Android 4.4 Settings 应用分析

http://www.tuicool.com/articles/aQ7RRnR

一次偶然要在设置里面增加一个菜单,需要修改到settings_headers.xml 文件(res/layout/xml) 文件,所以就觉得要看一下这个流程.就做一下笔记,语言组织能力不行啊.

分析Android 源码的时候导入单个应用的时候一般是会有很多错误的,因为需要导入系统编译之后生成的jar包才能消除eclipse 里面的哪些红色xx.

1.Settings的UI

2.流程分析

从AndroidManifest.xml 中查看

<category android:name="android.intent.category.LAUNCHER" /> 知道Settings.java 是这个应用入口activity.

Settings 继承了PreferenceActivity .他的布局文件是settings_headers.xml

这个文件里面都是这些header,效果可以参考上面的效果图1和图2.

<!-- WIRELESS and NETWORKS  分类-->
  <header android:id="@+id/wireless_section"
  android:title="@string/header_category_wireless_networks" />

  <!-- Sim management 普通项-->
  <header   android:id="@+id/sim_settings"
  android:icon="@drawable/ic_settings_dualsim"
  android:fragment="com.mediatek.gemini.SimManagement"
  android:title="@string/gemini_sim_management_title" />

com.android.settings.Settings.java 这个activity 是通过回调onBuildHeaders方法来加载进入应用之后的第一个布局文件的,然后调用 loadHeadersFromResource(R.xml.settings_headers, headers);

来解析 文件.

onBuildHeaders 和loadHeadersFromResource 方法都是父类PreferenceActivity 的方法.

Settings.java 重写onBuildHeaders 方法的实现的源码如下:

/**
  * Populate the activity with the top-level headers.
  */
  @Override
  public void onBuildHeaders(List<Header> headers) {
    if (!onIsHidingHeaders()) {
      PDebug.Start("loadHeadersFromResource");
      loadHeadersFromResource(R.xml.settings_headers, headers);
      PDebug.End("loadHeadersFromResource");
      updateHeaderList(headers);
    }
  }

loadHeadersFromResource 方法就是解析settings_headers.xml 文件并保持相关的数据到List<Header> headers 里面.

Header 定义很多变量来和settings_headers.xml 里面节点一一对应,

public long id = HEADER_ID_UNDEFINED;

public int titleRes;

public CharSequence title;

public String fragment;

public Bundle fragmentArguments;

public Intent intent;

public Bundle extras;

………

通过跟踪Setting.java 的父类(PreferenceActivity)的继承关系知道他其实也是一个ListActivity.java ,全部的设置项也是使用ListView来显示的.

HeaderAdapter这个适配类是Setting.java 的内部类,它会判断之后来加载对应的view和数据来显示UI.

HeaderAdapter已经定义了4中类型的View 类型

static final int HEADER_TYPE_CATEGORY = 0;//用来分类的
static final int HEADER_TYPE_NORMAL = 1;//常规项
static final int HEADER_TYPE_SWITCH = 2;//开关项
static final int HEADER_TYPE_BUTTON = 3;//按钮项

前3种应该都见过,为了让大家看到第4项,我把稍微修改了一下我的HeaderAdapter源码(见getview方法的中的有//add的部分),也就是上面图2中的security 选项.

HeaderAdapter 的getHeaderType 方法决定了配置在settings_headers.xml 里面的header的类型.

HeaderAdapter 的getView 方法根据header的类型 来加载对应的布局文件.

static int getHeaderType(Header header) {
      if (header.fragment == null && header.intent == null) {
        return HEADER_TYPE_CATEGORY;
      } else if (header.id == R.id.wifi_settings || header.id == R.id.bluetooth_settings
           || header.id == R.id.hotknot_settings) {
        return HEADER_TYPE_SWITCH;
      } else if (header.id == R.id.security_settings) {
        return HEADER_TYPE_BUTTON;
      } else {
        return HEADER_TYPE_NORMAL;
      }
    }

但要注意的是在getView方法里面,当发现一个header 的类型是button的时候也会给header 的button增加一个onclick事件的,这个事件和header本事的onHeaderClick 是没有冲突的,因为2者不受同一个控件.

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
      HeaderViewHolder holder;
      Header header = getItem(position);
      int headerType = getHeaderType(header);
      Log.d("zhangle","getHeaderType" + header.title  + " headerType=" + headerType);
      View view = null;

      if (convertView == null) {
        holder = new HeaderViewHolder();
        switch (headerType) {
          case HEADER_TYPE_CATEGORY:
            view = new TextView(getContext(), null,
                android.R.attr.listSeparatorTextViewStyle);
            holder.title = (TextView) view;
            break;

          case HEADER_TYPE_SWITCH:
            view = mInflater.inflate(R.layout.preference_header_switch_item, parent,
                false);
            holder.icon = (ImageView) view.findViewById(R.id.icon);
            holder.title = (TextView)
                view.findViewById(com.android.internal.R.id.title);
            holder.summary = (TextView)
                view.findViewById(com.android.internal.R.id.summary);
            holder.switch_ = (Switch) view.findViewById(R.id.switchWidget);
            break;

          case HEADER_TYPE_BUTTON:
            view = mInflater.inflate(R.layout.preference_header_button_item, parent,
                false);
            holder.icon = (ImageView) view.findViewById(R.id.icon);
            holder.title = (TextView)
                view.findViewById(com.android.internal.R.id.title);
            holder.summary = (TextView)
                view.findViewById(com.android.internal.R.id.summary);
            holder.button_ = (ImageButton) view.findViewById(R.id.buttonWidget);
            holder.divider_ = view.findViewById(R.id.divider);
            break;

          case HEADER_TYPE_NORMAL:
            view = mInflater.inflate(
                R.layout.preference_header_item, parent,
                false);
            holder.icon = (ImageView) view.findViewById(R.id.icon);
            holder.title = (TextView)
                view.findViewById(com.android.internal.R.id.title);
            holder.summary = (TextView)
                view.findViewById(com.android.internal.R.id.summary);
            break;
        }
        view.setTag(holder);
      } else {
        view = convertView;
        holder = (HeaderViewHolder) view.getTag();
      }

      // All view fields must be updated every time, because the view may be recycled
      switch (headerType) {
        case HEADER_TYPE_CATEGORY:
          holder.title.setText(header.getTitle(getContext().getResources()));
          break;

        case HEADER_TYPE_SWITCH:
          // Would need a different treatment if the main menu had more switches
          if (header.id == R.id.wifi_settings) {
            mWifiEnabler.setSwitch(holder.switch_);
          } else if (header.id == R.id.bluetooth_settings){
            mBluetoothEnabler.setSwitch(holder.switch_);
          } else if (header.id == R.id.hotknot_settings){
            mHotKnotEnabler.setSwitch(holder.switch_);
          }
          updateCommonHeaderView(header, holder);
          break;

        case HEADER_TYPE_BUTTON:
          if (header.id == R.id.security_settings) {
            boolean hasCert = DevicePolicyManager.hasAnyCaCertsInstalled();
            hasCert = true;//add
            if (hasCert) {
              holder.button_.setVisibility(View.VISIBLE);
              holder.divider_.setVisibility(View.VISIBLE);
              boolean isManaged = mDevicePolicyManager.getDeviceOwner() != null;
              isManaged = true; //add
              if (isManaged) {
                holder.button_.setImageResource(R.drawable.ic_settings_about);
              } else {
                holder.button_.setImageResource(
                    android.R.drawable.stat_notify_error);
              }
              holder.button_.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                  Intent intent = new Intent(
                      android.provider.Settings.ACTION_MONITORING_CERT_INFO);
                  getContext().startActivity(intent);
                }
              });
            } else {
              holder.button_.setVisibility(View.GONE);
              holder.divider_.setVisibility(View.GONE);
            }
          }
          updateCommonHeaderView(header, holder);
          break;

        case HEADER_TYPE_NORMAL:
          updateCommonHeaderView(header, holder);
          break;
      }
      // /M: add for sim management feature
      if (header.id == R.id.sim_settings) {
        /// M: Customize SIM string
        holder.title.setText(mExt.customizeSimDisplayString(
          getContext().getString(R.string.gemini_sim_management_title), SLOT_ALL));
        handleDisableHolder(holder, view);
      } else {
        handleEnableHolder(holder, view);
      }
      return view;
    }

那么每一个header 是如果响应点击操作的呢.这个就要看Setting.java的onHeaderClick 方法了, onHeaderClick 方法会调用父类的onHeaderClick方法来打开相关的应用,其父类是根据我们配置在settings_headers.xml里面的fragment和intent 来打开相对应的activity的.

Setting.java -- onHeaderClick

public void onHeaderClick(Header header, int position) {
  boolean revert = false;
  if (header.id == R.id.account_add) {
      revert = true;
  }

  super.onHeaderClick(header, position);

  if (revert && mLastHeader != null) {
      highlightHeader((int) mLastHeader.id);
  } else {
      mLastHeader = header;
  }
    }

PreferenceActivity -- onHeaderClick

public void onHeaderClick(Header header, int position) {
    if (header.fragment != null) {
      if (mSinglePane) {
        Log.d(TAG, "onHeaderClick, single pane and startWithFragment.");
        int titleRes = header.breadCrumbTitleRes;
        int shortTitleRes = header.breadCrumbShortTitleRes;
        if (titleRes == 0) {
          titleRes = header.titleRes;
          shortTitleRes = 0;
        }
        startWithFragment(header.fragment, header.fragmentArguments, null, 0,
            titleRes, shortTitleRes);
      } else {
        Log.d(TAG, "onHeaderClick, multiple pane and switchToHeader.");
        switchToHeader(header);
      }
    } else if (header.intent != null) {
      Log.d(TAG, "onHeaderClick, start activity with header intent.");
      startActivity(header.intent);
    }
  }