(true);
connection.setRequestMethod(WebRequestMethod.POST);
OutputStreamWriter streamWriter = new OutputStreamWriter(connection.getOutputStream());
streamWriter.write(current.getData());
streamWriter.flush();
streamWriter.close();
}
break;
}
InputStream response;
if(connection.getResponseCode() == 200)
{
/*
* Get the response stream.
* */
response = connection.getInputStream();
}
else
{
/*
* Get the error stream.
* */
response = connection.getErrorStream();
}
/**
* Read the stream.
* */
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(response));
StringBuilder builder = new StringBuilder();
String line;
while ((line = bufferedReader.readLine()) != null) {
builder.append(line);
}
bufferedReader.close();
/**
* Create a response
* */
responses.add(new WebResponse(current, builder.toString(), connection.getResponseCode()));
current.setExecutionDate(new Date());
connection.disconnect();
}
catch(Exception e)
{
/**
* Print the stack trace
* */
e.printStackTrace();
/**
* Log a error.
* */
Log.e("WebRequestTask", e.toString(), e);
/**
* Add a response with as text the error message
* */
responses.add(new WebResponse(current, e.toString(), 0));
}
}
return responses;
}
对象的状态：http://imgur.com/8ehGBUf
请求的创建和执行：
WebRequest request = new WebRequest.Builder()
.setId(MY_REQUEST_ID)
.setMethod(WebRequestMethod.POST)
.setUrl(new UrlBuilder().append("http://jotihunt-api_v2.mysite123.nl/login").build())
.setData("sfsf")
.create();
request.executeAsync(new WebRequest.OnWebRequestCompletedCallback() {
@Override
public void onWebRequestCompleted(WebResponse response) {
Log.i("",response.getData());
}
});
这是我得到的例外：
08-16 12:33:36.340 4277-4356/nl.rsdt.japp W/System.err: java.net.UnknownHostException: http://jotihunt-api_v2.mysite123.nl/login
08-16 12:33:36.342 4277-4356/nl.rsdt.japp W/System.err: at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:279)
08-16 12:33:36.344 4277-4356/nl.rsdt.japp W/System.err: at com.android.okhttp.internal.http.HttpEngine.sendSocketRequest(HttpEngine.java:255)
08-16 12:33:36.346 4277-4356/nl.rsdt.japp W/System.err: at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:206)
08-16 12:33:36.348 4277-4356/nl.rsdt.japp W/System.err: at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:345)
08-16 12:33:36.352 4277-4356/nl.rsdt.japp W/System.err: at com.android.okhttp.internal.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:89)
08-16 12:33:36.355 4277-4356/nl.rsdt.japp W/System.err: at com.android.okhttp.internal.http.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:197)
08-16 12:33:36.356 4277-4356/nl.rsdt.japp W/System.err: at com.rsdt.anl.WebRequestTask.doInBackground(WebRequestTask.java:53)
08-16 12:33:36.357 4277-4356/nl.rsdt.japp W/System.err: at com.rsdt.anl.WebRequestTask.doInBackground(WebRequestTask.java:21)
08-16 12:33:36.358 4277-4356/nl.rsdt.japp W/System.err: at android.os.AsyncTask$2.call(AsyncTask.java:288)
08-16 12:33:36.359 4277-4356/nl.rsdt.japp W/System.err: at java.util.concurrent.FutureTask.run(FutureTask.java:237)
08-16 12:33:36.360 4277-4356/nl.rsdt.japp W/System.err: at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
08-16 12:33:36.365 4277-4356/nl.rsdt.japp W/System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
08-16 12:33:36.372 4277-4356/nl.rsdt.japp W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
08-16 12:33:36.373 4277-4356/nl.rsdt.japp W/System.err: at java.lang.Thread.run(Thread.java:848)
更新 我可以使用InetAdress解析主机，但它仍无法正常工作
更新2 我在谷歌搜索后发现了类似的问题，似乎下划线不是有效的URL字符。
来源：
（我不能包含超过2个链接，所以我离开了链接的开头）
stackoverflow.com/questions/36074952/unknown-host-exception-using-emulator-and-httpurlconnection
code.google.com/p/android/issues/detail?id=37577
github.com/google/ExoPlayer/issues/239
答案 0 :(得分：1)
我更改了主机名，因此不包含下划线，这解决了我的问题。似乎旧版Android上的DNS不支持带下划线的URL
<强>来源：