contentprovider_provider

最新推荐文章于 2024-08-03 14:33:35 发布

原创最新推荐文章于 2024-08-03 14:33:35 发布 · 250 阅读

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本文深入探讨了Android中ContentProvider的实现方式，包括MainActivity的启动、MyContentProvider的具体操作如增删查改，以及MySQliteopenHelper的使用来创建和管理数据库。通过具体的代码示例，读者可以了解到如何在Android应用中正确地使用ContentProvider进行数据共享。

MainActivity

public class MainActivity extends AppCompatActivity {

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

MyContentProvider

import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.support.annotation.Nullable;

/**
 * @author alice
 * @version 1.0
 * @Date 2017/10/18 11:19
 */
public class MyContentProvider extends ContentProvider {
    String path = "content://alice.bw.com.contentprovider_provider/student";
    SQLiteDatabase db;
    @Override
    public boolean onCreate() {
        MySQliteopenHelper openher = new MySQliteopenHelper(getContext());
         db = openher.getReadableDatabase();
        return false;
    }

    @Nullable
    @Override
    public Cursor query(Uri uri, String[] strings, String s, String[] strings1, String s1) {
        Cursor c = db.query("student",strings,s,strings1,null,null,s1);
        return c;
    }

    @Nullable
    @Override
    public String getType(Uri uri) {
        return null;
    }

    @Nullable
    @Override
    public Uri insert(Uri uri, ContentValues contentValues) {
        long insert = db.insert("student", null, contentValues);
        Uri u = ContentUris.withAppendedId(Uri.parse(path),insert);
        return u;
    }

    @Override
    public int delete(Uri uri, String s, String[] strings) {
        return 0;
    }

    @Override
    public int update(Uri uri, ContentValues contentValues, String s, String[] strings) {
        return 0;
    }
}

MySQliteopenHelper

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

/**
 * @author alice
 * @version 1.0
 * @Date 2017/10/18 11:12
 */
public class MySQliteopenHelper extends SQLiteOpenHelper {

    public MySQliteopenHelper(Context context) {
        super(context, "student", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL("create  table  student(_id integer primary key autoincrement,name text,age text)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}

main布局

<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="alice.bw.com.contentprovider_provider.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"/>
</RelativeLayout>

权限

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="alice.bw.com.day16contentprovidermedia">
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        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>
    </application>

</manifest>