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

<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"/>
    
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>


<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）

<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" >

    

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

    
    

    <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: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.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 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 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 list = new ArrayList();
        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

<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" />
    
   <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>