Android数据库的Demo演示

来源：互联网发布：ubuntu 杀死进程编辑：程序博客网时间：2024/06/05 16:04

本Demo涉及知识点概述如下:

SQLite数据库与SimpleCursorAdapter适配器

SQLite的常用语法

SQLiteOpenHelper的用法

SQLite数据库实现CRUD的少参方法

ListView的数据展示

上下文菜单的展示

XML(主界面布局):

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:background="@drawable/bg_color" >    <ListView        android:id="@+id/lv"        android:layout_width="match_parent"        android:layout_height="match_parent" >    </ListView>    <TextView        android:id="@+id/tv_empty"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerInParent="true"        android:text="暂无联系人！"        android:textColor="#00f"        android:textSize="16sp" /></RelativeLayout>

XML(ListView单条目布局):

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:background="@drawable/bg_color" >    <ListView        android:id="@+id/lv"        android:layout_width="match_parent"        android:layout_height="match_parent" >    </ListView>    <TextView        android:id="@+id/tv_empty"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerInParent="true"        android:text="暂无联系人！"        android:textColor="#00f"        android:textSize="16sp" /></RelativeLayout>

XML(菜单布局):

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="#AAAAAA"    android:orientation="vertical" >    <EditText        android:id="@+id/et_name"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:background="@android:drawable/edit_text"        android:hint="请输入名称" >        <requestFocus />    </EditText>    <EditText        android:id="@+id/et_sex"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:background="@android:drawable/edit_text"        android:hint="请输入性别" />    <EditText        android:id="@+id/et_phone"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:background="@android:drawable/edit_text"        android:hint="请输入手机号"        android:inputType="phone" /></LinearLayout>

XML(menu文件夹下菜单布局):

<menu xmlns:android="http://schemas.android.com/apk/res/android" >    <item        android:id="@+id/action_insert"        android:icon="@drawable/add"        android:orderInCategory="100"        android:showAsAction="always"        android:title="添加联系人"/></menu>

XML(menu文件夹下菜单布局):

<?xml version="1.0" encoding="utf-8"?><menu xmlns:android="http://schemas.android.com/apk/res/android" >    <item android:id="@+id/action_delete" android:title="删除"/>    <item android:id="@+id/action_update" android:title="更新"/></menu>

Java代码示例:

public class MainActivity extends Activity {   private ListView lView;   private TextView empty;   private SQLiteDatabase db;   private Cursor cursor;   @Override   protected void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);      setContentView(R.layout.activity_main);      lView = (ListView) findViewById(R.id.lv);      empty = (TextView) findViewById(R.id.tv_empty);      lView.setEmptyView(empty); // 设置空视图      registerForContextMenu(lView); // 注册上下文对象      initDataBase(); // 初始化数据库      initData(); // ListView赋值   }   // 初始化数据库   private void initDataBase() {      // TODO Auto-generated method stub      // 创建数据库打开工具      OpenHelper helper = new OpenHelper(this);      // 获取数据库操作类 提成全局变量方便操作      db = helper.getReadableDatabase();   }   // ListView添加数据   private void initData() {      // cursor也提成全部变量 ,方便关闭      // cursor需要关闭,放置内存溢出 oom      cursor = db.rawQuery("select * from contact", null);      SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,            R.layout.list_item, cursor, new String[] { "_id", "name",                  "sex", "number" }, new int[] { R.id.tv_id,                  R.id.tv_name, R.id.tv_sex, R.id.tv_phoneNumber },            CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);      lView.setAdapter(adapter);   }   // 创建系统菜单 点击菜单弹出 DiaLog 填充数据   @Override   public boolean onCreateOptionsMenu(Menu menu) {      // TODO Auto-generated method stub      getMenuInflater().inflate(R.menu.main, menu);      return true;   }   @Override   public boolean onOptionsItemSelected(MenuItem item) {      // TODO Auto-generated method stub      // 点击添加联系人      AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);      builder.setIcon(R.drawable.icon); // 设置图片      builder.setTitle("添加联系人");      // 把布局转化成View      View view = LayoutInflater.from(this).inflate(R.layout.dialog_view,            null);      // 自定义Dialog      builder.setView(view);      final EditText namEditText = (EditText) view.findViewById(R.id.et_name);      final EditText sexEditText = (EditText) view.findViewById(R.id.et_sex);      final EditText phoneEditText = (EditText) view            .findViewById(R.id.et_phone);      builder.setPositiveButton("确定", new OnClickListener() {         @Override         public void onClick(DialogInterface dialog, int which) {            // TODO Auto-generated method stub            // 添加非空判断            // 添加操作            ContentValues cValues = new ContentValues();            cValues.put("name", namEditText.getText() + "");            cValues.put("sex", sexEditText.getText() + "");            cValues.put("number", phoneEditText.getText() + "");            long insert = db.insert("contact", null, cValues); // 添加到数据库            if (insert != -1) {               initData(); // 再次调用 当刷新使用               Toast.makeText(MainActivity.this, "添加成功",                     Toast.LENGTH_SHORT).show();            }         }      });      builder.setNegativeButton("取消", new OnClickListener() {         @Override         public void onClick(DialogInterface dialog, int which) {            // TODO Auto-generated method stub            dialog.dismiss(); // 取消直接关闭即可         }      });      builder.show(); // show方法 千万别忘了      return super.onOptionsItemSelected(item);   }   @Override   public void onCreateContextMenu(ContextMenu menu, View v,         ContextMenuInfo menuInfo) {      // TODO Auto-generated method stub      super.onCreateContextMenu(menu, v, menuInfo);      getMenuInflater().inflate(R.menu.contextmenu_listview_main, menu);      AdapterContextMenuInfo info = (AdapterContextMenuInfo) menuInfo;      // info.id      menu.setHeaderTitle("id:" + info.id);   }   // 上下文菜单监听   @Override   public boolean onContextItemSelected(MenuItem item) {      // TODO Auto-generated method stub      AdapterContextMenuInfo info = (AdapterContextMenuInfo) item            .getMenuInfo();      final long id = info.id; // 单条对应的数据库_id;      switch (item.getItemId()) {      case R.id.action_delete:         db.execSQL("delete from contact where _id =?", new Object[] { id });         initData();         break;      case R.id.action_update:         // 删除和更新         AlertDialog.Builder builder = new AlertDialog.Builder(               MainActivity.this);         builder.setTitle("更新联系人");         builder.setIcon(R.drawable.icon);         View view = LayoutInflater.from(MainActivity.this).inflate(               R.layout.dialog_view, null);         builder.setView(view); //设置自定义视图         final EditText namEditText = (EditText) view.findViewById(R.id.et_name);         final EditText sexEditText = (EditText) view.findViewById(R.id.et_sex);         final EditText phoneEditText = (EditText) view               .findViewById(R.id.et_phone);         //查数据显示到EditText         //查数据         Cursor cursor =               db.rawQuery("select * from contact where _id = ?", new String[]{""+id});         cursor.moveToFirst();  //游标移动到第一行         namEditText.setText(cursor.getString(cursor.getColumnIndex("name")));         sexEditText.setText(cursor.getString(cursor.getColumnIndex("sex")));         phoneEditText.setText(cursor.getString(cursor.getColumnIndex("number")));         builder.setPositiveButton("修改", new OnClickListener() {            @Override            public void onClick(DialogInterface dialog, int which) {               // TODO Auto-generated method stub               ContentValues contentValues = new ContentValues();               contentValues.put("name", namEditText.getText()+"");               contentValues.put("sex", sexEditText.getText()+"");               contentValues.put("number", phoneEditText.getText()+"");               db.update("contact", contentValues, "_id=?", new String []{id+""});               initData();            }         });         builder.setNegativeButton("取消", new OnClickListener() {            @Override            public void onClick(DialogInterface dialog, int which) {               // TODO Auto-generated method stub               dialog.dismiss(); //关闭            }         });         builder.show();         break;      }      return super.onContextItemSelected(item);   }}

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