开发App抽屉功能，彻底掌握了吗？

public class MainActivity extends AppCompatActivity {    
protected boolean statusBarCompat = true;    
   private static long DOUBLE_CLICK_TIME = 0L;    //声明相关变量
   private Toolbar toolbar;    
   private DrawerLayout mDrawerLayout;    
   private ActionBarDrawerToggle mDrawerToggle;    
   private ListView lvLeftMenu;    
   private String[] lvs = {"Android", "iOS", "Python", "Html5", "Java"};    
   private ArrayAdapter arrayAdapter;    @Override
   protected void onCreate(Bundle savedInstanceState) {        
   super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);        
   if (statusBarCompat) {
           StatusBarCompat.compat(this, ContextCompat.getColor(this, R.color.colorPrimary));
           transparent19and20();
       }
       findByIdViews(); //获取控件
       toolbar.setTitle("Drawerlayout");//设置标题
       toolbar.setTitleTextColor(Color.parseColor("#ffffff")); //设置标题颜色
       setSupportActionBar(toolbar);
       getSupportActionBar().setHomeButtonEnabled(true); //设置返回键可用
       getSupportActionBar().setDisplayHomeAsUpEnabled(true);        //创建返回键，并实现打开关/闭监听
       mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, toolbar, R.string.open, R.string.close) {            
       @Override
           public void onDrawerOpened(View drawerView) {                
           super.onDrawerOpened(drawerView);
           }            @Override
           public void onDrawerClosed(View drawerView) {                
           super.onDrawerClosed(drawerView);
           }
       };
       mDrawerToggle.syncState();
       mDrawerLayout.addDrawerListener(mDrawerToggle);        //设置菜单列表
       arrayAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, lvs);
       lvLeftMenu.setAdapter(arrayAdapter);
       lvLeftMenu.setOnItemClickListener(new AdapterView.OnItemClickListener() {            
           @Override
           public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
               Toast.makeText(MainActivity.this, "点击"+position , Toast.LENGTH_SHORT).show();
           }
       });
   }    
   //返回键监听
   @Override
   public boolean onKeyDown(int keyCode, KeyEvent event) {        
   if (event.getKeyCode() == KeyEvent.KEYCODE_MENU && mDrawerLayout != null) {            
   if (mDrawerLayout.isDrawerOpen(Gravity.LEFT)) {
               mDrawerLayout.closeDrawer(Gravity.LEFT);
           } else {
               mDrawerLayout.openDrawer(Gravity.LEFT);
           }            return true;
       }  else if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {            
       if (mDrawerLayout.isDrawerOpen(Gravity.LEFT)) {
               mDrawerLayout.closeDrawer(Gravity.LEFT);
           } else {                if ((System.currentTimeMillis() - DOUBLE_CLICK_TIME) > 2000) {
                   Toast.makeText(MainActivity.this, "再按一次退出", Toast.LENGTH_SHORT).show();
                   DOUBLE_CLICK_TIME = System.currentTimeMillis();
               } else {
                   finish();
               }
           }            return true;
       }        return super.onKeyDown(keyCode, event);
   }    protected void transparent19and20() {        
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT
               && Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
           getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
       }
   }    
       private void findByIdViews() {
       toolbar = (Toolbar) findViewById(R.id.tl_custom);
       mDrawerLayout = (DrawerLayout) findViewById(R.id.dl_left);
       lvLeftMenu = (ListView) findViewById(R.id.lv_left_menu);
   }
}