代码注释

app/src/main/java/net/micode/notes/data/Contact.java

@@ -25,10 +25,11 @@ import android.util.Log;
 
 import java.util.HashMap;
 
-public class Contact {
+public class Contact { //联系人
     private static HashMap<String, String> sContactCache;
     private static final String TAG = "Contact";
 
+    //定义字符串
     private static final String CALLER_ID_SELECTION = "PHONE_NUMBERS_EQUAL(" + Phone.NUMBER
     + ",?) AND " + Data.MIMETYPE + "='" + Phone.CONTENT_ITEM_TYPE + "'"
     + " AND " + Data.RAW_CONTACT_ID + " IN "
@@ -36,18 +37,20 @@ public class Contact {
             + " FROM phone_lookup"
             + " WHERE min_match = '+')";
 
+   //获取联系人
     public static String getContact(Context context, String phoneNumber) {
         if(sContactCache == null) {
             sContactCache = new HashMap<String, String>();
         }
 
+        //查找HashMap中是否已有phoneNumber信息
         if(sContactCache.containsKey(phoneNumber)) {
             return sContactCache.get(phoneNumber);
         }
 
         String selection = CALLER_ID_SELECTION.replace("+",
                 PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
-        Cursor cursor = context.getContentResolver().query(
+        Cursor cursor = context.getContentResolver().query( //再数据库中查找phoneNumber的信息
                 Data.CONTENT_URI,
                 new String [] { Phone.DISPLAY_NAME },
                 selection,
@@ -55,17 +58,17 @@ public class Contact {
                 null);
 
         if (cursor != null && cursor.moveToFirst()) {
-            try {
+            try {   //找到信息
                 String name = cursor.getString(0);
                 sContactCache.put(phoneNumber, name);
                 return name;
-            } catch (IndexOutOfBoundsException e) {
+            } catch (IndexOutOfBoundsException e) { //出错，后面的cursor.close()将不会执行
                 Log.e(TAG, " Cursor get string error " + e.toString());
                 return null;
             } finally {
-                cursor.close();
+                cursor.close();     //关闭cursor，释放资源
             }
-        } else {
+        } else {    //未找到信息
             Log.d(TAG, "No contact matched with number:" + phoneNumber);
             return null;
         }