AOSP 12 Launcher3 禁止卸载第三方app

 1.概述  

        在android12.0的系统rom开发中，预安装的方法来安装这个app.然后在Launcher3 拖拽卸载时，不让他卸载接下来就看Launcher3 app 长按卸载的流程
在luncher.xm中

<include
    android:id="@+id/drop_target_bar"
    layout="@layout/drop_target_bar" />

drop targe bar.xml

<?xml version="1.0" encoding="utf-8"?><!--
     Copyright (C) 2018 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.
-->
<com.android.launcher3.DropTargetBar xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="@dimen/dynamic_grid_drop_target_size"
    android:layout_gravity="center_horizontal|top"
    android:focusable="false"
    android:alpha="0"
    android:theme="@style/HomeScreenElementTheme"
    android:visibility="invisible">
 
    <!-- Delete target -->
    <com.android.launcher3.DeleteDropTarget
        android:id="@+id/delete_target_text"
        style="@style/DropTargetButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:text="@string/remove_drop_target_label" />
 
    <!-- Uninstall target -->
    <com.android.launcher3.SecondaryDropTarget
        android:id="@+id/uninstall_target_text"
        style="@style/DropTargetButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:text="@string/uninstall_drop_target_label" />
 
</com.android.launcher3.DropTargetBar>

从上述的drop targe bar.xml的相关源码分析发现DeleteDropTarget.java 是负责处理长按图标删除 快捷图标和时钟等等的而SecondaryDropTarget是负责处理长按图标卸载app的当app 长按时开始拖拽时，就会响应开始拖拽事件，在Workspace的app的列表页面 在SecondarvDropTarget.java 就会判断是否支持卸载，支持卸载 就会出现卸载字样
当移动到卸载区域内后就会 弹出卸载框 确定卸载就会卸载
先看看ButtonDropTarget.java 的相关源码

public abstract class ButtonDropTarget extends TextView
        implements DropTarget, DragController.DragListener, OnClickListener {
 
    private static final Property<ButtonDropTarget, Integer> TEXT_COLOR =
            new Property<ButtonDropTarget, Integer>(Integer.TYPE, "textColor") {
 
                @Override
                public Integer get(ButtonDropTarget target) {
                    return target.getTextColor();
                }
 
                @Override
                public void set(ButtonDropTarget target, Integer value) {
                    target.setTextColor(value);
                }
            };
 
              @Override
    public void onDragStart(DropTarget.DragObject dragObject, DragOptions options) {
        mActive = supportsDrop(dragObject.dragInfo);
        mDrawable.setColorFilter(null);
        if (mCurrentColorAnim != null) {
            mCurrentColorAnim.cancel();
            mCurrentColorAnim = null;
        }
        setTextColor(mOriginalTextColor);
        setVisibility(mActive ? View.VISIBLE : View.GONE);
 
        mAccessibleDrag = options.isAccessibleDrag;
        setOnClickListener(mAccessibleDrag ? this : null);
    }
}

在ButtonDropTarget.iava 的相关源码分析得知
在开始拖拽时 会在onDragStart()中 处理拖拽相关的事情通过supportsDrop(dragObject.dragInfo);来处理在拖拽app图标时 要不要显示卸载,然后完成卸载功能接下来看下SecondaryDropTarget.iava的supportsDrop(dragObiect.dragInfo):万法

   @Override
    protected boolean supportsDrop(ItemInfo info) {
        return supportsAccessibilityDrop(info, getViewUnderDrag(info));
    }
 
    @Override
    public boolean supportsAccessibilityDrop(ItemInfo info, View view) {
        if (view instanceof AppWidgetHostView) {
            if (getReconfigurableWidgetId(view) != INVALID_APPWIDGET_ID) {
                setupUi(RECONFIGURE);
                return true;
            }
            return false;
        }
 
        setupUi(UNINSTALL);
        Boolean uninstallDisabled = mUninstallDisabledCache.get(info.user);
        if (uninstallDisabled == null) {
            UserManager userManager =
                    (UserManager) getContext().getSystemService(Context.USER_SERVICE);
            Bundle restrictions = userManager.getUserRestrictions(info.user);
            uninstallDisabled = restrictions.getBoolean(UserManager.DISALLOW_APPS_CONTROL, false)
                    || restrictions.getBoolean(UserManager.DISALLOW_UNINSTALL_APPS, false);
            mUninstallDisabledCache.put(info.user, uninstallDisabled);
        }
        // Cancel any pending alarm and set cache expiry after some time
        mCacheExpireAlarm.setAlarm(CACHE_EXPIRE_TIMEOUT);
        if (uninstallDisabled) {
            return false;
        }
 
        if (info instanceof ItemInfoWithIcon) {
            ItemInfoWithIcon iconInfo = (ItemInfoWithIcon) info;
            if ((iconInfo.runtimeStatusFlags & FLAG_SYSTEM_MASK) != 0) {
                return (iconInfo.runtimeStatusFlags & FLAG_SYSTEM_NO) != 0;
            }
        }
        return getUninstallTarget(info) != null;
    }

在SecondaryDropTarget.ijava 的相关源码分析得知
这里会根据ltemInfo的属性判断是否是系统应用
所以我们要不让卸载第三方 app 可以根据他的tte 或者是contentDescription 来判断就行了 如果是就返回false 然后在拖拽时 就不会显示
卸载了 就实现了功能
具体修改如下:

 @Override
    public boolean supportsAccessibilityDrop(ItemInfo info, View view) {
               
                //add core start
		android.util.Log.e(TAG,"title:"+info.title+"--contentDescription:"+info.contentDescription);
		if(info.title!=null&&info.title.equals("JNITest"))return false;
               // add code end 
 
        if (view instanceof AppWidgetHostView) {
            if (getReconfigurableWidgetId(view) != INVALID_APPWIDGET_ID) {
                setupUi(RECONFIGURE);
                return true;
            }
            return false;
        }
 
        setupUi(UNINSTALL);
        Boolean uninstallDisabled = mUninstallDisabledCache.get(info.user);
        if (uninstallDisabled == null) {
            UserManager userManager =
                    (UserManager) getContext().getSystemService(Context.USER_SERVICE);
            Bundle restrictions = userManager.getUserRestrictions(info.user);
            uninstallDisabled = restrictions.getBoolean(UserManager.DISALLOW_APPS_CONTROL, false)
                    || restrictions.getBoolean(UserManager.DISALLOW_UNINSTALL_APPS, false);
            mUninstallDisabledCache.put(info.user, uninstallDisabled);
        }
        // Cancel any pending alarm and set cache expiry after some time
        mCacheExpireAlarm.setAlarm(CACHE_EXPIRE_TIMEOUT);
        if (uninstallDisabled) {
            return false;
        }
 
        if (info instanceof ItemInfoWithIcon) {
            ItemInfoWithIcon iconInfo = (ItemInfoWithIcon) info;
            if ((iconInfo.runtimeStatusFlags & FLAG_SYSTEM_MASK) != 0) {
                return (iconInfo.runtimeStatusFlags & FLAG_SYSTEM_NO) != 0;
            }
        }
        return getUninstallTarget(info) != null;
    }

2.重启完事