羊皮书APP（Android版）开发系列（十八）Android

前几篇文章介绍的底部菜单栏、图片循环自动轮播都非常常用，底部菜单栏也很常用，底部菜单栏是iOS的主要风格，而Android的风格则偏向侧滑菜单栏。侧滑菜单栏也是很常用的，本篇为大家介绍下一个侧滑菜单栏，个人感觉很不错，这里只贴出关键的代码，学习下。

效果如下：

首先定义一个Fragment，用来展示侧滑菜单，添加一些事件。FragmentDrawer代码如下：

package com.studyou.Fragment;

import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.GestureDetector;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;

import com.studyou.Adapter.NavigationDrawerAdapter;
import com.studyou.Entity.NavDrawerItem;

import java.util.ArrayList;
import java.util.List;

public class FragmentDrawer extends Fragment {

    private static String TAG = FragmentDrawer.class.getSimpleName();

    private RecyclerView recyclerView;
    private ActionBarDrawerToggle mDrawerToggle;
    private DrawerLayout mDrawerLayout;
    private NavigationDrawerAdapter adapter;
    private View containerView;
    private static String[] titles = null;
    private FragmentDrawerListener drawerListener;

    public FragmentDrawer() {

    }

    public void setDrawerListener(FragmentDrawerListener listener) {
        this.drawerListener = listener;
    }

    public static List<NavDrawerItem> getData() {
        List<NavDrawerItem> data = new ArrayList<>();


        // preparing navigation drawer items
        for (int i = 0; i < titles.length; i++) {
            NavDrawerItem navItem = new NavDrawerItem();
            navItem.setTitle(titles[i]);
            data.add(navItem);
        }
        return data;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // drawer labels
        titles = getActivity().getResources().getStringArray(R.array.nav_drawer_labels);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflating view layout
        View layout = inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
        recyclerView = (RecyclerView) layout.findViewById(R.id.drawerList);

        adapter = new NavigationDrawerAdapter(getActivity(), getData());
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        recyclerView.addOnItemTouchListener(new RecyclerTouchListener(getActivity(), recyclerView, new ClickListener() {
            @Override
            public void onClick(View view, int position) {
                drawerListener.onDrawerItemSelected(view, position);
                mDrawerLayout.closeDrawer(containerView);
            }

            @Override
            public void onLongClick(View view, int position) {

            }
        }));

        return layout;
    }


    public void setUp(int fragmentId, DrawerLayout drawerLayout, final Toolbar toolbar) {
        containerView = getActivity().findViewById(fragmentId);
        mDrawerLayout = drawerLayout;
        mDrawerToggle = new ActionBarDrawerToggle(getActivity(), drawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close) {
            @Override
            public void onDrawerOpened(View drawerView) {
                super.onDrawerOpened(drawerView);
                getActivity().invalidateOptionsMenu();
            }

            @Override
            public void onDrawerClosed(View drawerView) {
                super.onDrawerClosed(drawerView);
                getActivity().invalidateOptionsMenu();
            }

            @Override
            public void onDrawerSlide(View drawerView, float slideOffset) {
                super.onDrawerSlide(drawerView, slideOffset);
                toolbar.setAlpha(1 - slideOffset / 2);
            }
        };

        mDrawerLayout.setDrawerListener(mDrawerToggle);
        mDrawerLayout.post(new Runnable() {
            @Override
            public void run() {
                mDrawerToggle.syncState();
            }
        });

    }

    public static interface ClickListener {
        public void onClick(View view, int position);

        public void onLongClick(View view, int position);
    }

    static class RecyclerTouchListener implements RecyclerView.OnItemTouchListener {

        private GestureDetector gestureDetector;
        private ClickListener clickListener;

        public RecyclerTouchListener(Context context, final RecyclerView recyclerView, final ClickListener clickListener) {
            this.clickListener = clickListener;
            gestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
                @Override
                public boolean onSingleTapUp(MotionEvent e) {
                    return true;
                }

                @Override
                public void onLongPress(MotionEvent e) {
                    View child = recyclerView.findChildViewUnder(e.getX(), e.getY());
                    if (child != null && clickListener != null) {
                        clickListener.onLongClick(child, recyclerView.getChildPosition(child));
                    }
                }
            });
        }

        @Override
        public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {

            View child = rv.findChildViewUnder(e.getX(), e.getY());
            if (child != null && clickListener != null && gestureDetector.onTouchEvent(e)) {
                clickListener.onClick(child, rv.getChildPosition(child));
            }
            return false;
        }

        @Override
        public void onTouchEvent(RecyclerView rv, MotionEvent e) {
        }
    }

    public interface FragmentDrawerListener {
        public void onDrawerItemSelected(View view, int position);
    }
}

创建对应的NavigationDrawerAdapter

package com.studyou.Adapter;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.studyou.Fragment.R;
import com.studyou.Entity.NavDrawerItem;

import java.util.Collections;
import java.util.List;

public class NavigationDrawerAdapter extends RecyclerView.Adapter<NavigationDrawerAdapter.MyViewHolder> {
    List<NavDrawerItem> data = Collections.emptyList();
    private LayoutInflater inflater;
    private Context context;

    public NavigationDrawerAdapter(Context context, List<NavDrawerItem> data) {
        this.context = context;
        inflater = LayoutInflater.from(context);
        this.data = data;
    }

    public void delete(int position) {
        data.remove(position);
        notifyItemRemoved(position);
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.nav_drawer_row, parent, false);
        MyViewHolder holder = new MyViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        NavDrawerItem current = data.get(position);
        holder.title.setText(current.getTitle());
    }

    @Override
    public int getItemCount() {
        return data.size();
    }

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView title;

        public MyViewHolder(View itemView) {
            super(itemView);
            title = (TextView) itemView.findViewById(R.id.title);
        }
    }
}

在Activity中使用，MainActivity代码

package com.studyou.Fragment;


import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity implements FragmentDrawer.FragmentDrawerListener {

    private Toolbar mToolbar;
    private FragmentDrawer drawerFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mToolbar = (Toolbar) findViewById(R.id.toolbar);

        setSupportActionBar(mToolbar);
        getSupportActionBar().setDisplayShowHomeEnabled(true);

        drawerFragment = (FragmentDrawer)
                getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
        drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), mToolbar);
        drawerFragment.setDrawerListener(this);

        // display the first navigation drawer view on app launch
        displayView(0);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
        if (id == R.id.action_search){
            Toast.makeText(getApplicationContext(), "Search action is selected!", Toast.LENGTH_SHORT).show();
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onDrawerItemSelected(View view, int position) {
        displayView(position);
    }

    private void displayView(int position) {
        Fragment fragment = null;
        String title = getString(R.string.app_name);
        switch (position) {
            case 0:
                fragment = new HomeFragment();
                title = getString(R.string.title_home);
                break;
            case 1:
                fragment = new FriendsFragment();
                title = getString(R.string.title_friends);
                break;
            case 2:
                fragment = new MessagesFragment();
                title = getString(R.string.title_messages);
                break;
            default:
                break;
        }

        if (fragment != null) {
            FragmentManager fragmentManager = getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.container_body, fragment);
            fragmentTransaction.commit();

            // set the toolbar title
            getSupportActionBar().setTitle(title);
        }
    }
}

Activity中的代码也很简单，这个侧滑菜单主要的核心就在于FragmentDrawer和NavigationDrawerAdapter，大家可以认真的看下代码逻辑。
源码可到github上下载，下载地址：https://github.com/wjie2014/Slide_Navigation