android应用开发详解（二十一）-----------------------SQLite

package com.example.test_sqlite;
//这只是简单介绍SQLite的基本操作，不是运行的。。。
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.text.StaticLayout;
import android.view.Menu;


public class MainActivity extends Activity {


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// 实例化数据库帮助类
MyDBHelper helper = new MyDBHelper(this);
// 插入
helper.insert();
// 查询
helper.query();
}


// 数据库帮助类
class MyDBHelper extends SQLiteOpenHelper {
// 创建表SQL语句
private static final String CREATE_TABLE_SQL = "create table temp(_id integer,name text)";


// 构造方法
public MyDBHelper(Context context) {
super(context, "test.db", null, 0);
// TODO Auto-generated constructor stub
}


// SQLiteDatabase实例
private SQLiteDatabase db;


@Override
public void onCreate(SQLiteDatabase arg0) {
// TODO Auto-generated method stub
db.execSQL(CREATE_TABLE_SQL);
}


@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub


}


// 插入方法
private void insert() {
// 插入SQL语句
String sql = "insert into temp (_id,name) values(1,'jiangcuicui')";
// 执行插入
getWritableDatabase().execSQL(sql);
}


// 查询方法
private void query() {
// 获得游标
Cursor c = getWritableDatabase().query("temp", null, null, null,
null, null, null);
// 判断游标是否为空
if (c.moveToFirst()) {
// 遍历游标
for (int i = 0; i < c.getCount(); i++) {
c.move(i);
int id = c.getInt(0);
String name = c.getString(1);
System.out.println("id:" + id + "  name:" + name);
}
}
}


}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}


}

1、工程目录

2、DBHelper.java

package com.example.test_sqlite2;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;//数据库帮助类public class DBHelper extends SQLiteOpenHelper {// 数据库名称private static final String DB_NAME = "coll.db";// 数据表名称private static final String TABLE_NAME = "CollTable";private static final String CREATE_TABLE = "create table "+ "CollTable(_id integer primary key autoincrement,name text,url text,desc text)";// SQLiteDatabase实例private SQLiteDatabase db;// 构造方法public DBHelper(Context context) {super(context, DB_NAME, null, 2);// TODO Auto-generated constructor stub}// 创建表@Overridepublic void onCreate(SQLiteDatabase db) {// TODO Auto-generated method stubthis.db = db;db.execSQL(CREATE_TABLE);}// 插入方法public void insert(ContentValues values) {// 获得SQLiteDatabase实例SQLiteDatabase db = getWritableDatabase();// 插入db.insert(TABLE_NAME, null, values);db.close();}// 查询方法public Cursor query() {// 获得SQLiteDatabase实例SQLiteDatabase db = getWritableDatabase();// 获得查询游标Cursor c = db.query(TABLE_NAME, null, null, null, null, null, null);return c;}// 删除方法public void del(int id) {if (db == null)// 获得SQLiteDatabase实例db = getWritableDatabase();db.delete(TABLE_NAME, "_id=?", new String[] { String.valueOf(id) });}// 关闭数据库public void close() {if (db != null)db.close();}@Overridepublic void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {// TODO Auto-generated method stub}}

AddActivity.java

package com.example.test_sqlite2;import android.os.Bundle;import android.app.Activity;import android.content.ContentValues;import android.content.Intent;import android.database.sqlite.SQLiteDatabase;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;public class AddActivity extends Activity {private Button addBtn;private EditText myEdit01, myEdit02, myEdit03;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.add);myEdit01 = (EditText) findViewById(R.id.edit01);myEdit02 = (EditText) findViewById(R.id.edit02);myEdit03 = (EditText) findViewById(R.id.edit03);addBtn = (Button) findViewById(R.id.button01);// 设置当前Activity标题this.setTitle("添加收藏信息");addBtn.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stubString name = myEdit01.getText().toString();String url = myEdit02.getText().toString();String desc = myEdit03.getText().toString();ContentValues values = new ContentValues();values.put("name", name);values.put("url", url);values.put("desc", desc);// 实例化数据库帮助类DBHelper Helper = new DBHelper(getApplicationContext());// 插入数据Helper.insert(values);// 实例化intentIntent intent = new Intent(AddActivity.this,QueryActivity.class);// 启动activitystartActivity(intent);}});}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.add, menu);return true;}}

QueryActivity.java

<pre name="code" class="html">package com.example.test_sqlite2;import android.app.AlertDialog;import android.app.AlertDialog.Builder;import android.app.ListActivity;import android.content.DialogInterface;import android.content.DialogInterface.OnClickListener;import android.database.Cursor;import android.os.Bundle;import android.support.v4.widget.SimpleCursorAdapter;import android.view.View;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.ListView;public class QueryActivity extends ListActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);// 设置activity标题this.setTitle("浏览收藏信息");// 实例化数据库帮助类final DBHelper helper = new DBHelper(this);// 获得查询游标Cursor c = helper.query();// 列表项数组String[] from = { "_id", "name", "url", "desc" };// 列表项IDint[] to = { R.id.text01, R.id.text02, R.id.text03, R.id.text04 };// 适配器SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,R.layout.row, c, from, to);// 列表视图ListView listview = getListView();// 为列表添加适配器listview.setAdapter(adapter);// 提示对话框final AlertDialog.Builder builder = new AlertDialog.Builder(this);// 为listview设置单击监听器listview.setOnItemClickListener(new OnItemClickListener() {@Overridepublic void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {// TODO Auto-generated method stubfinal long temp = arg3;builder.setMessage("真的要删除该记录吗？").setPositiveButton("是",new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface arg0,int arg1) {// TODO Auto-generated method stub// 删除数据helper.del((int) temp);// 重新查询Cursor c = helper.query();String[] from = { "_id", "name", "url","dec" };int[] to = { R.id.text01, R.id.text02,R.id.text03, R.id.text04 };SimpleCursorAdapter adapter = new SimpleCursorAdapter(getApplicationContext(),R.layout.row, c, from, to);ListView listview = getListView();listview.setAdapter(adapter);}}).setNegativeButton("否", new OnClickListener() {@Overridepublic void onClick(DialogInterface arg0, int arg1) {// TODO Auto-generated method stub}}).create().show();}});helper.close();}}

3、布局文件

add.xml

<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="fill_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/textview01"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="网站名称" />    <EditText        android:id="@+id/edit01"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="" />    <TextView        android:id="@+id/textview02"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="URL" />    <EditText        android:id="@+id/edit02"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="" />    <TextView        android:id="@+id/textview03"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="网站描述" />    <EditText        android:id="@+id/edit03"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="" />    <Button        android:id="@+id/button01"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="添加" /></LinearLayout>

row.xml

<?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:orientation="horizontal" >    <TextView        android:id="@+id/text01"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="1" />    <TextView        android:id="@+id/text02"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:paddingLeft="10px"        android:text="2" />    <TextView        android:id="@+id/text03"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:paddingLeft="10px"        android:text="3" />    <TextView        android:id="@+id/text04"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:paddingLeft="10px"        android:text="4" /></LinearLayout>

ContentValues 和HashTable类似都是一种存储的机制 但是两者最大的区别就在于，contenvalues只能存储基本类型的数据，像string，int之类的，不能存储对象这种东西，而HashTable却可以存储对象。