Android 它们的定义ContentProvider和ContentObserver充分利用

在他们的定义ContentProvider结合ContentObserver一起使用时，自己写的ContentProvider,在运行完insert、delete和update后，要手动地调用getContentResolver().notifyChange()这种方法来通知修改的产生。

直接上代码：

MainActivity

package com.jackie.contentobserver;

import java.util.ArrayList;

import android.net.Uri;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.ContentValues;
import android.database.Cursor;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity {

private ArrayList<Person> mList;
private ListView mListView;
private ContentResolver resolver;
private MyBaseAdapter mBaseAdapter;
private Handler mHandler;

private AdapterContentObserver mAdapterContentObserver;

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

mListView = (ListView) findViewById(R.id.lv_person);
initData();

mBaseAdapter = new MyBaseAdapter(this, mList);
mListView.setAdapter(mBaseAdapter);

mHandler = new Handler();

mAdapterContentObserver = new AdapterContentObserver(this, mHandler);
resolver.registerContentObserver(Uri.parse("content://com.jackie.provider.person/person"), true, mAdapterContentObserver);
//注冊短信变化监听
//this.getContentResolver().registerContentObserver(Uri.parse("content://sms/"), true, content)
}

@Override
protected void onDestroy() {
resolver.unregisterContentObserver(mAdapterContentObserver);
super.onDestroy();
}

private ArrayList<Person> initData() {
mList = new ArrayList<Person>();
resolver = getContentResolver();
Cursor cursor = resolver.query(Uri.parse("content://com.jackie.provider.person/person"), null, null, null, null);
while (cursor.moveToNext()) {
Person person = new Person();
person.set_id(cursor.getInt(cursor.getColumnIndex("_id")));
person.setName(cursor.getString(cursor.getColumnIndex("name")));
mList.add(person);
}

return mList;
}

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

@Override
public boolean onMenuItemSelected(int featureId, MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_settings:
//			AlertDialog.Builder builder = new AlertDialog.Builder(this);
//			builder.setTitle("提示").setMessage("您确定要退出?");
//			builder.create().show();
ContentValues values = new ContentValues();
values.put("name", "Jackie");
Uri mUri = resolver.insert(Uri.parse("content://com.jackie.provider.person/person"), values);

//方法一： 又一次查询数据库实时刷新
//	        mBaseAdapter = new MyBaseAdapter(this, initData());
//	        mListView.setAdapter(mBaseAdapter);

//方法二： 当adapter绑定的list变化时，调用adapter的notifyDataSetChanged方法实时刷新（不用反复查询数据库，效率更高）
//			long id = ContentUris.parseId(mUri);
//			mList.add(new Person(id, "chengjie"));
//			mBaseAdapter.notifyDataSetChanged();

//方法三： 内容观察者ContentObserver
//自己写的ContentProvider,在运行完insert、delete和update后，要手动地调用getContentResolver().notifyChange()这种方法来通知修改的产生(请參考MyProvider.java的方法)

break;

default:
break;
}
return super.onMenuItemSelected(featureId, item);
}

}

AdapterContentObserver.java

package com.jackie.contentobserver;

import android.content.ContentResolver;
import android.content.Context;
import android.database.ContentObserver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Handler;
import android.util.Log;
import android.widget.Toast;

public class AdapterContentObserver extends ContentObserver {
private Context context;
private Handler handler;

private static final int PERSON_UPDATE = 0;

public AdapterContentObserver(Handler handler) {
super(handler);
// TODO Auto-generated constructor stub
}

public AdapterContentObserver(Context context, Handler handler) {
super(handler);
this.context = context;
this.handler = handler;
}

//当监听的Uri发生变化。便会运行这种方法
@Override
public void onChange(boolean selfChange, Uri uri) {
super.onChange(selfChange, uri);

ContentResolver resolver = context.getContentResolver();
// 获取最新的一条数据
Cursor cursor = resolver.query(uri, null, null, null, "_id desc limit 1");
while (cursor.moveToNext()) {
int _id = cursor.getInt(cursor.getColumnIndex("_id"));
Toast.makeText(context, "数据库更新了, _id 为： " + _id, Toast.LENGTH_SHORT).show();
}
cursor.close();
}
}

DBHelper.java

package com.jackie.contentobserver;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {

public DBHelper(Context context, String name, CursorFactory factory,
int version) {
super(context, name, factory, version);
// TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table if not exists person(_id integer primary key autoincrement, name text)");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

}

MyBaseAdapter.java

package com.jackie.contentobserver;

import java.util.ArrayList;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class MyBaseAdapter extends BaseAdapter {

private ViewHolder holder;
private Context context;
private ArrayList<Person> mList;

public MyBaseAdapter(Context context, ArrayList<Person> mList) {
this.context = context;
this.mList = mList;
}

@Override
public int getCount() {
return mList.size();
}

@Override
public Object getItem(int position) {
return mList.get(position);
}

@Override
public long getItemId(int position) {
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater mInflater = LayoutInflater.from(context);
if (convertView == null) {
holder = new ViewHolder();
convertView = mInflater.inflate(R.layout.listview_item, null);
holder.idTexitView = (TextView) convertView.findViewById(R.id.tv_id);
holder.nameTextView = (TextView) convertView.findViewById(R.id.tv_name);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.idTexitView.setText(mList.get(position).get_id() + "");
holder.nameTextView.setText(mList.get(position).getName());
return convertView;
}

class ViewHolder {
TextView idTexitView;
TextView nameTextView;
}
}

MyProvider.java

package com.jackie.contentobserver;

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;

public class MyProvider extends ContentProvider {
private final static String AUTHORITH = "com.jackie.provider.person";

private final static String PERSONS_PATH = "person";

private final static String PERSON_PATH = "person/#";

private final static int PERSON = 1;

private final static int PERSONS = 2;

private final static String DATABASE_NAME = "person_db";

private final static String TABLE_NAME = "person";

private final static String TABLE_COLUMN_ID = "_id";

private final static String TABLE_COLUMN_NAME = "name";

private final static UriMatcher mUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

static {
mUriMatcher.addURI(AUTHORITH, PERSONS_PATH, PERSONS);
mUriMatcher.addURI(AUTHORITH, PERSON_PATH, PERSON);
}

private DBHelper helper = null;

@Override
public boolean onCreate() {
helper  = new DBHelper(getContext(), DATABASE_NAME, null, 1);
return true;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteDatabase database = helper.getWritableDatabase();
switch (mUriMatcher.match(uri)) {
case PERSON:
long id = ContentUris.parseId(uri);
String where = TABLE_COLUMN_ID + "=" + id;
if (selection != null && !"".equals(selection)) {
selection = where + "and" + selection;
}
return database.query(TABLE_NAME, projection, selection, selectionArgs, null, null, sortOrder);

case PERSONS:
return database.query(TABLE_NAME, projection, selection, selectionArgs, null, null, sortOrder);

default:
throw new IllegalArgumentException("UnKnown uri: " + uri);
}
}

@Override
public String getType(Uri uri) {
switch (mUriMatcher.match(uri)) {
case PERSON:
return "vnd.android.cursor.item";

case PERSONS:
return "vnd.android.cursor.dir";

default:
throw new IllegalArgumentException("UnKnown uri: " + uri);
}
}

@Override
public Uri insert(Uri uri, ContentValues values) {
SQLiteDatabase database = helper.getWritableDatabase();
long id = database.insert(TABLE_NAME, TABLE_COLUMN_NAME, values);
//向外界通知该ContentProvider里的数据发生了变化 ,以便ContentObserver作出对应
getContext().getContentResolver().notifyChange(uri, null);
return ContentUris.withAppendedId(uri, id);
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
SQLiteDatabase database = helper.getWritableDatabase();
switch (mUriMatcher.match(uri)) {
case PERSON:
long id = ContentUris.parseId(uri);
String where = TABLE_COLUMN_ID + "=" + id;
if (selection != null && !"".equals(selection)) {
selection = where + "and" + selection;
}
return database.delete(TABLE_NAME, selection, selectionArgs);

case PERSONS:
return database.delete(TABLE_NAME, selection, selectionArgs);

default:
throw new IllegalArgumentException("UnKnown uri: " + uri);
}
}

@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// TODO Auto-generated method stub
return 0;
}

}

Person.java

package com.jackie.contentobserver;

public class Person {

private long _id;
private String name;
public Person(long _id, String name) {
super();
this._id = _id;
this.name = name;
}

public Person() {
super();
// TODO Auto-generated constructor stub
}

public long get_id() {
return _id;
}

public void set_id(long _id) {
this._id = _id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

}