Android 开发简单记事本程序（附源码）

2024-06-02 06:32| 来源: 网络整理| 查看: 265

简单介绍一下功能：简单记事本只能添加文字内容，首页用ListView显示所有保存的事项和保存的时间，添加页面添加内容，点击首页的ListView可以查看内容，删除内容。

先看一下运行效果：

先建立数据库：

package com.engineer.shizhibin.note; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; public class NoteDb 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 NoteDb(Context context) { super(context, "notes", null,1); } @Override public void onCreate(SQLiteDatabase db) { String sql ="create table "+TABLE_NAME+" ( "+ID+" integer primary key AUTOINCREMENT, "+CONTENT +" TEXT NOT NULL, "+TIME+" TEXT NOT NULL )"; db.execSQL(sql); } @Override public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) { } }

然后是MainActivity：

有显示目录的ListView，和添加按钮。他们都要设置点击监听事件。点击添加跳转到添加文字的activity 点击ListView跳转到Show Activity。

onResume() 在 Activity 从 Pause 状态转换到 Active 状态时被调用。在这个方法中访问SQLite数据库，通过Adapter将条目的内容和添加时间显示在ListView中。看代码： package com.engineer.shizhibin.note; 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.AdapterView; import android.widget.Button; import android.widget.ListView; public class MainActivity extends AppCompatActivity { private Button mButton; private ListView mList; private Intent mIntent; private MyAdapter mAdapter; private NoteDb mNotedb; private Cursor cursor; private SQLiteDatabase dbreader; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mList = (ListView) this.findViewById(R.id.list); mNotedb = new NoteDb(this); dbreader = mNotedb.getReadableDatabase(); mList.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView adapterView, View view, int i, long l) { cursor.moveToPosition(i); Intent intent = new Intent(MainActivity.this,ShowContent.class); intent.putExtra(NoteDb.ID,cursor.getInt(cursor.getColumnIndex(NoteDb.ID))); intent.putExtra(NoteDb.CONTENT,cursor.getString(cursor.getColumnIndex(NoteDb.CONTENT))); intent.putExtra(NoteDb.TIME,cursor.getString(cursor.getColumnIndex(NoteDb.TIME))); startActivity(intent); } }); } public void add(View v) { mIntent = new Intent(MainActivity.this,AddContent.class); startActivity(mIntent); } public void selectDb() { cursor = dbreader.query (NoteDb.TABLE_NAME,null,null,null,null,null,null); mAdapter = new MyAdapter(this,cursor); mList.setAdapter(mAdapter); } @Override protected void onResume() { super.onResume(); selectDb(); } }

为了方便程序扩展，以后有可能添加图片、视频内容我用了自定义的Adapter 继承自BadeAdapter：

package com.engineer.shizhibin.note; import android.content.Context; import android.database.Cursor; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.LinearLayout; import android.widget.TextView; public class MyAdapter extends BaseAdapter { private Context mContext; private Cursor mCursor; private LinearLayout mLayout; public MyAdapter(Context mContext,Cursor mCursor) { this.mContext = mContext; this.mCursor = mCursor; } @Override public int getCount() { return mCursor.getCount(); } @Override public Object getItem(int position) { return mCursor.getPosition(); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View view, ViewGroup viewGroup) { LayoutInflater inflater = LayoutInflater.from(mContext); mLayout = (LinearLayout) inflater.inflate(R.layout.item,null); TextView content = (TextView) mLayout.findViewById(R.id.list_content); TextView time = (TextView) mLayout.findViewById(R.id.list_time); mCursor.moveToPosition(position); String dbcontext = mCursor.getString(mCursor.getColumnIndex("content")); String dbtime = mCursor.getString(mCursor.getColumnIndex("time")); content.setText(dbcontext); time.setText(dbtime); return mLayout; } }

添加条目，向数据中添加数据用ContentValues以键值对的方式非常方便：

package com.engineer.shizhibin.note; import android.content.ContentValues; import android.database.sqlite.SQLiteDatabase; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.EditText; import java.text.SimpleDateFormat; import java.util.Date; public class AddContent extends AppCompatActivity { private EditText mEt; private NoteDb mDb; private SQLiteDatabase mSqldb; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_add_content); mEt = (EditText) this.findViewById(R.id.text); mDb = new NoteDb(this); mSqldb = mDb.getWritableDatabase(); } public void save(View v) { DbAdd(); finish(); } public void cancle(View v) { mEt.setText(""); finish(); } public void DbAdd() { ContentValues cv = new ContentValues(); cv.put(NoteDb.CONTENT,mEt.getText().toString()); cv.put(NoteDb.TIME,getTime()); mSqldb.insert(NoteDb.TABLE_NAME,null,cv); } public String getTime() { SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss"); Date date = new Date(); String str = sdf.format(date); return str; } }

查看条目：

package com.engineer.shizhibin.note; import android.database.sqlite.SQLiteDatabase; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.TextView; public class ShowContent extends AppCompatActivity { private TextView mTextview; private TextView time; private NoteDb mDb; private SQLiteDatabase mSql; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_show_content); mTextview = (TextView)this.findViewById(R.id.showtext); time = (TextView)this.findViewById(R.id.showtime); mDb = new NoteDb(this); mSql = mDb.getWritableDatabase(); mTextview.setText(getIntent().getStringExtra(NoteDb.CONTENT)); time.setText(getIntent().getStringExtra(NoteDb.TIME)); } public void delete(View v) { int id = getIntent().getIntExtra(NoteDb.ID,0); mSql.delete(NoteDb.TABLE_NAME," _id = " + id,null); finish(); } public void goBack(View v) { finish(); } }

MainActivity布局：

添加Activity布局：

查看页布局：

ListView布局

以上就是所有源码，明白Android目录结构，复制到相应的地方，就可以运行了！！！

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