[android] 新闻客户端实现左侧导航点击切换

设置主布局文件，为根布局设置一个id，作为内容区

给ListView的条目设置点击事件，setOnItemClickListener()方法，参数：上下文

当前的Fragment实现OnItemClickListener接口

实现onItemClick()方法

switch判断一下当前菜单的索引位置，根据索引来实例化不同的Fragment对象

调用getActivity()方法，得到宿主Activity对象，这个activity暴露一个方法，替换fragment

使用关键字instances of判断getActivity()得到的是MainActivity类的实例

调用宿主Activity对象的switchMenuFragment()方法，切换内容部分的fragment，参数：Fragment对象

宿主activity暴露方法switchMenuFragment()，切换内容区fragment，参数：Fragment对象

getSupportFragmentManager().beginTransaction().replace(R.id.ll_main_content, fragment).commit();

调用SlidingMenu对象的toggle()方法，关闭左侧菜单

设置默认，当app第一次打开时显示导航第一个的内容

MainActivity

package com.qingguow.news;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.Window;

import com.jeremyfeinstein.slidingmenu.lib.SlidingMenu;
import com.jeremyfeinstein.slidingmenu.lib.app.SlidingFragmentActivity;
import com.qingguow.news.fragment.IndexFragment;
import com.qingguow.news.fragment.MenuFragment;

public class MainActivity extends SlidingFragmentActivity {
    private SlidingMenu sm;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        //设置滑动菜单
        setBehindContentView(R.layout.menu);
        setContentView(R.layout.activity_main);
        sm=getSlidingMenu();
        sm.setMode(SlidingMenu.LEFT);
        sm.setBehindWidth(200);
        sm.setShadowDrawable(R.drawable.shape);
        sm.setShadowWidth(5);
        sm.setTouchModeAbove(SlidingMenu.TOUCHMODE_FULLSCREEN);
        
        FragmentTransaction ft=getSupportFragmentManager().beginTransaction();
        //替换导航fragemnt
        MenuFragment menuFragment=new MenuFragment();
        ft.replace(R.id.ll_left_menu, menuFragment);
        //替换内容fragment
        IndexFragment index=new IndexFragment();
        ft.replace(R.id.ll_main_content, index).commit();
        
    }
    /**
     * 暴露方法切换内容区
     * @param fragment
     */
    public void switchMenuFragment(Fragment fragment){
        getSupportFragmentManager().beginTransaction().replace(R.id.ll_main_content, fragment).commit();
        sm.toggle();
    }
}

MenuFragment.java

package com.qingguow.news.fragment;

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

import android.app.Activity;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;

import com.qingguow.news.MainActivity;
import com.qingguow.news.R;

public class MenuFragment extends Fragment implements OnItemClickListener {
    private View view;
    //加载布局文件
    @Override
    public View onCreateView(LayoutInflater inflater,
            @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.list_view, null);
        return view;
    }
    //设置listview数据
    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        ListView listview = (ListView) view.findViewById(R.id.lv_menu);
        
        List<String> data=new ArrayList<String>();
        data.add("新闻");
        data.add("发现");
        data.add("关注");
        ListAdapter adapter = new ArrayAdapter<>(getActivity(),
                android.R.layout.simple_list_item_1, android.R.id.text1,
                data);
        listview.setAdapter(adapter);
        listview.setOnItemClickListener(this);
        
    }
    /**
     * 导航点击
     */
    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position,
            long id) {
        Fragment fragment=null;
        switch (position) {
        case 0:
            fragment=new IndexFragment();
            break;

        default:
            break;
        }
        if(fragment!=null){
            Activity activity=getActivity();
            if(activity instanceof MainActivity){
                ((MainActivity) activity).switchMenuFragment(fragment);
            }
        }
    }
}