Android ContentProvider(内容提供者)+database

主类:

package com.example.contentprovider_database;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CursorAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private Button insert, update, delete, select;
    private ListView listview;

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

        insert = findViewById(R.id.insert);
        update = findViewById(R.id.update);
        delete = findViewById(R.id.delete);
        select = findViewById(R.id.select);
        listview = findViewById(R.id.listview);


        insert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                ContentValues values = new ContentValues();
                values.put("name", "李晓娜");
                getContentResolver().insert(MyContentProvider.duogeuri, values);
            }
        });


        update.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                ContentValues values = new ContentValues();
                values.put("name", "李孟媛");
                getContentResolver().update(MyContentProvider.duogeuri, values, "name = ?", new String[]{"李晓娜"});
            }
        });

        delete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getContentResolver().delete(MyContentProvider.duogeuri, "name = ?", new String[]{"李晓娜"});
            }
        });

        select.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Cursor cursor = getContentResolver().query(MyContentProvider.duogeuri, null, null, null, null);
                listview.setAdapter(new MyAdapter(MainActivity.this, cursor));
            }
        });

    }

    class MyAdapter extends CursorAdapter {

        public MyAdapter(Context context, Cursor c) {
            super(context, c);
        }

        @Override
        public View newView(Context context, Cursor cursor, ViewGroup parent) {
            View view = LayoutInflater.from(context).inflate(R.layout.shipei, null);
            return view;
        }

        @Override
        public void bindView(View view, Context context, Cursor cursor) {
            TextView viewById = view.findViewById(R.id.text_id);
            TextView viewByname = view.findViewById(R.id.text_name);

            String id = cursor.getString(cursor.getColumnIndex("_id"));
            String name = cursor.getString(cursor.getColumnIndex("name"));

            viewById.setText(id);
            viewByname.setText(name);
        }
    }
}

MyHelp:

package com.example.contentprovider_database;

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

public class MyHelp extends SQLiteOpenHelper {

    public MyHelp(Context context) {
        super(context, "lixiaona.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table user (_id Integer primary key autoincrement , name varchar(20))");
    }

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

    }
}

MyContentPrivider:

package com.example.contentprovider_database;

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;
import android.renderscript.Sampler;
import android.support.v4.view.ViewPager;
import android.widget.Toast;

public class MyContentProvider extends ContentProvider {
    static String authorities = "com.example.contentprovider_database.MyContentProvider";
    static String pathall = "vnd.cursor.android.dir/vnd.com.MyProvider";//所有的路径
    static String pathitem = "vnd.cursor.android.item/vnd.com.MyProvider";//单个的路径
    static int code = 1;
    static Uri duogeuri = Uri.parse("content://" + authorities + "/user");//所有uri
    static Uri yitiaouri = Uri.parse("content://" + authorities + "/user/#");//单个uri
    private MyHelp myHelp;

    static {
        UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(authorities, pathall, code);
        uriMatcher.addURI(authorities, pathitem, code);
    }

    public MyContentProvider() {
    }

    @Override
    public boolean onCreate() {
        myHelp = new MyHelp(getContext());
        return true;
    }

    //增加
    @Override
    public Uri insert(Uri uri, ContentValues values) {
        Uri uri1 = null;

        SQLiteDatabase writableDatabase = myHelp.getWritableDatabase();

        long la = writableDatabase.insert("user", null, values);
        if (la > 0) {
            Toast.makeText(getContext(), "添加成功", Toast.LENGTH_SHORT).show();
            uri1 = uri.withAppendedPath(uri, la + "");
        }
        return uri;
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        SQLiteDatabase writableDatabase = myHelp.getWritableDatabase();
        int i = writableDatabase.delete("user", selection, selectionArgs);
        return i;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        SQLiteDatabase writableDatabase = myHelp.getWritableDatabase();
        int i = writableDatabase.update("user", values, selection, selectionArgs);
        return i;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        SQLiteDatabase readableDatabase = myHelp.getReadableDatabase();
        Cursor cursor = readableDatabase.rawQuery("select * from user ", null);
        return cursor;
    }

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

主布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    android:orientation="vertical"
    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"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/insert"
        android:text="增加"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/update"
        android:text="修改"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/delete"
        android:text="删除"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/select"
        android:text="查看"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <ListView
        android:id="@+id/listview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    </ListView>


</LinearLayout>

适配xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    android:orientation="horizontal"
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/text_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/text_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

重点:

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

    <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>

        <provider
            android:name=".MyContentProvider"
            android:authorities="com.example.contentprovider_database.MyContentProvider"
            android:enabled="true"
            android:exported="true">

        </provider>
    </application>

</manifest>