解决：Android4.3锁屏界面Emergency calls only - China Unicom与EMERGENCY CALL语义重复

        从图片中我们可以看到，这里在语义上有一定的重复，当然这是谷歌的原始设计。这个问题在博客上进行共享从表面上来看着实没有什么太大的意义，不过由于Android4.3在锁屏功能上比起老版本做了很大的改动，而且通过常规方法（Strings.xml中字符串）对该问题的定位会有很大的难度，拿这个界面来说，EMERGENCY CALL并不是Strings中值，而是  <string name="lockscreen_emergency_call">Emergency call</string>，只是在显示的时候进行了大小写的转换。而且例如字符”-“在String.xml中是unicode编码表示的。例如：    <string name="kg_text_message_separator" product="default">" \u2014 "</string>。接下来我们对当前锁屏界面相关代码的定位进行一个简单的了解：

        在Android4.3当中当前的锁屏界面不是一个Activity而是一个View，该View位于/frameworks/base/policy/src/com/android/internal/policy/impl/keyguard目录下的KeyguardPatternView.java，其所对应的布局文件为keyguard_pattern_view.xml.

<?xml version="1.0" encoding="utf-8"?>
<!--
**
** Copyright 2012, The Android Open Source Project
**
** 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.
*/
-->

<!-- This is the screen that shows the 9 circle unlock widget and instructs
     the user how to unlock their device, or make an emergency call.  This
     is the portrait layout.  -->
<com.android.internal.policy.impl.keyguard.KeyguardPatternView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/keyguard_pattern_view"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_maxWidth="@dimen/keyguard_security_width"
    android:layout_maxHeight="@dimen/keyguard_security_height"
    android:gravity="center_horizontal"
    android:contentDescription="@string/keyguard_accessibility_pattern_unlock">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:orientation="vertical"
            android:layout_gravity="center">

            <include layout="@layout/keyguard_message_area"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
               />

          <FrameLayout
             android:id="@+id/keyguard_bouncer_frame"
             android:background="@*android:drawable/kg_bouncer_bg_white"
             android:layout_width="match_parent"
             android:layout_height="0dp"
             android:layout_weight="1"
             >
            <com.android.internal.widget.LockPatternView
                android:id="@+id/lockPatternView"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_weight="1"
                android:layout_marginEnd="8dip"
                android:layout_marginBottom="4dip"
                android:layout_marginStart="8dip"
                android:layout_gravity="center_horizontal"
                android:gravity="center"
                android:contentDescription="@string/keyguard_accessibility_pattern_area" />
          </FrameLayout>
          <include layout="@layout/keyguard_eca"
              android:id="@+id/keyguard_selector_fade_container"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:orientation="vertical"
              android:layout_gravity="bottom|center_horizontal"
              android:gravity="center_horizontal" />
        </LinearLayout>
    </FrameLayout>

</com.android.internal.policy.impl.keyguard.KeyguardPatternView>

而keyguard_eca即使我们需要修改的锁屏界面下的紧急拨号按钮所对应的布局Alias.xml中的keyguard_emergency_carrier_area.xml布局。

Alias.xml：

<resources>
    <!-- Alias used to reference one of two possible layouts in keyguard.  -->
    <item type="layout" name="keyguard_eca">@android:layout/keyguard_emergency_carrier_area</item>
</resources>
keyguard_emergency_carrier_area.xml
<?xml version="1.0" encoding="utf-8"?>
<!--
**
** Copyright 2012, The Android Open Source Project
** Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
** Not a Contribution.
**
** 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.
*/
-->

<!-- This contains emergency call button and carrier as shared by pin/pattern/password screens -->
<com.android.internal.policy.impl.keyguard.EmergencyCarrierArea
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:gravity="center"
    android:layout_gravity="center_horizontal"
    android:layout_alignParentBottom="true"
    android:clickable="true">

    <!-- Used only for Multi Sim case -->
    <ViewStub android:id="@+id/stub_msim_carrier_text"
        android:inflatedId="@+id/msim_keyguard_carrier_area"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout="@layout/msim_keyguard_carrier_area" />

    <com.android.internal.policy.impl.keyguard.CarrierText
        android:id="@+id/carrier_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:singleLine="true"
        android:ellipsize="marquee"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textSize="@dimen/kg_status_line_font_size"
        android:textColor="?android:attr/textColorSecondary"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="-10dip"
        style="?android:attr/buttonBarStyle"
        android:orientation="horizontal"
        android:gravity="center"
        android:weightSum="2">

        <com.android.internal.policy.impl.keyguard.EmergencyButton
            android:id="@+id/emergency_call_button"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:drawableLeft="@*android:drawable/lockscreen_emergency_button"
            android:text="@string/kg_emergency_call_label"
            style="?android:attr/buttonBarButtonStyle"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textSize="@dimen/kg_status_line_font_size"
            android:textColor="?android:attr/textColorSecondary"
            android:drawablePadding="8dip" />

        <Button android:id="@+id/forgot_password_button"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:drawableLeft="@*android:drawable/lockscreen_forgot_password_button"
            style="?android:attr/buttonBarButtonStyle"
            android:textSize="@dimen/kg_status_line_font_size"
            android:textColor="?android:attr/textColorSecondary"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:drawablePadding="8dip"
            android:visibility="gone"/>
    </LinearLayout>

</com.android.internal.policy.impl.keyguard.EmergencyCarrierArea>
上述代码中的CarrierText即是我们需要着的控件，它继承自TextView。

package com.android.internal.policy.impl.keyguard;

import android.content.Context;
import android.os.SystemProperties;
import android.provider.Settings;
import android.provider.Settings.SettingNotFoundException;
import android.telephony.TelephonyManager;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.TextView;

import com.android.internal.R;
import com.android.internal.telephony.IccCardConstants;
import com.android.internal.telephony.IccCardConstants.State;
import com.android.internal.widget.LockPatternUtils;

public class CarrierText extends TextView {
    private static final String TAG = "CarrierText";
    private static CharSequence mSeparator;

    private LockPatternUtils mLockPatternUtils;

    protected boolean mAirplaneMode;

    // For prop key to show carrier.
    static final String PROP_KEY_SHOW_CARRIER = "persist.env.sys.SHOW_CARRIER";
    static final String PROP_ENV_SPEC = SystemProperties.get("persist.env.spec");

    static final int ORIGIN_CARRIER_NAME_ID = R.array.origin_carrier_names;
    static final int LOCALE_CARRIER_NAME_ID = R.array.locale_carrier_names;
    static final int LOCKSCREEN_CARRIER_DEFAULT_ID =
            R.string.lockscreen_carrier_default;


    private KeyguardUpdateMonitorCallback mCallback = new KeyguardUpdateMonitorCallback() {
        private CharSequence mPlmn;
        private CharSequence mSpn;
        private State mSimState;

        @Override
        public void onRefreshCarrierInfo(CharSequence plmn, CharSequence spn) {
            mPlmn = plmn;
            mSpn = spn;
            updateCarrierText(mSimState, mPlmn, mSpn);
        }

        @Override
        public void onSimStateChanged(IccCardConstants.State simState) {
            mSimState = simState;
            updateCarrierText(mSimState, mPlmn, mSpn);
        }

        @Override
        void onAirplaneModeChanged(boolean on) {
            mAirplaneMode = on;
            updateCarrierText(mSimState, mPlmn, mSpn);
        }
    };
    /**
     * The status of this lock screen. Primarily used for widgets on LockScreen.
     */
    private static enum StatusMode {
        Normal, // Normal case (sim card present, it's not locked)
        PersoLocked, // SIM card is 'perso locked'.
        SimMissing, // SIM card is missing.
        SimMissingLocked, // SIM card is missing, and device isn't provisioned; don't allow access
        SimPukLocked, // SIM card is PUK locked because SIM entered wrong too many times
        SimLocked, // SIM card is currently locked
        SimPermDisabled, // SIM card is permanently disabled due to PUK unlock failure
        SimNotReady, // SIM is not ready yet. May never be on devices w/o a SIM.
        SimIOError; //The sim card is faulty
    }

    public CarrierText(Context context) {
        this(context, null);
    }

    public CarrierText(Context context, AttributeSet attrs) {
        super(context, attrs);
        mLockPatternUtils = new LockPatternUtils(mContext);
        try {
            mAirplaneMode = Settings.System.getInt(mContext.getContentResolver(),
                    Settings.System.AIRPLANE_MODE_ON) == 1;
        } catch (SettingNotFoundException snfe) {
            Log.e(TAG, "get airplane mode exception");
        }
    }

    protected void updateCarrierText(State simState, CharSequence plmn, CharSequence spn) {
        CharSequence text = "";

        if (mAirplaneMode) {
            // if airplane mode is on, show "airplane mode"
            text = getContext().getText(R.string.lockscreen_airplane_mode_on);
        } else {
            text = getCarrierTextForSimState(simState, plmn, spn);
        }

        setText(text);
    }

    @Override
    protected void onFinishInflate() {
        super.onFinishInflate();
        mSeparator = getResources().getString(R.string.kg_text_message_separator);
        setSelected(true); // Allow marquee to work.
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        if (KeyguardUpdateMonitor.sIsMultiSimEnabled) {
            return;
        }
        KeyguardUpdateMonitor.getInstance(mContext).registerCallback(mCallback);
    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        KeyguardUpdateMonitor.getInstance(mContext).removeCallback(mCallback);
    }

    /**
     * Top-level function for creating carrier text. Makes text based on simState, PLMN
     * and SPN as well as device capabilities, such as being emergency call capable.
     *
     * @param simState
     * @param plmn
     * @param spn
     * @return
     */
    protected CharSequence getCarrierTextForSimState(IccCardConstants.State simState,
            CharSequence plmn, CharSequence spn) {
        CharSequence carrierText = null;
        StatusMode status = getStatusForIccState(simState);

        Log.d(TAG, "getCarrierTextForSimState, plmn: " + plmn + ", spn: " + spn);
        String localPlmn = null;
        if (plmn != null) {
            localPlmn= mContext.getLocalString(plmn.toString(),
                com.android.internal.R.array.origin_carrier_names,
                com.android.internal.R.array.locale_carrier_names);
        }
        String localSpn = null;
        if (spn != null) {
            localSpn= mContext.getLocalString(spn.toString(),
                com.android.internal.R.array.origin_carrier_names,
                com.android.internal.R.array.locale_carrier_names);
        }
        Log.d(TAG, "getCarrierTextForSimState, localPlmn: "
            + localPlmn + ", localSpn: " + localSpn);


        int resTextIdOfNoSimCard = R.string.lockscreen_missing_sim_message_short;
        if (PROP_ENV_SPEC.equalsIgnoreCase("ChinaTelecom")) {
            resTextIdOfNoSimCard = R.string.lockscreen_missing_uim_message_short;
        }

        // For CMCC requirement to show 3G in plmn if camping in TD_SCDMA.
        TelephonyManager tm =  (TelephonyManager)getContext()
                .getSystemService(Context.TELEPHONY_SERVICE);
        boolean show3G = !mAirplaneMode && tm != null && plmn != null &&
                tm.getVoiceNetworkType() == TelephonyManager.NETWORK_TYPE_TD_SCDMA;
        if (show3G && localPlmn != null) {
            localPlmn = localPlmn + " 3G";
        }

        switch (status) {
            case Normal:
                carrierText = concatenate(localPlmn, localSpn);
                break;

            case SimNotReady:
                carrierText = null; // nothing to display yet.
                break;

            case PersoLocked:
                carrierText = makeCarrierStringOnEmergencyCapable(
                        getContext().getText(R.string.lockscreen_perso_locked_message),
                        plmn);
                break;

            case SimMissing:
                // Shows "No SIM card | Emergency calls only" on devices that are voice-capable.
                // This depends on mPlmn containing the text "Emergency calls only" when the radio
                // has some connectivity. Otherwise, it should be null or empty and just show
                // "No SIM card"
                carrierText =  makeCarrierStringOnEmergencyCapable(
                        getContext().getText(resTextIdOfNoSimCard),
                        plmn);
                break;

            case SimPermDisabled:
                carrierText = getContext().getText(
                        R.string.lockscreen_permanent_disabled_sim_message_short);
                break;

            case SimMissingLocked:
                carrierText =  makeCarrierStringOnEmergencyCapable(
                        getContext().getText(resTextIdOfNoSimCard),
                        plmn);
                break;

            case SimLocked:
                carrierText = makeCarrierStringOnEmergencyCapable(
                        getContext().getText(R.string.lockscreen_sim_locked_message),
                        plmn);
                break;

            case SimPukLocked:
                carrierText = makeCarrierStringOnEmergencyCapable(
                        getContext().getText(R.string.lockscreen_sim_puk_locked_message),
                        plmn);
                break;

            case SimIOError:
                carrierText = makeCarrierStringOnEmergencyCapable(
                        getContext().getText(R.string.lockscreen_sim_error_message_short),
                        plmn);
                break;
        }

        return carrierText;
    }

    /*
     * Add emergencyCallMessage to carrier string only if phone supports emergency calls.
     */
    private CharSequence makeCarrierStringOnEmergencyCapable(
            CharSequence simMessage, CharSequence emergencyCallMessage) {
        if (mLockPatternUtils.isEmergencyCallCapable()) {
            return concatenate(simMessage, emergencyCallMessage);
        }
        return simMessage;
    }

    /**
     * Determine the current status of the lock screen given the SIM state and other stuff.
     */
    private StatusMode getStatusForIccState(IccCardConstants.State simState) {
        // Since reading the SIM may take a while, we assume it is present until told otherwise.
        if (simState == null) {
            return StatusMode.Normal;
        }

        final boolean missingAndNotProvisioned =
                !KeyguardUpdateMonitor.getInstance(mContext).isDeviceProvisioned()
                && (simState == IccCardConstants.State.ABSENT ||
                        simState == IccCardConstants.State.PERM_DISABLED);

        // Assume we're PERSO_LOCKED if not provisioned
        simState = missingAndNotProvisioned ? IccCardConstants.State.PERSO_LOCKED : simState;
        switch (simState) {
            case ABSENT:
                return StatusMode.SimMissing;
            case PERSO_LOCKED:
                return StatusMode.PersoLocked;
            case NOT_READY:
                return StatusMode.SimNotReady;
            case PIN_REQUIRED:
                return StatusMode.SimLocked;
            case PUK_REQUIRED:
                return StatusMode.SimPukLocked;
            case READY:
                return StatusMode.Normal;
            case PERM_DISABLED:
                return StatusMode.SimPermDisabled;
            case UNKNOWN:
                return StatusMode.SimMissing;
            case CARD_IO_ERROR:
                return StatusMode.SimIOError;
        }
        return StatusMode.SimMissing;
    }

    private static CharSequence concatenate(CharSequence plmn, CharSequence spn) {
        final boolean plmnValid = !TextUtils.isEmpty(plmn);
        final boolean spnValid = !TextUtils.isEmpty(spn);
        /*if (plmnValid && spnValid) {
            return new StringBuilder().append(plmn).append(mSeparator).append(spn).toString();
        } else if (plmnValid) {
            return plmn;
        } else if (spnValid) {
            return spn;
        } else {
            return "";
        }*/

        if (spnValid) {
            return spn;
        } else {
            return "";
        }
    }

    private CharSequence getCarrierHelpTextForSimState(IccCardConstants.State simState,
            String plmn, String spn) {
        int carrierHelpTextId = 0;
        StatusMode status = getStatusForIccState(simState);
        switch (status) {
            case PersoLocked:
                carrierHelpTextId = R.string.lockscreen_instructions_when_pattern_disabled;
                break;

            case SimMissing:
                carrierHelpTextId = R.string.lockscreen_missing_sim_instructions_long;
                break;

            case SimPermDisabled:
                carrierHelpTextId = R.string.lockscreen_permanent_disabled_sim_instructions;
                break;

            case SimMissingLocked:
                carrierHelpTextId = R.string.lockscreen_missing_sim_instructions;
                break;

            case Normal:
            case SimLocked:
            case SimPukLocked:
                break;
        }

        return mContext.getText(carrierHelpTextId);
    }
上述加粗标红的代码就是我们需要作出修改的位置。