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);
}