Fragment的用法

模擬微信界面，可滑動切換，也可以點擊下面圖標切換

public class MainActivity extends FragmentActivity {
    private MyFirstFragment myFirstFragment;
    private MySecondFragment mySecondFragment;
    private MyThirdFragment myThirdFragment;
    private FragmentManager mFragmentmanager;
    private RadioGroup mRadioGroup;
    private ViewPager mViewPager;
    private FragmentPagerAdapter mAdapter;
    private List<Fragment> mFragments;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mFragmentmanager = getSupportFragmentManager();
        mFragments = new ArrayList<>();
        myFirstFragment = new MyFirstFragment();
        mySecondFragment = new MySecondFragment();
        myThirdFragment = new MyThirdFragment();
        mFragments.add(myFirstFragment);
        mFragments.add(mySecondFragment);
        mFragments.add(myThirdFragment);
        mViewPager = (ViewPager) findViewById(R.id.viewpager);
        mRadioGroup = (RadioGroup) findViewById(R.id.radiogroup);
        mAdapter = new MyFragmentAdapter(mFragmentmanager,mFragments);
        mViewPager.setAdapter(mAdapter);
        mRadioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int checkedId) {
                switch (checkedId){
                    case R.id.radiobutton1:
                        mViewPager.setCurrentItem(0);
                        break;
                    case R.id.radiobutton2:
                        mViewPager.setCurrentItem(1);
                        break;
                    case R.id.radiobutton3:
                        mViewPager.setCurrentItem(2);
                        break;
                }
            }
        });
        mRadioGroup.check(R.id.radiobutton1);
    }

需要寫一個adapter，注意繼承FragmentPagerAdapter，複寫相關方法，

public class MyFragmentAdapter extends FragmentPagerAdapter {
    private List<Fragment> mFragments;
    public MyFragmentAdapter(FragmentManager fm, List<Fragment> mFragments) {
        super(fm);
        this.mFragments = mFragments;
    }

    @Override
    public Fragment getItem(int position) {
        return mFragments.get(position);
    }

    @Override
    public int getCount() {
        return mFragments.size();
    }
}

佈局文件，注意viewpager的寫法，要寫完整的包名

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_weight="1"
        android:layout_height="match_parent">
    </android.support.v4.view.ViewPager>

    <RadioGroup
        android:id="@+id/radiogroup"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:orientation="horizontal"
        android:background="@color/gray">
        <RadioButton
            android:id="@+id/radiobutton1"
            style="@style/main_activity"
            android:background="@drawable/msg_background"/>
        <RadioButton
            android:id="@+id/radiobutton2"
            style="@style/main_activity"
            android:background="@drawable/fri_background" />
        <RadioButton
            android:id="@+id/radiobutton3"
            style="@style/main_activity"
            android:background="@drawable/dyn_background" />
    </RadioGroup>

</LinearLayout>

數據存儲

java課程中講過三種存儲方式：
1、文本存儲
2、MySql 數據庫存儲
3、網絡存儲—Server Lite
Android中有五種存儲方式：
1、xml存儲
2、文件存儲，包括緩存和本地文件
3、數據庫—SQLite(最新版本是SQLite3)
4、網絡存儲
5、ContentProvider 最常見的是手機聯繫人的存儲
存儲分爲內部存儲和外部存儲

public class MainActivity extends Activity implements View.OnClickListener{
    private TextView mTextview;
    private EditText mEditText;
    private Button mButtonRead;
    private Button mButtonWrite;
    private Button mButtonWriteCache;
    private Button mButtonReadCache;
    private Button mButtonWriteCacheDir;
    private Button mButtonWriteSdcard;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextview = (TextView) findViewById(R.id.textview);
        mEditText = (EditText) findViewById(R.id.edittext);
        mButtonRead = (Button) findViewById(R.id.button_read);
        mButtonWrite = (Button) findViewById(R.id.button_write);
        mButtonWriteCache = (Button) findViewById(R.id.button_write_cache);
        mButtonReadCache = (Button) findViewById(R.id.button_read_cache);
        mButtonWriteCacheDir = (Button) findViewById(R.id.button_write_cache_dir);
        mButtonWriteSdcard = (Button) findViewById(R.id.button_write_sdcard);
        mButtonRead.setOnClickListener(this);
        mButtonWrite.setOnClickListener(this);
        mButtonWriteCache.setOnClickListener(this);
        mButtonReadCache.setOnClickListener(this);
        mButtonWriteCacheDir.setOnClickListener(this);
        mButtonWriteSdcard.setOnClickListener(this);
    }
    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.button_read:
                SharedPreferences preferences = getSharedPreferences("preferences_test", MODE_PRIVATE);
//                SharedPreferences preferences = getPreferences(MODE_PRIVATE);
                String content = preferences.getString("edittext_input","默認值");
                mTextview.setText(content);
                break;
            case R.id.button_write:
                SharedPreferences preferences2 = getSharedPreferences("preferences_test",MODE_PRIVATE);
                SharedPreferences.Editor editor = preferences2.edit();
                editor.putString("edittext_input",mEditText.getText().toString());
                editor.commit();
                break;
            case R.id.button_write_cache:
                try {
                    FileOutputStream outputStream = openFileOutput("HelloCache",MODE_PRIVATE);
                    PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputStream));
                    writer.write("你好，緩存");
                    writer.flush();
                    writer.close();
                    outputStream.close();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            case R.id.button_read_cache:
                try {
                    FileInputStream is = openFileInput("HelloCache");
                    BufferedReader br = new BufferedReader(new InputStreamReader(is));
                    String line = br.readLine();
                    while (line!=null){
                        Log.d("readcache",""+line);
                        line = br.readLine();
                    }
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                break;
            case R.id.button_write_cache_dir:
                File file = new File(getCacheDir(),"helloworld.txt");
                if (!file.exists()){
                    try {
                        file.createNewFile();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                FileOutputStream outputStream = null;
                try {
                    outputStream = new FileOutputStream(file);
                    PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputStream));
                    writer.write("你好，新的緩存");
                    writer.flush();
                    writer.close();
                    outputStream.close();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                break;
            case R.id.button_write_sdcard:
                Toast toast = Toast.makeText(getApplicationContext(),"寫入本地磁盤cache",Toast.LENGTH_SHORT);
                File file1 = new File(Environment.getExternalStorageDirectory(),"helloworld.txt");
                if (!file1.exists()){
                    try {
                        file1.createNewFile();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                FileOutputStream outputStream1 = null;
                try {
                    outputStream = new FileOutputStream(file1);
//                    PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputStream));
//                    writer.write("你好，本地磁盤");
//                    writer.flush();
//                    writer.close();
                    outputStream.write("你好，本地磁盤".getBytes());
                    outputStream.flush();
                    outputStream.close();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                break;
            default:
                break;
        }
    }

<TextView
        android:id="@+id/textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <EditText
        android:id="@+id/edittext"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/button_read"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="讀取數據"/>
    <Button
        android:id="@+id/button_write"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="寫入數據"/>
    <Button
        android:id="@+id/button_write_cache"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="寫入緩存數據"/>
    <Button
        android:id="@+id/button_read_cache"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="讀取緩存數據"/>
    <Button
        android:id="@+id/button_write_cache_dir"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="寫入緩存數據到cache文件夾"/>
    <Button
        android:id="@+id/button_write_sdcard"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="寫入本地磁盤"/>

注意讀寫權限的設置，在manifest裏面

<!--插拔式擴展卡讀寫權限-->
    <uses-permission android:name="ANDROID.PERMISSION.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission>
    <!--手機本身存儲的讀寫權限-->
    <uses-permission android:name="ANDROID.PERMISSION.WRITE_EXTERNAL_STORAGE"></uses-permission>

數據庫 SQLite

SQLite庫可以解析大部分標準SQL語言。但它也省去了一些特性並且加入了一些自己的新特性。
需要寫一個類繼承SQLiteOpenHelper，複寫相應方法，寫構造器，注意參數的設定

public class TestSqliteOpenHelper extends SQLiteOpenHelper {
    public TestSqliteOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }
    public TestSqliteOpenHelper(Context context,String name){
        this(context,name, null,1);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL("create table if not exists user(id integer primary key autoincrement,name varchar(20),password varchar(20))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}

public class MainActivity extends Activity implements View.OnClickListener{
    private Button mButtonCreateDB;
    private Button mButtonInsert;
    private SQLiteDatabase db;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TestSqliteOpenHelper helper = new TestSqliteOpenHelper(getApplicationContext(),"my_first_db");
        db =  helper.getWritableDatabase();
        mButtonCreateDB = (Button) findViewById(R.id.button_create_db);
        mButtonInsert = (Button) findViewById(R.id.button_insert);
        mButtonCreateDB.setOnClickListener(this);
        mButtonInsert.setOnClickListener(this);
    }
    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.button_create_db:
                break;
            case R.id.button_insert:
                ContentValues values = new ContentValues();
                values.put("name","zhangsan");
                values.put("password","123456");
                db.insert("user",null,values);
                break;
        }
    }
}

數據庫SQLite(重新認識)

2016-08-02
數據庫的創建，並且創建了兩個表book 和Category，並且在onUpgrade方法中完成數據庫的升級。

package com.example.databasetest;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;

public class MyDatabaseHelper extends SQLiteOpenHelper {

    private static final String CREATE_BOOK = "create table book("  //創建一個book表
            +"id integer primary key autoincrement," 
            +"author text,"
            +"price real,"
            +"pages integer,"
            +"name text)";
    private static final String CREATE_CATEGORY = "create table Category(" +  //創建一個category表
            "id integer primary key autoincrement," +
            "category_name text," +
            "category_code integer)";
    private Context mContext;

    public MyDatabaseHelper(Context context, String name,
            CursorFactory factory, int version) {
        super(context, name, factory, version);
        mContext = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_BOOK);
        db.execSQL(CREATE_CATEGORY);
        Toast.makeText(mContext, "創建數據庫成功", Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("drop table if exists book");    //刪除表book
        db.execSQL("drop table if exists Category");//刪除表category
        onCreate(db);  //然後再創建數據庫，在activity的onCreate方法中，設置數據庫version爲2，實現了數據庫的升級
    }

}

在activity中進行數據庫的操作，包括創建數據庫，數據的增刪改查，使用事務替換數據。

package com.example.databasetest;

import android.support.v7.app.ActionBarActivity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;


public class MainActivity extends ActionBarActivity implements OnClickListener{
    private Button mButtonCreate;
    private Button mButtonAdd;
    private Button mButtonUpdate;
    private Button mButtonDelete;
    private Button mButtonSelect;
    private Button mButtonReplace;
    private MyDatabaseHelper dbHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 2);//版本升級爲2
        mButtonCreate = (Button) findViewById(R.id.create_db);
        mButtonAdd = (Button) findViewById(R.id.add_data);
        mButtonUpdate = (Button) findViewById(R.id.update_data);
        mButtonDelete = (Button) findViewById(R.id.delate_data);
        mButtonSelect = (Button) findViewById(R.id.select_data);
        mButtonReplace = (Button) findViewById(R.id.replace_data);
        mButtonCreate.setOnClickListener(this);
        mButtonAdd.setOnClickListener(this);
        mButtonUpdate.setOnClickListener(this);
        mButtonDelete.setOnClickListener(this);
        mButtonSelect.setOnClickListener(this);
        mButtonReplace.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
        case R.id.create_db:
            dbHelper.getWritableDatabase();//以讀寫方式打開數據庫，一旦數據庫的磁盤空間滿了，數據庫就只能讀而不能寫，
            break;
        case R.id.add_data:
            SQLiteDatabase db = dbHelper.getWritableDatabase();
            ContentValues values = new ContentValues();
            //開始組裝第一條數據
            values.put("name", "第一行代碼");
            values.put("author", "guo");
            values.put("pages", 456);
            values.put("price", 16.2);
            db.insert("book", null, values);//插入第一條數據
            values.clear();
            //開始組裝第二條數據
            values.put("name", "java編程思想");
            values.put("author", "li");
            values.put("pages", 566);
            values.put("price", 19.2);
            db.insert("book", null, values);//插入第二條數據
            break;

        case R.id.update_data:
            SQLiteDatabase db2 = dbHelper.getWritableDatabase();
            ContentValues values2 = new ContentValues();
            values2.put("price", 29.99);
            db2.update("book", values2, "name = ?", new String[] {"第一行代碼"}); //將《第一行代碼》的價格改爲29.99
            break;
        case R.id.delate_data:
            SQLiteDatabase db3 = dbHelper.getWritableDatabase();
            db3.delete("book", "pages > ?", new String[]{"500"});  //刪除頁碼超過500頁的書
            break;
        case R.id.select_data:
            SQLiteDatabase db4 = dbHelper.getWritableDatabase();
            //查詢book表中的所有數據
            Cursor cursor = db4.query("book", null, null, null, null, null, null);
            if (cursor.moveToFirst()) {
                do {
                    //遍歷Cursor對象，取出數據並打印
                    String name = cursor.getString(cursor.getColumnIndex("name"));
                    String author = cursor.getString(cursor.getColumnIndex("author"));
                    int pages = cursor.getInt(cursor.getColumnIndex("pages"));
                    double price = cursor.getDouble(cursor.getColumnIndex("price"));

                    Log.d("MainActivity", "book name is "+name);
                    Log.d("MainActivity", "book author is "+author);
                    Log.d("MainActivity", "book pages is "+pages);
                    Log.d("MainActivity", "book price is "+price);
                } while (cursor.moveToNext());
            }
            break;
        case R.id.replace_data://使用事務替換數據
            SQLiteDatabase db5 = dbHelper.getWritableDatabase();
            db5.beginTransaction();//開啓事務
            try{
                db5.delete("book", null, null);
                if (true) {
//                  throw new NullPointerException();
                }
                ContentValues values3 = new ContentValues();
                values3.put("name", "權利的遊戲");
                values3.put("author", "Martin");
                values3.put("pages", 720);
                values3.put("price", 20.85);
                db5.insert("Book", null, values3);
                db5.setTransactionSuccessful();//事務執行成功
            }catch (Exception e) {
                e.printStackTrace();
            }finally{
                db5.endTransaction();//結束事務
            }
            break;
        default:

            break;
        }
    }

}

佈局文件，只是按鈕而已

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.databasetest.MainActivity" >

    <Button 
        android:id="@+id/create_db"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="創建數據庫"/>
    <Button 
        android:id="@+id/add_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="添加數據"/>
    <Button 
        android:id="@+id/update_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="更新數據"/>
    <Button 
        android:id="@+id/delate_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="刪除數據"/>
    <Button 
        android:id="@+id/select_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="查詢數據"/>
    <Button 
        android:id="@+id/replace_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="替換數據"/>

</LinearLayout>

Fragment實例，數據存儲，數據庫SQLite

Fragment的用法

數據存儲

數據庫 SQLite

數據庫SQLite(重新認識)

SoundPool、 VedioView、 MediaRecorder、 SurfaceView、 Camera、

自定義Notification 聊天界面的編寫

Service IntentService Android中的線程 MediaPlayer

ViewPager添加圓點，循環翻頁。fragment的使用

數據庫部分、ContentProvider、BroadcastReceiver、Service

Mac下配置sublime實現LaTeX

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

linux以太網驅動總結