Implemented hosts auto downloader

app/src/main/java/org/itxtech/daedalus/Daedalus.java

@@ -59,6 +59,8 @@ public class Daedalus extends Application {
             "wikipedia.org"
     };
 
+    public static String hostsPath;
+
     private static Daedalus instance = null;
     private static SharedPreferences prefs;
     private static Thread mHostsResolver;
@@ -71,6 +73,8 @@ public class Daedalus extends Application {
         mHostsResolver = new Thread(new HostsResolver());
         mHostsResolver.start();
 
+        hostsPath = getExternalFilesDir(null).getPath() + "/hosts";
+
         instance = this;
     }
 
@@ -97,7 +101,7 @@ public class Daedalus extends Application {
                     return;
                 }
             }
-            HostsResolver.startLoad(instance.getExternalFilesDir(null).getPath() + "/hosts");
+            HostsResolver.startLoad(hostsPath);
         }
     }
     public static SharedPreferences getPrefs() {

app/src/main/java/org/itxtech/daedalus/fragment/HostsFragment.java

@@ -2,15 +2,23 @@ package org.itxtech.daedalus.fragment;
 
 import android.app.Fragment;
 import android.os.Bundle;
+import android.os.Handler;
+import android.os.Message;
+import android.support.design.widget.Snackbar;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ArrayAdapter;
+import android.widget.Button;
 import android.widget.Spinner;
 import org.itxtech.daedalus.Daedalus;
 import org.itxtech.daedalus.R;
 import org.itxtech.daedalus.util.HostsProvider;
 
+import java.io.*;
+import java.net.URL;
+import java.net.URLConnection;
+
 /**
  * Daedalus Project
  *
@@ -22,14 +30,111 @@ import org.itxtech.daedalus.util.HostsProvider;
  * the Free Software Foundation, version 3.
  */
 public class HostsFragment extends Fragment {
+
+    private Thread mThread = null;
+    private View view = null;
+    private HostsHandler mHandler = null;
+
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
-        View view = inflater.inflate(R.layout.fragment_hosts, container, false);
+        view = inflater.inflate(R.layout.fragment_hosts, container, false);
 
-        Spinner spinnerHosts = (Spinner) view.findViewById(R.id.spinner_hosts);
+        mHandler = new HostsHandler().setView(view);
+
+        final Spinner spinnerHosts = (Spinner) view.findViewById(R.id.spinner_hosts);
         ArrayAdapter spinnerArrayAdapter = new ArrayAdapter<>(Daedalus.getInstance(), android.R.layout.simple_list_item_1, HostsProvider.getHostsProviderNames());
         spinnerHosts.setAdapter(spinnerArrayAdapter);
         spinnerHosts.setSelection(0);
+
+        Button buttonDownload = (Button) view.findViewById(R.id.button_download_hosts);
+        buttonDownload.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                if (mThread == null) {
+                    Snackbar.make(view, R.string.notice_start_download, Snackbar.LENGTH_LONG)
+                            .setAction("Action", null).show();
+                    mThread = new Thread(new Runnable() {
+                        @Override
+                        public void run() {
+                            try {
+                                URLConnection connection = new URL(HostsProvider.getDownloadUrlByName(spinnerHosts.getSelectedItem().toString())).openConnection();
+                                InputStream inputStream = connection.getInputStream();
+                                BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
+                                StringBuilder builder = new StringBuilder();
+                                String result;
+                                while ((result = reader.readLine()) != null) {
+                                    builder.append("\n").append(result);
+                                }
+                                reader.close();
+
+                                mHandler.obtainMessage(HostsHandler.MSG_DOWNLOADED, builder.toString()).sendToTarget();
+                                stopThread();
+                            } catch (Exception e) {
+                                e.printStackTrace();
+                            }
+                        }
+                    });
+                    mThread.start();
+                } else {
+                    Snackbar.make(view, R.string.notice_now_downloading, Snackbar.LENGTH_LONG)
+                            .setAction("Action", null).show();
+                }
+            }
+        });
         return view;
     }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+
+        stopThread();
+        mHandler.shutdown();
+        mHandler = null;
+        view = null;
+    }
+
+    private void stopThread() {
+        if (mThread != null) {
+            mThread.interrupt();
+            mThread = null;
+        }
+    }
+
+    private static class HostsHandler extends Handler {
+        static final int MSG_DOWNLOADED = 0;
+
+        private View view = null;
+
+        HostsHandler setView(View view) {
+            this.view = view;
+            return this;
+        }
+
+        void shutdown() {
+            view = null;
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            super.handleMessage(msg);
+
+            switch (msg.what) {
+                case MSG_DOWNLOADED:
+                    try {
+                        String result = (String) msg.obj;
+                        File file = new File(Daedalus.hostsPath);
+                        FileOutputStream stream = new FileOutputStream(file);
+                        stream.write(result.getBytes());
+                        stream.close();
+                    } catch (Exception e) {
+                        e.printStackTrace();
+                    }
+
+                    Snackbar.make(view, R.string.notice_downloaded, Snackbar.LENGTH_LONG)
+                            .setAction("Action", null).show();
+                    break;
+            }
+        }
+    }
 }

app/src/main/java/org/itxtech/daedalus/util/HostsProvider.java

@@ -39,4 +39,13 @@ public class HostsProvider {
         String[] stringServers = new String[Daedalus.HOSTS_PROVIDERS.size()];
         return servers.toArray(stringServers);
     }
+
+    public static String getDownloadUrlByName(String name) {
+        for (HostsProvider hostsProvider : Daedalus.HOSTS_PROVIDERS) {
+            if (hostsProvider.getName().equals(name)) {
+                return hostsProvider.getDownloadURL();
+            }
+        }
+        return null;
+    }
 }

app/src/main/res/values-zh/strings.xml

@@ -48,7 +48,10 @@
     <string name="settings_advanced_on">开启</string>
     <string name="settings_local_hosts_resolve">本地 hosts 解析</string>
     <string name="notice_need_restart">重新启用 Daedalus 以应用设置。</string>
-    <string name="notice_need_storage_perm">本应用需要访问外部储存以实现本地 hosts 解析。</string>
+    <string name="notice_need_storage_perm">Daedalus 需要访问外部储存以实现本地 hosts 解析。</string>
     <string name="action_hosts">Hosts</string>
     <string name="button_text_download_hosts">下载 hosts</string>
+    <string name="notice_start_download">正在下载 hosts，请稍等 ……</string>
+    <string name="notice_downloaded">已下载 hosts 。</string>
+    <string name="notice_now_downloading">Daedalus 当前正在下载hosts，请稍等。</string>
 </resources>

app/src/main/res/values/strings.xml

@@ -47,9 +47,11 @@
     <string name="settings_advanced_on">On</string>
     <string name="settings_local_hosts_resolve">Local hosts resolution</string>
     <string name="notice_need_restart">Re-activate Daedalus to make the settings take effect.</string>
-    <string name="notice_need_storage_perm">This application requires access to external storage for local host
+    <string name="notice_need_storage_perm">Daedalus requires access to external storage for local host resolution.
-        resolution.
     </string>
     <string name="action_hosts">Hosts</string>
     <string name="button_text_download_hosts">Download hosts</string>
+    <string name="notice_start_download">Downloading hosts, please wait …</string>
+    <string name="notice_downloaded">Hosts has been downloaded.</string>
+    <string name="notice_now_downloading">Daedalus is currently downloading hosts, please wait.</string>
 </resources>