Android SQLite 数据操作 1

import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class ActivityMain extends Activity {
    //定义一些内容
    OnClickListener listener1 = null;
    OnClickListener listener2 = null;
    OnClickListener listener3 = null;
    OnClickListener listener4 = null;
    OnClickListener listener5 = null;

    Button button1;
    Button button2;
    Button button3;
    Button button4;
    Button button5;

    DatabaseHelper mOpenHelper;
   
    private static final String DATABASE_NAME = "dbForTest.db";
    private static final int DATABASE_VERSION = 1;
    private static final String TABLE_NAME = "diary";
    private static final String TITLE = "title";
    private static final String BODY = "body";
   
    //通过扩展SQLite类进行
    private static class DatabaseHelper extends SQLiteOpenHelper {
        DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override //当数据库第一次生成的时候会调用这个犯法
        public void onCreate(SQLiteDatabase db) {

            String sql = "CREATE TABLE " + TABLE_NAME + " (" + TITLE
                    + " text not null, " + BODY + " text not null " + ");";
            Log.i("haiyang:createDB=", sql);
            db.execSQL(sql);

        }

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

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        prepareListener(); //定义事件监听器
        initLayout(); //将按钮在上面
        mOpenHelper = new DatabaseHelper(this); //这个对象可以创建一个数据库，如果已经创建就返回这个数据库，见上面。

    }

    private void initLayout() {
        button1 = (Button) findViewById(R.id.button1);
        button1.setOnClickListener(listener1);

        button2 = (Button) findViewById(R.id.button2);
        button2.setOnClickListener(listener2);

        button3 = (Button) findViewById(R.id.button3);
        button3.setOnClickListener(listener3);
        button4 = (Button) findViewById(R.id.button4);
        button4.setOnClickListener(listener4);

        button5 = (Button) findViewById(R.id.button5);
        button5.setOnClickListener(listener5);

    }

    private void prepareListener() {
        listener1 = new OnClickListener() {
            public void onClick(View v) {
                CreateTable();
            }
        };
        listener2 = new OnClickListener() {
            public void onClick(View v) {
                dropTable();
            }
        };
        listener3 = new OnClickListener() {
            public void onClick(View v) {
                insertItem();
            }
        };
        listener4 = new OnClickListener() {
            public void onClick(View v) {
                deleteItem();
            }
        };
        listener5 = new OnClickListener() {
            public void onClick(View v) {
                showItems();
            }
        };
    }

    /*
     * 重新建立数据表
     */
    private void CreateTable() {
        SQLiteDatabase db = mOpenHelper.getWritableDatabase();
        String sql = "CREATE TABLE " + TABLE_NAME + " (" + TITLE
                + " text not null, " + BODY + " text not null " + ");";
        Log.i("haiyang:createDB=", sql);

        try {
            db.execSQL("DROP TABLE IF EXISTS diary");
            db.execSQL(sql);
            setTitle("数据表成功重建");
        } catch (SQLException e) {
            setTitle("数据表重建错误");
        }
    }

    /*
     * 删除数据表
     */
    private void dropTable() {
        SQLiteDatabase db = mOpenHelper.getWritableDatabase();
        String sql = "drop table " + TABLE_NAME;
        try {
            db.execSQL(sql);
            setTitle("数据表成功删除：" + sql);
        } catch (SQLException e) {
            setTitle("数据表删除错误");
        }
    }

    /*
     * 插入两条数据
     */
    private void insertItem() {
        SQLiteDatabase db = mOpenHelper.getWritableDatabase();
        String sql1 = "insert into " + TABLE_NAME + " (" + TITLE + ", " + BODY
                + ") values('haiyang', 'android的发展真是迅速啊');";
        String sql2 = "insert into " + TABLE_NAME + " (" + TITLE + ", " + BODY
                + ") values('icesky', 'android的发展真是迅速啊');";
        try {
            Log.i("haiyang:sql1=", sql1); //写测试日志
            Log.i("haiyang:sql2=", sql2);
            db.execSQL(sql1); //执行SQL的语法
            db.execSQL(sql2);
            setTitle("插入两条数据成功");
        } catch (SQLException e) {
            setTitle("插入两条数据失败");
        }
    }

    /*
     * 删除其中的一条数据
     */
    private void deleteItem() {
        try {
            SQLiteDatabase db = mOpenHelper.getWritableDatabase();
            db.delete(TABLE_NAME, " title = 'haiyang'", null);  //删除
            setTitle("删除title为haiyang的一条记录");
        } catch (SQLException e) {

        }

    }

    /*
     * 在屏幕的title区域显示当前数据表当中的数据的条数。
     */
    private void showItems() {

        SQLiteDatabase db = mOpenHelper.getReadableDatabase();
        String col[] = { TITLE, BODY };
        Cursor cur = db.query(TABLE_NAME, col, null, null, null, null, null); //查询
        Integer num = cur.getCount();
        setTitle(Integer.toString(num) + " 条记录");
    }