Add UrlPreference, add help

app/src/main/java/com/hippo/preference/UrlPreference.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2016 Hippo Seven
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hippo.preference;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.preference.Preference;
+import android.util.AttributeSet;
+
+import com.hippo.ehviewer.R;
+import com.hippo.ehviewer.UrlOpener;
+
+public class UrlPreference extends Preference {
+
+    private String mUrl;
+
+    public UrlPreference(Context context) {
+        super(context);
+        init(context, null, 0, 0);
+    }
+
+    public UrlPreference(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        init(context, attrs, 0, 0);
+    }
+
+    public UrlPreference(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        init(context, attrs, defStyleAttr, 0);
+    }
+
+    private void init(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
+        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.UrlPreference, defStyleAttr, defStyleRes);
+        mUrl = a.getString(R.styleable.UrlPreference_url);
+        a.recycle();
+    }
+
+    @Override
+    public CharSequence getSummary() {
+        if (null != mUrl) {
+            return mUrl;
+        } else {
+            return super.getSummary();
+        }
+    }
+
+    @Override
+    protected void onClick() {
+        UrlOpener.openUrl(getContext(), mUrl, true, true);
+    }
+}