android之SQLite数据库应用（一）

先上一个小程序，具体的解析介绍会在以后的文章中详细说明，已经凌晨0：40了，我实在是困了，只能把这活移到明天了。今天先把代码粘贴上。

效果图：（向数据库中存入数据，然后再把数据读出来）

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/textView"
    />
</LinearLayout>

activity的代码

package cn.com.SQLite;

import java.util.ArrayList;

import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

/**
 * 
 * @author chenzheng_java
 * @description SQLite数据库在android中的应用
 * @since 2011/03/05
 * 
 */
public class SQLiteActivity extends Activity {
    private String result = "结果:/n";
    private String tableName = "chenzheng_Java";
    public static final int version_1 = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        run();
        TextView textView = (TextView) findViewById(R.id.textView);
        textView.setText(result);
    }

    /**
     *@description 对数据进行增删改查
     */
    private void run() {
        clear();
        save();
        read();
    }

    /**
     * 从数据表中读出记录
     */
    private void read() {
        MySqliteOpenHandler handler = new MySqliteOpenHandler(this, tableName,
                null, version_1);
        SQLiteDatabase database = handler.getWritableDatabase();
        Cursor cursor = database.query(tableName, null, null, null, null, null,
                null);
        int count = cursor.getCount();
        Log.i("通知", "总记录数" + count);

        int index = cursor.getColumnIndex("name");
        Log.i("通知", "nameIndex" + index);
        int indexOfAge = cursor.getColumnIndex("age");

        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            Log.i("通知", "here");
            String name = cursor.getString(index);
            result += "/n 姓名:" + name;
            int age = cursor.getInt(indexOfAge);
            result += " 年龄:" + age;
            cursor.moveToNext();
        }
        database.close();
    }

    /**
     * 保存一些数据到表中
     */
    private void save() {
        ArrayList<Beauty> beautyList = getData();
        MySqliteOpenHandler handler = new MySqliteOpenHandler(
                SQLiteActivity.this, tableName, null, version_1);
        SQLiteDatabase database = handler.getWritableDatabase();
        for (Beauty beauty : beautyList) {
            // 开始事物
            database.beginTransaction();
            // 以键值对形式存储列名和值的对象
            ContentValues contentValues = new ContentValues();
            contentValues.put("name", beauty.getName());
            contentValues.put("age", beauty.getAge());
            long flag = database.insertOrThrow(tableName, "age", contentValues);
            Log.i("通知", beauty.toString());
            if (flag == -1) {
                Log.i("通知", "insert操作失败");
            } else {
                database.setTransactionSuccessful();
            }
            // 结束事物
            database.endTransaction();
        }

        database.close();

    }

    /**
     * 清除表中原有的记录
     */
    private void clear() {
        MySqliteOpenHandler handler = new MySqliteOpenHandler(
                SQLiteActivity.this, tableName, null, version_1);
        SQLiteDatabase database = handler.getWritableDatabase();
        database.delete(tableName, null, null);
        database.close();

    }

    /**
     * 
     * @return 初始化数据
     */
    private ArrayList<Beauty> getData() {
        ArrayList<Beauty> beautyList = new ArrayList<Beauty>();
        Beauty beauty = null;

        beauty = new Beauty("小医仙", 23);
        beautyList.add(beauty);

        beauty = new Beauty("萧薰儿", 21);
        beautyList.add(beauty);

        beauty = new Beauty("杜梅莎女王", 24);
        beautyList.add(beauty);

        return beautyList;

    }

    /**
     * @author chenzheng_java
     * @description 实现我们自己的sqlite的创建及更新帮助类
     * @since 2011/03/05
     */
    private class MySqliteOpenHandler extends SQLiteOpenHelper {

        public MySqliteOpenHandler(Context context, String name,
                CursorFactory factory, int version) {
            super(context, name, factory, version);
            Log.i("通知", "MySqliteOpenHandler实例化完毕");
        }

        /**
         * onCreate方法在系统中不存在用户查询的表时执行，我们在这里可以实现该方法并做一些额外的操作
         */
        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("drop table  if  exists " + tableName);
            db
                    .execSQL("create table if not exists '"
                            + tableName
                            + "' (id INTEGER primary key,name varchar(20),age INTEGER)");

            Log.i("通知", "创建表成功！");
        }

        /**
         * onUpgrade方法在系统中应用版本发生改变的时候执行
         */
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            Log.i("通知", "版本升级成功！");

        }

    }

    /**
     * 
     * @author chenzheng_Java
     * @description 美人实体类
     */
    private class Beauty {
        String name;
        int age;

        public Beauty() {
        }

        public Beauty(String name, int age) {
            this.name = name;
            this.age = age;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }

        @Override
        public String toString() {
            return "Beauty [age=" + age + ", name=" + name + "]";
        }

    }

}

其他都为默认。运行，便可得到如上结果。

------------------------------------------------------------------------

这里请注意一点，MySqliteOpenHandler该类的构造方法中，第二个参数，实际上代表的是数据库的名字，而并非表名称，这里直接使用了表名进行构建，是为了让代码看的稍微少些，也满足下笔者偷懒的欲望，呵呵。切记 切记