n编写一个掌上日记本应用程序，用SQLite数据库保存信息。界面效果如下图所示, 不要标题，自动加入日期，只需要正文和日期。
运行演示
strings.xml源代码如下:
<resources>
<string name="app_name">MyDiary</string>
<string name="menu_insert">添加一篇新日记</string>
<string name="search">查找内容</string>
<string name="time">时间</string>
<string name="body">内容</string>
<string name="confirm">保存</string>
<string name="back">返回</string>
<string name="delete">删除</string>
<string name="edit_diary">编辑日记</string>
</resources>
操作数据库的文件MyDiaryDatabase.java源代码如下：
package com.example.mydiary;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class MyDiaryDatabase {
private DatabaseHelper mOpenHelper;
static final String Database_name = "MyDiary.db";//数据库名称
static final int Database_Version = 1;
static final String TABLE_NAME = "diary";//数据表名称，日记
static final String ID = "id"; //ID编号，数据表的主键
static final String BODY = "body"; //正文
static final String TIME= "time"; //时间
private SQLiteDatabase db;
private Context context;
//数据库的版本管理类
private static class DatabaseHelper extends SQLiteOpenHelper {
private DatabaseHelper(Context context) {
super(context, Database_name, null, Database_Version);
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
/*
* 构造器，传递 Context
*/
public MyDiaryDatabase(Context c) {
context =c;
mOpenHelper = new DatabaseHelper(context);
}
/*
* 打开或创建数据库
*/
public boolean openMydb() {
int mode = Context.MODE_PRIVATE;
try {
db = context.openOrCreateDatabase(Database_name, mode, null);//创建数据库
Log.i("SQLite","打开或创建数据库");
return true;
} catch (SQLException e) {
return false;
}
}
/*
* 创建数据表
*/
public boolean CreateMyTable() {
//数据表如不存在就创建
String DATABASE_CREATE =
"CREATE TABLE IF NOT EXISTS " + TABLE_NAME + " ("
+ ID + " INTEGER primary key autoincrement,"//ID自动编号
+ BODY + " text not null,"
+ TIME + " text not null);";
try {
db.execSQL(DATABASE_CREATE);//创建数据表
Log.i("SQLite","创建数据表");
return true;
} catch (SQLException e) {
return false;
}
}
/*
* 删除数据库
*/
public void deleteMydb() {
context.deleteDatabase(Database_name);
Log.i("SQLite","删除数据库");
}
/*
* 插入数据
*/
public boolean insertdata(ContentValues values) {
try {
db.insert(TABLE_NAME,ID,values);
Log.i("SQLite","插入数据记录");
return true;
} catch (SQLException e) {
return false;
}
}
/*
* 删除符合条件的数据
*/
public boolean deletedata(Integer id) {
try {
String args[] = {id.toString()};
db.delete(TABLE_NAME, ID +"= ?", args);// ? 代表一个参数，先占位
Log.i("SQLite","删除符合条件的数据");
return true;
} catch (SQLException e) {
return false;
}
}
/*
* 修改数据
*/
public boolean update(ContentValues values,Integer id) {
try {
String args[] = {id.toString()};
db.update(TABLE_NAME,values,ID + "= ?", args);
Log.i("SQLite","修改数据");
return true;
} catch (SQLException e) {
return false;
}
}
/*
* 获取符合ID 条件的记录，精确查询
*/
public Cursor getdata(Integer id) {
String args[] = {id.toString()};
String col[] = { BODY,TIME };
//String col[] = { BODY,TIME,TIME2 };
Cursor cur = db.query(TABLE_NAME, col, ID + "= ?", args, null, null, null);
Log.i("SQLite","获取符合条件的数据");
return cur;
}
/*
* 获取body 符合条件的记录，模糊查询
*/
public Cursor sousuo(String s) {
String sql="select * from "+TABLE_NAME+" where body like '%"+s+"%'";
Cursor cur = db.rawQuery(sql,null);
Log.i("SQLite","获取符合条件的数据");
return cur;
}
/*
* 获取数据表的全部记录
*/
public Cursor getAllNotes() {
String col[] = { ID, BODY,TIME };
Log.i("SQLite","获取全部记录");
return db.query(TABLE_NAME, col, null, null, null, null, null);
}
}
