BottomBar

第一次用此控件，所以在用的过程中出现了一些问题，现将使用方法和问题及解决方案做个记录。

使用步骤：
一、在build.gradle中添加依赖；

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.1.1'
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:design:25.1.1'
    compile 'com.jakewharton:butterknife:5.1.1'
    //  添加bottombar的依赖
    compile 'com.roughike:bottom-bar:1.3.3'
}

问题一、在创建调用BottomBar的方法后出现以下问题：
error resolve：com.roughhike:bottom-bar:1.3.3。
怎么解决呢？
在网上找了一些资料，链接如下：
https://stackoverflow.com/questions/39435772/eror-resolve-com-roughikebottom-bar1-4-0-1
https://stackoverflow.com/questions/46023971/failed-to-resolve-com-android-supportsupport-annotations-26-0-1
综合资料在build.gradle中添加以下代码后问题解决（具体是什么原因本人也不是很清楚~~）

allprojects {
    repositories {
        jcenter()
        maven {
            url 'https://maven.google.com'
        }
    }
}

二、代码中初始化BottomBar并实现点击监听；

//初始化Fragment
        mSparseArray = new SparseArray<>();
        mSparseArray.append(R.id.bottombar_menu_home, new HomeFragment());
        mSparseArray.append(R.id.bottombar_menu_mv, new MVFragment());
        mSparseArray.append(R.id.bottombar_menu_vbang, new VBangFragment());
        mSparseArray.append(R.id.bottombar_menu_yuedan, new YueDanFragment());

        //底部栏
        BottomBar bottomBar = BottomBar.attach(this, savedInstanceState);
        bottomBar.setItemsFromMenu(R.menu.bottombar_menu, new OnMenuTabClickListener() {
            @Override
            public void onMenuTabSelected(@IdRes int menuItemId) {
                Fragment fragment = mSparseArray.get(menuItemId);
                switchFragment(fragment);
            }

            @Override
            public void onMenuTabReSelected(@IdRes int menuItemId) {
                Toast.makeText(MainActivity.this, "MenuTabReSelected", Toast.LENGTH_SHORT).show();
            }
        });

public void switchFragment(Fragment fragment){
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.container, fragment);
        transaction.commit();
    }

三、创建底部Tab的配置文件bottombar_menu.xml

至此，BottomBar的简单功能实现就完成了，做到最后效果实现了，但我发现在布局文件中并没有添加BottomBar控件，看了下源码，原来诀窍在attatch方法~~

public static BottomBar attach(Activity activity, Bundle savedInstanceState) {
        BottomBar bottomBar = new BottomBar(activity);
        bottomBar.onRestoreInstanceState(savedInstanceState);

        ViewGroup contentView = (ViewGroup) activity.findViewById(android.R.id.content);
        View oldLayout = contentView.getChildAt(0);
        contentView.removeView(oldLayout);

        bottomBar.setPendingUserContentView(oldLayout);
        contentView.addView(bottomBar, 0);

        return bottomBar;
    }