简单笔记本应用实现

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笔记本应用简介,用户通过密码登陆该应用,用户可以修改密码,登陆后可以创建一个笔记,笔记由标题和内容组成,用户的密码和笔记将会保存到数据库中,笔记标题采用ListView来展示,并可修改,工程由4个类实现,一个帮助类,3个activity,Login(登陆),NoteList(主题),Edit(编辑记事).

首先创建一个帮助类,增删改查

package com.pms.db;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DbHelper extends SQLiteOpenHelper {

private final static String DATABASE_NAME = "note_db"; //数据库名
private final static int DATABASE_VERSION = 1;//版本号

private final static String TABLE_NAME = "notepad";
public final static String NOTE_ID = "_id";
public final static String NOTE_TITLE = "title";
public final static String NOTE_CONTENT = "content";

public final static String LOGIN_TABLE_NAME = "login";
public final static String LOGIN_USER = "admin";
public final static String LOGIN_PWD = "password";

/*构造函数*/
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

/*创建数据库*/
@Override
public void onCreate(SQLiteDatabase db) {
String sql = "create table "+TABLE_NAME+" ("
+NOTE_ID+" integer primary key autoincrement, "
+NOTE_TITLE+" text, "
+NOTE_CONTENT+" text )";
db.execSQL(sql);

sql = "create table "+LOGIN_TABLE_NAME+" ("
+LOGIN_USER+" text, "
+LOGIN_PWD+" text )";
db.execSQL(sql);
}

/*更新数据库*/
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
String sql = "drop table if exists "+TABLE_NAME;
db.execSQL(sql);

sql = "drop table if exists "+LOGIN_TABLE_NAME;
db.execSQL(sql);
onCreate(db);
}
/**插入密码
* @param password
* 要插入的密码
* */
public long insertPwd(String password){
SQLiteDatabase db = this.getWritableDatabase(); //取得可写的数据库对象
ContentValues cv = new ContentValues();
cv.put(LOGIN_USER, LOGIN_USER);
cv.put(LOGIN_PWD, password);
return db.insert(LOGIN_TABLE_NAME, null, cv);
}

/**更新密码
* @param password
* 新密码
* */
public int updatePwd(String password){
SQLiteDatabase db = this.getWritableDatabase();
String where = LOGIN_USER+"=?";
String[] whereValues = {LOGIN_USER};
ContentValues cv = new ContentValues();
cv.put(LOGIN_PWD, password);
return db.update(LOGIN_TABLE_NAME, cv, where, whereValues);
}

/**取得密码
* @return 返回密码，没有则返回""
* */
public String getPwd(){
SQLiteDatabase db = this.getReadableDatabase();
String where = LOGIN_USER+"=?";
String[] whereValues = {LOGIN_USER};
Cursor cursor = db.query(LOGIN_TABLE_NAME, null, where, whereValues, null, null, null);
if(cursor.moveToFirst()){
return cursor.getString(cursor.getColumnIndex(LOGIN_PWD));
}else{
return "";
}
}
/**查询记事本表中的内容
*/
public Cursor selectNotes(){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_NAME, null, null, null, null, null, null);
return cursor;
}

/**插入记事
* */
public long insertNote(String title, String content){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(NOTE_TITLE, title);
cv.put(NOTE_CONTENT, content);
return db.insert(TABLE_NAME, null, cv);
}

/**删除记事
* @param id
* _id字段
* */
public void deleteNote(String id){
SQLiteDatabase db = this.getWritableDatabase();
String where = NOTE_ID+"=?";
String[] whereValues = {id};
db.delete(TABLE_NAME, where, whereValues);
}

/**更新记事
* */
public int updateNote(String id,String title, String content){
SQLiteDatabase db = this.getWritableDatabase();
String where = NOTE_ID+"=?";
String[] whereValues = {id};
ContentValues cv = new ContentValues();
cv.put(NOTE_TITLE, title);
cv.put(NOTE_CONTENT, content);
return db.update(TABLE_NAME, cv, where, whereValues);
}

}

package com.pms.note;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.pms.db.DbHelper;

public class Edit extends Activity{

private EditText et_title, et_content; //输入框对象
private Button bt;//按钮对象
private DbHelper db;//数据库对象
private String id;//从NoteList传过来的id
private String listTitle, listContent;//从NoteList传过来的标题和内容

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.edit);

/*取得对象*/
et_title = (EditText) findViewById(R.id.et_title);
et_content = (EditText) findViewById(R.id.et_content);
bt = (Button) findViewById(R.id.bt);
db = new DbHelper(this);

Intent intent = getIntent(); //得到Intent对象
/*取出从NoteList传来的值*/
id = intent.getStringExtra(DbHelper.NOTE_ID);
listTitle = intent.getStringExtra(DbHelper.NOTE_TITLE);
listContent = intent.getStringExtra(DbHelper.NOTE_CONTENT);

if(listTitle!= null){ //标题内容不为空
et_title.setText(listTitle);//显示该标题

}
if(listContent!=null){//正文内容不为空
et_content.setText(listContent);//显示该正文
}

/*绑定按钮点击事件*/
bt.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {

/*取得用户的输入内容*/
String title = et_title.getText().toString();
String content = et_content.getText().toString();

//判断是否为空
if(title.equals("")){
Toast.makeText(Edit.this, "标题不能为空！", Toast.LENGTH_SHORT).show();
}
else if(id!=null){ //判断是否存在该id的记事
if(db.updateNote(id, title, content)>0){//存在则更新，返回值大于0，更新成功
Toast.makeText(Edit.this, "编辑成功！", Toast.LENGTH_SHORT).show();
}
else{
Toast.makeText(Edit.this, "编辑失败", Toast.LENGTH_SHORT).show();
}
}
else if(db.insertNote(title, content)!= -1)//不存在则插入，返回值不等于-1，插入成功
{
Toast.makeText(Edit.this, "添加成功！", Toast.LENGTH_SHORT).show();
}
else
{
Toast.makeText(Edit.this, "添加失败！", Toast.LENGTH_SHORT).show();
}
/*设置需要返回到NoteList的内容*/
Intent intent = new Intent();
setResult(RESULT_OK,intent);
finish(); //关闭这个Activity
}

});

}

}
Login类

package com.pms.note;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.Toast;

import com.pms.db.DbHelper;

public class Login extends Activity {

/*得到各个控件对象*/
private EditText et;
private Button bt_login, bt_update;

private DbHelper db; //数据库对象
private String pwd; //密码

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

/*取得各个控件*/
et = (EditText) findViewById(R.id.password_edit);
bt_login = (Button) findViewById(R.id.login_button);
bt_update = (Button) findViewById(R.id.update_button);

db = new DbHelper(this); //得到DbHelper对象

pwd = db.getPwd(); //从数据库中取得密码

if(pwd.equals("")) //为空
{
Toast.makeText(Login.this, "这是你第一次登录，请初始化密码！", Toast.LENGTH_LONG)
.show();//弹出Toast消息
bt_login.setText("注册"); //将Button显示的文字变为注册
}
else //不为空
{
Toast.makeText(Login.this, "欢迎回来，请输入密码登录！", Toast.LENGTH_LONG).show();
}

/*为注册或者登陆绑定监听事件*/
bt_login.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
String password = et.getText().toString(); //取得输入的密码
if(pwd.equals("")) //为空
{
changePwd(); //调用该方法

}
else if(password.equals("")){ //如果输入为空
//弹出Toast消息
Toast.makeText(Login.this, "不能为空！", Toast.LENGTH_LONG).show();
}
else if(password.equals(pwd)){ //如果输入匹配
Toast.makeText(Login.this, "登录成功！", Toast.LENGTH_LONG).show();
Intent intent = new Intent(Login.this, NoteList.class);
startActivity(intent); //跳转到记事列表
}
else{
//不匹配弹出消息提示密码错误
Toast.makeText(Login.this, "密码错误！", Toast.LENGTH_LONG).show();
}
}
});

/*为修改密码按钮绑定监听事件*/
bt_update.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
String password = et.getText().toString(); //取得输入框的内容
if(password.equals(pwd)){ //匹配
changePwd(); //调用该方法
}
else{
//不匹配弹出消息
Toast.makeText(Login.this, "初始密码错误", Toast.LENGTH_LONG).show();
}
}
});

}

/**修改密码
* */
public void changePwd(){
/*装载对话框布局*/
LinearLayout newPwd = (LinearLayout) getLayoutInflater()
.inflate(R.layout.login_dialog, null);

//取得对话框中的输入框对象
final EditText et_dia_new = (EditText) newPwd.findViewById(R.id.etnew);
final EditText et_dia_con = (EditText) newPwd.findViewById(R.id.etconfirm);

/*新建一个对话框*/
new AlertDialog.Builder(Login.this)
.setTitle("输入密码") //设置标题
.setView(newPwd) //设置对话框绑定的视图
.setPositiveButton("确定", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
//取得输入框的内容
String dia_new = et_dia_new.getText().toString();
String dia_con = et_dia_con.getText().toString();

if(dia_new.equals("")||dia_con.equals("")){ //判断是否有空值
Toast.makeText(Login.this, "不能为空！", Toast.LENGTH_LONG).show();
}
else if(dia_new.equals(dia_con)){ //如果两个输入一致
if(db.getPwd()!=null){
db.updatePwd(dia_new); //如果已经设置过密码，更新
}
else{
db.insertPwd(dia_new); //插入密码
}
pwd = dia_new; //新的密码
bt_login.setText("登录"); //把Button的文字显示为登录
//弹出Toast消息
Toast.makeText(Login.this, "你可以使用该密码登录了！", Toast.LENGTH_LONG)
.show();

}

}
})
//设置一个取消按钮
.setNegativeButton("取消", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {

}
})
.show();
}
}

NoteList

package com.pms.note;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;

import com.pms.db.DbHelper;

public class NoteList extends Activity{

/*变量声明*/
private ListView lv;
private TextView tv;
private DbHelper db;
private Cursor cursor;
private static final int ADD = Menu.FIRST;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.notelist);

/*取得控件对象*/
lv = (ListView) findViewById(R.id.lv);
tv = (TextView) findViewById(R.id.tv);

registerForContextMenu(lv); //注册一个上下文菜单
db = new DbHelper(this); //获得数据库对象
cursor = db.selectNotes();//取得数据库中的记事
refreshListView();

/*绑定点击事件*/
lv.setOnItemClickListener(new OnItemClickListener() {

@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
cursor.moveToPosition(position); //将cursor指向position
Intent intent = new Intent(NoteList.this, Edit.class); //创建一个Intent对象，跳转到Edit
/*传递记事的id，标题，内容,这些内容从数据库中相应的字段中取得*/
intent.putExtra(DbHelper.NOTE_ID, String.valueOf(id));
intent.putExtra(DbHelper.NOTE_TITLE, cursor.getString(cursor.getColumnIndexOrThrow(DbHelper.NOTE_TITLE)));
intent.putExtra(DbHelper.NOTE_CONTENT, cursor.getString(cursor.getColumnIndexOrThrow(DbHelper.NOTE_CONTENT)));
startActivityForResult(intent, 0);//跳转
}

});

}

/**刷新ListView
*/
public void refreshListView() {
cursor = db.selectNotes();
if(cursor.moveToFirst()){
startManagingCursor(cursor);//让Activity来管理cursor
String[] from = {DbHelper.NOTE_TITLE};//数据库中的列名
int[] to = {R.id.itemtv};//数据库中列的内容绑定的视图
//SimpleCursorAdapter将数据库中的值绑定到listview
//参数分别为上下文，listview的布局，游标，数据库中列的值，值所要绑定的视图
SimpleCursorAdapter adapter = new SimpleCursorAdapter(NoteList.this,
R.layout.listitem,cursor, from, to);
lv.setAdapter(adapter); //listview绑定适配器
tv.setVisibility(View.GONE);
lv.setVisibility(View.VISIBLE);
}
else{
tv.setVisibility(View.VISIBLE); //设置为可见
//设置显示的文本
tv.setText("还没有你的私人笔记，点击menu添加");
lv.setVisibility(View.GONE);
}

}

/*创建上下文菜单*/
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
menu.add(0, 1, 1, "删除");

}

/*创建菜单*/
@Override
public boolean onCreateOptionsMenu(Menu menu) {

menu.add(0, ADD, 1, "添加笔记")
.setIcon(R.drawable.menu_add);
return super.onCreateOptionsMenu(menu);

}

/*设置上下文菜单点击事件*/
@Override
public boolean onContextItemSelected(final MenuItem item) {
final AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
if(item.getItemId()==1){
new AlertDialog.Builder(this) //新建对话框
.setTitle("警告")
.setMessage("确定要删除么？")
.setIcon(R.drawable.plugin_notice) //设置图标
.setPositiveButton("确定", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
db.deleteNote(String.valueOf(info.id)); //删除数据库中该项内容
refreshListView(); //刷新listview
}
})
.setNegativeButton("取消", new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {

}
})
.show();
}
return super.onContextItemSelected(item);
}

/*设置menu选择事件*/
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if(item.getItemId()==ADD)
{
Intent intent = new Intent(NoteList.this, Edit.class);
startActivityForResult(intent, 1);//跳转到Edit
}
return super.onOptionsItemSelected(item);
}

/*从Edit这个Activity返回是调用*/
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
refreshListView(); //刷新listview
}

}

清单文件
<?xml version="1.0" encoding="UTF-8"?>
-<manifest android:versionName="1.0" android:versionCode="1" package="com.pms.note" xmlns:android="http://schemas.android.com/apk/res/android"> -<application android:label="@string/app_name" android:icon="@drawable/icon"> -<activity android:label="@string/app_name" android:name="Login"> -<intent-filter> <action android:name="android.intent.action.MAIN"/> <category android:name="android.intent.category.LAUNCHER"/> </intent-filter> </activity> <activity android:name=".Edit"/> <activity android:name=".NoteList"/> </application> </manifest>

<?xml version="1.0" encoding="UTF-8"?>

notelist.xml
<?xml version="1.0" encoding="UTF-8"?>
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:background="@drawable/login_bg" android:layout_height="fill_parent" android:layout_width="fill_parent" android:orientation="vertical"> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:visibility="gone" android:textColor="#FF7A00FF" android:textSize="20sp" android:id="@+id/tv"/> <ListView android:layout_height="fill_parent" android:layout_width="fill_parent" android:id="@+id/lv" android:cacheColorHint="#00000000" android:divider="@drawable/divider"/> </LinearLayout>

edit.xml

<?xml version="1.0" encoding="UTF-8"?>
-<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:background="@drawable/login_bg" android:layout_height="fill_parent" android:layout_width="fill_parent"> <EditText android:layout_height="wrap_content" android:layout_width="fill_parent" android:singleLine="true" android:id="@+id/et_title"/> <EditText android:layout_height="330dp" android:layout_width="fill_parent" android:id="@+id/et_content" android:layout_below="@id/et_title"/> <Button android:background="@drawable/reg_button" android:layout_height="wrap_content" android:layout_width="120dp" android:id="@+id/bt" android:text="确定" android:layout_margin="3dp" android:layout_alignParentRight="true" android:layout_alignParentBottom="true"/> </RelativeLayout>

listItem.xml

<?xml version="1.0" encoding="UTF-8"?>
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_height="fill_parent" android:layout_width="fill_parent" android:orientation="horizontal"> <TextView android:layout_height="wrap_content" android:layout_width="wrap_content" android:padding="15dp" android:textColor="#FF7A00FF" android:textSize="27sp" android:id="@+id/itemtv"/> </LinearLayout>

login_dialog.xm

<?xml version="1.0"?>