android之Content Provider

最新推荐文章于 2024-05-01 19:14:09 发布

YDCookie

最新推荐文章于 2024-05-01 19:14:09 发布

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本文链接：https://blog.youkuaiyun.com/YDCookie/article/details/75268649

本文介绍了一个简单的Android内容提供者实现方法，通过自定义MyProvider类来管理数据库操作，包括查询、插入、删除和更新等，并展示了如何在另一项目中使用ContentResolver访问这些数据。

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1.知识图谱

制作一个简易的获取内容提供者和访问者

在你的创建数据库的那个项目里，在新建一个MyProvider.java

package com.example.cookie.android0625sqlite;

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

import com.yindan.db.DbHelper;

/**
 * Created by Administrator on 2017/7/17 0017.
 */

public class MyProvider extends ContentProvider {
    @Override
    public boolean onCreate() {
        Log.i("test","onCreate");
        return false;
    }

    @Nullable
    @Override
    public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection, @Nullable String[] selectionArgs, @Nullable String sortOrder) {
        Log.i("test","query");
        //把数据查询出来
        DbHelper dbHelper=new DbHelper(getContext(),"CookieOne.db",null,1);
        SQLiteDatabase sqLiteDatabase=dbHelper.getReadableDatabase();
        return sqLiteDatabase.rawQuery("select * from login",null);
    }

    @Nullable
    @Override
    public String getType(@NonNull Uri uri) {
        Log.i("test","getType");
        return null;
    }

    @Nullable
    @Override
    public Uri insert(@NonNull Uri uri, @Nullable ContentValues values) {
        Log.i("test","insert");
        return null;
    }

    @Override
    public int delete(@NonNull Uri uri, @Nullable String selection, @Nullable String[] selectionArgs) {
        Log.i("test","delete");
        return 0;
    }

    @Override
    public int update(@NonNull Uri uri, @Nullable ContentValues values, @Nullable String selection, @Nullable String[] selectionArgs) {
        Log.i("test","update");
        return 0;
    }
}

在该项目里面进行配置

 <provider
            android:authorities="com.example.cookie.android0625sqlite.LOGIN"
            android:name="com.example.cookie.android0625sqlite.MyProvider"
            android:exported="true"
            ></provider>

再new一个项目

package com.example.cookie.android0717contentresolver;

import android.content.ContentProvider;
import android.content.ContentResolver;
import android.database.Cursor;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

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

        //获取16次课的数据
        //获取内容访问者
        ContentResolver cr=getContentResolver();
        Uri uri=Uri.parse("content://com.example.cookie.android0625sqlite.LOGIN");
        Cursor cursor=cr.query(uri,null,null,null,null);
        while(cursor.moveToNext()){
            int uid=cursor.getInt(cursor.getColumnIndex("uid"));
            String uname=cursor.getString(cursor.getColumnIndex("uname"));
            String upass=cursor.getString(cursor.getColumnIndex("upass"));
            Log.i("test",uid+" "+uname+" "+upass);
        }

    }
}