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深圳网站制作公司资讯,国外引擎搜索,做b2b网站赚钱,免费商标logo在线制作软件SQLiteOpenHelper SQLiteOpenHelper是android提供的一个管理数据库的工具类，可用于管理数据库的创建和版本更新。一般的用法是创建SQLiteOpenHelper的子类，并扩展它的onCreate(SQLiteDatabase db)和onUpgrade(SQLiteDatabase db,int oldVersion,newVers…

SQLiteOpenHelper

SQLiteOpenHelper是android提供的一个管理数据库的工具类，可用于管理数据库的创建和版本更新。

一般的用法是创建SQLiteOpenHelper的子类，并扩展它的onCreate(SQLiteDatabase db)和onUpgrade(SQLiteDatabase db,int oldVersion,newVersion)方法。

SQLiteOpenHelper包含如下常用方法：

sychronized SQLiteDatabase getReadableDatabase()	以读写的方式打开数据库对应的SQLiteDataBase对象
sychronized SQLiteDatabase getWriteableDataBase()	以写的方式打开数据库对应的SQLiteDataBase对象
abstract void onCreate(SQLiteDatabase db)	当第一次创建数据库时回调该方法
abstract void onUpgrade(SQLiteDatabase db,int oldVersion,newVersion)	当数据库版本更新时回调该方法
sychronized void close()	关闭所有打开的SQLiteDatabase

实例如下：

布局文件==》main
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"tools:context=".MainActivity" ><EditTextandroid:id="@+id/edit1"android:layout_width="match_parent"android:layout_height="wrap_content" /><EditTextandroid:id="@+id/edit2"android:layout_width="match_parent"android:layout_height="wrap_content" /><Buttonandroid:id="@+id/btnInsert"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="添加生词" /><EditTextandroid:id="@+id/edit3"android:layout_width="match_parent"android:layout_height="wrap_content" /><Buttonandroid:id="@+id/btnQuery"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="查询" /></LinearLayout>
result.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="vertical" ><ListViewandroid:id="@+id/lv"android:layout_width="match_parent"android:layout_height="match_parent" /><EditTextandroid:id="@+id/word"android:layout_width="match_parent"android:layout_height="wrap_content" /><EditTextandroid:id="@+id/detial"android:layout_width="match_parent"android:layout_height="wrap_content" /></LinearLayout>

代码实现==》
package com.example.mysqlite2;import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;public class MyDatabaseHelper extends SQLiteOpenHelper
{final String CREATE_TABLE_SQL = "create table dict(_id integer primary key autoincrement,word,detial)";public MyDatabaseHelper(Context context, String name, int version){super(context, name, null, version);Log.i("swg", "-----------MyDatabaseHelper------------");}@Overridepublic void onCreate(SQLiteDatabase db){// 第一个使用数据库时自动见表db.execSQL(CREATE_TABLE_SQL);Log.i("swg", "-----------创建表成功------------");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){System.out.println("-----------onUpgrade----------" + oldVersion + "-------->" + newVersion);}}package com.example.mysqlite2;import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;public class MainActivity extends Activity
{MyDatabaseHelper dbHelper;EditText edit1;EditText edit2;EditText edit3;String dbName = "test.db3";@Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// 创建MyDatabaseHelper对象，指定数据库版本为1，此处使用相对路径// 数据库文件会自动保存在程序的数据文件夹下的databases目录下dbHelper = new MyDatabaseHelper(this, dbName, 1);edit1 = (EditText) this.findViewById(R.id.edit1);edit2 = (EditText) this.findViewById(R.id.edit2);edit3 = (EditText) this.findViewById(R.id.edit3);Button btnInsert = (Button) this.findViewById(R.id.btnInsert);Button btnQuery = (Button) this.findViewById(R.id.btnQuery);btnInsert.setOnClickListener(new MyButtonOnClick());btnQuery.setOnClickListener(new MyButtonOnClick());}private class MyButtonOnClick implements OnClickListener{@Overridepublic void onClick(View v){switch (v.getId()){case R.id.btnInsert:String word = edit1.getText().toString();String detial = edit2.getText().toString();Log.i("swg", "insert content==" + word + "=========" + detial);// 插入生词记录insertData(dbHelper.getReadableDatabase(), word, detial);Toast.makeText(MainActivity.this, "添加生词成功", Toast.LENGTH_LONG).show();break;case R.id.btnQuery:String key = edit3.getText().toString();Log.i("swg", "key==" + key);// 执行查询String sql = "select * from dict where word like ? or detial like ? ";Cursor cursor = dbHelper.getReadableDatabase().rawQuery(sql,new String[] { "%" + key + "%", "%" + key + "%" });Bundle data = new Bundle();data.putSerializable("data", convertCursorToList(cursor));Intent intent = new Intent(MainActivity.this, ResultActivity.class);intent.putExtras(data);startActivity(intent);break;}}private ArrayList<Map<String, String>> convertCursorToList(Cursor cursor){ArrayList<Map<String, String>> result = new ArrayList<Map<String, String>>();while (cursor.moveToNext()){Map<String, String> map = new HashMap<String, String>();map.put("word", cursor.getString(1));map.put("detial", cursor.getString(2));result.add(map);}return result;}private void insertData(SQLiteDatabase db, String word, String detial){String sql = "insert into dict values (null,?,?)";db.execSQL(sql, new String[] { word, detial });}}@Overridepublic 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;}@Overrideprotected void onDestroy(){super.onDestroy();// 退出程序时关闭MyDatabaseHelper里的SQLitedatabaseif (dbHelper != null)dbHelper.close();}}package com.example.mysqlite2;import java.util.List;
import java.util.Map;import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.widget.ListView;
import android.widget.SimpleAdapter;public class ResultActivity extends Activity
{@Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.result);ListView lv = (ListView) this.findViewById(R.id.lv);Intent intent = getIntent();Bundle data = intent.getExtras();@SuppressWarnings("unchecked")List<Map<String, String>> list = (List<Map<String, String>>) data.getSerializable("data");// 将list封装成SimpleAdapterSimpleAdapter adapter = new SimpleAdapter(ResultActivity.this, list, R.layout.result,new String[] { "word", "detial" }, new int[] { R.id.word, R.id.detial });int count = adapter.getCount();Log.i("swg", "查到" + count + "条");lv.setAdapter(adapter);}}

注意：AndroidMainfest.xml需要添加==》<activity android:name="com.example.mysqlite2.ResultActivity" android:theme="@android:style/Theme.Dialog"/>

运行效果：