ContentProvider内容提供者

1.为什么需要内容提供者(ContentProvider)

    [1].如何创建一个数据库，定义一个类继承SqliteOpenHelper

    [2].打开数据库 ：(1)adb shell  (2)cd data/data  (3)ls  (4)cd con.eson.db (5)ls (6)cd databases    (7)ls       (8)sqlite3 数据库名 (9) select * from 表名

    [3]创建数据库例子：

第一步：创建 MyOpenHelper类 继承 SQLiteOpenHelper

package com.eson.db ;

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

public class MyOpenHelper extends SQLiteOpenHelper {

    /**
     *
     * @param context
     * name 数据库的名字
     *
     * factory 游标工厂
     */
    public MyOpenHelper(Context context) {
        super (context , "Account.db" , null, 1 ) ;
    }

    //表结构的初始化
    @Override
    public void onCreate (SQLiteDatabase db) {

        db.execSQL( "create table info(_id integer primary key autoincrement,name varchar(20),money varchar(20))" ) ;
        db.execSQL( "insert into info(name,money) values(?,?)" , new String[]{ "张三" , "5000" }) ;
        db.execSQL( "insert into info(name,money) values(?,?)" , new String[]{ "李四" , "3000" }) ;

    }

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

    }

}

    

第二步：在MainActivity读取数据库

package com.eson.db ;

import android.os.Bundle ;
import android.support.v7.app.AppCompatActivity ;

public class MainActivity extends AppCompatActivity {

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

        MyOpenHelper myOpenHelper = new MyOpenHelper(getApplicationContext()) ;
        myOpenHelper.getReadableDatabase() ;
    }

}

   [4]利用Cursor结果集将数据库内容打印在控制台上

MyOpenHelper myOpenHelper = new MyOpenHelper(getApplicationContext()) ;
SQLiteDatabase database = myOpenHelper.getReadableDatabase() ;

Cursor cursor = database.query( "info" , null, null, null, null, null, null ) ;

if (cursor!= null &&cursor.getCount()> 0 ){
    while (cursor.moveToNext()){

        String name=cursor.getString( 1 ) ;
        String phone=cursor.getString( 2 ) ;
        System. out .println( "name:" +name+ "------" + "phone:" +phone) ;

    }

}

[5]用chcp 65001 命令将cmd编码改为utf-8 

 [6] 用adb shell  ,cd data/data/com.eson.db/databases进入到databases里面,  用chmod 777  Account.db将Account.db的权限修改为可读可写可执行。

[7]使用内容提供者，把私有的数据库暴露出来

2.内容提供者原理

   [1].内容提供者的作用：

   [2].内容提供者将数据封装然后把提供出来，其他应用都可以通过内容解析者(ContentResolver)来访问。

   [3].写一个类去继承内容提供者，实现内容提供者的方法。

3.实现内容提供者步骤

   [1].定义一个类继承ContentProvider

   [2].在清单文件里配置内容提供者

    <provider
    android :authorities= "com.eson.provider"

    android :name=".AccountProvider"></provider>

   [3]定义一个UriMatcher 定义匹配器并且定义静态代码块，定义匹配规则

//定义一个UriMatcher  定义匹配器
private static final UriMatcher sUriMatcher = new UriMatcher(UriMatcher. NO_MATCH ) ;
//定义静态代码块，定义匹配规则

private static final int QUERYSUCCESS = 1 ;

static {

     sUriMatcher.addURI( "com.eson.provider" ,"query", QUERYSUCCESS); }

   [4]在onCreate方法初始化

public boolean onCreate () {

    myOpenHelper = new MyOpenHelper(getContext()) ;

    return false;

}

 

[5].实现query方法

public Cursor query (Uri uri , String[] projection , String selection , String[] selectionArgs , String sortOrder) {

    int code= sUriMatcher .match(uri) ;
    if (code== QUERYSUCCESS ){
        SQLiteDatabase db = myOpenHelper .getReadableDatabase() ;

        db.query( "info" , projection , selection , selectionArgs ,null,null, sortOrder) ;
    } else {

        throw new IllegalArgumentException( "您的路径不匹配，请检查路径" ) ;

    }
    return null;

}

[6]暴露想要暴露的方法(增删改查)

[7]在另外一个应用中查询数据库

Uri uri=Uri. parse( "content://com.esom.provider/query" ) ;

Cursor cursor = getContentResolver().query(uri , null, null, null, null ) ;

if (cursor!= null &&cursor.getCount()> 0 ){

    while (cursor.moveToNext()){
        String name = cursor.getString( 1 ) ;
        String phone = cursor.getString( 2 ) ;

        System. out .println( "name:" +name+ "    " + "phone:" +phone) ;

    }

}

4.备份短信案例

  [1].在content布局里设置按钮

    <Button
        android :onClick= "click"
        android :layout_width= "wrap_content"
        android :layout_height= "wrap_content"
        android :text= "短信备份"
        />

 

  [2].实现按钮的点击事件

//点击按钮 查询短信数据内容 然后进行备份
public void click (View v){
    try {
        //[1]获取xml序列化实例
        XmlSerializer serializer = Xml. newSerializer() ;
        //[2]设置序列化参数

        File file = new File(Environment.getExternalStorageDirectory ().getPath() , "smsBackUp.xml" ) ;
        FileOutputStream fos = new  FileOutputStream(file) ;
        serializer.setOutput(fos , "utf-8" ) ;

        //[3]开始写xml文档开头
        serializer.startDocument( "utf-8" , true ) ;
        //[4]开始写根节点
        serializer.startTag( null, "smss" ) ;
        //[5]由于短信数据库 系统也通过内容提供者给暴露出来了了 所以我们只需要通过内容解析者去操作数据库
        Uri uri = Uri. parse( "content://sms/" ) ;
        Cursor cursor = getContentResolver().query(uri , new String[]{ "address" , "date" , "body" } , null, null, null ) ;
        while (cursor.moveToNext()) {
            String address = cursor.getString( 0 ) ;
            String date = cursor.getString( 1 ) ;
            String body= cursor.getString( 2 ) ;

            //[6]写sms节点

            serializer.startTag( null, "sms" ) ;
            //[7]写address节点
            serializer.startTag( null, "address" ) ;
            serializer.text(address) ;
            serializer.endTag( null, "address" ) ;

            //[8]写body节点
            serializer.startTag( null, "body" ) ;
            serializer.text(body) ;
            serializer.endTag( null, "body" ) ;

            //[9]写date节点
            serializer.startTag( null, "date" ) ;
            serializer.text(date) ;
            serializer.endTag( null, "date" ) ;

            serializer.endTag( null, "sms" ) ;


        }

        serializer.endTag( null, "smss" ) ;
        serializer.endDocument() ;

    } catch (Exception e) {
        e.printStackTrace() ;
    }

}

[ 3].添加权限

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

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

5.利用内容提供者插入短信

  [1]设置按钮布局   

<Button
    android :onClick= "click"
    android :layout_width= "wrap_content"
    android :layout_height= "wrap_content"
    android :text= "插入短信"

    />

  [2]设置按钮点击事件

public void click (View v){
    Uri uri = Uri.parse( "content://sms" ) ;
    ContentValues values = new ContentValues() ;
    values.put( "address" , "95555" ) ;
    values.put( "body" , "您的余额为0.0000元" ) ;
    values.put( "date" , System. currentTimeMillis()) ;
    Uri insert = getContentResolver().insert(uri , values) ;

}

[3].添加权限

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

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

6.读取联系人案例

  [1].在MainActivity中

public class MainActivity extends AppCompatActivity {

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

        List<Contact> readContacts=ReadContactUtils. readContact(getApplicationContext()) ;

         for (Contact contact:readContacts){

             System. out .println( "contact" +contact) ;
         }
    }

}

  [2].创建读取联系人方法

public class ReadContactUtils {
    public static List<Contact> readContact (Context context){
       //创建集合对象
        ArrayList<Contact> contactsLists = new ArrayList<>() ;

        //由于联系人的数据库也是通过内容提供者暴露出来的，所以可以造作数据库直接用内容解析者
        //先查询raw_contacts表 contact_id列
        Uri uri = Uri. parse( "content://com.android.contacts/raw_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()){
            String contact_id = cursor.getString( 0 ) ;
            if (contact_id != null ) {
                System. out .println( "contact_id:" +contact_id) ;
                //创建javabean对象
                Contact contact= new Contact() ;
                contact.setId(contact_id) ;

                //根据raw_contact_id去查询data表   data1列和mimetype_id列
                //小细节 查询的不是data表 查询的是view_data的视图
                Cursor dataCursor = context.getContentResolver().query(dataUri , new String[]{ "data1" , "mimetype" } , "raw_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)){

                        System. out .println( "姓名" +data1) ;
                        contact.setName(data1) ;
                    } else if ( "vnd.android.cursor.item/phone_v2" .equals(mimetype)){
                        System. out .println( "电话号码：" +data1) ;
                        contact.setPhone(data1) ;
                    } else if ( "vnd.android.cursor.item/email_v2" .equals(mimetype)){
                        System. out .println( "邮箱：" +data1) ;
                        contact.setEmail(data1) ;
                    }
                }
                //把javabean对象加入到结合中
                contactsLists.add(contact) ;
            }
        }


        return contactsLists ;
    }

}

[3]javabean对象

public class Contact {
    private String id ;
    private  String email ;
    private String name ;
    private String phone ;

    public String getEmail () {
        return email ;
    }

    public void setEmail (String email) {
        this . email = email ;
    }



    public String getId () {
        return id ;
    }

    public void setId (String id) {
        this . id = id ;
    }

    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 ;
    }

    @Override
    public String toString () {
        return "Contact{" +
                "id='" + id + ' \' ' +
                ", name='" + name + ' \' ' +
                ", phone='" + phone + ' \' ' +
                '}' ;
    }

}

[4].添加权限

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