Android整理：SQlite数据库的使用以及通过listView显示数据

前言：上个月与同学一起做了一个简单的Android应用，这段时间正好没有很多事情所以趁热整理一下学习到的知识，刚开始学习Android还有很多不懂的地方，继续努力吧！

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作业中需要用到数据库，当然首选Android集成了的SQLite数据库。

直接使用数据库可以这样：

//打开或创建test.db数据库
SQLiteDatabase db = openOrCreateDatabase("test.db", Context.MODE_PRIVATE, null);  

//创建person表
db.execSQL("CREATE TABLE IF NOT EXISTS person([id] INTEGER PRIMARY KEY, [name] TEXT)");

//查询
Cursor cursor = db.rawQuery("select * from person where name = " + "'urbain'", null);
if(cursor.moveToNext()) {
    id = Integer.parseInt( cursor.getString(0) );
    name = cursor.getString(1);
}

//更新删除操作均可用db.execSQL(string)来操作

利用listView显示数据库中的数据要加一个adapter，步骤：

1.将Sqlite数据库的内容查询出来并放入数组列表中，形成ListView的数据源；

2.adapter适配器绑定数据源，显示在ListView item中。

自己写类DatabaseHelper继承SQLiteOpenHelper并实现部分数据库操作：

package com.zkurbain.wenriji;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHelper extends SQLiteOpenHelper{

    private static final int VERSION = 1;
    public DatabaseHelper(Context context, String name, CursorFactory factory,
            int version) {
        super(context, name, factory, version);
    }

    public DatabaseHelper(Context context, String name){
            this(context, name, VERSION);
    }

    public DatabaseHelper(Context context, String name, int version){
        this(context, name, null, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        //创建表
        String crtWenTable = "CREATE TABLE IF NOT EXISTS [wenti]([wentiHash] INTENGER PRIMARY KEY, [wentiName] TEXT)" ;
        db.execSQL(crtWenTable);

        //如果数据库为空，则预置一些数据
        Cursor cursor = db.rawQuery("select * from wenti", null);
        if( !cursor.moveToNext()){
            String[] swen = {"我今天读书了吗？",    "我明天打算做什么？",   "今天吃啥好吃的？"};

            db.beginTransaction(); //开始事务处理
            for (String s : swen) {
                db.execSQL("insert into wenti values(" + s.hashCode() + ", '"+ s +"')");
            }
            db.setTransactionSuccessful();  //设置事务标志为成功，当结束事务时就会提交事务
            db.endTransaction(); //结束事务
        }
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

在主类中，借助SimpleAdapter使数据显示在listView：

package com.zkurbain.wenriji;

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

import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class ChooseWen extends Activity {

    private ListView listView = null;
    private List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
    private SimpleAdapter simpleAdapter = null;

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

        listView = (ListView) findViewById(android.R.id.list);

        simpleAdapter = new SimpleAdapter(this, getdata(), R.layout.list,
                new String[] { "wentiName" }, new int[] { R.id.wenti });

        //listView绑定adapter
        listView.setAdapter(simpleAdapter);
    }

    private List<Map<String, Object>> getdata() {
        DatabaseHelper dbHelper = new DatabaseHelper(ChooseWen.this,
                "wenriji.db");
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select * from wenti", null);

        // 清空list
        list.clear();
        // 查询到的数据添加到list集合
        while (cursor.moveToNext()) {
            String wenti = cursor.getString(1);
            Map<String, Object> map = new HashMap<String, Object>();
            map.put("wentiName", wenti); // 获取name
            list.add(map);
        }

        return list;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.choose_wen, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        return super.onOptionsItemSelected(item);
    }
}

下面是XML文件内容:

<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="com.wenriji.wenriji.ChooseWen"
    android:id="@+id/activity_choose_wen" >

    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true" >
        <requestFocus />
    </ListView>

</RelativeLayout>