在Android系统settings里添加设置选项

目的：在通话设置菜单下，添加一dect设置菜单，里面再添加一checkBOxPreference 
来使能硬件模块。 
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目前做的项目，需要在系统settings里面添加一选项来使能硬件模块，里面涉及到的preference知识，请网上了解，这里记录下方法。 


1,settings 应用一般在 目录：\packages\apps\Settings,我们先找到通话设置的布局位置，看看它在那个包路径下，进入\packages\apps\Settings\res\xml，打开settings.xml文件： 

     android:key="call_settings"
     settings:icon="@drawable/ic_settings_call"
     android:title="@string/call_settings_title">

         android:action="android.intent.action.MAIN"
         android:targetPackage="com.android.phone"
         android:targetClass="com.android.phone.CallFeaturesSetting" />

android:targetPackage="com.android.phone"  
android:targetClass="com.android.phone.CallFeaturesSetting"  
targetPackage：表示包名，根据此我们可以找到通话设置的路径。 
targetClass：表示此布局文件被那个类所引用，根据此类，我们可以知道在那个文件里面管理我们的通话设置功能。 
2.根据包名，我们可以看到在\packages\apps\Phone 目录下，进入\res\xml目录下 
找到通话布局文件：call_feature_setting.xml，根据类名，很容易找到布局文件。 
里面内容如下： 

 "button_misc_category_key"
         android:title="@string/other_settings"
         android:persistent="false" />





         android:key="dect_settings"
         android:title="@string/dect_module_title"
         android:summary="@string/dect_module_title" >

             android:action="android.intent.action.MAIN"
             android:targetPackage="com.android.phone"
             android:targetClass="com.android.phone.DectSettings" />



         android:key="button_auto_retry_key"
         android:title="@string/auto_retry_mode_title"
         android:persistent="false"
         android:summary="@string/auto_retry_mode_summary"/>

Dect setting 就是新添加进入的设置菜单，我们的原则尽量不大量修改源码，所以添加一个PreferenceScreen，新增一个类文件来管理DECt菜单选项。 

android:targetPackage="com.android.phone" 
android:targetClass="com.android.phone.DectSettings"  
我们指明了包名，类名后，因这是个activity，所以我们需要到Phone目录下修改 
AndroidManifest.xml文件，指明启动的activity的类名. 

       "CdmaCallOptions"
           android:label="@string/cdma_options">

               "android.intent.action.MAIN" />



       "DectSettings"
           android:label="@string/dect_module_title">

               "android.intent.action.MAIN" />

3.修改好后，我们必须在此activity里添加preference布局文件。 
  在此目录Phone\res\xml下，新增dect_settings.xml 

 "1.0" encoding="utf-8"?>
 "http://schemas.android.com/apk/res/android"
         android:title="@string/dect_module_title">


         android:key="button_dect_module_key"
         android:title="@string/dect_module_title"
         android:defaultValue="true"
         android:summaryOn="@string/dect_module_start"
         android:summaryOff="@string/dect_module_stop"
         />

好了，总体布局已经完成 
4.在\packages\apps\Phone\src\com\android\phone目录下 
新增DectSettings.java文件 

加载布局文件：       
//dect xml 
addPreferencesFromResource(R.xml.dect_settings);  
里面涉及到的MidPhoneServce服务，是自己添加的，主要通过此服务的AIDL接口跟硬件打交道。想了解系统服务，请网上查找资料。 

源码如下： 

 package com.android.phone;

 import android.content.DialogInterface;
 import android.os.AsyncResult;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.preference.CheckBoxPreference;
 import android.preference.Preference;
 import android.preference.PreferenceActivity;
 import android.preference.PreferenceScreen;
 import android.content.SharedPreferences;
 import android.content.SharedPreferences.Editor;
 import android.content.pm.ActivityInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
 import android.os.Bundle;
 import android.os.Handler;
 import android.util.Log;
 import android.content.Context;
 import com.android.phone.R;
 import android.os.IMidPhoneService;
 import android.os.RemoteException;
 import android.os.ServiceManager;
 import android.provider.Settings;

 public class DectSettings extends PreferenceActivity {
     private static final String TAG = "DectSettings";

     private static final String BUTTON_DECT_KEY  = "button_dect_module_key";

     private CheckBoxPreference mButtonDect;
     public IMidPhoneService midphoneservice = null;

     @Override
     protected void onCreate(Bundle icicle) {
         super.onCreate(icicle);

             //dect xml
         addPreferencesFromResource(R.xml.dect_settings);

         mButtonDect = (CheckBoxPreference)findPreference(BUTTON_DECT_KEY);
         mButtonDect.setPersistent(false);

         if(mButtonDect != null) {

             int dect_state = Settings.System.getInt(
                 getContentResolver(),Settings.System.DECT_SAVED_STATE, 1);
             mButtonDect.setChecked( dect_state!= 0);

             Settings.System.putInt(getContentResolver(),
                         Settings.System.DECT_SAVED_STATE,dect_state);
             Log.e(TAG,"settings:------------->" + dect_state);
         }
     }

     @Override
     public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen, Preference preference) {
         if (preference == mButtonDect ) {

             int dect = mButtonDect.isChecked() ? 1 : 0;
             boolean state;
             if(dect == 1)
                 state = true;
             else
                 state = false;
             try{
                     midphoneservice = IMidPhoneService.Stub.asInterface(ServiceManager.getService("midphone"));
                     Settings.System.putInt(getContentResolver(),
                         Settings.System.DECT_SAVED_STATE,dect);
                     midphoneservice.setDectEnabled(state);

                     Log.e(TAG,"settings:------------->" + dect);
                 } catch (RemoteException e) {
                     e.printStackTrace();
                 }
             return true;
         }
         return false;
     }

   @Override
     protected void onResume() {
         super.onResume();

         if (mButtonDect != null) {
             mButtonDect.setChecked(Settings.System.getInt(
                 getContentResolver(),
                 Settings.System.DECT_SAVED_STATE, 1) != 0);
         }
     }
 }

5.编译，烧录。