android通过ContentProvider实现应用间的数据共享

此demo通过ContentProvider实现应用间的数据共享，并且定义了全局常量（当然也可以定义全局变量）。

demo：下载地址

manifest文件：

<?xml version="1.0" encoding="utf-8"?>

MyContentProvider.java文件（只实现了插入和搜索）：

package fk.androiddemo_015;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.database.sqlite.SQLiteQueryBuilder;import android.net.Uri;import android.text.TextUtils;import java.sql.SQLException;import java.util.HashMap;import fk.androiddemo_015.MyProviderMetaData.UserTableMetaDate;//此类已在Mainfest中声明，需要时系统会自动调用它public class MyContentProvider extends ContentProvider {    public static final UriMatcher uriMatcher;    public static final int INCOMING_USER_COLLECTION = 1;    public static final int INCOMING_USER_SINGLE = 2;    private DatabaseHelper dh;//注意    static {        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);        uriMatcher.addURI(MyProviderMetaData.AUTHORIY, "/users", INCOMING_USER_COLLECTION);        uriMatcher.addURI(MyProviderMetaData.AUTHORIY, "/users/#", INCOMING_USER_SINGLE);    }    public static HashMap userProjectionMap;    static {        userProjectionMap = new HashMap<>();        userProjectionMap.put(UserTableMetaDate._ID, UserTableMetaDate._ID);        userProjectionMap.put(UserTableMetaDate.USER_NAME, UserTableMetaDate.USER_NAME);    }    public MyContentProvider() {    }    @Override    public int delete(Uri uri, String selection, String[] selectionArgs) {        // Implement this to handle requests to delete one or more rows.        throw new UnsupportedOperationException("Not yet implemented");    }    @Override    public String getType(Uri uri) {        // TODO: Implement this to handle requests for the MIME type of the data        // at the given URI.        System.out.println("getType");        switch (uriMatcher.match(uri)) {            case INCOMING_USER_COLLECTION:                return UserTableMetaDate.CONTENT_TYPE;            case INCOMING_USER_SINGLE:                return UserTableMetaDate.CONTENT_TYPE_ITEM;            default:                throw new IllegalArgumentException("Unknown URI" + uri);        }    }    @Override    public Uri insert(Uri uri, ContentValues values) {        // TODO: Implement this to handle requests to insert a new row.        System.out.println("insert");        SQLiteDatabase db = dh.getWritableDatabase();        long rowId = db.insert(UserTableMetaDate.TABLE_NAME, null, values);        if (rowId > 0) {            Uri insertedUserUri = ContentUris.withAppendedId(UserTableMetaDate.CONTENT_URI, rowId);            getContext().getContentResolver().notifyChange(insertedUserUri, null);            return insertedUserUri;        } else {            try {                throw new SQLException("Failed to insert row into" + uri);            } catch (SQLException e) {                System.out.println("Failed to insert row into" + uri);            }            return uri;        }    }    @Override    public boolean onCreate() {        // TODO: Implement this to initialize your content provider on startup.        dh = new DatabaseHelper(getContext(), MyProviderMetaData.DATABASE_NAME);        System.out.println("onCreat");        return true;    }    @Override    public Cursor query(Uri uri, String[] projection, String selection,                        String[] selectionArgs, String sortOrder) {        // TODO: Implement this to handle query requests from clients.        SQLiteQueryBuilder qb = new SQLiteQueryBuilder();        switch (uriMatcher.match(uri)) {            case INCOMING_USER_COLLECTION:                qb.setTables(UserTableMetaDate.TABLE_NAME);                qb.setProjectionMap(userProjectionMap);                break;            case INCOMING_USER_SINGLE:                qb.setTables(UserTableMetaDate.TABLE_NAME);                qb.setProjectionMap(userProjectionMap);                qb.appendWhere(UserTableMetaDate._ID + "=" + uri.getPathSegments().get(1));                break;        }        String orderBy;        if (TextUtils.isEmpty(sortOrder)) {            orderBy = UserTableMetaDate.DEFAULT_SORT_ORDER;        } else orderBy = sortOrder;        SQLiteDatabase db = dh.getWritableDatabase();        Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, orderBy);        c.setNotificationUri(getContext().getContentResolver(), uri);        return c;    }    @Override    public int update(Uri uri, ContentValues values, String selection,                      String[] selectionArgs) {        // TODO: Implement this to handle requests to update one or more rows.        throw new UnsupportedOperationException("Not yet implemented");    }}

MyProviderMetaData.java（一些全局常量）：

package fk.androiddemo_015;import android.net.Uri;import android.provider.BaseColumns;/** * Created by Administrator on 2016/10/4. *///定义一些全局常量public class MyProviderMetaData {    //注意和manifests中声明的保持一样    public static final String AUTHORIY = "FK.bbs.MyContentProvider";    public static final String DATABASE_NAME = "MyProvider.db";    public static final String USER_TABLE_NAME = "users";    public static final int DATABASE_VERSION = 1;    public static final class UserTableMetaDate implements BaseColumns {        public static final String TABLE_NAME = "users";        public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORIY + "/users");        public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.myprovider.user";        public static final String CONTENT_TYPE_ITEM = "vnd.android.cursor.item/vnd.myprovider.user";        public static final String USER_NAME = "name";        public static final String DEFAULT_SORT_ORDER = "_id desc";    }}

DatabaseHelper.java（数据库工具类）：

package fk.androiddemo_015;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import fk.androiddemo_015.MyProviderMetaData.UserTableMetaDate;/** * Created by Administrator on 2016/10/4. *///MyContentProvider中要用public class DatabaseHelper extends SQLiteOpenHelper {    private static final int VERSION = 1;    public DatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory,                          int version) {        super(context, name, factory, version);    }    public DatabaseHelper(Context context, String name, int version) {        this(context, name, null, version);    }    public DatabaseHelper(Context context, String name) {        this(context, name, VERSION);    }    @Override    public void onCreate(SQLiteDatabase db) {        System.out.println("create a database");        db.execSQL("create table "+UserTableMetaDate.TABLE_NAME+"(" + UserTableMetaDate._ID + " INTEGER PRIMARY KEY AUTOINCREMENT,name varchar(20))");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {        System.out.println(oldVersion + " update to " + newVersion);    }}

主界面：

package fk.androiddemo_015;//1,在MyProviderMetaData定义元数据//2,在MyContentProvider继承实现ContentProvider（在里面实现对相应数据库的操作）//3,在Manifest中声明MyContentProviderimport android.content.ContentValues;import android.database.Cursor;import android.net.Uri;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import fk.androiddemo_015.MyProviderMetaData.UserTableMetaDate;public class MainActivity extends AppCompatActivity implements View.OnClickListener{    Button but1,but2;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        but1 = (Button) findViewById(R.id.but1);        but1.setOnClickListener(this);        but2 = (Button) findViewById(R.id.but2);        but2.setOnClickListener(this);    }    @Override    public void onClick(View view) {        if (view == but1) {//向数据库中插入数据，没有会自动创建一个            ContentValues values = new ContentValues();            values.put(UserTableMetaDate.USER_NAME, "boboshen");            Uri uri = getContentResolver().insert(UserTableMetaDate.CONTENT_URI, values);            System.out.println("uri--->" + uri.toString());        } else {//查询数据库，没有会自动创建一个            Cursor c = getContentResolver().query(UserTableMetaDate.CONTENT_URI, null, null, null, null);            while (c.moveToNext())                System.out.println(c.getString(c.getColumnIndex(UserTableMetaDate.USER_NAME)));        }    }}

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