1 files changed, 72 insertions, 0 deletions
diff --git a/src/mining/AbstractRequester.java b/src/mining/AbstractRequester.java
new file mode 100644
index 0000000..a42eb80
--- /dev/null
+++ b/src/mining/AbstractRequester.java
@@ -0,0 +1,72 @@
+package mining;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLConnection;
+import org.apache.commons.io.Charsets;
+import org.apache.commons.io.IOUtils;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+/**
+ * Performs an API Request.
+ *
+ * @author Peter Wu
+ */
+public abstract class AbstractRequester implements Requester {
+
+    @Override
+    public JSONObject getJSON(String resource) throws IOException {
+        HttpURLConnection conn = open(buildUrl(resource));
+        preconnect(conn);
+        if (conn.getResponseCode() != 200) {
+            // TODO: print more helpful details
+            throw new IOException("Unexpected response code");
+        }
+        return getResponseAsJson(conn);
+    }
+
+    protected final URL buildUrl(String resource) throws IOException {
+        String spec = "https://api.twitter.com/1.1/";
+        // TODO: detect API version? For example, drop 1.1 for oauth2/token
+        spec += resource;
+        return new URL(spec);
+    }
+
+    /**
+     * Opens a connection to the URL.
+     */
+    protected final HttpURLConnection open(URL url) throws IOException {
+        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
+        // set default param: fail if no response within 5 seconds
+        conn.setReadTimeout(5000);
+        return conn;
+    }
+
+    /**
+     * Reads the response body from a connection (in JSON format).
+     */
+    protected final JSONObject getResponseAsJson(URLConnection conn)
+            throws IOException {
+        StringWriter writer = new StringWriter();
+        IOUtils.copy(conn.getInputStream(), writer, Charsets.UTF_8);
+        try {
+            return new JSONObject(writer.toString());
+        } catch (JSONException ex) {
+            // treat JSON errors as if an I/O error occurred
+            throw new IOException(ex);
+        }
+    }
+
+    /**
+     * Prepare the request before it gets send.
+     *
+     * @param conn A connection for the request.
+     * @throws java.io.IOException on failing to prepare the request.
+     */
+    protected abstract void preconnect(URLConnection conn)
+            throws IOException;
+}