简单的安卓记事本

在Android系统的手机开发平台之上，研究与开发一个记事本软件，提供适用手机的记事本功能服务。

流程图：

数据库设计实现：

        该系统所有数据存在数据库中，本次实验采用SQLite来对数据库进行操作。 SQLite，是一款轻型的数据库，是遵守ACID的关系型数据库管理系统，它包含在一个相对小的C库中。它具有零配置、足够小、操作速度快等优点，被广泛应用于手机应用软件中。         新建DatabaseHelper类作为数据库辅助类，继承SQLiteOpenHelper类。在DatabaseHelper类的构造方法中创建数据库，并在onCreate上创建表及属性。

package cn.edu.nbut.mytextbook; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; /** * Created by ~polm on 2016/12/14. */ public class DatabaseHelper extends SQLiteOpenHelper { static String name="book.db"; static int version=1; public DatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) { super(context, name, factory, version); } public void onCreate(SQLiteDatabase db) { String sql="create table mytext(id integer primary key autoincrement,title text not null, content text,time datetime not null default getDate())"; db.execSQL(sql); } public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { } }

模块功能+界面设计+Activity实现代码

封面：         封面主要是用户在打开页面是展示出来的一张图片，有一个良好的过渡作用。界面就是由一张有关于记事本的图片所构成，该图片填充与整个界面，为了美观将界面的标题栏隐藏。该界面停留三秒自动转入到主页面，时间不长，不会让用户感到等待的烦躁。

package cn.edu.nbut.mytextbook; import android.content.Intent; import android.os.Message; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.KeyEvent; import android.view.View; import android.widget.ImageView; import java.util.Timer; import java.util.TimerTask; import java.util.logging.Handler; public class FirstActivity extends AppCompatActivity { final Timer timer = new Timer(); ImageView imageView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); getSupportActionBar().hide(); setContentView(R.layout.activity_first); imageView = (ImageView)findViewById(R.id.imageView); timerinit(); } private void timerinit() { TimerTask task = new TimerTask() { @Override public void run() { Intent intent = new Intent(FirstActivity.this, MainActivity.class); startActivity(intent); finish(); } };timer.schedule(task, 3000); } public boolean OnKeyDown(int keyCode, KeyEvent event) { timer.cancel(); return super.onKeyDown(keyCode, event); } }

当天记事内容：         当天记事内容主要用于向用户展示用户当天所添加或更改的记事。该模块方便用户查看自己的最新动态，记事内容将按时间顺序在页面上排列，第一行数据则是用户最新添加或更改的记事。实现方法：用户界面防止一个listview控件，该控件向数据库中读取数据，设两个数组，一个存放整型，一个存放字符型。整型数组存放的是一条记事的id，字符型数组存放的是title和time。字符型数组用于展示在页面上，整型数组用于listview适配器上，再对listview中的每一条item添加触发事件。

package cn.edu.nbut.mytextbook; import android.content.Intent; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.ListView; import android.widget.Toast; import java.sql.Timestamp; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; public class MainActivity extends AppCompatActivity { private ListView listView; private static final int NEWBACK = 3; private static final int NEWBACK2 = 3; final static int Menu_New = Menu.FIRST; final static int Menu_Before = Menu.FIRST+1; final static int Menu_Exit = Menu.FIRST+2; Menu menu; ArrayList<Integer> IdArray = new ArrayList<Integer>(); class itemListener implements AdapterView.OnItemClickListener { @Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { Intent intent = new Intent(MainActivity.this, UpdateActivity.class); intent.putExtra("id", IdArray.get(arg2)); startActivityForResult(intent, NEWBACK2); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); listView = (ListView)findViewById(R.id.listView); InitData(); listView.setOnItemClickListener(new itemListener()); } public void InitData() { Date date = new Date(); Timestamp timestamp = new Timestamp(date.getTime()); DateFormat format = new SimpleDateFormat("yyyy-MM-dd"); String timenow = format.format(timestamp); DatabaseHelper helper = new DatabaseHelper(MainActivity.this, "book.db", null, 1); SQLiteDatabase db = helper.getReadableDatabase(); Cursor cs = db.query("mytext", new String[]{"id", "title", "time"}, null, null, null, null, "time desc"); ArrayList<String> al = new ArrayList<String>(); IdArray.clear(); while(cs.moveToNext()) { int id = cs.getInt(cs.getColumnIndex("id")); String title = cs.getString(cs.getColumnIndex("title")); String time = cs.getString(cs.getColumnIndex("time")); if (time.compareTo(timenow) >= 0) { IdArray.add(id); al.add(title + "\n" + time); } } ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, al); listView.setAdapter(adapter); } @Override public boolean onCreateOptionsMenu (Menu menu) { menu.add(0, Menu_New, 0, "添加"); menu.add(0, Menu_Before, 0, "历史记录"); menu.add(0, Menu_Exit, 0, "退出"); return true; } @Override public boolean onOptionsItemSelected (MenuItem item) { switch (item.getItemId()) { case Menu_New: Intent intent = new Intent(MainActivity.this, NewActivity.class); startActivityForResult(intent, NEWBACK); break; case Menu_Before: Intent intent1 = new Intent(MainActivity.this, BeforeActivity.class); startActivity(intent1); MainActivity.this.finish(); break; case Menu_Exit: System.exit(0); } return true; } @Override protected void onResume() { super.onResume(); InitData(); Toast.makeText(MainActivity.this, "刷新成功", Toast.LENGTH_LONG).show(); } }

历史记事内容：         历史记事内容用来向用户展示用户非今天所添加修改的记事。将历史与当天设成两个模块，防止界面展示太多的记事内容，使用户翻看困难。该模块实现功能与当天记事内容相同，区别在于两者向数据库读取数据所限制的时间范围不同。时间的比较采用字符串比较，获取当前时间与记事时间相比较。

package cn.edu.nbut.mytextbook; import android.content.Intent; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.ListView; import android.widget.Toast; import java.sql.Timestamp; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; public class BeforeActivity extends AppCompatActivity { private ListView listView; private static final int NEWBACK2 = 3; final static int Menu_Back = Menu.FIRST; final static int Menu_Exit = Menu.FIRST+1; Menu menu; ArrayList<Integer> IdArray = new ArrayList<Integer>(); class itemListener2 implements AdapterView.OnItemClickListener { @Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { Intent intent = new Intent(BeforeActivity.this, UpdateActivity.class); intent.putExtra("id", IdArray.get(arg2)); startActivityForResult(intent, NEWBACK2); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_before); listView = (ListView)findViewById(R.id.listView2); InitData(); listView.setOnItemClickListener(new itemListener2()); } public void InitData() { Date date = new Date(); Timestamp timestamp = new Timestamp(date.getTime()); DateFormat format = new SimpleDateFormat("yyyy-MM-dd"); String timenow = format.format(timestamp); DatabaseHelper helper = new DatabaseHelper(BeforeActivity.this, "book.db", null, 1); SQLiteDatabase db = helper.getReadableDatabase(); Cursor cs = db.query("mytext", new String[]{"id", "title", "time"}, null, null, null, null, "time desc"); ArrayList<String> al = new ArrayList<String>(); IdArray.clear(); while(cs.moveToNext()) { int id = cs.getInt(cs.getColumnIndex("id")); String title = cs.getString(cs.getColumnIndex("title")); String time = cs.getString(cs.getColumnIndex("time")); if (time.compareTo(timenow) >= 0) {} else { IdArray.add(id); al.add(title + "\n" + time); } } ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, al); listView.setAdapter(adapter); } @Override public boolean onCreateOptionsMenu (Menu menu) { menu.add(0, Menu_Back, 0, "返回"); menu.add(0, Menu_Exit, 0, "退出"); return true; } @Override public boolean onOptionsItemSelected (MenuItem item) { switch (item.getItemId()) { case Menu_Back: Intent intent = new Intent(BeforeActivity.this, MainActivity.class); startActivity(intent); BeforeActivity.this.finish(); break; case Menu_Exit: System.exit(0); } return true; } @Override protected void onResume() { super.onResume(); InitData(); Toast.makeText(BeforeActivity.this, "刷新成功", Toast.LENGTH_LONG).show(); } }

添加新记事：         添加新记事主要是完成用户添加新记事这项功能。该界面上有两个textview、两个edittext和一个button。textview用于提示用户该项所要填写的用户，edittext用于用户填写内容，button用于实现将用户填写内容添加到数据库的功能。button实现原理：先获取用户填写的标题和内容，再实现系统当前时间。将要传入数据库的内容打包在ContentValues的变量value中，利用SQLiteDatabase中的insert函数将value加入到数据库中。

package cn.edu.nbut.mytextbook; import android.content.ContentValues; import android.content.Intent; import android.database.sqlite.SQLiteDatabase; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; import java.sql.Time; import java.sql.Timestamp; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Date; public class NewActivity extends AppCompatActivity { EditText editTitle, editContent; Button fini; class finishListener implements View.OnClickListener{ @Override public void onClick(View arg0) { String title = editTitle.getText().toString(); String content = editContent.getText().toString(); Date date = new Date(); Timestamp timestamp = new Timestamp(date.getTime()); DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String time = format.format(timestamp); DatabaseHelper help = new DatabaseHelper(NewActivity.this, "book.db", null, 1); SQLiteDatabase db = help.getWritableDatabase(); ContentValues value = new ContentValues(); value.put("title", title); value.put("content", content); value.put("time", time); db.insert("mytext", null, value); Toast.makeText(NewActivity.this, "添加成功", Toast.LENGTH_LONG).show(); NewActivity.this.setResult(RESULT_OK, getIntent()); NewActivity.this.finish(); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_new); editTitle = (EditText)findViewById(R.id.editTitle); editContent = (EditText)findViewById(R.id.editContent); fini = (Button)findViewById(R.id.but_finish); final Intent intent = this.getIntent(); fini.setOnClickListener(new finishListener()); } }

修改记事：         修改记事主要用于用户修改已添加的的记事。界面上放置两个textview、两个edittext和两个button。textview用于提示用户该项所要填写的用户，edittext用于填充从数据库中读取的数据，button分别完成删除和保存修改的功能。数据填充利用SQLiteDatebase中的query来完成数据从数据库中读取，然后再分别填充。记事的修改保存类似于完成添加新记事，但是将利用update函数而不是insert了。删除利用SQLiteDatabase中的delete函数，根据id关键字进行删除。

package cn.edu.nbut.mytextbook; import android.content.ContentValues; import android.content.Intent; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; import java.sql.Timestamp; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Date; public class UpdateActivity extends AppCompatActivity { public int id; EditText editTitle, editContent; Button chan, dele; class changeListener implements View.OnClickListener { @Override public void onClick(View v) { Date date = new Date(); Timestamp timestamp = new Timestamp(date.getTime()); DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String timenow = format.format(timestamp); DatabaseHelper helper = new DatabaseHelper(UpdateActivity.this, "book.db", null, 1); SQLiteDatabase db = helper.getWritableDatabase(); ContentValues value = new ContentValues(); String title = editTitle.getText().toString(); String content = editContent.getText().toString(); value.put("title", title); value.put("content", content); value.put("time", timenow); db.update("mytext", value, "id=?", new String[]{id+""}); db.close(); Toast.makeText(UpdateActivity.this, "更新成功", Toast.LENGTH_LONG).show(); UpdateActivity.this.setResult(RESULT_OK, getIntent()); UpdateActivity.this.finish(); } } class deleteListener implements View.OnClickListener{ @Override public void onClick(View arg0) { DatabaseHelper helper = new DatabaseHelper(UpdateActivity.this, "book.db", null, 1); SQLiteDatabase db = helper.getWritableDatabase(); db.delete("mytext", "id=?", new String[]{id+""}); db.close(); editTitle.setText(""); editContent.setText(""); Toast.makeText(UpdateActivity.this, "删除成功", Toast.LENGTH_LONG).show(); UpdateActivity.this.setResult(RESULT_OK, getIntent()); UpdateActivity.this.finish(); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_update); editTitle = (EditText)findViewById(R.id.etTitle); editContent = (EditText)findViewById(R.id.etContent); chan = (Button)findViewById(R.id.but_change); dele = (Button)findViewById(R.id.but_delete); Intent intent = this.getIntent(); id = intent.getIntExtra("id", 1); fillData(); chan.setOnClickListener(new changeListener()); dele.setOnClickListener(new deleteListener()); } private void fillData() { DatabaseHelper helper = new DatabaseHelper(UpdateActivity.this, "book.db", null, 1); SQLiteDatabase db = helper.getReadableDatabase(); Cursor cs = db.query("mytext", new String[]{"id", "title", "content"}, "id=?", new String[]{id+""}, null, null, null); while(cs.moveToNext()) { String title = cs.getString(cs.getColumnIndex("title")); String content = cs.getString(cs.getColumnIndex("content")); editTitle.setText(title); editContent.setText(content); } db.close(); } }

以上就是整个代码实现了，只实现了基础功能，能力还不足，大家请多多指教^ ^