ContentProvider 使用详解
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本篇文章主要介绍 Android 开发中的部分知识点，通过阅读本篇文章，您将收获以下内容:
- ContentProvider
- 获取联系人信息的方法
- 获取短信内容的方法
- ContentResolver 内容解析者
- ContentObserver 内容观察者
- ContentProvider ContentResolver ContentObserver 三者关系
ContentProvider 是Android 四大组件之一，其本质上是一个标准化的数据管道，它屏蔽了底层的数据管理和服务等细节，以标准化的方式在Android 应用间共享数据。用户可以灵活实现ContentProvider 所封装的数据存储以及增删改查等，所有的ContentProvider 必须实现一个对外统一的接口（URI）。
1. ContentProvider 实现
ContentProvider 继承关系
java.lang.Object
↳ android.content.ContentProvider
四大组件之一，必须在Androidmainfest.xml 中注册
<provider
android:name="com.programandroid.CustomContentProviderMethod"
android:authorities="ProgramAndroid"
android:exported="true" />
注意 :
URI 中的元素
android:authorities="ProgramAndroid"
继承 ContentProvider 实现增删改查等方法
package com.programandroid.ContentProvider;
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;
import android.support.annotation.Nullable;
/*
* ContentProviderMethod.java
*
* Created on: 2017-9-13
* Author: wangjie
*
* Welcome attention to weixin public number get more info
*
* WeiXin Public Number : ProgramAndroid
* 微信公众号 ：程序员Android
*
*/
public class CustomContentProviderMethod extends ContentProvider {
private SQLiteDatabase db;
private static final String MAUTHORITIESNAME = "ProgramAndroid";
private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
private static final int PERSON = 1;
private static final int PERSON_NUMBER = 2;
private static final int PERSON_TEXT = 3;
private static final String TABLE_NAME = "table_person";
// 构建URI
static {
// content://programandroid/person
matcher.addURI(MAUTHORITIESNAME, "person", PERSON);
// # 代表任意数字content://programandroid/person/4
matcher.addURI(MAUTHORITIESNAME, "person/#", PERSON_NUMBER);
// * 代表任意文本 content://programandroid/person/filter/ssstring
matcher.addURI(MAUTHORITIESNAME, "person/filter/*", PERSON_TEXT);
}
@Override
public boolean onCreate() {
DBHelper helper = new DBHelper(getContext());
// 创建数据库
db = helper.getWritableDatabase();
return true;
}
@Nullable
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// 过滤URI
int match = matcher.match(uri);
switch (match) {
case PERSON:
// content://autoname/person
return db.query(TABLE_NAME, projection, selection, selectionArgs,
null, null, sortOrder);
case PERSON_NUMBER:
break;
case PERSON_TEXT:
break;
default:
break;
}
return null;
}
@Nullable
@Override
public Uri insert(Uri uri, ContentValues values) {
// 过滤URI
int match = matcher.match(uri);
switch (match) {
case PERSON:
// content://autoname/person
long id = db.insert(TABLE_NAME, null, values);
// 将原有的uri跟id进行拼接从而获取新的uri
return ContentUris.withAppendedId(uri, id);
case PERSON_NUMBER:
break;
case PERSON_TEXT:
break;
default:
break;
}
return null;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
return 0;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
return 0;
}
@Nullable
@Override
public String getType(Uri uri) {
return null;
}
}
提供对外提供操作的数据库方法
package com.programandroid.ContentProvider;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
/*
* DBHelper.java
*
* Created on: 2017-9-13
* Author: wangjie
*
* Welcome attention to weixin public number get more info
*
* WeiXin Public Number : ProgramAndroid
* 微信公众号 ：程序员Android
*
*/
public class DBHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "persons.db";
private static final int DB_VERSION = 1;
private static final String TABLE_NAME = "table_person";
private static final String ID = "_id";
private static final String NAME = "name";
public DBHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql = "CREATE TABLE " + TABLE_NAME + "(" + ID
+ " INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL" + "," + NAME
+ " CHAR(10) )";
db.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
其他APK 访问此ContentProvider 数据库的方法
public class MainActivity extends Activity {
private String uri = "content://ProgramAndroid/person";
private EditText mEditText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mEditText = (EditText) findViewById(R.id.ed_name);
}
public void QureyData(View view) {
String name = null;
Cursor cursor = getContentResolver().query(Uri.parse(uri), null, null, null, null);
while (cursor.moveToNext()) {
name = cursor.getString(cursor.getColumnIndex("name"));
}
mEditText.setText(name);
}
public void InsertData(View view) {
String editName = mEditText.getText().toString();
ContentValues values = new ContentValues();
values.put("name, editName);
Uri result = getContentResolver().insert(Uri.parse(uri), values);
// 注意 ： 此条添加上才ContentObserver可以监听数据库改变
getContentResolver().notifyChange(Uri.parse(uri),null);
long parseid = ContentUris.parseId(result);
if (parseid > 0) {
Toast.makeText(MainActivity.this, "保存成功", Toast.LENGTH_LONG).show();
mEditText.setText("");
}
}
}
注意 ：
// 此条添加上才ContentObserver可以监听数据库改变
getContentResolver().notifyChange(Uri.parse(uri),null);
至此，自定义ContentProvider的使用方法已经实现。
2. 获取联系人信息的方法
Android 系统自带一下ContentProvider ,比如 联系人
例如： 源码 packages\providers 下的内容
本段主要实现获取系统联系人(ContactProvider)提供的一些信息
获取联系人实现方法
public class ContactListActivity extends Activity {
private static final String tag = "ContactListActivity";
private ListView lv_contact_list;
private List<HashMap<String, String>> mContactList = new ArrayList<HashMap<String, String>>();
private Handler mHandler = new Handler() {
public void handleMessage(android.os.Message msg) {
// 给数据适配器设置数据
MyAdapter myAdapter = new MyAdapter();
TextView emptyView = new TextView(getApplicationContext());
emptyView.setLayoutParams(new LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
emptyView.setText(getResources().getString(
R.string.please_add_contanct));
emptyView.setVisibility(View.GONE);
emptyView.setTextColor(Color.BLACK);
emptyView.setTextSize(20);
emptyView.setGravity(Gravity.CENTER);
((ViewGroup) lv_contact_list.getParent()).addView(emptyView);
lv_contact_list.setEmptyView(emptyView);
lv_contact_list.setAdapter(myAdapter);
};
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact_list);
initUI();
initData();
}
/**
* 从系统数据库中获取联系人数据,权限,读取联系人
*/
private void initData() {
new Thread() {
public void run() {
// 1,获取内容解析器(访问地址(后门))
ContentResolver contentResolver = getContentResolver();
// 2,对数据库指定表进行查询操作
Cursor cursor = contentResolver.query(Uri
.parse("content://com.android.contacts/raw_contacts"),
new String[] { "contact_id" }, null, null, null);
// 3,判断游标中是否有数据,有数据一直度
while (cursor.moveToNext()) {
String id = cursor.getString(0);
Log.i(tag, "id = " + id);// 1,2,3
// 4,通过此id去关联data表和mimetype表生成视图,data1(数据),mimetype(数据类型)
Cursor indexCursor = contentResolver.query(
Uri.parse("content://com.android.contacts/data"),
new String[] { "data1", "mimetype" },
"raw_contact_id = ?", new String[] { id }, null);
HashMap<String, String> hashMap = new HashMap<String, String>();
// 5,游标向下移动获取数据过程
while (indexCursor.moveToNext()) {
String data = indexCursor.getString(0);
String type = indexCursor.getString(1);
// Log.i(tag, "data = "+data);
// Log.i(tag, "type = "+type);
if (type.equals("vnd.android.cursor.item/phone_v2")) {
// data就为电话号码
hashMap.put("phone", data);
} else if (type.equals("vnd.android.cursor.item/name")) {
// data 为联系人名字
hashMap.put("name", data);
}
}
indexCursor.close();
mContactList.add(hashMap);
}
cursor.close();
// 告知主线程集合中的数据以及准备完毕,可以让主线程去使用此集合,填充数据适配器
mHandler.sendEmptyMessage(0);
};
}.start();
}
private void initUI() {
lv_contact_list = (ListView) findViewById(R.id.lv_contact_list);
lv_contact_list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// 1,position点中条目的索引值,集合的索引值
String phone = mContactList.get(position).get("phone");
// 2,将此电话号码传递给前一个界面
Intent intent = new Intent();
intent.putExtra("phone", phone);
setResult(0, intent);
// 3,关闭此界面
finish();
}
});
}
class MyAdapter extends BaseAdapter {
@Override
public int getCount() {
return mContactList.size();
}
@Override
public HashMap<String, String> getItem(int position) {
return mContactList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Holder holder;
if (convertView == null) {
holder = new Holder();
// 1,生成当前listview一个条目相应的view对象
convertView = View.inflate(getApplicationContext(),
R.layout.list_item_contact, null);
// 2,找到view中的控件
holder.tv_name = (TextView) convertView
.findViewById(R.id.tv_name);
holder.tv_phone = (TextView) convertView
.findViewById(R.id.tv_phone);
convertView.setTag(holder);
} else {
holder = (Holder) convertView.getTag();
}
// 3,给控件赋值
holder.tv_name.setText(getItem(position).get("name"));
holder.tv_phone.setText(getItem(position).get("phone"));
return convertView;
}
}
class Holder {
public TextView tv_name;
public TextView tv_phone;
}
}
ListView 显示布局如下
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ListView
android:id="@+id/lv_contact_list"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</ListView>
</LinearLayout>
item 布局如下：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:orientation="vertical" >
<TextView
android:text="联系人名称"
android:id="@+id/tv_name"
android:textSize="18sp"
android:textColor="@color/black"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView
android:text="联系人电话号码"
android:id="@+id/tv_phone"
android:textSize="18sp"
android:textColor="@color/grey"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
注意：
获取联系人需要申请权限
<!-- 读取联系人的权限 -->
<uses-permission android:name="android.permission.READ_CONTACTS" />
至此，已经可以获取并显示联系人信息。
3.获取短信内容的方法
短信内容数据也是Android 系统提供的，获取方法如下：
- 获取方法如下
package com.programandroid.ContentProvider;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.widget.CursorAdapter;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import android.widget.TextView;
import com.programandroid.MainActivity;
import com.programandroid.R;
/*
* MmsListActivity.java
*
* Created on: 2017-9-13
* Author: wangjie
*
* Welcome attention to weixin public number get more info
*
* WeiXin Public Number : ProgramAndroid
* 微信公众号 ：程序员Android
*
*/
public class MmsListActivity extends Activity {
private ContentResolver resolver;
private ListView listView;
private static final String SMS_URI = "content://sms";
private Cursor cursor;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mms_list);
listView = (ListView) findViewById(R.id.lv_mms);
resolver = getContentResolver();
}
public void GetMMSBtn(View view) {
// 插入数据
ContentValues values = new ContentValues();
values.put("address", "136259");
values.put("body", "测试数据中。。。。。");
resolver.insert(Uri.parse(SMS_URI), values);
// 查询数据方法
cursor = resolver.query(Uri.parse(SMS_URI), null, null, null, null);
// 将数据显示到ListView中
listView.setAdapter(new MyAdapter(MmsListActivity.this, cursor,
CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER));
}
@Override
protected void onDestroy() {
super.onDestroy();
if (cursor != null) {
// 关闭cursor
// cursor.close();
}
}
class MyAdapter extends CursorAdapter {
public MyAdapter(Context context, Cursor c, int flags) {
super(context, c, flags);
}
// 创建一个视图，引入listview要展示的子视图
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
return getLayoutInflater().inflate(R.layout.list_item_mms, null);
}
// 绑定数据的方法
@Override
public void bindView(View view, Context context, Cursor cursor) {
TextView tvNumber = (TextView) view.findViewById(R.id.tv_number);
TextView tvContent = (TextView) view.findViewById(R.id.tv_content);
TextView tvState = (TextView) view.findViewById(R.id.tv_state);
TextView tvDate = (TextView) view.findViewById(R.id.tv_date);
TextView tvId = (TextView) view.findViewById(R.id.tv_id);
TextView tvRead = (TextView) view.findViewById(R.id.tv_read);
String number = cursor.getString(cursor.getColumnIndex("address"));
String body = cursor.getString(cursor.getColumnIndex("body"));
String date = cursor.getString(cursor.getColumnIndex("date"));
int read = cursor.getInt(cursor.getColumnIndex("read"));
int id = cursor.getInt(cursor.getColumnIndex("_id"));
int type = cursor.getInt(cursor.getColumnIndex("type"));
if (read == 0) {
tvRead.setText("短信状态：未读");
} else {
tvRead.setText("短信状态：已读");
}
tvNumber.setText("手机号：" + number);
tvContent.setText("短信内容：" + body);
tvDate.setText("接收短信时间:" + date);
tvId.setText("短信Id：" + id);
if (type == 1) {
tvState.setText("短信状态：已接收");
} else {
tvState.setText("短信状态：已发送");
}
}
}
}
ListView 布局如下
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ListView
android:id="@+id/lv_mms"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
item 布局如下：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/tv_number"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_state"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_date"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
<TextView
android:id="@+id/tv_read"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="ddd" />
</LinearLayout>
4. ContentResolver 内容解析者
ContentResolver 主要是通过URI调用getContentResolver()获取ContentProvider 提供的数据接口，进而进行增删改查等操作。
// 查询
Cursor cursor = getContentResolver().query(Uri.parse(uri), null, null, null, null);
// 插入数据到指定 URI 中
getContentResolver().insert(Uri.parse(uri), ContentValues);
5.ContentObserver 内容观察者
ContentObserver 内容观察者通过指定URI 监听ContentProvider数据是否改变。
自定义 ContentObserver 内容观察者
1.注册ContentObserver 内容观察者 registerContentObserver
/**
* 监听ContentProvider数据库变化
*/
private void ContentObserverDatabase() {
// [1]注册内容观察者
Uri uri = Uri.parse("content://ProgramAndroid/person");
// false 观察的uri 必须是一个确切的uri 如果是true
getContentResolver().registerContentObserver(uri, true,
new CustomContentObserver(new Handler()));
}
2.继承 ContentObserver 实现 onChange方法
package com.programandroid.ContentProvider;
import android.database.ContentObserver;
import android.os.Handler;
/*
* CustomContentObserver.java
*
* Created on: 2017-9-13
* Author: wangjie
*
* Welcome attention to weixin public number get more info
*
* WeiXin Public Number : ProgramAndroid
* 微信公众号 ：程序员Android
*
*/
public class CustomContentObserver extends ContentObserver {
/**
* @param handler
*/
public CustomContentObserver(Handler handler) {
super(handler);
// TODO Auto-generated constructor stub
}
// 当我们观察的uri发生改变的时候调用
@Override
public void onChange(boolean selfChange) {
System.out.println(" 数据库被操作了 ");
super.onChange(selfChange);
}
}
至此自定义内容观察者已经实现完成
调用ContentObserver 监听短信数据改变
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//[1]注册一个内容观察者
Uri uri = Uri.parse("content://sms/");
getContentResolver().registerContentObserver(uri, true, new MyContentObserver(new Handler()));
}
private class MyContentObserver extends ContentObserver{
public MyContentObserver(Handler handler) {
super(handler);
}
//当观察的内容发生改变的时候调用
@Override
public void onChange(boolean selfChange) {
System.out.println(" 短信的数据库发生了改变");
super.onChange(selfChange);
}
}
6. ContentProvider ContentResolver ContentObserver 三者关系
- 三者关系图如下
至此，本篇已结束，如有不对的地方，欢迎您的建议与指正。同时期待您的关注，感谢您的阅读，谢谢！
