Android进阶篇Sqlite使用(二)

Hello.java:

public class Hello{
    @DatabaseField(generatedId = true,unique=true)
    int id;
    @DatabaseField
    String word;
    //这是必须加的，否则会出错
    public Hello(){}
    public int getId()
    {
        return id;
    }
    public Hello(String word)
    {
        super();
        this.word = word;
    }
    public void setId(int id)
    {
        this.id = id;
    }

    public String getWord()
    {
        return word;
    }

    public void setWord(String word)
    {
        this.word = word;
    }

    @Override
    public String toString()
    {
        StringBuilder sb = new StringBuilder();
        sb.append("id=").append(id);
        sb.append(" ,word=").append(word);
        return sb.toString();
    }

}

注明:每个字段前面必须@DatabaseField，要不然不能创建这个字段

MainActivity.java:

private void initSqlite(){
        SqliteHelper sqliteHelper = new SqliteHelper(this);
        Dao<Hello, Integer> dao = sqliteHelper.getHelloDao();
        
        // 添加数据  
        try {
            for(int i=0;i<3;i++){
                Hello hello = new Hello("hello" + i);
                dao.create(hello);
            }
            
            // 查询添加的数据  
            List<Hello> hellos = null;
            hellos = dao.queryForAll();
            for (Hello h : hellos){
                Log.i(TAG, "-------查询添加的数据  --------");
                Log.i(TAG, "word= " + h.getWord());
            }
            
            //删除数据第一条数据  
            dao.delete(hellos.get(0));  
            // 重新查询数据  
            hellos = dao.queryForAll();  
            for (Hello h : hellos){  
                Log.i(TAG, "------- 删除数据第一条数据  --------");
                Log.i(TAG, "word= " + h.getWord());
            }  
            
            // 修改数据  
            Hello h1 = hellos.get(0);  
            h1.setWord("这是修改过的数据");  
            dao.update(h1);  
            hellos = dao.queryForAll();  
            for (Hello h : hellos){  
                Log.i(TAG, "-------修改数据    --------");
                Log.i(TAG, "word= " + h.getWord()); 
            }  
            
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

SqliteHelper.java:

public class SqliteHelper extends OrmLiteSqliteOpenHelper{
    private static final String TAG = SqliteHelper.class.getSimpleName();

    private static final String DATABASE_NAME = "HelloOrmlite.db";//数据库名字
    private static final int DATABASE_VERSION = 1;//数据库的版本号
    private Dao<Hello, Integer> helloDao = null; 
        
    public SqliteHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase arg0, ConnectionSource arg1) {
        try{  
            TableUtils.createTable(connectionSource, Hello.class);  
        }catch (java.sql.SQLException e) {
            // TODO Auto-generated catch block
            Log.i(TAG, "创建数据库失败", e);  
            e.printStackTrace();
        }  
    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, ConnectionSource arg1, int arg2,
            int arg3) {
        // TODO Auto-generated method stub
       try{  
            TableUtils.dropTable(connectionSource, Hello.class, true);  
            onCreate(arg0, connectionSource);  
        }catch (java.sql.SQLException e) {
            // TODO Auto-generated catch block
            Log.e(TAG, "更新数据库失败", e);  
            e.printStackTrace();
        }  
    }

    @Override
    public void close() {
        // TODO Auto-generated method stub
        super.close();
        helloDao = null; 
    }

    public Dao<Hello, Integer> getHelloDao() {
        if (helloDao == null){  
            try {
                helloDao = getDao(Hello.class);
            } catch (java.sql.SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }  
        }  
        return helloDao;
    }
    
}