Android 4.4 Settings 应用初步分析

 

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);
        }
    }