Android使用内容提供者实现增删改查操作

这里需要建立两个项目:SiYouShuJuKu(使用内容提供者暴露相关的操作),DQDYGApplication(使用内容解析者对第一个应用进行相关的解析)

A.第一个项目:SiYouShuJuKu

结构图如下:

AccountProvider:

package com.demo.siyoushujuku;

import android.content.ContentProvider;

import android.content.ContentValues;

import android.content.UriMatcher;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.net.Uri;

public class AccountProvider extends ContentProvider {

    //1.定义一个urimatcher 定义路径匹配器

    private static final UriMatcher sURIMatcher = new UriMatcher(UriMatcher.NO_MATCH);

    private static final int QUERYSUCCESS = 0;

    private static final int INSERTSUCCESS = 1;

    private static final int UPDATESUCCESS = 2;

    private static final int DELETESUCCESS = 3;

    private MyOpenHelper myOpenHelper;

//    c+s+U 变大写

    //2.定义静态代码块 添加匹配规则

    static {

        /**

         * authority:

         * 要和你在清单文件定义的一样

         *

         * uri:http://com.provider/query

         *

         *

         */

        sURIMatcher.addURI("com.provider", "query", QUERYSUCCESS);

        sURIMatcher.addURI("com.provider", "insert", INSERTSUCCESS);

        sURIMatcher.addURI("com.provider", "update", UPDATESUCCESS);

        sURIMatcher.addURI("com.provider", "delete", DELETESUCCESS);

        //3.写一个静态代码块 添加匹配规则

    }

    @Override

    public boolean onCreate() {

        myOpenHelper = new MyOpenHelper(getContext());

        return false;

    }

    //查询

    @Override

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

        int code = sURIMatcher.match(uri);

        if (code == QUERYSUCCESS) {

            //说明路径匹配成功

            // 把query方法实现一下 数据库查询 对数据库进行查询 想操作数据库

            SQLiteDatabase db = myOpenHelper.getReadableDatabase();

            Cursor cursor = db.query("info", projection, selection, selectionArgs,

                    null, null, sortOrder

            );

            //注意cursor不能关 在这里

            return cursor;

        } else {

            //路径不匹配

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

        }

//        return null;

    }

    @Override

    public String getType(Uri uri) {

        return null;

    }

    @Override

    public Uri insert(Uri uri, ContentValues values) {

        int code = sURIMatcher.match(uri);

        if(code == INSERTSUCCESS){

            //操作数据库

            SQLiteDatabase db = myOpenHelper.getReadableDatabase();

            //代表新插入行数的id

            long insert = db.insert("info", null, values);

            Uri uri2 = Uri.parse("com.insert/"+insert);

            System.out.println("insert==>"+insert);

            return uri2;

        }else{

            //路径不匹配

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

        }

    }

    @Override

    public int delete(Uri uri, String selection, String[] selectionArgs) {

        int code = sURIMatcher.match(uri);

        if(code == DELETESUCCESS){

            //说明路径匹配成功,对数据库进行删除的操作

            SQLiteDatabase db = myOpenHelper.getReadableDatabase();

            //这里代表影响的行数

            int delete = db.delete("info", selection, selectionArgs);

            return delete;

        }else{

            //路径不匹配

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

        }

    }

    @Override

    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {

        int code = sURIMatcher.match(uri);

        if(code == UPDATESUCCESS){

            //说明路径匹配成功,对数据库进行删除的操作

            SQLiteDatabase db = myOpenHelper.getReadableDatabase();

            //这里代表影响的行数

            int update = db.update("info", values,selection, selectionArgs);

            return update;

        }else{

            //路径不匹配

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

        }

    }

}

MainActivity:

package com.demo.siyoushujuku;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.LayoutInflater;

public class MainActivity extends AppCompatActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        MyOpenHelper myOpenHelper = new MyOpenHelper(getApplicationContext());

        SQLiteDatabase db = myOpenHelper.getReadableDatabase();

        Cursor cursor = db.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);

            }

        }

    }

}

MyOpenHelper:

package com.demo.siyoushujuku;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

public class MyOpenHelper  extends SQLiteOpenHelper {

    public MyOpenHelper( Context context,  String name,  SQLiteDatabase.CursorFactory factory, int version) {

        super(context, name, factory, version);

    }

    public MyOpenHelper(Context context) {

        super(context, "Account.db", null, 1);

    }

    /**

     * 数据库的名字

     *

     */

    @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) {

    }

}

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.demo.siyoushujuku">

    <application

        android:allowBackup="true"

        android:icon="@mipmap/ic_launcher"

        android:label="@string/app_name"

        android:roundIcon="@mipmap/ic_launcher_round"

        android:supportsRtl="true"

        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

        <!--内容提供者-->

        <provider

            android:authorities="com.provider"

            android:name=".AccountProvider"

            android:exported="true"

            >

        </provider>

    </application>

</manifest>

B.第一个项目:DQDYGApplication

结构图如下:

MainActivity:

package com.demo.dqdygapplication;

import android.content.ContentValues;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.net.Uri;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Toast;

/**

 * 内容提供者吧数据进行封装 然后提供出来 其他应用都是

 * 通过内容解析者来访问

 */

public class MainActivity extends AppCompatActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        MyOpenHelper myOpenHelper = new MyOpenHelper(getApplicationContext());

        //需求 读取第一个应用私有数据库

        /**

         * path路径 accound.db

         *

         * factory:游标工厂

         *

         * flages:访问模式

         *

         */

//        SQLiteDatabase db = myOpenHelper.getReadableDatabase();

        SQLiteDatabase db = SQLiteDatabase.openDatabase(

                "/data/data/com.demo.dqdygapplication/databases/Account.db",

                null, SQLiteDatabase.OPEN_READWRITE

        );

        Cursor cursor = db.query("info", null,

                null, null,

                null, null,

                null

        );

        //由于数据库由第一个内容提供者暴露出来了 所以我们来解析即可

        //1.拿到内容的解析者

        Uri uri = Uri.parse("content://com.provider/query"); //路径和你定义的路径一样

        Cursor cursor1 = getContentResolver().query(uri, null, null,

                null, null

        );

        if (cursor1 != null && cursor1.getCount() > 0) {

            while (cursor.moveToNext()) {

                String name = cursor.getString(1);

                String phone = cursor.getString(2);

                System.out.println("第二个应用:name==>" + name + "   phone==>" + phone);

            }

        }

    }

    //增加

    public void click1(View view) {

        Uri uri = Uri.parse("content://com.provider/insert"); //路径和你定义的路径一样

        ContentValues values = new ContentValues();

        //key 对应表的字段 value的对应值

        values.put("name","zhaoliu");

        values.put("money",11111);

        Uri insert = getContentResolver().insert(uri, values);

        System.out.println("insert==>"+insert);

    }

    //删除

    public void click2(View view) {

        Uri uri = Uri.parse("content://com.provider/delete"); //路径和你定义的路径一样

        int delete = getContentResolver().delete(uri, "name=?", new String[]{"zhaoliu"});

        Toast.makeText(getApplicationContext(),"删除了"+delete+"行",Toast.LENGTH_LONG).show();

    }

    //修改

    public void click3(View view) {

        Uri uri = Uri.parse("content://com.provider/update"); //路径和你定义的路径一样

        ContentValues values = new ContentValues();

        values.put("money",0.1111);

        int update = getContentResolver().update(uri, values,"name=?", new String[]{"zhaoliu"});

        Toast.makeText(getApplicationContext(),"更新了"+update+"行",Toast.LENGTH_LONG).show();

    }

    //查找

    public void click4(View view) {

//1.拿到内容的解析者

        Uri uri = Uri.parse("content://com.provider/query"); //路径和你定义的路径一样

        Cursor cursor1 = getContentResolver().query(uri, null, null,

                null, null

        );

        if (cursor1 != null && cursor1.getCount() > 0) {

            while (cursor1.moveToNext()) {

                String name = cursor1.getString(1);

                String phone = cursor1.getString(2);

                System.out.println("第二个应用:name==>" + name + "   phone==>" + phone);

            }

        }

    }

}

MyOpenHelper:

package com.demo.dqdygapplication;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

public class MyOpenHelper extends SQLiteOpenHelper {

    public MyOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {

        super(context, name, factory, version);

    }

    public MyOpenHelper(Context context) {

        super(context, "Account.db", null, 1);

    }

    /**

     * 数据库的名字

     */

    @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) {

    }

}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical"

    tools:context=".MainActivity">

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="Hello World!"

        app:layout_constraintBottom_toBottomOf="parent"

        app:layout_constraintLeft_toLeftOf="parent"

        app:layout_constraintRight_toRightOf="parent"

        app:layout_constraintTop_toTopOf="parent" />

    <Button

        android:onClick="click1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="add"

        />

    <Button

        android:onClick="click2"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="delete"

        />

    <Button

        android:onClick="click3"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="update"

        />

    <Button

        android:onClick="click4"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="find"

        />

</LinearLayout>