Android SQLite数据库使用示例

简单介绍一下，现在的主流移动设备像Android、iPhone等都使用SQLite作为复杂数据的存储引擎，在我们为移动设备开发应用程序时，也许就要使用到SQLite来存储我们大量的数据，所以我们就需要掌握移动设备上的SQLite开发技巧。对于Android平台来说，系统内置了丰富的API来供开发人员操作SQLite，我们可以轻松的完成对数据的存取。

下面我们用SQLite来开发一个英语词典。下图是项目结构……

MySQLite.java

package sn.qdj.sqlitedemo;

import android.content.Context;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
/**
 * SQLite数据库操作
 * @author qingdujun
 *
 */
public class MySQLite extends SQLiteOpenHelper {

	/**
	 * 构造SQL语句创建表
	 */
	final String CREATE_TABLE_SQL =
			"CREATE TABLE dict(uid integer primary key autoincrement," +
			"word interge," +
			"detail varchar)";
	public MySQLite(Context context, String name, CursorFactory factory,
			int version) {
		super(context, name, factory, version);
		// TODO Auto-generated constructor stub
	}

	public MySQLite(Context context, String name, CursorFactory factory,
			int version, DatabaseErrorHandler errorHandler) {
		super(context, name, factory, version, errorHandler);
		// TODO Auto-generated constructor stub
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		// 第一次使用数据库时自动建表
		db.execSQL(CREATE_TABLE_SQL);
		Log.i("create", "ok");
	}

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

	}

}

MainActicity.java

package sn.qdj.sqlitedemo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
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 {

	MySQLite dbHelpher;
	Button insert = null;
	Button search = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        /**
         * 创建MySQLite对象，指定数据库版本为1
         */
        dbHelpher = new MySQLite(this, "myDict.db3", null,1);
        insert = (Button)findViewById(R.id.btn_insert);
        search = (Button)findViewById(R.id.btn_search);
        /**
         * 插入事件
         */
        insert.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				Log.i("insert", "front");
				String word = ((EditText)findViewById(R.id.et_word)).getText().toString();
				String detail = ((EditText)findViewById(R.id.et_detail)).getText().toString();
				//插入语句
				myInsert(dbHelpher.getReadableDatabase(), word, detail);
				Log.i("insert", "after");
				Toast.makeText(getApplicationContext(), "插入成功", 800).show();
			}
		});
        /**
         * 查询事件
         */
        search.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				String key = ((EditText)findViewById(R.id.et_word)).getText().toString();
				String sql = "SELECT * FROM dict WHERE word LIKE ? OR detail LIKE ?";
				String selectionArgs[] = {"%"+key+"%","%"+key+"%"};
				Cursor cursor = dbHelpher.getReadableDatabase().rawQuery(sql, selectionArgs);

				//创建一个Bundle对象
				Bundle data = new Bundle();
				data.putSerializable("data", converCursorToList(cursor));
				//创建一个Intent
				Intent intent = new Intent(MainActivity.this, ResultActivity.class);
				intent.putExtras(data);
				//启动Activity
				startActivity(intent);
			}
		});

    }

    protected ArrayList<Map<String, String>> converCursorToList(Cursor cursor) {

    	ArrayList<Map<String, String>> result = new ArrayList<Map<String,String>>();
    	//遍历结果集
    	while (cursor.moveToNext()) {
			Map<String, String> map = new HashMap<String, String>();
			map.put("word", cursor.getString(1));
			map.put("detail", cursor.getString(2));
			result.add(map);
		}
		return result;
	}
    /**
     *
     * @param db
     * @param word  单词
     * @param detail  解释
     */
    private void myInsert(SQLiteDatabase db, String word, String detail){

    	db.execSQL("INSERT INTO dict values(null,?,?)",
    			new String[]{word, detail});
    }

    @Override
    public void onDestroy(){
    	super.onDestroy();
    	/**
    	 * 退出程序时，关闭SQLiteDatabase
    	 */
    	if (dbHelpher != null) {
			dbHelpher.close();
		}
    }
}

activity_main.xml

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="sn.qdj.sqlitedemo.MainActivity" >

    <EditText
        android:id="@+id/et_word"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="word" />
    <EditText
        android:id="@+id/et_detail"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/et_word"
        android:hint="detail" />

    <Button
        android:id="@+id/btn_search"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentBottom="true"
        android:text="查询" />

    <Button
        android:id="@+id/btn_insert"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentBottom="true"
        android:text="插入" />

</RelativeLayout>

ResultActivity.java

package sn.qdj.sqlitedemo;

import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class ResultActivity extends Activity {

	@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.result);

        ListView listView = (ListView)findViewById(R.id.show);

        Intent intent = getIntent();
        //获取intent携带的数据
        Bundle data = intent.getExtras();
        //从Bundle中取出数据
        List<Map<String, String>> list = (List<Map<String,String>>) data.getSerializable("data");
        //将List封装成SimpleAdapter
        SimpleAdapter adapter = new SimpleAdapter(ResultActivity.this, list, R.layout.line,
        		new String[]{"word","detail"},new int[]{R.id.word,R.id.detail} );
        //填充ListView
        listView.setAdapter(adapter);
	}

}

result.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ListView
        android:id="@+id/show"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
    </ListView>

</RelativeLayout>

line.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <TextView
        android:id="@+id/find"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:text="找到的单词" />
    <TextView
        android:id="@+id/word"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/find"
        android:text="TextView" />
    <TextView
        android:id="@+id/explain"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/word"
        android:text="解释" />
    <TextView
        android:id="@+id/detail"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/explain"
        android:text="" />

</RelativeLayout>

Mainifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="sn.qdj.sqlitedemo"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="15"
        android:targetSdkVersion="15" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".ResultActivity"
            android:label="@string/app_name" >
        </activity>
    </application>

</manifest>

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参考文献：《疯狂Android讲义（第2版）》  李刚 编著