ContentProvider

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ContentProivde 内容提供者，内部封装了对数据库的代码操作过程，对外暴露几个方法，可以提供给其他应用程序对本程序的数据库进行操作的的方法。

public class Constant {    public static final String AUTHORITIES="com.example.emma.demo0504.provider.peoplecontentprovider";    public static final String TABLENAME="t_person";    public static final String TABLE_PERSON_ID="_id";    public static final String TABLE_PERSON_NAME="name";    public static final String TABLE_PERSON_AGE="age";    public static final String TABLE_PERSON_ADDR="addr";}

public class PeopleContentProvider extends ContentProvider {    private Bean bean;    private static UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);    private static final int MULTITUDE = 2;    private static final int SINGLE = 1;    static {        uriMatcher.addURI(Constant.AUTHORITIES, "/people", MULTITUDE);        uriMatcher.addURI(Constant.AUTHORITIES, "/people/#", SINGLE);    }    @Override    public boolean onCreate() {        bean = Bean.getInstance(getContext());        return true;    }    @Nullable    @Override    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {        int matchCode = uriMatcher.match(uri);        switch (matchCode) {            case MULTITUDE:                return bean.select(projection, selection, selectionArgs, sortOrder);            case SINGLE:                long id = ContentUris.parseId(uri);                if (selection == null) {                    return bean.select(projection, "_id=" + id, selectionArgs, sortOrder);                } else {                    return bean.select(projection, selection + " AND _id=" + id, selectionArgs, sortOrder);                }            default:                throw new RuntimeException("非法Uri");        }    }    @Nullable    @Override    public String getType(Uri uri) {        int matchCode = uriMatcher.match(uri);        switch (matchCode) {            case MULTITUDE:                return "vnd.android.cursor/dir";            case SINGLE:                return "vnd.android.cursor/item";            default:                throw new RuntimeException("非法Uri");        }    }    @Nullable    @Override    public Uri insert(Uri uri, ContentValues values) {        int matchCode = uriMatcher.match(uri);        switch (matchCode) {            case MULTITUDE:                long id = bean.insert(values);                return Uri.withAppendedPath(uri, String.valueOf(id));            default:                throw new RuntimeException("非法Uri");        }    }    @Override    public int delete(Uri uri, String selection, String[] selectionArgs) {        int matchCode = uriMatcher.match(uri);        switch (matchCode) {            case MULTITUDE:                return bean.delete(selection, selectionArgs);            case SINGLE:                long id = ContentUris.parseId(uri);                if (selection == null) {                    return bean.delete("_id=" + id, selectionArgs);                } else {                    return bean.delete(selection + " AND _id=" + id, selectionArgs);                }            default:                throw new RuntimeException("非法Uri");        }    }    @Override    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {        int matchCode = uriMatcher.match(uri);        switch (matchCode) {            case SINGLE:                return bean.update(values, selection, selectionArgs);            default:                throw new RuntimeException("非法Uri");        }    }}

注册Provider
最后一句表示授予其他程序访问的权限

 <provider            android:name=".provider.PeopleContentProvider"            android:authorities="com.example.emma.demo0504.provider.peoplecontentprovider"            android:exported="true"></provider>

操作数据库的类

public class Bean extends SQLiteOpenHelper {    private static Bean bean;    private static String DBNAME = "person.db";    private static int VERSION = 1;    private Bean(Context context) {        super(context, DBNAME, null, VERSION, null);    }    public static Bean getInstance(Context context) {        if (bean == null) {            bean = new Bean(context);        }        return bean;    }    @Override    public void onCreate(SQLiteDatabase db) {        StringBuffer creat = new StringBuffer();        creat.append("CREATE TABLE IF NOT EXISTS ")                .append(Constant.TABLENAME)                .append("(")                .append(Constant.TABLE_PERSON_ID)                .append(" INTEGER PRIMARY KEY AUTOINCREMENT,")                .append(Constant.TABLE_PERSON_NAME)                .append(" VARCHAR(200),")                .append(Constant.TABLE_PERSON_AGE)                .append(" INTEGER DEFAULT 1 CHECK (age BETWEEN 1 AND 150),")                .append(Constant.TABLE_PERSON_ADDR)                .append(" VARCHAR(200)")                .append(")");        db.execSQL(creat.toString());        StringBuffer insert = new StringBuffer();        insert.append("INSERT INTO ")                .append(Constant.TABLENAME)                .append("(")                .append(Constant.TABLE_PERSON_ID + ",")                .append(Constant.TABLE_PERSON_NAME + ",")                .append(Constant.TABLE_PERSON_AGE + ",")                .append(Constant.TABLE_PERSON_ADDR)                .append(")")                .append(" VALUES ")                .append("(null,?,?,?)");        db.execSQL(insert.toString(), new String[]{"赵", String.valueOf(21), "上海"});        db.execSQL(insert.toString(), new String[]{"钱", String.valueOf(22), "温州"});        db.execSQL(insert.toString(), new String[]{"孙", String.valueOf(23), "北京"});        db.execSQL(insert.toString(), new String[]{"李", String.valueOf(24), "杭州"});        db.execSQL(insert.toString(), new String[]{"周", String.valueOf(25), "丽水"});        db.execSQL(insert.toString(), new String[]{"吴", String.valueOf(26), "天津"});        db.execSQL(insert.toString(), new String[]{"郑", String.valueOf(27), "福州"});        db.execSQL(insert.toString(), new String[]{"王", String.valueOf(28), "莆田"});        db.execSQL(insert.toString(), new String[]{"冯", String.valueOf(29), "福鼎"});        db.execSQL(insert.toString(), new String[]{"陈", String.valueOf(30), "金华"});        db.execSQL(insert.toString(), new String[]{"楚", String.valueOf(31), "嘉兴"});        db.execSQL(insert.toString(), new String[]{"魏", String.valueOf(32), "广州"});        db.execSQL(insert.toString(), new String[]{"蒋", String.valueOf(33), "深圳"});        db.execSQL(insert.toString(), new String[]{"沈", String.valueOf(34), "香港"});        db.execSQL(insert.toString(), new String[]{"韩", String.valueOf(35), "澳门"});        db.execSQL(insert.toString(), new String[]{"杨", String.valueOf(36), "南京"});    }    public Cursor select(String[] projection, String selection, String[] selectionArgs, String sortOrder) {        SQLiteDatabase db = null;        db = bean.getWritableDatabase();        return db.query(Constant.TABLENAME, projection, selection, selectionArgs, null, null, sortOrder);    }    public long insert(ContentValues values) {        SQLiteDatabase db = null;        try {            db = bean.getWritableDatabase();            return db.insert(Constant.TABLENAME, "hello", values);        } catch (Exception e) {            e.printStackTrace();            return 0;        } finally {            if(db!=null&&db.isOpen()){                db.close();                db=null;            }        }    }    public int delete(String selection, String[] selectionArgs) {        SQLiteDatabase db = null;        try {            db = bean.getWritableDatabase();            return db.delete(Constant.TABLENAME, selection, selectionArgs);        } catch (Exception e) {            e.printStackTrace();            return 0;        } finally {            if(db!=null&&db.isOpen()){                db.close();                db=null;            }        }    }    public int update(ContentValues values, String selection, String[] selectionArgs) {        SQLiteDatabase db = null;        try {            db = bean.getWritableDatabase();            return db.update(Constant.TABLENAME,values,selection,selectionArgs);        } catch (Exception e) {            e.printStackTrace();            return 0;        } finally {            if(db!=null&&db.isOpen()){                db.close();                db=null;            }        }    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    }}

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