Android之ContentProvider与ContentResolver(简单Log版)

本文主要是记录一些零碎的知识点

有人跟我说上一篇搞的太复杂了，我就删，最后只剩log输出，看一下最后的显现效果

注意看日志，信息都在日志里了，布局就四个增删改查的按钮

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".ContentResolverActivity"
    android:orientation="vertical">

    <TextView android:text="ContentProvider与ContentResolve"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:textSize="20dp"
        />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="false"
        android:text="add"
        android:onClick="add"
        />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="false"
        android:text="delete"
        android:onClick="delete"
        />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="false"
        android:text="update"
        android:onClick="update"
        />
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAllCaps="false"
        android:text="select"
        android:onClick="select"
    />


</LinearLayout>

有了大概的布局后，下面跟着我一步一步的实现

先新建一个类，继承SQLiteOpenHelper，把数据库的创建与更新管理起来

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

/**
 * Created by Administrator on 2016/3/21.
 */
public class SlackDbHelper extends SQLiteOpenHelper {
    public SlackDbHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
        Log.i("slack", "SlackDbHelper constructor..............");
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.i("slack", "SlackDbHelper onCreate SQLiteDatabase..............");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.i("slack", "SlackDbHelper onUpgrade..............");
    }
}

接着新建一个类，继承ContentProvider，把这个数据库封装起来，提供该数据库的信息，该类里封装了上面的SlackDbHelper

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.Nullable;
import android.util.Log;

/**
 * Created by Administrator on 2016/3/21.
 */
public class SlackContentProvider extends ContentProvider {

    private SlackDbHelper slackDbHelper;
    private SQLiteDatabase sqLiteDatabase;

    @Override
    public boolean onCreate() {
        Log.i("slack","SlackContentProvider onCreate..............");
        slackDbHelper = new SlackDbHelper(getContext(),"user",null,1);
        sqLiteDatabase = slackDbHelper.getWritableDatabase();
        Log.i("slack","SlackContentProvider getWritableDatabase..............");
        return true;
    }

    @Nullable
    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        Log.i("slack","SlackContentProvider query..............");
        return null;
    }

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

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

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

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

增删改查的部分全部都是日志输出

在AndroidManifes t.xml文件里注册该privider，注册的位置在Application 里面，Activity的外面，居然有人不知道说的，还需要添加写外存的权限，因为数据库是真的建好了

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="android.addre.com.content" >

    <!--write storage-->
    <uses-permission android:name="android.permission.WRITE_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=".ContentResolverActivity" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

        <!--SlackContentProvider-->
        <provider
            android:authorities="com.slack"
            android:name=".SlackContentProvider"
            android:exported="true"></provider>

    </application>


</manifest>

以上就把提供者全部建立好了，接着就是使用者通过uri（ AndroidManifes t.xml文件里注册的authorities）地址访问提供者的数据。

import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class ContentResolverActivity extends AppCompatActivity {

    private Uri uri;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_content_resolver);
        //Restful style
        uri=Uri.parse("content://com.slack");
        Log.i("slack", "ContentResolverActivity onCreate done..............");
    }

    public void add(View view) {
        Log.i("slack", "ContentResolverActivity add ..............");
        //public final Uri insert (Uri url, ContentValues values)
        getContentResolver().insert(uri,null);
        Log.i("slack", "ContentResolverActivity add done..............");
    }

    public void delete(View view) {
        Log.i("slack", "ContentResolverActivity delete..............");
        //public final int delete (Uri url, String where, String[] selectionArgs)
        getContentResolver().delete(uri,null,null);
        Log.i("slack", "ContentResolverActivity delete done..............");
    }

    public void update(View view) {
        Log.i("slack", "ContentResolverActivity update..............");
        //public final int update (Uri uri, ContentValues values, String where, String[] selectionArgs)
        getContentResolver().update(uri,null,null,null);
        Log.i("slack", "ContentResolverActivity update done..............");
    }

    public void select(View view) {
        Log.i("slack", "ContentResolverActivity select..............");
        //public final Cursor query (Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
        getContentResolver().query(uri,null,null,null,null);
        Log.i("slack", "ContentResolverActivity select done..............");
    }
}

uri是Restful的风格的

附件：源码下载地址：http://download.csdn.net/detail/i_do_can/9467642