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

packagecom.eson.db;

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

public class MyOpenHelper extends SQLiteOpenHelper {

    /**
     *
     * @paramcontext
     * 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(?,?)", newString[]{"张三","5000"});
        db.execSQL( "insert into info(name,money) values(?,?)", newString[]{"李四","3000"});

    }

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

    }

}

    

第二步：在MainActivity读取数据库

packagecom.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 =newMyOpenHelper(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 finalUriMatchersUriMatcher=newUriMatcher(UriMatcher.NO_MATCH);
//定义静态代码块，定义匹配规则

private static final intQUERYSUCCESS=1;

static {

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

   [4]在onCreate方法初始化

public booleanonCreate() {

    myOpenHelper = new MyOpenHelper(getContext()) ;

    return false;

}

 

[5].实现query方法

publicCursorquery(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 voidclick(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, newString[]{"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-permissionandroid:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android :name="android.permission.READ_SMS"/>

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

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

6.读取联系人案例

  [1].在MainActivity中

public classMainActivityextendsAppCompatActivity {

    @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 classReadContactUtils {
    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, newString[]{"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=newContact();
                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, newString[]{"data1","mimetype"},"raw_contact_id=?", newString[]{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 classContact {
    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-permissionandroid:name="android.permission.READ_CONTACTS"/>