android content provider(内容提供者） 学习总结

**

content provider 是什么？干什么？

**

当应用继承ContentProvider类，并重写该类用于提供数据和存储数据的方法，就可以向其他应用共享其数据。虽然使用其他方法也可以对外共享数据，但数据访问方式会因数据存储的方式而不同，而使用ContentProvider共享数据的好处是统一了数据访问方式。

简单直白的说就是把一个应用的数据暴露给其他应用使用，不过实际开发中一般不会把自己应用的数据暴露出来，所以往往是使用该类访问系统的短信 联系人等应用数据

**

小实验

**

短信备份和向短信应用的数据库中插入短信

配置文件如下

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.alleged.smsoperate"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />

<uses-permission android:name="android.permission.READ_SMS" />
<uses-permission android:name="android.permission.WRITE_SMS"/>
<!-- 在SDCard中创建与删除文件权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>

<!-- 往SDCard写入数据权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

</manifest>

布局文件layout(使用了fragment）

<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.alleged.smsoperate.MainActivity" >

<!--
As the main content view, the view below consumes the entire
space available using match_parent in both dimensions.
-->

<FrameLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" />

<!--
android:layout_gravity="start" tells DrawerLayout to treat
this as a sliding drawer on the left side for left-to-right
languages and on the right side for right-to-left languages.
If you're not building against API 17 or higher, use
android:layout_gravity="left" instead.
-->
<!--
The drawer is given a fixed width in dp and extends the full height of
the container.
-->

<fragment
android:id="@+id/navigation_drawer"
android:name="com.alleged.smsoperate.NavigationDrawerFragment"
android:layout_width="@dimen/navigation_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
tools:layout="@layout/fragment_navigation_drawer" />

</android.support.v4.widget.DrawerLayout>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:
4000
paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.alleged.smsoperate.MainActivity$PlaceholderFragment" >

<TextView
android:id="@+id/section_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

<Button
android:id="@+id/insertSms"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/section_label"
android:layout_centerHorizontal="true"
android:layout_marginTop="49dp"
android:text="插入短信"
android:onClick="insert" />

<Button
android:id="@+id/copySms"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/insertSms"
android:layout_below="@+id/insertSms"
android:layout_marginTop="111dp"
android:text="短信备份"
android:onClick="copy" />

</RelativeLayout>

<ListView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#cccc"
android:choiceMode="singleChoice"
android:divider="@android:color/transparent"
android:dividerHeight="0dp"
tools:context="com.alleged.smsoperate.NavigationDrawerFragment" />

具体的实现类 copy()方法和insert()实现了相应的类

package com.alleged.smsoperate;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import org.xmlpull.v1.XmlSerializer;

import android.app.Activity;
import android.support.v7.app.ActionBarActivity;
import android.util.Xml;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.widget.DrawerLayout;
import android.widget.ArrayAdapter;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity implements NavigationDrawerFragment.NavigationDrawerCallbacks {

/**
* Fragment managing the behaviors, interactions and presentation of the
* navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;

/**
* Used to store the last screen title. For use in
* {@link #restoreActionBar()}.
*/
private CharSequence mTitle;

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

mNavigationDrawerFragment = (NavigationDrawerFragment) getSupportFragmentManager()
.findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();

// Set up the drawer.
mNavigationDrawerFragment.setUp(R.id.navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout));

}
//点击后向系统短信应用插入一条短信
public void insert(View v){
/*  实现逻辑
* 实现内容解析者
* 创建出来ContentValues对象承载内容*/
//具体实现
Uri uri = Uri.parse("content://sms/");
ContentValues newSms = new ContentValues();
//这里的key代表你要插入数据库表的列名  values代表要插入的值
newSms.put("address", "13054569999");
newSms.put("body", "晚上小树林见");
newSms.put("date", System.currentTimeMillis());
//通过内容解析者调用系统的短信的插入方法
getContentResolver().insert(uri, newSms);
System.out.println("插入成功");
}
/*短信备份
* 实现逻辑
* 通过ContentResolver对象（内容解析器）调用查询方法
* 把查询到的结果保存到xml文件中
* */
public void copy(View v){
try {
//1 判断保存短信的xml文件是否存在，不存在就创建
File file = new File(Environment.getExternalStorageDirectory().getPath(),"smsbackup.xml");
if(!file.exists()){
try {
file.createNewFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//获取文件的输出流
FileOutputStream fos = new FileOutputStream(file);
//获取XmlSerializer类对象帮助操作文件
XmlSerializer xmlserializer = Xml.newSerializer();
//设置序列化参数
xmlserializer.setOutput(fos, "utf-8");
//设置文档的开头
xmlserializer.startDocument("utf-8", true);
//写xml的根节点  第一个参数是命名空间 是节点名
xmlserializer.startTag(null, "smss");
//构建url
Uri uri = Uri.parse("content://sms/");
//第一个参数代表从那里查 2 代表查询的列 3 代表查询的条件 4代表查询的参数 5 排序方式
Cursor reslut = getContentResolver().query(uri, new String[]{"address","date","body"}, null, null, null);
while(reslut.moveToNext()){
xmlserializer.startTag(null, "sms");
String address = reslut.getColumnName(0);
String date = reslut.getColumnName(1);
String body = reslut.getColumnName(2);
xmlserializer.startTag(null, "address");
xmlserializer.text(address);
xmlserializer.endTag(null, "address");
xmlserializer.startTag(null, "date");
xmlserializer.text(date);
xmlserializer.endTag(null, "date");
xmlserializer.startTag(null, "body");
xmlserializer.text(body);
xmlserializer.endTag(null, "body");
xmlserializer.endTag(null, "sms");
}
xmlserializer.endTag(null, "smss");
xmlserializer.endDocument();
fos.close();
System.out.println("备份完成");

} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//
}
@Override
public void onNavigationDrawerItemSelected(int position) {
// update the main content by replacing fragments
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.container, PlaceholderFragment.newInstance(position + 1))
.commit();
}

public void onSectionAttached(int number) {
switch (number) {
case 1:
mTitle = getString(R.string.title_section1);
break;
case 2:
mTitle = getString(R.string.title_section2);
break;
case 3:
mTitle = getString(R.string.title_section3);
break;
}
}

public void restoreActionBar() {
ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
if (!mNavigationDrawerFragment.isDrawerOpen()) {
// Only show items in the action bar relevant to this screen
// if the drawer is not showing. Otherwise, let the drawer
// decide what to show in the action bar.
getMenuInflater().inflate(R
11d2a
.menu.main, menu);
restoreActionBar();
return true;
}
return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}

/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";

/**
* Returns a new instance of this fragment for the given section number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}

public PlaceholderFragment() {
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}

@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(getArguments().getInt(ARG_SECTION_NUMBER));
}
}
}

读取联系人和插入联系人

*这里要注意联系人的数据库是比较特殊的，标识用户的主键是存放在contacts表中，联系人的信息是以列的形式存放在data表中data1列中，区分各个信息是使用mimetype列的值

*小细节

还有就是联系人的id在两张表里的名称也是一样，在contacts表中叫做contact_id,在data表中是raw_contact_id。一定要注意***。*

代码如下

package com.alleged.contacts;

import android.support.v7.app.ActionBarActivity;

import java.util.List;

import com.alleged.ContentResolver.contactsResolver;
import com.alleged.javaBean.contacts;

import android.content.Context;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity {
private Context context;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = this;
/*
* 业务逻辑 创建出来一个类，提供两个方法，查看联系人返回一个集合 插入一个联系人，返回boolean
*/
}
//插入联系人  从控件上取得值传入到contactsResolver 的insert方法中实现添加
public void insertContacts(View v) {
EditText name = (EditText) findViewById(R.id.contactsName);
EditText phone = (EditText) findViewById(R.id.contactsPhone);
EditText email = (EditText) findViewById(R.id.contactsEmail);
String contactsname = name.getText().toString().trim();
String contactsphone = phone.getText().toString().trim();
String contactsemail = email.getText().toString().trim();
if (contactsemail != null && contactsname != null && contactsphone != null) {
contactsResolver re = new contactsResolver(context);
boolean success = re.insert(contactsname, contactsphone, contactsemail);
if (success) {
Toast.makeText(context, "添加成功", 0).show();
} else {
Toast.makeText(context, "添加失败", 0).show();
}
}else{
Toast.makeText(context, "添加内容为空", 0).show();
}
}

public void lookContacts(View v) {
List<contacts> list = new contactsResolver(context).look();
if (!list.isEmpty()) {
for (contacts item : list) {
System.out.println(item.getName() + "\t" + item.getPhone() + "\t" + item.getEmail());
}
} else {
System.out.println("联系人为空");
}
}

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

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}

实现类 contactsResolver

package com.alleged.ContentResolver;

import java.util.ArrayList;
import java.util.List;

import com.alleged.javaBean.contacts;

import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;

public class contactsResolver {

private Context context;

public contactsResolver(Context context) {
this.context = context;
}

public boolean insert(String name,String phone,String email){
//把传过来的数据插入到数据库中
/*业务逻辑
*  [1]先往row_contacts表插入数据   contact_id
[2]在往data表里面插入数据  data1
*/
Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");
Uri dauri = Uri.parse("content://com.android.contacts/data");
//插入contact_id前先查询有多少条数据，contact_id就是数据量加一
ContentResolver contentResolver = context.getContentResolver();
Cursor couser = contentResolver.query(uri, null, null, null, null);
int id = couser.getCount()+1;
ContentValues values = new ContentValues();
//插入联系人的id
values.put("contact_id",id);
//先向row_contacts表添加上联系人
contentResolver.insert(uri, values);

//把name phone email添加到data
ContentValues content = new ContentValues();
content.put("data1", name);
//☆ ☆ ☆ ☆ ☆ 插入的数据要告诉数据库 属于第几条联系人  和  数据类型
content.put("raw_contact_id", id);
content.put("mimetype", "vnd.android.cursor.item/name");
context.getContentResolver().insert(dauri, content);

ContentValues phoneValues = new ContentValues();
phoneValues.put("data1", phone);
phoneValues.put("mimetype", "vnd.android.cursor.item/phone_v2");
phoneValues.put("raw_contact_id", id);
contentResolver.insert(dauri, phoneValues);

ContentValues emailValues = new ContentValues();
emailValues.put("data1", email);
emailValues.put("mimetype", "vnd.android.cursor.item/email_v2");
emailValues.put("raw_contact_id", id);
contentResolver.insert(dauri, emailValues);
return true;
}
public List<contacts> look() {
if(context!=null){
// 1 查询row_contacts表的 contact_id列 获取到共有多少个联系人对象
ContentResolver contacts = context.getContentResolver();
// 第一个参数 要查看的数据库的某张表 第二个 查询的列 第三个 查询的条件 第四个 查询的方式 第五个 排序方式
Uri uri = Uri.parse("content://com.android.contacts/raw_contacts");
List<contacts> list = new ArrayList<contacts>();
Uri datauri = Uri.parse("content://com.android.contacts/data");
Cursor cursor = context.getContentResolver().query(uri,new String[]{"contact_id"} , null, null, null);
while (cursor.moveToNext()) {
// 取得当前的联系人id
String contact_id = cursor.getString(0);
if(contact_id!=null){
contacts Contact = new contacts();
// 如果联系人id 不为空 查询data表 取得数据
Cursor datacursor = contacts.query(datauri, new String[] { "data1", "mimetype" }, "contact_id=?",
new String[] { contact_id }, null);
while (datacursor.moveToNext()) {
String data1 = datacursor.getString(0);
String mimetype = datacursor.getString(1);

if ("vnd.android.cursor.item/name".equals(mimetype)) {
Contact.setName(data1);
} else if ("vnd.android.cursor.item/phone_v2".equals(mimetype)) {
Contact.setPhone(data1);
} else if ("vnd.android.cursor.item/email_v2".equals(mimetype)) {
Contact.setEmail(data1);
}
}
list.add(Contact);
}
}
return list;
}else{
System.out.println("context is null!!");
return null;
}
}
}

联系人的javaBean对象

package com.alleged.javaBean;

public class contacts {
private String name;
private String phone;
private String email;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}

布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context="com.alleged.contacts.MainActivity" >
<EditText
android:id="@+id/contactsName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入联系人姓名"
/>
<EditText
android:id="@+id/contactsPhone"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入电话号码"
/>
<EditText
android:id="@+id/contactsEmail"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入联系人邮箱"
/>
<Button
android:id="@+id/insertContacts"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:onClick="insertContacts"
android:text="添加联系人"
/>
<Button
android:id="@+id/lookContacts"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:onClick="lookContacts"
android:text="查看联系人"/>

</LinearLayout>

配置文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.alleged.contacts"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />
<!-- 读写联系人权限 -->
<uses-permission android:name="android.permission.SEND_DOWNLOAD_COMPLETED_INTENTS" />
<uses-permission android:name="android.permission.READ_CONTACTS"/>
<uses-permission android:name="android.permission.WRITE_CONTACTS"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

</manifest>