android中的数据库框架OrmLite，是对android中自带数据库的封装。下面按步骤说明如何使用。
最重要的是继承OrmLiteSqliteOpenHelper，获取得到helper对象
在里面重写onCreate，onUpgrade，close等方法，完成数据库表的创建，更新，资源释放。
获取到helper对象后，就可以使用helper的getDao方法获取dao来对数据表进行操作。下面是对数据库访问的Dao进行的封装
1.继承OrmLiteSqliteOpenHelper获取helper对象
<span style="font-size:14px;">public class DataBaseHelper extends OrmLiteSqliteOpenHelper {
private static final String DATABASE_NAME = "ormlitesample.db";
private static final int DATABASE_VERSION = 1;
public DataBaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase arg0, ConnectionSource arg1) {
createTable(arg1);
}
@Override
public void onUpgrade(SQLiteDatabase arg0, ConnectionSource arg1, int arg2,
int arg3) {
dropTable(arg1);
onCreate(arg0, arg1);
}
@Override
public void close() {
super.close();
for (String key : daos.keySet()) {
Dao dao = daos.get(key);
dao = null;
}
daos.clear();
}
private static DataBaseHelper instance;
public static DataBaseHelper getInstance() {
return instance;
}
public static void setInstance(DataBaseHelper instance) {
DataBaseHelper.instance = instance;
}
public static void releaseHelper() {
if (DataBaseHelper.getInstance() != null) {
OpenHelperManager.releaseHelper();
DataBaseHelper.setInstance(null);
}
}
/**
* 单例获取该Helper
*
* @param context
* @return
*/
public static synchronized DataBaseHelper getHelper(Context context) {
if (instance == null) {
synchronized (DataBaseHelper.class) {
if (instance == null)
instance = new DataBaseHelper(context);
}
}
return instance;
}
/************************must mode start******************************/
/**
* create all tables
*
* @param connectionSource
*/
protected static void createTable(ConnectionSource connectionSource) {
try {
TableUtils.createTableIfNotExists(connectionSource, Account.class);
TableUtils.createTableIfNotExists(connectionSource, AccountOne.class);
TableUtils.createTableIfNotExists(connectionSource, Order.class);
TableUtils.createTableIfNotExists(connectionSource, AccountMany.class);
TableUtils.createTableIfNotExists(connectionSource, OrderMany.class);
// TODO create other tables
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
* delete all tables
*
* @param connectionSource
*/
protected static void dropTable(ConnectionSource connectionSource) {
try {
TableUtils.dropTable(connectionSource, Account.class, true);
TableUtils.dropTable(connectionSource, AccountOne.class, true);
TableUtils.dropTable(connectionSource, Order.class, true);
TableUtils.dropTable(connectionSource, AccountMany.class, true);
TableUtils.dropTable(connectionSource, OrderMany.class, true);
// TODO drop other tables
} catch (SQLException e) {
e.printStackTrace();
}
}
/************************mode end******************************/
private Map<String, Dao> daos = new HashMap<String, Dao>();
public synchronized <T> Dao<T, Integer> getDaos(Class<T> clazz) {
Dao<T, Integer> dao = null;
String className = clazz.getSimpleName();
if (daos.containsKey(className)) {
dao = daos.get(className);
}
if (dao == null) {
try {
dao = getDao(clazz);
} catch (SQLException e) {
e.printStackTrace();
}
daos.put(className, dao);
}
return (Dao<T, Integer>) dao;
}
}</span>
2.定义数据库对外的操作接口
<span style="font-size:14px;">/**
* 按需要添加方法
* @author ZhangSheng
*
* @param <T>
*/
public interface IDao<T> {
public abstract T getSingleById(int id);
public abstract List<T> getAll();
public abstract boolean update(T t);
public abstract int deleteByIds(Collection<Integer> ids);
public abstract boolean delete(T t);
public abstract boolean add(T t);
public int updateBySQL(String statement, String... arguments);
public List<T> getListByFieldAndOrderBy(Map<String, Object> fieldValues,
Map<String, Boolean> orderBy);
} </span>
3.定义抽象的数据库AbstractDao
根据得到的helper得到dao进行数据表的操作,在实际开发中继承该抽象类即可，就可完成数据表的操作了
<span style="font-size:14px;">AbstractDao</span>
<span style="font-size:14px;">public abstract class AbstractDao<T> implements IDao<T> {
public Dao<T, Integer> dao;
public AbstractDao(Context context, Class<T> clazz) {
try {
dao = DataBaseHelper.getHelper(context).getDaos(clazz);
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public T getSingleById(int id) {
if (dao == null)
return null;
try {
return dao.queryForId(id);
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return null;
}
@Override
public List<T> getListByFieldAndOrderBy(Map<String, Object> fieldValues,
Map<String, Boolean> orderBy) {
if (dao == null)
return null;
try {
QueryBuilder<T, Integer> qb = dao.queryBuilder();
if (orderBy != null) {
for (Map.Entry<String, Boolean> entry : orderBy.entrySet()) {
qb.orderBy(entry.getKey(), entry.getValue());
}
}
if (fieldValues != null) {
Where<T, Integer> where = qb.where();
for (Map.Entry<String, Object> entry : fieldValues.entrySet()) {
where.eq(entry.getKey(), entry.getValue());
}
}
return qb.query();
// return dao.queryForFieldValuesArgs(fieldValues);
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return null;
}
@Override
public List<T> getAll() {
if (dao == null)
return null;
try {
return dao.queryForAll();
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return null;
}
public List<T> getAllOrderBy(String columnName, boolean ascending) {
if (dao == null)
return null;
try {
return dao.queryBuilder().orderBy(columnName, ascending).query();
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return null;
}
@Override
public boolean update(T t) {
if (dao == null)
return false;
try {
int update = dao.update(t);
Log.d("ormlite", "update="+update);
return update == 1;
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return false;
}
public int updateBySQL(String statement, String... arguments) {
if (dao == null)
return 0;
try {
return dao.updateRaw(statement, arguments);
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return 0;
}
@Override
public int deleteByIds(Collection<Integer> ids) {
if (dao == null)
return 0;
try {
return dao.deleteIds(ids);
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return 0;
}
public boolean deleteAll(String table) {
if (dao == null)
return false;
try {
int raw = dao.executeRaw("DELETE FROM " + table); //返回成功删除的个数
Log.d("ormlite", "deleteAll="+raw);
return raw > 0;
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return false;
}
@Override
public boolean delete(T t) {
if (dao == null)
return false;
try {
int delete = dao.delete(t);
Log.d("ormlite", "delete="+delete);
return delete == 1;
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return false;
}
@Override
public boolean add(T t) {
if (dao == null)
return false;
try {
int b = dao.create(t); //成功返回1
Log.d("ormlite", "add="+b);
return b==1;
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
return false;
}
} </span>
4.几种建表时对应的表间关系：
单表，一对一，一对多，多对多的关系；实际使用时主要工作量就在这里了。建立表后，顺便建立表对应的Dao对象，这个就是继承AbstractDao。
a.建立单一的表Account，与其他表无任何关系
<span style="font-size:14px;">/**
* Example account object that is persisted to disk by the DAO and other example classes.
*/
@DatabaseTable(tableName = "accounts")
public class Account {
// for QueryBuilder to be able to find the fields
public static final String NAME_FIELD_NAME = "name";
public static final String PASSWORD_FIELD_NAME = "passwd";
@DatabaseField(generatedId = true)
private int id;
@DatabaseField(columnName = NAME_FIELD_NAME, canBeNull = false)
private String name;
@DatabaseField(columnName = PASSWORD_FIELD_NAME)
private String password;
Account() {
//必须要有无参数构造函数
// all persisted classes must define a no-arg constructor with at least package visibility
}
public Account(String name) {
this.name = name;
}
public Account(String name, String password) {
this.name = name;
this.password = password;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public int hashCode() {
return name.hashCode();
}
@Override
public boolean equals(Object other) {
if (other == null || other.getClass() != getClass()) {
return false;
}
return name.equals(((Account) other).name);
}
} </span>
b.建立一对一的表结构：一个Order对应一个Account
<span style="font-size:14px;">Account的实体定义与a中的定义相同。
/**
* Example order object that is persisted to disk by the DAO and other example classes.
*/
@DatabaseTable(tableName = "orders")
public class Order {
public static final String ACCOUNT_ID_FIELD_NAME = "account_id";
@DatabaseField(generatedId = true)
private int id;
@DatabaseField(foreign = true, columnName = ACCOUNT_ID_FIELD_NAME)
private Account account; //这里在表Order中字段是account_id，并不是account
@DatabaseField
private int itemNumber;
@DatabaseField
private int quantity;
@DatabaseField
private float price;
Order() {
// all persisted classes must define a no-arg constructor with at least package visibility
}
public Order(Account account, int itemNumber, float price, int quantity) {
this.account = account;
this.itemNumber = itemNumber;
this.price = price;
this.quantity = quantity;
}
public int getId() {
return id;
}
public Account getAccount() {
return account;
}
public void setAccount(Account account) {
this.account = account;
}
public int getItemNumber() {
return itemNumber;
}
public void setItemNumber(int itemNumber) {
this.itemNumber = itemNumber;
}
public int getQuantity() {
return quantity;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
}</span>
c.建立一对多的表结构：Account一对多Order
<span style="font-size:14px;">/**
* Example account object that is persisted to disk by the DAO and other example classes.
*/
@DatabaseTable(tableName = "accounts")
public class Account {
// for QueryBuilder to be able to find the fields
public static final String NAME_FIELD_NAME = "name";
public static final String PASSWORD_FIELD_NAME = "passwd";
@DatabaseField(generatedId = true)
private int id;
@DatabaseField(columnName = NAME_FIELD_NAME, canBeNull = false)
private String name;
@DatabaseField(columnName = PASSWORD_FIELD_NAME)
private String password;
@ForeignCollectionField //一个account持有多个order,一对多的关系
private ForeignCollection<Order> orders;
Account() {
// all persisted classes must define a no-arg constructor with at least package visibility
}
public Account(String name) {
this.name = name;
}
public Account(String name, String password) {
this.name = name;
this.password = password;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public ForeignCollection<Order> getOrders() {
return orders;
}
@Override
public int hashCode() {
return name.hashCode();
}
@Override
public boolean equals(Object other) {
if (other == null || other.getClass() != getClass()) {
return false;
}
return name.equals(((Account) other).name);
}
}</span>
<span style="font-size:14px;">/**
* Example order object that is persisted to disk by the DAO and other example classes.
*/
@DatabaseTable(tableName = "orders")
public class Order {
public static final String ACCOUNT_ID_FIELD_NAME = "account_id";
@DatabaseField(generatedId = true)
private int id;
@DatabaseField(foreign = true, foreignAutoRefresh = true, columnName = ACCOUNT_ID_FIELD_NAME)
private Account account;
@DatabaseField
private int itemNumber;
@DatabaseField
private int quantity;
@DatabaseField
private float price;
Order() {
// all persisted classes must define a no-arg constructor with at least package visibility
}
public Order(Account account, int itemNumber, float price, int quantity) {
this.account = account;
this.itemNumber = itemNumber;
this.price = price;
this.quantity = quantity;
}
public int getId() {
return id;
}
public Account getAccount() {
return account;
}
public void setAccount(Account account) {
this.account = account;
}
public int getItemNumber() {
return itemNumber;
}
public void setItemNumber(int itemNumber) {
this.itemNumber = itemNumber;
}
public int getQuantity() {
return quantity;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
}</span>
d.建立多对多的表结构:就是在2个单表(Post,User)的基础上在新建立一个索引表(UserPost)，索引表持有这2各表的id字段。
<span style="font-size:14px;">/**
* Post to some blog with String content.
*/
public class Post {
// we use this field-name so we can query for posts with a certain id
public final static String ID_FIELD_NAME = "id";
// this id is generated by the database and set on the object when it is passed to the create method
@DatabaseField(generatedId = true, columnName = ID_FIELD_NAME)
int id;
// contents of the post
@DatabaseField
String contents;
Post() {
// for ormlite
}
public Post(String contents) {
this.contents = contents;
}
}
/**
* A user object with a name.
*/
public class User {
// we use this field-name so we can query for users with a certain id
public final static String ID_FIELD_NAME = "id";
// this id is generated by the database and set on the object when it is passed to the create method
@DatabaseField(generatedId = true, columnName = ID_FIELD_NAME)
int id;
@DatabaseField
String name;
User() {
// for ormlite
}
public User(String name) {
this.name = name;
}
}
/**
* Join table which links users to their posts.
*
* <p>
* For more information about foreign objects, see the <a href="http://ormlite.com/docs/foreign" >online docs</a>
* </p>
*/
public class UserPost {
public final static String USER_ID_FIELD_NAME = "user_id";
public final static String POST_ID_FIELD_NAME = "post_id";
/**
* This id is generated by the database and set on the object when it is passed to the create method. An id is
* needed in case we need to update or delete this object in the future.
*/
@DatabaseField(generatedId = true)
int id;
// This is a foreign object which just stores the id from the User object in this table.
@DatabaseField(foreign = true, columnName = USER_ID_FIELD_NAME)
User user;
// This is a foreign object which just stores the id from the Post object in this table.
@DatabaseField(foreign = true, columnName = POST_ID_FIELD_NAME)
Post post;
UserPost() {
// for ormlite
}
public UserPost(User user, Post post) {
this.user = user;
this.post = post;
}
} </span>
5.完成上面的步骤后，就可以在activity中获取到一张表的dao对象，来对表进行增删改查了。
下面列出些基本的dao操作,至于上面的几种表间关系，框架已经帮我们维护了 ，这几种关系的表间操作也是与单表是一样的。下面列出对单个表的操作方法，其中操作方法可以仔细看api提示。
定义表对应的dao:
<span style="font-size:14px;">//单表Account对应Dao
public class AccountDao extends AbstractDao<Account> {
public AccountDao(Context context, Class<Account> clazz) {
super(context, clazz);
}
}</span>
获取dao:
<span style="font-size:14px;">private void getDaos() {
accountDao = new AccountDao(this, Account.class);
}</span>
增加：
<span style="font-size:14px;">private void add() {
String name = Utils.getRandomString(5);
String password = Utils.getRandomString(5);
Account t = new Account(name, password);
accountDao.add(t);
}</span>
删除：
<span style="font-size:14px;">private void delete() {
accountDao.deleteAll("accounts");
}</span>
查询：
<span style="font-size:14px;">private List<Account> searchAll() {
List<Account> list = accountDao.getAll();
tv.setText(list == null ? "" : list.toString());
return list;
}</span>
修改：
<span style="font-size:14px;">private void update() {
List<Account> list = searchAll();
if(list!=null && list.size()>0){
Account endAccount = list.get(list.size()-1);
endAccount.setPassword("mode_"+Utils.getRandomString(5));
accountDao.update(endAccount);
}
}</span>
释放资源：
<span style="font-size:14px;">@Override
protected void onDestroy() {
super.onDestroy();
DataBaseHelper.releaseHelper();
}</span>
到这里基本就结束了。具体详细了解可以自己去开源项目doc：点我
里面有关于如何在android项目中使用，在android项目中使用需要用到2个jar:
ormlite-android-4.41.jar
ormlite-core-4.41.jar
时间： 2024-12-24 08:57:32