Android ContentProvider 简单学习-白红宇

Android ContentProvider 简单学习

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发布时间：2019-06-08

本文共 12570 字，大约阅读时间需要 41 分钟。

当应用继承ContentProvider类，并重写该类用于提供数据和存储数据的方法，就可以向其他应用共享其数据。以前我们学习过文件的操作模式，通过指定文件的操作模式为Context.MODE_WORLD_READABLE 或Context.MODE_WORLD_WRITEABLE同样可以对外共享数据，但数据的访问方式会因数据存储的方式而不同，如：采用xml文件对外共享数据，需要进行xml解析来读写数据；采用sharedpreferences共享数据，需要使用sharedpreferences API读写数据。而使用ContentProvider共享数据的好处是统一了数据访问方式。

1.第一步需要继承ContentProvider并重写下面方法：

public class PersonContentProvider extends ContentProvider{

public boolean onCreate()

public Uri insert(Uri uri, ContentValues values)

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

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

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

public String getType(Uri uri)}

2. 第二步需要在AndroidManifest.xml使用<provider>对该ContentProvider进行配置，为了能让其他应用找到该ContentProvider ， ContentProvider 采用了authorities（主机名/域名）对它进行唯一标识，你可以把 ContentProvider看作是一个网站（想想，网站也是提供数据者），authorities 就是他的域名：

</application>

</manifest>

注意：一旦应用继承了ContentProvider类，后面我们就会把这个应用称为ContentProvider（内容提供者）。

ProviderDemo 拥有DB，提供Provider，供外围进行增删改查。（这里可以类比通讯录）

OneApp对他进行操作

provider定义：

/** *  */package com.example.providerdemo;import android.content.ContentProvider;import android.content.ContentUris;import android.content.ContentValues;import android.content.UriMatcher;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.net.Uri;/** *  * @author baoxing.gbx * @version $Id: UserProvider.java, v 0.1 2015年8月21日 上午10:25:48 baoxing.gbx Exp $ */public class UserProvider extends ContentProvider{        private DBopenHelper dbOpenHelper;    private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH);    private static final int UserOne = 1;    private static final int UserList = 2;    static{        MATCHER.addURI("com.example.providerdemo.userProvider", "user", UserList);        MATCHER.addURI("com.example.providerdemo.userProvider", "user/#", UserOne);    }    @Override    public boolean onCreate() {        dbOpenHelper = new DBopenHelper(this.getContext());        return true;    }    @Override    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,                        String sortOrder) {        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        switch (MATCHER.match(uri)) {            case UserOne:                long key = ContentUris.parseId(uri);                String where = "id = "+ key;                if(selection!=null && !"".equals(selection.trim())){                    where += " and "+ selection;                }                Cursor cursor = db.query("user", null, where, selectionArgs, null, null, null, null);                return cursor;            case UserList:                 cursor = db.query("user", null, null, selectionArgs, null, null, null, null);                return cursor;            default:                throw new IllegalArgumentException("this is Unknown Uri:"+ uri);            }    }    @Override    public String getType(Uri uri) {        // TODO Auto-generated method stub        return null;    }    @Override    public Uri insert(Uri uri, ContentValues values) {        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        switch (MATCHER.match(uri)) {        case UserOne:            long rowid = db.insert("user", "", values);//主键值            Uri insertUri = ContentUris.withAppendedId(uri, rowid);            this.getContext().getContentResolver().notifyChange(uri, null);//发出数据变化通知            return insertUri;        default:            throw new IllegalArgumentException("this is Unknown Uri:"+ uri);        }    }    @Override    public int delete(Uri uri, String selection, String[] selectionArgs) {        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        int nnum = 0;        switch (MATCHER.match(uri)) {                        case UserOne:                long key = ContentUris.parseId(uri);                String where = "id = " + key;                if (null != selection && !"".equals(selection)) {                    where += "and " + selection;                }                nnum = db.delete("user", where, selectionArgs);                return nnum;                            case UserList:                nnum = db.delete("user", selection, selectionArgs);                return nnum;                        default:                throw new IllegalArgumentException("this is Unknown Uri:"+ uri);        }    }    @Override    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();            int nnum = 0 ;            switch (MATCHER.match(uri)) {            case UserOne:                long key = ContentUris.parseId(uri);                String where = "id = " + key;                if (null != selection && !"".equals(selection)) {                    where += "and " + selection;                }                nnum = db.update("user", values, where, selectionArgs);                return nnum;                            case UserList:                                nnum = db.update("user", values, selection, selectionArgs);                return nnum;            default:                throw new IllegalArgumentException("this is Unknown Uri:"+ uri);        }    }}

DB操作：

package com.example.providerdemo;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;import android.nfc.Tag;import android.os.Build.VERSION;import android.util.Log; /** * * @author baoxing.gbx * @version $Id: DBopenHelper.java, v 0.1 2015年7月11日 下午9:39:03 baoxing.gbx Exp $ */public class DBopenHelper extends SQLiteOpenHelper{     /** 数据库名称  */    private static final String DB_NAME = "test.db";         private static final int  VERSION = 1;         private static final String Tag = "DBopenHelper";             // 初始化数据库开启装置    public DBopenHelper(Context context) {        super(context, DB_NAME, null, VERSION);        // TODO Auto-generated constructor stub    }     //    @Override    public void onCreate(SQLiteDatabase db) {        Log.i(Tag, "onCreate 被调用");        db.execSQL("create table user (id integer primary key autoincrement, name varchar(20),sex varchar(20), age integer )");    }     @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {        Log.i(Tag, "onUpgrade 被调用");        db.execSQL("DROP TABLE IF EXISTS person");        onCreate(db);    } }

OneApp测试

/** *  */package com.demo.oneapp.test;import java.util.Date;import android.R.integer;import android.content.ContentResolver;import android.content.ContentValues;import android.database.Cursor;import android.net.Uri;import android.test.AndroidTestCase;import android.util.Log;/** *  * @author baoxing.gbx * @version $Id: TestProvider.java, v 0.1 2015年8月20日 下午8:50:13 baoxing.gbx Exp $ */public class TestProvider extends AndroidTestCase {        public void testAdd() {        Uri uri = Uri.parse("content://com.example.providerdemo.userProvider/user");        ContentResolver resolver = this.getContext().getContentResolver();                for (int i = 0; i < 10; ++i) {            ContentValues values = new ContentValues();             values.put("name", "muyou" + i);            values.put("sex", "男");            values.put("age", 18 + i);            Uri uri2 =  resolver.insert(uri, values);            System.out.println("完成：" + uri2);        }    }        public void testDel() {        // 查询单个        Uri uri = Uri.parse("content://com.example.providerdemo.userProvider/user/2");        ContentResolver resolver = this.getContext().getContentResolver();                Cursor cursor = resolver.query(uri, null, null, null, null);        while (cursor.moveToNext()) {                        int id = cursor.getInt(cursor.getColumnIndex("id"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String sex = cursor.getString(cursor.getColumnIndex("sex"));            int age = cursor.getInt(cursor.getColumnIndex("age"));                       Log.i("testQuery",           "id="+ id + "name=" + name + "sex=" + sex + "age=" + age);        }                 uri = Uri.parse("content://com.example.providerdemo.userProvider/user/2");         resolver = this.getContext().getContentResolver();         resolver.delete(uri, null, null);                  // 查询单个         uri = Uri.parse("content://com.example.providerdemo.userProvider/user/2");         resolver = this.getContext().getContentResolver();                  cursor = resolver.query(uri, null, null, null, null);         while (cursor.moveToNext()) {                          int id = cursor.getInt(cursor.getColumnIndex("id"));             String name = cursor.getString(cursor.getColumnIndex("name"));             String sex = cursor.getString(cursor.getColumnIndex("sex"));             int age = cursor.getInt(cursor.getColumnIndex("age"));                         Log.i("testQuery",            "id="+ id + "name=" + name + "sex=" + sex + "age=" + age);         }    }        public void testUpdate() {        // 查询单个        Uri uri = Uri.parse("content://com.example.providerdemo.userProvider/user/3");        ContentResolver resolver = this.getContext().getContentResolver();                Cursor cursor = resolver.query(uri, null, null, null, null);        while (cursor.moveToNext()) {                        int id = cursor.getInt(cursor.getColumnIndex("id"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String sex = cursor.getString(cursor.getColumnIndex("sex"));            int age = cursor.getInt(cursor.getColumnIndex("age"));                       Log.i("testQuery",           "id="+ id + "name=" + name + "sex=" + sex + "age=" + age);        }                 uri = Uri.parse("content://com.example.providerdemo.userProvider/user/3");         resolver = this.getContext().getContentResolver();         ContentValues values = new ContentValues();         values.put("name", "cool");         resolver.update(uri, values, null, null);                  // 查询单个         uri = Uri.parse("content://com.example.providerdemo.userProvider/user/3");         resolver = this.getContext().getContentResolver();                  cursor = resolver.query(uri, null, null, null, null);         while (cursor.moveToNext()) {                          int id = cursor.getInt(cursor.getColumnIndex("id"));             String name = cursor.getString(cursor.getColumnIndex("name"));             String sex = cursor.getString(cursor.getColumnIndex("sex"));             int age = cursor.getInt(cursor.getColumnIndex("age"));                         Log.i("testQuery",            "id="+ id + "name=" + name + "sex=" + sex + "age=" + age);         }    }            public void testQuery() {                // 查询所有        Uri uri = Uri.parse("content://com.example.providerdemo.userProvider/user");        ContentResolver resolver = this.getContext().getContentResolver();                Cursor cursor = resolver.query(uri, null, null, null, null);        while (cursor.moveToNext()) {                        int id = cursor.getInt(cursor.getColumnIndex("id"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String sex = cursor.getString(cursor.getColumnIndex("sex"));            int age = cursor.getInt(cursor.getColumnIndex("age"));                       Log.i("testQuery",           "id="+ id + "name=" + name + "sex=" + sex + "age=" + age);        }                // 查询单个        uri = Uri.parse("content://com.example.providerdemo.userProvider/user/5");        resolver = this.getContext().getContentResolver();                cursor = resolver.query(uri, null, null, null, null);        while (cursor.moveToNext()) {                        int id = cursor.getInt(cursor.getColumnIndex("id"));            String name = cursor.getString(cursor.getColumnIndex("name"));            String sex = cursor.getString(cursor.getColumnIndex("sex"));            int age = cursor.getInt(cursor.getColumnIndex("age"));                       Log.i("testQuery",           "id="+ id + "name=" + name + "sex=" + sex + "age=" + age);        }    }        }

转载于:https://www.cnblogs.com/E-star/p/4748602.html

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