Answers:
这是一个非常古老的答案。我绝对不会再推荐Apache的客户端。而是使用以下任一方法：
首先，请求访问网络的权限，在清单中添加以下内容：
<uses-permission android:name="android.permission.INTERNET" />然后，最简单的方法是使用与Android捆绑在一起的Apache http客户端：
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response = httpclient.execute(new HttpGet(URL));
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpStatus.SC_OK){
ByteArrayOutputStream out = new ByteArrayOutputStream();
response.getEntity().writeTo(out);
String responseString = out.toString();
out.close();
//..more logic
} else{
//Closes the connection.
response.getEntity().getContent().close();
throw new IOException(statusLine.getReasonPhrase());
}如果希望它在单独的线程上运行，建议您扩展AsyncTask：
class RequestTask extends AsyncTask<String, String, String>{
@Override
protected String doInBackground(String... uri) {
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response;
String responseString = null;
try {
response = httpclient.execute(new HttpGet(uri[0]));
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpStatus.SC_OK){
ByteArrayOutputStream out = new ByteArrayOutputStream();
response.getEntity().writeTo(out);
responseString = out.toString();
out.close();
} else{
//Closes the connection.
response.getEntity().getContent().close();
throw new IOException(statusLine.getReasonPhrase());
}
} catch (ClientProtocolException e) {
//TODO Handle problems..
} catch (IOException e) {
//TODO Handle problems..
}
return responseString;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
//Do anything with response..
}
}然后，您可以通过以下方式提出请求：
new RequestTask().execute("http://stackoverflow.com");除非您有明确的理由选择Apache HttpClient，否则应首选java.net.URLConnection。您可以在网络上找到许多有关如何使用它的示例。
自您的原始文章以来，我们还改进了Android文档：http : //developer.android.com/reference/java/net/HttpURLConnection.html
我们已经在官方博客上讨论了权衡问题：http：//android-developers.blogspot.com/2011/09/androids-http-clients.html
注意：现在不建议使用与Android捆绑在一起的Apache HTTP Client，而推荐使用HttpURLConnection。请参阅Android开发者博客以了解更多详细信息。
添加<uses-permission android:name="android.permission.INTERNET" />到您的清单。
然后，您将像这样检索一个网页：
URL url = new URL("http://www.android.com/");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
InputStream in = new BufferedInputStream(urlConnection.getInputStream());
readStream(in);
}
finally {
urlConnection.disconnect();
}我还建议在单独的线程上运行它：
class RequestTask extends AsyncTask<String, String, String>{
@Override
protected String doInBackground(String... uri) {
String responseString = null;
try {
URL url = new URL(myurl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
if(conn.getResponseCode() == HttpsURLConnection.HTTP_OK){
// Do normal input or output stream reading
}
else {
response = "FAILED"; // See documentation for more info on response handling
}
} catch (ClientProtocolException e) {
//TODO Handle problems..
} catch (IOException e) {
//TODO Handle problems..
}
return responseString;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
//Do anything with response..
}
}请参阅文档以获取有关响应处理和POST请求的更多信息。
readStream甚至没有定义。
最简单的方法是使用名为Volley的Android库
排球有以下好处：
自动安排网络请求。多个并发网络连接。具有标准HTTP缓存一致性的透明磁盘和内存响应缓存。支持请求优先级。取消请求API。您可以取消单个请求，也可以将请求的阻止或范围设置为取消。易于定制，例如重试和退避。强大的排序功能使您可以轻松地使用从网络异步获取的数据正确填充UI。调试和跟踪工具。
您可以发送一个简单的http / https请求：
// Instantiate the RequestQueue.
RequestQueue queue = Volley.newRequestQueue(this);
String url ="http://www.yourapi.com";
JsonObjectRequest request = new JsonObjectRequest(url, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
if (null != response) {
try {
//handle your response
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
queue.add(request);在这种情况下，您不必自己考虑“在后台运行”或“使用缓存”，因为所有这些已经由Volley完成。
private String getToServer(String service) throws IOException {
HttpGet httpget = new HttpGet(service);
ResponseHandler<String> responseHandler = new BasicResponseHandler();
return new DefaultHttpClient().execute(httpget, responseHandler);
}问候
带螺纹：
private class LoadingThread extends Thread {
Handler handler;
LoadingThread(Handler h) {
handler = h;
}
@Override
public void run() {
Message m = handler.obtainMessage();
try {
BufferedReader in =
new BufferedReader(new InputStreamReader(url.openStream()));
String page = "";
String inLine;
while ((inLine = in.readLine()) != null) {
page += inLine;
}
in.close();
Bundle b = new Bundle();
b.putString("result", page);
m.setData(b);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
handler.sendMessage(m);
}
}我使用Gson lib使Web服务能够在URL上重新查询：
客户：
public EstabelecimentoList getListaEstabelecimentoPorPromocao(){
EstabelecimentoList estabelecimentoList = new EstabelecimentoList();
try{
URL url = new URL("http://" + Conexao.getSERVIDOR()+ "/cardapio.online/rest/recursos/busca_estabelecimento_promocao_android");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
if (con.getResponseCode() != 200) {
throw new RuntimeException("HTTP error code : "+ con.getResponseCode());
}
BufferedReader br = new BufferedReader(new InputStreamReader((con.getInputStream())));
estabelecimentoList = new Gson().fromJson(br, EstabelecimentoList.class);
con.disconnect();
} catch (IOException e) {
e.printStackTrace();
}
return estabelecimentoList;
}看看这个很棒的新库，可以通过gradle获取它：)
build.gradle： compile 'com.apptakk.http_request:http-request:0.1.2'
用法：
new HttpRequestTask(
new HttpRequest("http://httpbin.org/post", HttpRequest.POST, "{ \"some\": \"data\" }"),
new HttpRequest.Handler() {
@Override
public void response(HttpResponse response) {
if (response.code == 200) {
Log.d(this.getClass().toString(), "Request successful!");
} else {
Log.e(this.getClass().toString(), "Request unsuccessful: " + response);
}
}
}).execute();按照上面的建议使用Volley。将以下内容添加到build.gradle中（模块：app）
implementation 'com.android.volley:volley:1.1.1'将以下内容添加到AndroidManifest.xml中：
<uses-permission android:name="android.permission.INTERNET" />并向您添加以下活动代码：
public void httpCall(String url) {
RequestQueue queue = Volley.newRequestQueue(this);
StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
// enjoy your response
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
// enjoy your error status
}
});
queue.add(stringRequest);
}它取代了HTTP客户程序，非常简单。
这是android中HTTP Get / POST请求的新代码。HTTPClient被贬低，可能无法使用，因为在我的情况下
首先在build.gradle中添加两个依赖项：
compile 'org.apache.httpcomponents:httpcore:4.4.1'
compile 'org.apache.httpcomponents:httpclient:4.5'然后在ASyncTaskin doBackground方法中编写此代码。
URL url = new URL("http://localhost:8080/web/get?key=value");
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
urlConnection.setRequestMethod("GET");
int statusCode = urlConnection.getResponseCode();
if (statusCode == 200) {
InputStream it = new BufferedInputStream(urlConnection.getInputStream());
InputStreamReader read = new InputStreamReader(it);
BufferedReader buff = new BufferedReader(read);
StringBuilder dta = new StringBuilder();
String chunks ;
while((chunks = buff.readLine()) != null)
{
dta.append(chunks);
}
}
else
{
//Handle else
}对我来说，最简单的方法是使用名为Retrofit2的库
我们只需要创建一个包含我们的请求方法，参数的接口，还可以为每个请求创建自定义标头：
public interface MyService {
@GET("users/{user}/repos")
Call<List<Repo>> listRepos(@Path("user") String user);
@GET("user")
Call<UserDetails> getUserDetails(@Header("Authorization") String credentials);
@POST("users/new")
Call<User> createUser(@Body User user);
@FormUrlEncoded
@POST("user/edit")
Call<User> updateUser(@Field("first_name") String first,
@Field("last_name") String last);
@Multipart
@PUT("user/photo")
Call<User> updateUser(@Part("photo") RequestBody photo,
@Part("description") RequestBody description);
@Headers({
"Accept: application/vnd.github.v3.full+json",
"User-Agent: Retrofit-Sample-App"
})
@GET("users/{username}")
Call<User> getUser(@Path("username") String username);
}最好的是，我们可以使用enqueue方法轻松地异步完成此操作
由于没有一个答案描述了使用OkHttp执行请求的方法，OkHttp是当今在Android和Java上非常流行的HTTP客户端，因此，我将提供一个简单的示例：
//get an instance of the client
OkHttpClient client = new OkHttpClient();
//add parameters
HttpUrl.Builder urlBuilder = HttpUrl.parse("https://www.example.com").newBuilder();
urlBuilder.addQueryParameter("query", "stack-overflow");
String url = urlBuilder.build().toString();
//build the request
Request request = new Request.Builder().url(url).build();
//execute
Response response = client.newCall(request).execute();该库的明显优势在于，它使我们从一些底层细节中抽象出来，从而提供了更友好，更安全的方式与它们进行交互。语法也得到了简化，并允许编写漂亮的代码。