Android本地数据存储之SQLite关系型数据库 ——SQLiteDatabase

数据库的创建,获取,执行sql语句:

框架搭建:dao

思考:

1.数据库保存在哪里?

2.如何创建数据库?如何创建表?

3.如何更新数据库?如何更改表的列数据?

4.如何获取数据库?

5.如何修改数据库中的表的数据?

框架思想

思考:如何使得编程更加简单?

一个sql语言,容易写错;

1.使用占位符;

2.框架解析重建法:搭建框架,对增删改查功能进行单独封装,传入容器对象即可;

思考:

1.数据库保存在哪里?

data/data/包名/databases/xiaoo.db

2.如何创建数据库?如何创建表?

db.execSQL("CREATE TABLE person (personid integer primary key autoincrement, name varchar(20))");

3.如何更新数据库?如何更改表的列数据?

db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL ");

4.如何获取数据库?

5.如何修改数据库中的表的数据?

一、创建数据库打开助手:

二、创建dao

三、测试dao

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

public class MyDBOpenHelper extends SQLiteOpenHelper {

    /**
     *
     * @param context 应用程序上下文
     * @param name    数据库的名字
     * @param factory 查询数据库的游标工厂 一般情况下 用sdk默认的
     * @param version  数据库的版本 版本号必须不小1
     *
     */
    public MyDBOpenHelper(Context context) {
        super(context, );
    }

    // 在mydbOpenHelper 在数据库第一次被创建的时候  会执行onCreate();
    @Override
    public void onCreate(SQLiteDatabase db) {
        System.out.println("我被调用了 oncreate");
        db.execSQL("CREATE TABLE person (personid integer primary key autoincrement, name varchar(20))");
    }
        // 通过version的增加来执行数据库版本更新,版本号改为6的同时,调用onUpgrade ,让程序员执行具体更新;
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        System.out.println("on update ");
        db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL ");
    }
}

二、创建dao

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import cn.itcast.db.MyDBOpenHelper;
import cn.itcast.db.domain.Person;

public class PersonDao {
    private static final String TAG = "PersonDao";
    private MyDBOpenHelper dbOpenHelper;

    // 在personDao被new出来的时候 就完成初始化

    public PersonDao(Context context) {
        dbOpenHelper = new MyDBOpenHelper(context);
        // dbOpenHelper.getReadableDatabase()
        // dbOpenHelper.getWritableDatabase()
    }

    // 增删改查

    /**
     * 往数据库添加一条数据
     */
    public void add(String name, String phone) {
        boolean result = find(name);
        if (result)
            return;

        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        if (db.isOpen()) {
            db.execSQL("insert into person (name,phone) values (?,?)",
                    new Object[] { name, phone });
            // 关闭数据库 释放数据库的链接
            db.close();
        }
    }

    /**
     * 查找数据库的操作
     */
    public boolean find(String name) {
        boolean result = false;
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        if (db.isOpen()) {
            Cursor cursor = db.rawQuery("select * from person where name=?",
                    new String[] { name });
            if (cursor.moveToFirst()) {
                int index = cursor.getColumnIndex("phone"); // 得到phone在表中是第几列
                String phone = cursor.getString(index);
                Log.i(TAG, "phone =" + phone);
                result = true;

            }
            // 记得关闭掉 cursor
            cursor.close();
            result = false;
            // 释放数据库的链接
            db.close();
        }
        return result;
    }

    /**
     * 删除一条记录
     *
     * @param name
     */
    public void delete(String name) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        if (db.isOpen()) {
            db.execSQL("delete from person where name =?",
                    new Object[] { name });
            db.close();
        }
    }

    /**
     * 更新一条记录
     *
     */
    public void update(String name, String newname, String newphone) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        if (db.isOpen()) {
            db.execSQL("update person set name=? , phone=? where name=?",
                    new Object[] { newname, newphone, name });
            db.close();
        }
    }

    /**
     * 查找全部
     */
    public List<Person> getAllPersons() {
        List<Person> persons=null;
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        if (db.isOpen()) {
            persons = new ArrayList<Person>();
            Cursor cursor = db.rawQuery("select * from person ", null);
            while (cursor.moveToNext()) {
                Person person = new Person();
                int nameindex = cursor.getColumnIndex("name");
                int phoneindex = cursor.getColumnIndex("phone");
                String name = cursor.getString(nameindex);
                String phone = cursor.getString(phoneindex);
                person.setName(name);
                person.setNumber(phone);
                persons.add(person);
            }
            cursor.close();
            db.close();
        }
        return persons;
    }

}

三、单元测试:测试dao

1.配置

instrumentation 和 uses-library

    <instrumentation
        android:name="android.test.InstrumentationTestRunner"   //使用测试框架中的哪个测试运行器
        android:targetPackage="cn.xiaoo.db" />      //测试哪个工程?

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <uses-library android:name="android.test.runner" />      //该程序需要添加哪个jar包(用于测试)?

2.编程测试

package cn.itcast.db.dao.test;

import java.util.List;

import cn.itcast.db.dao.PersonDao;
import cn.itcast.db.domain.Person;
import android.test.AndroidTestCase;

public class TestPersonDao extends AndroidTestCase {
    PersonDao dao;
    // 测试在执行测试代码时候的流程
    //1 .new TestPersonDao 框架new出来
    //2. 调用 setUp()
    //3. testAdd()  这个时候 上下文 才被创建出来 

/*    @Override
    protected void setUp() throws Exception {
        dao = new PersonDao(getContext());
        super.setUp();
    }*/
    public void testAdd() throws Exception{
        PersonDao dao = new PersonDao(getContext());
        ;i<;i++){
        dao.add("+i);
        }
    }
    public void testdelete() throws Exception{
        PersonDao dao = new PersonDao(getContext());
        dao.delete("lisi99");
    }
    public void testupdate() throws Exception{
        PersonDao dao = new PersonDao(getContext());
        dao.update(");
    }

    public void testFindAll() throws Exception{
        PersonDao dao = new PersonDao(getContext());
        List<Person>  persons  = dao.getAllPersons();
        assertEquals(, persons.size());
    }

    /**
     * 测试的流程:
     */
    /*
    [2012-10-05 13:47:51 - db] ------------------------------
    [2012-10-05 13:47:51 - db] Android Launch!    //系统启动
    [2012-10-05 13:47:51 - db] adb is running normally.   //调试桥正常运行
    [2012-10-05 13:47:51 - db] Performing android.test.InstrumentationTestRunner JUnit launch   //运行测试运行器,启动JUnit
    [2012-10-05 13:47:51 - db] Automatic Target Mode: using existing emulator 'emulator-5554' running compatible AVD '2.3.3_QVGA'
    [2012-10-05 13:47:53 - db] Application already deployed. No need to reinstall.//不需要重新安装
    [2012-10-05 13:47:53 - db] Launching instrumentation android.test.InstrumentationTestRunner on device emulator-5554//在设备上运行测试运行器
    [2012-10-05 13:47:53 - db] Collecting test information //收集运行信息
    [2012-10-05 13:47:56 - db] Sending test information to Eclipse  //发送测试信息到Eclipse
    [2012-10-05 13:47:56 - db] Running tests...    //执行代码
    [2012-10-05 13:47:58 - db] Test run finished   //执行完毕
    */
 }

框架思想

思考:如何使得编程更加简单?

一条sql语句,容易写错;

操作表
insert into person (name,phone) values (?,?)---------public long insert(String table, String nullColumnHack, ContentValues values)
delete from person where name =?---------------------public int delete(String table, String whereClause, String[] whereArgs)
update person set name=? , phone=? where name=?------public int update(String table, ContentValues values, String whereClause, String[] whereArgs)
select * from person where name=?--------------------public Cursor query(boolean distinct, String table, String[] columns,
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;                                                              String selection, String[] selectionArgs, String groupBy,
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;                                                              String having, String orderBy, String limit)
insert:在哪张表插入哪些数据?string string contentvalues
delete:在哪张表删除哪些数据?String String String[]
update:在哪张表的那条数据上更改什么数据? String ContentValues String  String[]
query:是否保证唯一?查哪张表?查哪些列?
       什么查询条件?占位符值?分组?
       包含?排序?区间?
操作数据库:
CREATE TABLE person (personid integer primary key autoincrement, name varchar())
ALTER TABLE person ADD phone VARCHAR() NULL 

怎办办?

1.使用占位符;

2.框架解析重建法:搭建框架,对增删改查功能进行单独封装,传入容器对象即可;

.原生:  db.execSQL("insert into person (name,age) values ("xiaoli",20)");

.站位符:db.execSQL(});

.框架 :

            ContentValues values = new ContentValues();
            values.put("name", name);
            values.put("age", age);
            db.insert("person", null, values);

 public void add(String name, int age) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        if (db.isOpen()) {

            ContentValues values = new ContentValues();
            values.put("name", name);
            values.put("age", age);
            // 如果 contentvalues为空
            db.insert("person", null, values); // 组拼sql语句完成的添加的操作

            // insert into person name values (NULL) ;
            db.close();
        }
}

最复杂的方法是查询:query

我们一起来看看底层是怎么封装的:

    public static String buildQueryString(
            boolean distinct, String tables, String[] columns, String where,
            String groupBy, String having, String orderBy, String limit) {
        if (TextUtils.isEmpty(groupBy) && !TextUtils.isEmpty(having)) {
            throw new IllegalArgumentException(
                    "HAVING clauses are only permitted when using a groupBy clause");
        }
        if (!TextUtils.isEmpty(limit) && !sLimitPattern.matcher(limit).matches()) {
            throw new IllegalArgumentException("invalid LIMIT clauses:" + limit);
        }

        StringBuilder query = );

        query.append("SELECT ");
        if (distinct) {
            query.append("DISTINCT ");
        }
        ) {
            appendColumns(query, columns);
        } else {
            query.append("* ");
        }
        query.append("FROM ");
        query.append(tables);
        appendClause(query, " WHERE ", where);
        appendClause(query, " GROUP BY ", groupBy);
        appendClause(query, " HAVING ", having);
        appendClause(query, " ORDER BY ", orderBy);
        appendClause(query, " LIMIT ", limit);

        return query.toString();
    }

另一种增删改查:dao

import java.util.ArrayList;
import java.util.List;

import cn.itcast.db.MyDBOpenHelper;
import cn.itcast.db.domain.Person;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

public class PersonDBDao {
    private Context context;
    MyDBOpenHelper dbOpenHelper;

    public PersonDBDao(Context context) {
        this.context = context;
        dbOpenHelper = new MyDBOpenHelper(context);
    }

    /**
     * 添加一条记录
     */
    public void add(String name, int age) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        if (db.isOpen()) {
            // db.execSQL("insert into person (name,age) values (?,?)",new
            // Object[]{name,age});
            // db.execSQL("insert into person ",null) // 不合法的sql语句
            ContentValues values = new ContentValues();
            values.put("name", name);
            values.put("age", age);
            // 如果 contentvalues为空
            db.insert("person", null, values); // 组拼sql语句完成的添加的操作

            // insert into person name values (NULL) ;
            db.close();
        }

    }

    /**
     * 删除一条记录
     */
    public void delete(String name) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        if (db.isOpen()) {
            db.delete("person", "name=?", new String[] { name });
            db.close();
        }
    }

    /**
     * 数据库的更改操作
     */
    public void update(String name, String newname, int newage) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        if (db.isOpen()) {
            ContentValues values = new ContentValues();
            values.put("name", newname);
            values.put("age", newage);
            db.update("person", values, "name=?", new String[] { name });
            db.close();
        }
    }

    /**
     * 数据库的查询操作
     */
    public boolean find(String name) {
        boolean result = false;
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        if (db.isOpen()) {
            // select * from person
            Cursor cursor = db.query("person", null, "name=?",
                    new String[] { name }, null, null, null);
            if (cursor.moveToFirst()) {
                result = true;
            }
            cursor.close();
            db.close();
        }
        return result;

    }

    /**
     * 查询所有信息
     */
    public List<Person> findAll() {
        List<Person> persons = null;
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        if (db.isOpen()) {
            Cursor cursor = db.query("person", null, null, null, null, null,
                    null);
            persons = new ArrayList<Person>();
            while (cursor.moveToNext()) {
                Person person = new Person();
                String name = cursor.getString(cursor.getColumnIndex("name"));
                person.setName(name);
                int age = cursor.getInt(cursor.getColumnIndex("age"));
                person.setAge(age);
                persons.add(person);
            }
            cursor.close();
            db.close();
        }
        return persons;
    }
    /**
     * 查询所有信息
     */
    public Cursor findAllbyCursor() {
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        if (db.isOpen()) {
            /*Cursor cursor = db.query("person", null, null, null, null, null,
                    null);*/
            Cursor cursor = db.rawQuery("select personid as _id,age,name from person", null);

            return cursor;
            // 注意了  一定不要把数据库 关闭了
            }
        return null;

    }

&nbsp;&nbsp;&nbsp;&nbsp;   /**
&nbsp;&nbsp; &nbsp;    * 银行转账的方法
&nbsp;&nbsp;  &nbsp;   * 1.开始事务:db.beginTransaction();
&nbsp;&nbsp; &nbsp;    * 2.设置事务成功:db.setTransactionSuccessful();
&nbsp;&nbsp;   &nbsp;  * 3.结束事务:db.endTransaction();
&nbsp;&nbsp; &nbsp;    * 4.关闭连接:db.close();
&nbsp;&nbsp; &nbsp;    */
    public void transaction() {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        if (db.isOpen()) {

            try {
                // 开启数据库的事务
                db.beginTransaction();
                // 给张三设置1000块钱的账户
                db.execSQL("update person set account=? where name=?",
                        , "zhangsan98" });
                // 把张三的账户扣除200块钱
                db.execSQL("update person set account=account-? where name=?",
                        , "zhangsan98" });
                // 出现了异常
                // 把张三的钱给李四
                //初始化李四账户 为 0
                db.execSQL("update person set account=? where name=?",
                        , "lisi" });
                db.execSQL("update person set account=account+? where name=?",
                        , "lisi" });
                db.setTransactionSuccessful();
            }
            // 显示的设置事务是否成功
            catch (Exception e) {
                // TODO: handle exception
            } finally {
                db.endTransaction();
                db.close();
            }
        }
    }
}
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