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package com.turbomanage.httpclient;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.CookieHandler;
import java.net.CookieManager;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Map;
import java.util.TreeMap;
/**
* Lightweight HTTP client that facilitates GET, POST, PUT, and DELETE requests
* using {@link HttpURLConnection}. Extend this class to support specialized
* content and response types (see {@link BasicHttpClient} for an example). To
* enable streaming, buffering, or other types of readers / writers, set an
* alternate {@link RequestHandler}.
*
* @author David M. Chandler
*/
public abstract class AbstractHttpClient {
public static final String URLENCODED = "application/x-www-form-urlencoded;charset=UTF-8";
public static final String MULTIPART = "multipart/form-data";
public static final String JSON = "application/json;charset=UTF-8";
protected String baseUrl = "";
protected RequestLogger requestLogger = new ConsoleRequestLogger();
protected final RequestHandler requestHandler;
private Map requestHeaders = new TreeMap();
/**
* Default 2s, deliberately short. If you need longer, you should be using
* {@link AsyncHttpClient} instead.
*/
protected int connectionTimeout = 2000;
/**
* Default 8s, reasonably short if accidentally called from the UI thread.
*/
protected int readTimeout = 8000;
/**
* Indicates connection status, used by timeout logic
*/
private boolean isConnected;
/**
* Constructs a client with empty baseUrl. Prevent sub-classes from calling
* this as it doesn't result in an instance of the subclass.
*/
@SuppressWarnings("unused")
private AbstractHttpClient() {
this("");
}
/**
* Constructs a new client with base URL that will be appended in the
* request methods. It may be empty or any part of a URL. Examples:
* http://turbomanage.com http://turbomanage.com:987
* http://turbomanage.com:987/resources
*
* @param baseUrl
*/
private AbstractHttpClient(String baseUrl) {
this(baseUrl, new BasicRequestHandler() {
});
}
/**
* Construct a client with baseUrl and RequestHandler.
*
* @param baseUrl
* @param requestHandler
*/
public AbstractHttpClient(String baseUrl, RequestHandler requestHandler) {
this.baseUrl = baseUrl;
this.requestHandler = requestHandler;
}
/**
* Execute a HEAD request and return the response. The supplied parameters
* are URL encoded and sent as the query string.
*
* @param path
* @param params
* @return Response object
*/
public HttpResponse head(String path, ParameterMap params) {
return execute(new HttpHead(path, params));
}
/**
* Execute a GET request and return the response. The supplied parameters
* are URL encoded and sent as the query string.
*
* @param path
* @param params
* @return Response object
*/
public HttpResponse get(String path, ParameterMap params) {
return execute(new HttpGet(path, params));
}
/**
* Execute a POST request with parameter map and return the response.
*
* @param path
* @param params
* @return Response object
*/
public HttpResponse post(String path, ParameterMap params) {
return execute(new HttpPost(path, params));
}
/**
* Execute a POST request with a chunk of data and return the response.
*
* To include name-value pairs in the query string, add them to the path
* argument or use the constructor in {@link HttpPost}. This is not a
* common use case, so it is not included here.
*
* @param path
* @param contentType
* @param data
* @return Response object
*/
public HttpResponse post(String path, String contentType, byte[] data) {
return execute(new HttpPost(path, null, contentType, data));
}
/**
* Execute a PUT request with the supplied content and return the response.
*
* To include name-value pairs in the query string, add them to the path
* argument or use the constructor in {@link HttpPut}. This is not a
* common use case, so it is not included here.
*
* @param path
* @param contentType
* @param data
* @return Response object
*/
public HttpResponse put(String path, String contentType, byte[] data) {
return execute(new HttpPut(path, null, contentType, data));
}
/**
* Execute a DELETE request and return the response. The supplied parameters
* are URL encoded and sent as the query string.
*
* @param path
* @param params
* @return Response object
*/
public HttpResponse delete(String path, ParameterMap params) {
return execute(new HttpDelete(path, params));
}
/**
* This method wraps the call to doHttpMethod and invokes the custom error
* handler in case of exception. It may be overridden by other clients such
* {@link AsyncHttpClient} in order to wrap the exception handling for
* purposes of retries, etc.
*
* @param httpRequest
* @return Response object (may be null if request did not complete)
*/
public HttpResponse execute(HttpRequest httpRequest) {
HttpResponse httpResponse = null;
try {
httpResponse = doHttpMethod(httpRequest.getPath(),
httpRequest.getHttpMethod(), httpRequest.getContentType(),
httpRequest.getContent());
} catch (HttpRequestException hre) {
requestHandler.onError(hre);
} catch (Exception e) {
// In case a RuntimeException has leaked out, wrap it in HRE
requestHandler.onError(new HttpRequestException(e, httpResponse));
}
return httpResponse;
}
/**
* This is the method that drives each request. It implements the request
* lifecycle defined as open, prepare, write, read. Each of these methods in
* turn delegates to the {@link RequestHandler} associated with this client.
*
* @param path Whole or partial URL string, will be appended to baseUrl
* @param httpMethod Request method
* @param contentType MIME type of the request
* @param content Request data
* @return Response object
* @throws HttpRequestException
*/
@SuppressWarnings("finally")
protected HttpResponse doHttpMethod(String path, HttpMethod httpMethod, String contentType,
byte[] content) throws HttpRequestException {
HttpURLConnection uc = null;
HttpResponse httpResponse = null;
try {
isConnected = false;
uc = openConnection(path);
prepareConnection(uc, httpMethod, contentType);
appendRequestHeaders(uc);
if (requestLogger.isLoggingEnabled()) {
requestLogger.logRequest(uc, content);
}
// Explicit connect not required, but lets us easily determine when
// possible timeout exception occurred
uc.connect();
isConnected = true;
if (uc.getDoOutput() && content != null) {
writeOutputStream(uc, content);
}
if (uc.getDoInput()) {
httpResponse = readInputStream(uc);
} else {
httpResponse = new HttpResponse(uc, null);
}
} catch (Exception e) {
// Try reading the error stream to populate status code such as 404
try {
httpResponse = readErrorStream(uc);
} catch (Exception ee) {
e.printStackTrace();
// Must catch IOException, but swallow to show first cause only
} finally {
// if status available, return it else throw
if (httpResponse != null && httpResponse.getStatus() > 0) {
return httpResponse;
}
throw new HttpRequestException(e, httpResponse);
}
} finally {
if (requestLogger.isLoggingEnabled()) {
requestLogger.logResponse(httpResponse);
}
if (uc != null) {
uc.disconnect();
}
}
return httpResponse;
}
/**
* Validates a URL and opens a connection. This does not actually connect
* to a server, but rather opens it on the client only to allow writing
* to begin. Delegates the open operation to the {@link RequestHandler}.
*
* @param path Appended to this client's baseUrl
* @return An open connection (or null)
* @throws IOException
*/
protected HttpURLConnection openConnection(String path) throws IOException {
String requestUrl = baseUrl + path;
try {
new URL(requestUrl);
} catch (MalformedURLException e) {
throw new IllegalArgumentException(requestUrl + " is not a valid URL", e);
}
return requestHandler.openConnection(requestUrl);
}
protected void prepareConnection(HttpURLConnection urlConnection, HttpMethod httpMethod,
String contentType) throws IOException {
urlConnection.setConnectTimeout(connectionTimeout);
urlConnection.setReadTimeout(readTimeout);
requestHandler.prepareConnection(urlConnection, httpMethod, contentType);
}
/**
* Append all headers added with {@link #addHeader(String, String)} to the
* request.
*
* @param urlConnection
*/
private void appendRequestHeaders(HttpURLConnection urlConnection) {
for (String name : requestHeaders.keySet()) {
String value = requestHeaders.get(name);
urlConnection.setRequestProperty(name, value);
}
}
/**
* Writes the request to the server. Delegates I/O to the {@link RequestHandler}.
*
* @param urlConnection
* @param content to be written
* @return HTTP status code
* @throws Exception in order to force calling code to deal with possible
* NPEs also
*/
protected int writeOutputStream(HttpURLConnection urlConnection, byte[] content) throws Exception {
OutputStream out = null;
try {
out = requestHandler.openOutput(urlConnection);
if (out != null) {
requestHandler.writeStream(out, content);
}
return urlConnection.getResponseCode();
} finally {
// catch not necessary since method throws Exception
if (out != null) {
try {
out.close();
} catch (Exception e) {
// Swallow to show first cause only
}
}
}
}
/**
* Reads the input stream. Delegates I/O to the {@link RequestHandler}.
*
* @param urlConnection
* @return HttpResponse, may be null
* @throws Exception
*/
protected HttpResponse readInputStream(HttpURLConnection urlConnection) throws Exception {
InputStream in = null;
byte[] responseBody = null;
try {
in = requestHandler.openInput(urlConnection);
if (in != null) {
responseBody = requestHandler.readStream(in);
}
return new HttpResponse(urlConnection, responseBody);
} finally {
if (in != null) {
try {
in.close();
} catch (Exception e) {
// Swallow to avoid dups
}
}
}
}
/**
* Reads the error stream to get an HTTP status code like 404.
* Delegates I/O to the {@link RequestHandler}.
*
* @param urlConnection
* @return HttpResponse, may be null
* @throws Exception
*/
protected HttpResponse readErrorStream(HttpURLConnection urlConnection) throws Exception {
InputStream err = null;
byte[] responseBody = null;
try {
err = urlConnection.getErrorStream();
if (err != null) {
responseBody = requestHandler.readStream(err);
}
return new HttpResponse(urlConnection, responseBody);
} finally {
if (err != null) {
try {
err.close();
} catch (Exception e) {
// Swallow to avoid dups
}
}
}
}
/**
* Convenience method creates a new ParameterMap to hold query params
*
* @return Parameter map
*/
public ParameterMap newParams() {
return new ParameterMap();
}
/**
* Adds to the headers that will be sent with each request from this client
* instance. The request headers added with this method are applied by
* calling {@link HttpURLConnection#setRequestProperty(String, String)}
* after {@link #prepareConnection(HttpURLConnection, HttpMethod, String)},
* so they may supplement or replace headers which have already been set.
* Calls to {@link #addHeader(String, String)} may be chained. To clear all
* headers added with this method, call {@link #clearHeaders()}.
*
* @param name
* @param value
* @return this client for method chaining
*/
public AbstractHttpClient addHeader(String name, String value) {
requestHeaders.put(name, value);
return this;
}
/**
* Clears all request headers that have been added using
* {@link #addHeader(String, String)}. This method has no effect on headers
* which result from request properties set by this class or its associated
* {@link RequestHandler} when preparing the {@link HttpURLConnection}.
*/
public void clearHeaders() {
requestHeaders.clear();
}
/**
* Returns the {@link CookieManager} associated with this client.
*
* @return CookieManager
*/
public static CookieManager getCookieManager() {
return (CookieManager) CookieHandler.getDefault();
}
/**
* Sets the logger to be used for each request.
*
* @param logger
*/
public void setRequestLogger(RequestLogger logger) {
this.requestLogger = logger;
}
/**
* Initialize the app-wide {@link CookieManager}. This is all that's
* necessary to enable all Web requests within the app to automatically send
* and receive cookies.
*/
public static void ensureCookieManager() {
if (CookieHandler.getDefault() == null) {
CookieHandler.setDefault(new CookieManager());
}
}
/**
* Determines whether an exception was due to a timeout. If the elapsed time
* is longer than the current timeout, the exception is assumed to be the
* result of the timeout.
*
* @param t Any Throwable
* @return true if caused by connection or read timeout
*/
protected boolean isTimeoutException(Throwable t, long startTime) {
long elapsedTime = System.currentTimeMillis() - startTime + 10; // fudge
if (requestLogger.isLoggingEnabled()) {
requestLogger.log("ELAPSED TIME = " + elapsedTime + ", CT = " + connectionTimeout
+ ", RT = " + readTimeout);
}
if (isConnected) {
return elapsedTime >= readTimeout;
} else {
return elapsedTime >= connectionTimeout;
}
}
/**
* Sets the connection timeout in ms. This is the amount of time that
* {@link HttpURLConnection} will wait to successfully connect to the remote
* server. The read timeout begins once connection has been established.
*
* @param connectionTimeout
*/
public void setConnectionTimeout(int connectionTimeout) {
this.connectionTimeout = connectionTimeout;
}
/**
* Sets the read timeout in ms, which begins after connection has been made.
* For large amounts of data expected, bump this up to make sure you allow
* adequate time to receive it.
*
* @param readTimeout
*/
public void setReadTimeout(int readTimeout) {
this.readTimeout = readTimeout;
}
}
