毕业设计：HomeFragment

Posted 2020-09-08 学海无涯，回头是岸

一、长按item时的响应

      在长按item时，我希望能让CheckBox显示出来，并且呼出全选、反选、取消菜单，以及下载、删除、移动、复制操作菜单。

      我在具体实现的时候发现处理item布局是一个很大的问题，因为不知道怎么在Fragment里面去改变每一个item的CheckBox状态。经过考虑，我打算把这些方法都写在ListViewAdapter里，并且在这个类里设置一个Map对象，记录每一个position对应的isCheck状态。当我点击每一个CheckBox或者从Fragment里面点击全选/反选时，改变这个Map的值，然后通过重写adapter里的getView方法来控制哪些CheckBox显示为已选，哪些为未选。

      而另外的两个菜单，我在HomeFragment布局里面都把他们写了出来，然后初始化为不可见。当长按item触发OnItemLongClickedListener的时候将他们设置为可见，并且把他们覆盖了的组件设置为不可见（避免不可见但仍能响应Click事件的问题）

      另外还有一个变量isSelecting我认为非常重要，它用来判断当前Fragment是否是处于选择阶段。

二、FileListAdapter

package com.example.vcloud_3_25.utils;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.annotation.SuppressLint;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.SimpleAdapter;

import com.example.vcloud_3_25.R;

public class FileListAdapter extends SimpleAdapter {

    private Map<Integer, Boolean> isSelected;
    private boolean isSelecting;
    private List<Map<String, Object>> mResList;

    
    @SuppressWarnings("unchecked")
    public FileListAdapter(Context context,
            List<? extends Map<String, ?>> data, int resource, String[] from,
            int[] to) {
        super(context, data, resource, from, to);
        this.mResList = (List<Map<String, Object>>)data;
        init();
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        View view = super.getView(position, convertView, parent);
        CheckBox cb = (CheckBox) view.findViewById(R.id.file_checkbox);
        if (!isSelecting) {
            cb.setVisibility(View.INVISIBLE);
        } else {
            cb.setVisibility(View.VISIBLE);
            cb.setChecked(isSelected.get(position));
        }
        cb.setOnCheckedChangeListener(new OnCheckedChangeListener() {
            
            @Override
            public void onCheckedChanged(CompoundButton checkBox, boolean flag) {
                    isSelected.put(position, flag);
            }
        });
        return view;
    }

    @SuppressLint("UseSparseArrays") 
    public void init() {
        isSelected = new HashMap<Integer,Boolean>();
        for (int i = 0; i < mResList.size(); i++) {
            isSelected.put(i, false);
            
        }
        isSelecting = false;
    }
    public void setIsSelecting(boolean flag){
        this.isSelecting = flag;
    }
    public void setSelected(int position,boolean flag){
        isSelected.put(position, flag);
    }
    public Map<Integer,Boolean> getSelected(){
        return isSelected;
    }
    public void selectAll(){
        for (int i = 0; i < mResList.size(); i++) {
            isSelected.put(i, true);
        }
    }
    public void selectReverse(){
        for (int i = 0; i < mResList.size(); i++) {
            isSelected.put(i, !isSelected.get(i));
        }
    }
}

三、HomeFragment里面的一些核心函数

        mListView.setOnItemLongClickListener(new OnItemLongClickListener() {

            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View item,
                    int position, long id) {

                if (!isSelecting) {
                    mFolderIndicator.setVisibility(View.INVISIBLE);
                    mSelectBar.setVisibility(view.VISIBLE);
                    mSelectActionBar.setVisibility(view.VISIBLE);

                    isSelecting = true;
                    adapter.init();
                    adapter.setIsSelecting(isSelecting);
                    adapter.setSelected(position, true);
                    refreshListView();
                }

                return true;
            }
        });
        mSelectCancelButton.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                backToNormal();
            }
        });
        
        mSelectAllButton.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                adapter.selectAll();
                refreshListView();
            }
        });
        mSelectReverseButton.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                adapter.selectReverse();
                refreshListView();
            }
        });

        }
    private void refreshListView() {
        mResList.clear();
        mResList.addAll(getResList(recentPid));
        adapter.notifyDataSetChanged();
    }
    private void backToNormal() {
        adapter.init();
        isSelecting = false;
        refreshListView();
        mFolderIndicator.setVisibility(View.VISIBLE);
        mSelectBar.setVisibility(View.INVISIBLE);
        mSelectActionBar.setVisibility(View.INVISIBLE);
    }