Android平台上，集成了一个嵌入式关系型数据库—SQLite，SQLite3(版本号)支持 NULL、INTEGER、REAL（浮点数字）、TEXT(字符串文本)和BLOB(二进制对象)数据类型，SQLite可以解析大部分标准SQL语句
SQLiteOpenHelper对数据库进行管理,提供了两个重要的方法，分别是
onCreate(SQLiteDatabase db):初次使用软件时生成数据库表,SQLiteOpenHelper的getWritableDatabase()或者getReadableDatabase()方法获取用于操作数据库的SQLiteDatabase实例的时候，若数据库不存在，Android系统会自动生成一个数据库，
onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)：升级软件时更新数据库表结构
功能实现：
使用android内部的数据库SQLite添加日记数据库并进行日记的增、删、改、查操作
使用Menu菜单弹出菜单项进行添加、删除操作
主页面实现一个淡入效果
效果演示：
i
点击Menu菜单时弹出两个菜单项
代码实现：
1：创建数据库帮助类DBHelper：
下面是png格式的不能够复制代码，望大家见谅，但是亲们可以看看过程，自己编写记忆更深。
2:编写实体类Diary
public class Diary { private int id; private String title;//日记标题 private String content;//内容 private String pubdate; public Diary(String title, String content) { super(); this.title = title; this.content = content; } public Diary(String title, String content, String pubdate) { super(); this.title = title; this.content = content; this.pubdate = pubdate; } getId，setId //显示日记列表时，标题长度限制
public String getSubTitle() {
if (title.length() > 8)
return title.substring(0, 7) + "……";
return title;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
getContent，setContent，getPubdate，setPubdate方法 }
}
3:编写对数据库的操作类
在进行操作时可以使用SQLite内的封装的增删改查方法
此是源码,但是有字节颜色大小设置，遮盖了源码，不方便查看，后面png格式会看得清楚些
public class DiaryDao {
private SQLiteDatabase sqLiteDatabase;
private DBHelper dbHelper;
// 构造方法，带有context参数，以便下一对象操作
public DiaryDao(Context context){
dbHelper=new DBHelper(context);
}
public void add(Diary diary) {
String sql = "insert into td_diary(title,content,pubdate) values(?,?,?)";
// 得到SQLite数据库
sqLiteDatabase = dbHelper.getWritableDatabase();
// 执行sql语句
sqLiteDatabase.execSQL(sql,new String[] { diary.getTitle(), diary.getContent(),
diary.getPubdate() });
}
public void delete(int id) {
String sql = "delete from td_diary where id=?";
// 得到SQLite数据库
sqLiteDatabase = dbHelper.getWritableDatabase();
// 执行sql语句
sqLiteDatabase.execSQL(sql, new String[] { Integer.toString(id) });
}
public void update(Diary diary) {
String sql = "update td_diary set title=?,content=? where id=?";
// 得到SQLite数据库
sqLiteDatabase = dbHelper.getWritableDatabase();
sqLiteDatabase.execSQL(
sql,
new String[] { diary.getTitle(), diary.getContent(),
Integer.toString(diary.getId()) });
}
public Diary select(int id) {
Diary diary =null;
String sql="select * from td_diary where id=?";
sqLiteDatabase=dbHelper.getReadableDatabase();
Cursor cursor=sqLiteDatabase.rawQuery(sql, new String[]{Integer.toString(id)});
if(cursor.moveToFirst()){
String title=cursor.getString(cursor.getColumnIndex("title"));
String content=cursor.getString(cursor.getColumnIndex("content"));
String pubdate=cursor.getString(cursor.getColumnIndex("pubdate"));
diary = new Diary(title, content, pubdate);
}
return diary;
}
public List<Diary> getAllDiarys(){
List<Diary> list=new ArrayList<Diary>();
sqLiteDatabase=dbHelper.getReadableDatabase();
Cursor cursor=sqLiteDatabase.rawQuery("select * from td_diary", null);
while(cursor.moveToNext()){
int id=cursor.getInt(cursor.getColumnIndex("id"));
String title=cursor.getString(cursor.getColumnIndex("title"));
String content=cursor.getString(cursor.getColumnIndex("content"));
String pubdate=cursor.getString(cursor.getColumnIndex("pubdate"));
Diary diary = new Diary(title, content, pubdate);
diary.setId(id);
list.add(diary);
}
return list;
}
}
下面的就是截取的代码图片格式，不能够复制代码，若有用可复制上面的代码：
增、删、改、查方法
sqLiteDatabase.insert/delete/update/query
查找所有信息时可以返回Cursor游标类型，给其绑定SimpleCursorAdapter就可获取值
即：填充列表时用键，及数据库的列名。
4：主页面的淡入效果，然后几秒钟调转日记列表页面
public class MainActivity extends Activity {
private ImageView image;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
image = (ImageView) this.findViewById(R.id.image);
image.setImageResource(R.drawable.tp);
AlphaAnimation animation = new AlphaAnimation(0.0f, 1.0f);//alpha变化范围
animation.setDuration(3000);//显示时间
animation.setStartOffset(100);
image.setAnimation(animation);
// 新建一个handler实现演示跳转
new Handler().postDelayed(new Runnable() {
public void run() {
Intent i = new Intent(MainActivity.this, DiaryActivity.class);
startActivity(i);
}
}, 3000);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
5:列表页面代码
public class DiaryActivity extends Activity {
private ListView listview;
private DiaryDao dao = new DiaryDao(this);
List<Map<String, Object>> data;
List<Diary> diarys;
int POSITION = 0;
int id=1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_diary);
// 查找组件
listview = (ListView) this.findViewById(R.id.listView1);
// 创建数据库操作实例类
data = new ArrayList<Map<String, Object>>();
diarys = new ArrayList<Diary>();
diarys = dao.getAllDiarys();
for (Diary d : diarys) {
Map<String, Object> map = new HashMap<String, Object>();
map.put("title", d.getSubTitle());
map.put("pubdate", d.getPubdate());
data.add(map);
}
SimpleAdapter adapter = new SimpleAdapter(this, data,
R.layout.item_diary, new String[] { "title", "pubdate" },
new int[] { R.id.title, R.id.date });
//绑定适配器
listview.setAdapter(adapter);
listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
//点击列表项时跳转修改日志页面，将当前的日志信息传过去。
public void onItemClick(AdapterView<?> a, View v, int position,
long l) {
Diary diary = diarys.get(position);
Intent intent = new Intent(DiaryActivity.this,
DiaryUpdateActivity.class);
intent.putExtra("id", diary.getId());
intent.putExtra("title", diary.getTitle());
intent.putExtra("content", diary.getContent());
startActivity(intent);
}
});
listview.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> arg0, View v, int arg2,
long arg3) {
//从数据库获得选择的当前id号
//id = dao.getAllDiarys().get(arg2).getId();
id=(int) arg3;//直接获取id，内部封装好的arg3与数据库id一致
//在列表中位置
POSITION=arg2;
}
public void onNothingSelected(AdapterView<?> arg0) {
}
});
}
// 菜单删除操作
private void delete() {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setIcon(android.R.drawable.ic_dialog_alert);
builder.setTitle("请确认");
builder.setMessage("确定要删除第"+(POSITION+1)+"条记录吗？");
//点击确定按钮则删除当前的日志，刷新主页面，显示列表
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
System.out.println("删除的日志id是:"+id);
dao.delete(id);
Intent i = new Intent();
Intent in = new Intent(DiaryActivity.this, DiaryActivity.class);
startActivity(in);
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
builder.create().show();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_diary, menu);
menu.getItem(0).setIcon(android.R.drawable.ic_menu_add);
menu.getItem(1).setIcon(android.R.drawable.ic_menu_delete);
// 简单的菜单选择时设置监听 删除日志
/*menu.getItem(1).setOnMenuItemClickListener(
new MenuItem.OnMenuItemClickListener() {
//@Override
public boolean onMenuItemClick(MenuItem item) {
delete();
return false;
}
});*/
// 添加日志
/*menu.getItem(0).setOnMenuItemClickListener(
new MenuItem.OnMenuItemClickListener() {
//@Override
public boolean onMenuItemClick(MenuItem item) {
Intent in = new Intent(DiaryActivity.this, DiaryAddActivity.class);
startActivity(in);
return false;
}
});*/
return true;
}
//重写菜单选项被选择时调用方法
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch(item.getItemId()){
case R.id.delete:
delete();
break;
case R.id.add:
Intent in = new Intent(DiaryActivity.this, DiaryAddActivity.class);
startActivity(in);
break;
}
return super.onOptionsItemSelected(item);
}
}
6:添加或更新日记布局代码
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="标题" />
<EditText
android:id="@+id/tit"
android:inputType="text"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="内容" />
<EditText
android:id="@+id/cont"
android:gravity="top"
android:inputType="textMultiLine"
android:minLines="4"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<Button
android:id="@+id/add"
android:layout_width="50dp"
android:layout_height="40dp"
android:text="添加"//保存
/>
</LinearLayout>
主页面布局：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>
<TextView
android:text="心语日志"
android:textSize="50dp"
android:textColor="#1045ff"
android:layout_gravity="center_horizontal"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
/>
<ImageView
android:id="@+id/image"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
/>
</LinearLayout>
7。更新日记java代码：
public class DiaryUpdateActivity extends Activity {
private EditText title;
private EditText content;
private Button save;
private DiaryDao dao;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.update_diary);
// 查找组件
title = (EditText) this.findViewById(R.id.edit1);
content = (EditText) this.findViewById(R.id.edit2);
save = (Button) this.findViewById(R.id.save);
// 获取上个视图传的参数值
Intent i = getIntent();
final int id = i.getIntExtra("id", 0);
System.out.println(id);
// 设置文本
title.setText(i.getStringExtra("title"));
content.setText(i.getStringExtra("content"));
// 添加事件点击处理监听
save.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Diary diary = new Diary( title.getText().toString(), content
.getText().toString());
diary.setId(id);
//执行更新
dao=new DiaryDao(DiaryUpdateActivity.this);
dao.update(diary);
//提示
Toast.makeText(DiaryUpdateActivity.this, "保存成功",
Toast.LENGTH_LONG).show();
//更新后跳转到日志列表视图
Intent in = new Intent(DiaryUpdateActivity.this,
DiaryActivity.class);
startActivity(in);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.update_diary, menu);
return true;
}
}
菜单布局代码：
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<group >
<item android:id="@+id/add"
android:title="添加新的日志"
android:orderInCategory="100" />
<item android:id="@+id/delete"
android:title="删除日志"
android:orderInCategory="100" />
</group>
</menu>
列表项的布局代码：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<TextView
android:id="@+id/title"
android:textColor="#228B22"
android:textSize="20dp"
android:layout_width="wrap_content"
android:layout_height="40dp"
android:gravity="left"
/>
<TextView
android:id="@+id/date"
android:textColor="#340000"
android:textSize="18dp"
android:layout_width="fill_parent"
android:layout_height="40dp"
android:gravity="right" />
</LinearLayout>
任何程序都要理清思绪之后再编码，学习会更加有效率。