// 將數(shù)據(jù)存儲(chǔ)到指定的文件中
// name為文件名，mode為文件的操作模式
FileOutputStream fos = openFileOutput(String name,int mode);
// 讀取指定文件中的數(shù)據(jù)
FileInputStream  fis = openFileInput(String name);

public class UserInfoIO {
	// 數(shù)據(jù)的寫(xiě)入
	public static boolean saveUserInfo(String username, String password, Context context){
	    // openFileOutput(要操作的文件名，文件訪問(wèn)模式)
	    FileOutputStream fos = null;
	    String msg = null;
	    try { // 在操作文件的時(shí)候可能會(huì)報(bào)異常，需要進(jìn)行捕獲
	        fos = context.openFileOutput("MyData.txt",Context.MODE_PRIVATE);
	        msg = username + ":" + password;
	        // getBytes()將字符串轉(zhuǎn)換為字節(jié)流
	        fos.write(msg.getBytes());
	        return true;
	    } catch (IOException e) {
	        e.printStackTrace();
	        return false;
	    }
	    finally {
	        try {
	            fos.close(); // 流是系統(tǒng)中的稀缺資源，在使用完后要及時(shí)關(guān)閉
	        } catch (IOException e) {
	            e.printStackTrace();
	        }
	}
}
// 用戶數(shù)據(jù)的讀取
public static Map<String,String> getUserInfo(Context context){
    // 獲取文件輸入流
    FileInputStream fis = null;
    try {
        fis = context.openFileInput("MyData.txt");
        byte[] buffer = new byte[fis.available()];
        fis.read(buffer);
        // 字節(jié)轉(zhuǎn)換為字符串
        String msg = new String(buffer);
        String[] userInfo = msg.split(":");
        Map<String,String> userMap = new HashMap<>();
        userMap.put("username",userInfo[0]);
        userMap.put("password",userInfo[1]);
        return userMap;
    } catch (IOException e) {
        e.printStackTrace();
        return null;
    }
    finally {
        try {
            fis.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
}

public class UserInfoSharedPre {
    // 用戶數(shù)據(jù)的存儲(chǔ)
    public static boolean saveUserInfo(String username, String password, Context context) {
        // 獲取SharedPreferences對(duì)象，同時(shí)指定文件名稱和訪問(wèn)權(quán)限
        SharedPreferences sp = context.getSharedPreferences("MyData", Context.MODE_PRIVATE);
        // 獲取獲取SharedPreferences的編輯器對(duì)象
        SharedPreferences.Editor edit = sp.edit();
        // 通過(guò)編輯器進(jìn)行數(shù)據(jù)的存儲(chǔ)
        edit.putString("Uname",username);
        edit.putString("Pwd",password);
        edit.commit();
        return true;
    }
   // 讀取用戶數(shù)據(jù)
   public static Map<String,String> getUserInfo(Context context) {
       // 獲取SharedPreferences對(duì)象，同時(shí)指定文件名稱和訪問(wèn)權(quán)限
       SharedPreferences sp = context.getSharedPreferences("MyData", Context.MODE_PRIVATE);
       String username = sp.getString("Uname", "");
       String password = sp.getString("Pwd","");
       Map<String,String> userMap = new HashMap<>();
       userMap.put("username",username);
       userMap.put("password",password);
       return userMap;
   }
}

class MyDbHelper extends SQLiteOpenHelper {
    // 構(gòu)造器的作用:(參數(shù):上下文，數(shù)據(jù)庫(kù)文件的名稱，結(jié)果集工廠，版本號(hào))定義數(shù)據(jù)庫(kù)
    public MyDbHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }
    // 數(shù)據(jù)庫(kù)初始化時(shí)創(chuàng)建的表，用于創(chuàng)建表或視圖文件
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL("create table user(user_id integer primary key autoincrement,userName varchar(10),password varchar(10))");
    }
    // 升級(jí)方法(當(dāng)數(shù)據(jù)庫(kù)的版本號(hào)增加時(shí)調(diào)用)
    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
    }
}

// 設(shè)置數(shù)據(jù)庫(kù)的相關(guān)參數(shù)，初始化數(shù)據(jù)庫(kù)
MyDbHelper myDbHelper = new MyDbHelper(SQLiteActivity.this,"MyDatabase.db",null,1);
// 通過(guò)幫助類獲取到數(shù)據(jù)庫(kù)對(duì)象
SQLiteDatabase db = myDbHelper.getWritableDatabase();

// 創(chuàng)建ContentValues對(duì)象用于存儲(chǔ)記錄的字段值（鍵值對(duì)方式：鍵對(duì)應(yīng)字段名，值對(duì)應(yīng)字段具體的值）
ContentValues contentValues = new ContentValues();
contentValues.put("userName","張三");
contentValues.put("password","123456");
db.insert("user",null,contentValues);

db.execSQL("insert into user(userName,password) values (?,?)",new Object[]{<!--{C}%3C!%2D%2D%20%2D%2D%3E-->"張三","123456"});

db.close();

public Cursor query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit)

// Cursor: 結(jié)果集，內(nèi)有游標(biāo)指向結(jié)果集中的某一條記錄，初始時(shí)指向第一條
Cursor cursor = db.query("user", new String[]{"userName,password"}, null, null, null, null, null, null);
cursor.moveToFirst();
while (cursor.moveToNext()) { // 移動(dòng)游標(biāo)指向下一行數(shù)據(jù)
	showInfo.append("\n" + "用戶名" + cursor.getString(0) + ",密碼" + 	cursor.getString(1));
}
cursor.close();
db.close();

public boolean deleteData(String deleteId) {
	int i = db.delete("user", "id=?", new String[]{deleteId});
	return i > 0 ? true : false;
}

ContentValues contentValues = new ContentValues();
contentValues.put("userName","李四");
contentValues.put("password","123123");
int i = db.update("user", contentValues, "id=?", new String[]{updateId});

db.execSQL("update user set userName=?,password=? where id=?",new Object[]{<!--{C}%3C!%2D%2D%20%2D%2D%3E-->username1,password1,id});

 UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
 // 常量UriMatcher.NO_MATCH表示不匹配任何路徑的返回碼(-1)

matcher.addURI("cn.itcast.contentprovider", "people", 1);  
// 添加需要匹配uri，如果匹配就會(huì)返回匹配碼"1"
matcher.addURI("cn.itcast.contentprovider", "person/#", 2);
// #表示通配符，任意內(nèi)容的意思

public class MyDBhelper extends SQLiteOpenHelper {
    public MyDBhelper(Context context) {
        super(context, "person.db", null, 1);
    }
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL("create table user(id integer primary key autoincrement,userName varchar(10),phone varchar(10))");
    }
    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
    }
}

<application ......>
    ......	
    <provider
        android:name=".MyContentProvider"
        android:authorities="cn.com.myapp"
        android:enabled="true"
        android:exported="true" >
   </provider>
</application>

public class MyContentProvider extends ContentProvider {
    private static UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
    private static final int SUCCESS = 1;
    private MyDBhelper myDBhelper;
    // 靜態(tài)代碼塊，MyContentProvider對(duì)象沒(méi)有創(chuàng)建出來(lái)之前就已經(jīng)存在
    static {
        // 加載時(shí)為uri適配器添加匹配規(guī)則
        uriMatcher.addURI("cn.com.myapp","user",SUCCESS);
        // 查詢表中的某條記錄
        uriMatcher.addURI("cn.com.myapp","user/#",2);
    }
    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.
        throw new UnsupportedOperationException("Not yet implemented");
    }
    @Override
    public Uri insert(Uri uri, ContentValues values) {
        // TODO: Implement this to handle requests to insert a new row.
        throw new UnsupportedOperationException("Not yet implemented");
    }
    @Override
    public boolean onCreate() {
        // 創(chuàng)建數(shù)據(jù)庫(kù)和初始化表的內(nèi)容
        myDBhelper = new MyDBhelper(getContext());
        return false;
    }
    @Override
    // 未來(lái)會(huì)有另外一個(gè)app通過(guò)uri來(lái)調(diào)用query方法
    public Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
        // TODO: Implement this to handle query requests from clients.
        // 匹配傳入的uri，如果匹配得上再做相應(yīng)的查詢
        int match = uriMatcher.match(uri);
        if(match == 1) {
            // 查詢user表中的數(shù)據(jù)并返回
            SQLiteDatabase db = myDBhelper.getWritableDatabase();
            return db.query("user",projection,selection,selectionArgs,null,null,sortOrder);
        } else if(match == 2) {
            // 查詢表中的某條記錄
        } else {
            return null;
        }
    }
    @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");
    }
}

public class firstApplicationActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first_application);
        MyDBhelper myDBhelper = new MyDBhelper(firstApplicationActivity.this);
        SQLiteDatabase db = myDBhelper.getWritableDatabase();
        db.execSQL("insert into user(userName,phone) values ('tom','8888')");
        db.execSQL("insert into user(userName,phone) values ('jeny','18888')");
        db.execSQL("insert into user(userName,phone) values ('jack','38888')");
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".secondApplicationActivity"
    android:orientation="vertical"
    >
    <TextView
        android:id="@+id/show"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="9"/>
    <Button
        android:id="@+id/btn"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:text="獲取共享數(shù)據(jù)"
        />
</LinearLayout>

public class secondApplicationActivity extends AppCompatActivity implements View.OnClickListener {
private Button btn;
private TextView tv_show;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second_application);
        initViews();
        setListener();
    }
    protected void initViews() {
        btn = findViewById(R.id.btn);
        tv_show = findViewById(R.id.show);
    }
    protected void setListener() {
        btn.setOnClickListener(this);
    }
    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn:
                // 創(chuàng)建uri，通過(guò)uri來(lái)指向共享的數(shù)據(jù)文件
                Uri uri = Uri.parse("content://cn.com.myapp/user");
                // 獲取訪問(wèn)對(duì)象(內(nèi)容解析者)
                ContentResolver contentResolver = getContentResolver();
                Cursor cursor = contentResolver.query(uri, new String[]{"userName", "phone"}, null, null, null);
                while (cursor.moveToNext()) {
                    tv_show.append("用戶名：" + cursor.getString(0) + "----：" + cursor.getString(1) + "\n");
                }
        }
    }
}