基于Andriod的简易记事本APP设计与实现

本设计完成后，能够实现以下功能：

(1)设计实现“添加新记事”,“编辑内容”,“保存和删除当前记事”这三个主要的功能模块。

(2)分析并解决实现中的若干技术问题,像组件的选择以及保存方式的选择。

(3)进行测试并分析结果。

具体过程如下：

组件设计：

本项目涉及到以下组件:

1. TextView：“记事本”，“编辑”等标题；
2. Button：“添加”，“保存”，“取消”按钮等；
3. Switch：设置目录里用于转换语言文本等功能；
4. ImageView：设置APP背景；
5. ScrollView：滚动界面功能。

本次设计的基于Android简易记事本APP系统，方便用户随时随地记录，操作简单，更大的发挥了用户的自定义功能。

程序设计：

(1)主函数设计：

package com.example.michaelxuzhi.notebook2;
        import android.app.Activity;
        import android.content.Intent;
        import android.database.Cursor;
        import android.database.sqlite.SQLiteDatabase;
        import android.os.Bundle;
        import android.view.View;
        import android.widget.AdapterView;
        import android.widget.Button;
        import android.widget.ListView;
      //import java.util.Timer;
public class MainActivity extends Activity implements View.OnClickListener {
    private ListView lv;
    private SQLiteDatabase dbReader;
    private Cursor cursor;
    private NotesDB notesDB;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }
    private void initView() {
        Button addbtn = (Button) findViewById(R.id.main_add);
        lv = (ListView) findViewById(R.id.main_list);
        addbtn.setOnClickListener(this);
        notesDB = new NotesDB(this);
        dbReader = notesDB.getReadableDatabase();
        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView parent, View view, int position, long id) {
                cursor.moveToPosition(position);
                Intent i = new Intent(MainActivity.this, SelectAct.class);
                i.putExtra(NotesDB.ID, cursor.getInt(cursor.getColumnIndex(NotesDB.ID)));
                i.putExtra(notesDB.CONTENT, cursor.getString(cursor.getColumnIndex(NotesDB.CONTENT)));
                i.putExtra(notesDB.TIME, cursor.getString(cursor.getColumnIndex(NotesDB.TIME)));
                startActivity(i);
            }
        });
    }
    @Override
    public void onClick(View v) {
        Intent i = new Intent(this, Addcontent.class);
        startActivity(i);
    }
    private void selectDB() {
        cursor = dbReader.query(NotesDB.TABLE_NAME, null, null, null, null, null, null);
        MyAdapter adapter = new MyAdapter(this, cursor);
        lv.setAdapter(adapter);
    }
    @Override
    protected void onResume() {
        super.onResume();
        selectDB();
    }
}

(2)添加内容程序设计：

public class Addcontent extends Activity implements View.OnClickListener {
    private EditText ettext;
    private SQLiteDatabase dbWriter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.add_list);
        Button savebtn = (Button) findViewById(R.id.add_save);
        Button deletebtn = (Button) findViewById(R.id.add_delete);
        ettext = (EditText) findViewById(R.id.add_etv);
        savebtn.setOnClickListener(this);
        deletebtn.setOnClickListener(this);
        NotesDB notesDB = new NotesDB(this);
        dbWriter = notesDB.getWritableDatabase();
    }
    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.add_save:
                addDB();
                finish();
                break;
            case R.id.add_delete:
                finish();
                break;
        }
    }
    private void addDB() {
        ContentValues cv = new ContentValues();
        cv.put(NotesDB.CONTENT, ettext.getText().toString());
        cv.put(NotesDB.TIME, getTime());
        dbWriter.insert(NotesDB.TABLE_NAME, null, cv);
    }
    public String getTime() {
        SimpleDateFormat format = new SimpleDateFormat("yyy年MM月dd日 HH:mm:ss");
        Date curDate = new Date();
        String str = format.format(curDate);
        return str;
    }
}

(3)项目驱动程序设计：

public class MyAdapter extends BaseAdapter {
    private Context context;
    private Cursor cursor;
    public MyAdapter(MainActivity context, Cursor cursor){
        this.context = context;
        this.cursor = cursor;
    }
    @Override
    public int getCount() {
        return cursor.getCount();
    }
    @Override
    public Object getItem(int position) {
        return cursor.getPosition();
    }
    @Override
    public long getItemId(int position) {
        return position;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = LayoutInflater.from(context);
        LinearLayout layout = (LinearLayout) inflater.inflate(R.layout.list, null);
        TextView contenttv = (TextView) layout.findViewById(R.id.list_content);
        TextView timetv = (TextView) layout.findViewById(R.id.list_time);
        cursor.moveToPosition(position);
        String content = cursor.getString(cursor.getColumnIndex("content"));
        String time = cursor.getString(cursor.getColumnIndex("time"));
        contenttv.setText(content);
        timetv.setText(time);
        return layout;
    }
}

(4)选择功能程序设计：

public class SelectAct extends Activity implements View.OnClickListener {
    private Button s_delete, s_back;
    private TextView s_tv;
    private NotesDB notesDB;
    private SQLiteDatabase dbWriter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.select);
        s_back = (Button) findViewById(R.id.s_back);
        s_delete = (Button) findViewById(R.id.s_delete);
        s_tv = (TextView) findViewById(R.id.s_tv);
        notesDB = new NotesDB(this);
        dbWriter = notesDB.getWritableDatabase();
        s_back.setOnClickListener(this);
        s_delete.setOnClickListener(this);
        s_tv.setText(getIntent().getStringExtra(NotesDB.CONTENT));
    }
    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.s_delete:
                deleteDate();

(5)笔记功能程序设计：

public class NotesDB extends SQLiteOpenHelper {
    public static final String TABLE_NAME = "notes";
    public static final String CONTENT = "content";
    public static final String ID = "_id";
    public static final String TIME = "time";
    public NotesDB(Context context) {
        super(context, "notes", null, 1);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + TABLE_NAME + " (" + ID + " integer primary key autoincrement,"
                + CONTENT + " text not null," + TIME + " text not null)");
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }
}