Android应用开发之多选删除之二
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MultiSelectDeleteActivity.java
package cn.lynn.multisel;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.ContentUris;
import android.content.Context;
import android.content.DialogInterface;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.provider.ContactsContract.Contacts;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ListView;
import android.widget.TextView;
public class MultiSelectDeleteActivity extends Activity implements OnClickListener, OnItemClickListener {
private static final String TAG = "MultiSelectDeleteActivity";
private ListView delList;
private Button delBtn;
private Button canBtn;
private CheckBox selAllChk;
private Cursor cursor;
private int count;
private DeleteListAdapter delListAdapter;
// 期望查询的联系人字段
private static final String[] PROJECTION = new String[] {Contacts._ID, Contacts.DISPLAY_NAME};
private static final int CONTACTS_ID_INDEX = 0;
private static final int DISPLAY_NAME_INDEX = 1;
// 用于保存记录是否被选中的状态，这里定义为静态变量是为了防止Home键切换之后普通成员变量无法保存切换之前的数据
private static HashMap<Integer, Boolean> statusMap;
/**
* 用于删除的联系人记录的封装类
*/
private final class ViewHolder {
TextView nameTxt;
CheckBox selectChk;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
statusMap = new HashMap<Integer, Boolean>();
delList = (ListView) findViewById(R.id.del_list);
delBtn = (Button) findViewById(R.id.del_btn);
canBtn = (Button) findViewById(R.id.can_btn);
selAllChk = (CheckBox) findViewById(R.id.select_all).findViewById(R.id.select_all_chk);
delList.setOnItemClickListener(this);
delBtn.setOnClickListener(this);
canBtn.setOnClickListener(this);
selAllChk.setOnClickListener(new SelectAllClickListener());
}
@Override
protected void onDestroy() {
super.onDestroy();
statusMap.clear();
// 静态变量，提示和加快GC回收它，否则有很大可能要等到VM Full gc时才能回收
statusMap = null;
}
@Override
public void onResume() {
super.onResume();
refreshData();
}
@Override
protected void onPause() {
super.onPause();
// 保存切换之前的记录数
count = cursor.getCount();
}
/**
* 查询联系人数据库记录
*/
private void refreshData() {
selAllChk.setEnabled(false);
delBtn.setEnabled(false);
cursor = getContentResolver().query(Contacts.CONTENT_URI, PROJECTION, null, null, null);
if(cursor.getCount() > 0) {
selAllChk.setEnabled(true);
// Home键切换到Contacts应用增加联系人
if(count < cursor.getCount()) {
selAllChk.setChecked(false);
}
}
if(statusMap.containsValue(true)) {
delBtn.setEnabled(true);
}
Log.i(TAG, "cursor= " + cursor);
delListAdapter = new DeleteListAdapter(this, cursor);
delList.setAdapter(delListAdapter);
delListAdapter.notifyDataSetChanged();
}
/**
* 单独为全选CheckBox设置点击事件的监听器，因为它的布局是从当前Activity的子布局文件R.id.select_all中加载而来，
* 这样做的好处是防止多个按钮都在Activity布局层次上监听同类点击事件时出现“屏蔽”现象
*/
private class SelectAllClickListener implements OnClickListener {
@Override
public void onClick(View v) {
if(selAllChk.isChecked()) {
for (int i = 0; i < delListAdapter.getCount(); i++) {
statusMap.put(i, true);
delListAdapter.cursor.moveToPosition(i);
delListAdapter.idSet.add(delListAdapter.cursor.getInt(CONTACTS_ID_INDEX) + "");
}
delBtn.setEnabled(true);
} else {
for (int i = 0; i < delListAdapter.getCount(); i++) {
statusMap.put(i, false);
}
delListAdapter.idSet.clear();
delBtn.setEnabled(false);
}
// 数据发生变化，通知UI更新
delListAdapter.notifyDataSetChanged();
}
}
/**
* 为ListView设置删除联系人记录的Adapter
*/
private class DeleteListAdapter extends BaseAdapter {
Cursor cursor;
// 保存被选中的联系人Id
HashSet<String> idSet;
public DeleteListAdapter(Context context, Cursor cursor) {
this.cursor = cursor;
idSet = new HashSet<String>();
for (int i = 0; i < cursor.getCount(); i++) {
// 初始化新的联系人记录为未选中的状态
if(statusMap.containsKey(i)) continue;
statusMap.put(i, false);
}
Log.i(TAG, "statusMap size=" + statusMap.size());
}
@Override
public int getCount() {
return cursor.getCount();
}
@Override
public Object getItem(int position) {
if(cursor.moveToPosition(position)) {
return cursor;
} else {
return null;
}
}
@Override
public long getItemId(int position) {
return position;
}
// 这里启用了convertView缓存，并创建ViewHolder类以提高ListView执行效率
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
if(convertView == null) {
convertView = LayoutInflater.from(MultiSelectDeleteActivity.this).inflate(R.layout.list_item, null);
holder = new ViewHolder();
holder.nameTxt = (TextView) convertView.findViewById(R.id.name_txt);
holder.selectChk = (CheckBox) convertView.findViewById(R.id.select_chk);
convertView.setTag(holder);
}
cursor.moveToPosition(position);
holder = (ViewHolder) convertView.getTag();
final String name = cursor.getString(DISPLAY_NAME_INDEX);
holder.nameTxt.setText(name);
holder.selectChk.setChecked(statusMap.get(position));
if(statusMap.get(position)) {
// 存储选中状态的记录的Id
idSet.add(cursor.getInt(CONTACTS_ID_INDEX)+"");
} else {
// 移除非选中状态的记录的Id
idSet.remove(cursor.getInt(CONTACTS_ID_INDEX)+"");
}
return convertView;
}
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Log.i(TAG, "onItemClick...");
ViewHolder holder = (ViewHolder) view.getTag();
holder.selectChk.toggle();
statusMap.put(position, holder.selectChk.isChecked());
delListAdapter.notifyDataSetChanged();
// 判断是否有记录没被选中，以便更改全选CheckBox的勾选状态
if(statusMap.containsValue(false)) {
selAllChk.setChecked(false);
} else {
selAllChk.setChecked(true);
}
Log.i(TAG, "------------statusMap data--------------");
for (Map.Entry<Integer, Boolean> entry: statusMap.entrySet()) {
Log.i(TAG, "statusMap key=" + entry.getKey() + ", value= " + entry.getValue());
}
// 判断是否有记录被选中，以便更改删除Button的可用状态
if(statusMap.containsValue(true)) {
delBtn.setEnabled(true);
} else {
delBtn.setEnabled(false);
}
}
@Override
public void onClick(View v) {
switch (v.getId()) {
// 删除按钮
case R.id.del_btn:
new AlertDialog.Builder(this)
.setTitle(R.string.clearConfirmation_title)
.setMessage(R.string.clearConfirmation)
.setNegativeButton(android.R.string.cancel, null)
.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@SuppressWarnings("unchecked")
@Override
public void onClick(DialogInterface dialog, int which) {
final ProgressDialog progressDialog = ProgressDialog.show(MultiSelectDeleteActivity.this, getString(R.string.clearProgress_title), "", true, false);
final AsyncTask<HashSet<String>, Integer, Cursor> deleteWork = new AsyncTask<HashSet<String>, Integer, Cursor>() {
Uri uri = null;
@Override
protected Cursor doInBackground(HashSet<String> ... params) {
// 后台工作线程执行删除联系人记录操作
HashSet<String> ids = params[0];
for (String id : ids) {
Log.i(TAG, "deleted id= " + id);
uri = ContentUris.withAppendedId(Contacts.CONTENT_URI, Long.valueOf(id));
MultiSelectDeleteActivity.this.getContentResolver().delete(uri, null, null);
}
Log.i(TAG, "doInBackground statusMap size=" + statusMap.size());
// 清除所有被选中的联系人Id
delListAdapter.idSet.clear();
cursor = MultiSelectDeleteActivity.this.getContentResolver().query(Contacts.CONTENT_URI, PROJECTION, null, null, null);
return cursor;
}
// 删除操作的实时进度，本案例不对此做任何处理
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
}
// 删除操作执行完毕后回调此方法，可以得到处理结果，并通知UI更新
@Override
protected void onPostExecute(Cursor result) {
super.onPostExecute(result);
Log.i(TAG, "result getCount= " + result.getCount());
if(result.getCount() == 0){
// 删除全部记录后，全选CheckBox应该被禁用（不能再点击），当有新记录加入时才可以重新启用它
selAllChk.setChecked(false);
selAllChk.setEnabled(false);
}
delBtn.setEnabled(false);
statusMap.clear();
// 删除操作完成后，重置剩下的记录为未选中状态
for (int i = 0; i < result.getCount(); i++) {
statusMap.put(i, false);
}
delListAdapter.cursor = result;
delListAdapter.notifyDataSetChanged();
progressDialog.dismiss();
}
};
progressDialog.show();
deleteWork.execute(delListAdapter.idSet);
}
})
.setCancelable(true)
.create()
.show();
break;
// 取消按钮
case R.id.can_btn:
break;
}
}
}
3案例效果展示
