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/** * 抽象接口，定义增删改查等操作 * @param 
   
     */public interface IBaseDao
    
      {    Long inserrt(T entity);    int update(T entity, T where);}
    
   

/** * 用于通过对象的字段获取对应数据库的字段名称 */@Target(ElementType.FIELD)@Retention(RetentionPolicy.RUNTIME)public @interface DbFiled {
       String value();}

/** * 用于获取表名 */@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)public @interface DbTable {
       String value();}

//对应表名称@DbTable("tb_user")public class User {
       //对应表的字段名称    @DbFiled("name")    public String name;    @DbFiled("password")    public String password;    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;    }}

/** * 对应的表 */public class UserDao extends BaseDao {
       @Override    public String createDataBase() {        return "create table if not exists tb_user(name varchar(20),password varchar(10))";    }}

/** * 核心类 * 实现了增删改查接口的方法 * 确立了表字段和表对象字段的对应关系 * @param 
   
     */public abstract class BaseDao
    
      implements IBaseDao
     
       {
       private SQLiteDatabase sqLiteDatabase;    private boolean isInit = false;    private String tableName;    private Class
      
        entityClass;    private Map
       
         cacheMap = new HashMap();;    public synchronized void init(Class
        
          entity, SQLiteDatabase sqLiteDatabase) { if (!isInit) { this.sqLiteDatabase = sqLiteDatabase; this.tableName = entity.getAnnotation(DbTable.class).value(); this.entityClass = entity; sqLiteDatabase.execSQL(createDataBase()); initCacheMap(); } } /** * 找到数据库字段和表对象(User对象)对应的子段,创建Map */ protected void initCacheMap() { String sql = "select * from " + this.tableName + " limit 1,0"; Cursor cursor = null; try { cursor = this.sqLiteDatabase.rawQuery(sql, null); String[] columnNames = cursor.getColumnNames(); Field[] columnFields = entityClass.getFields(); for (Field field : columnFields) { field.setAccessible(true); } for (String columnName : columnNames) { for (Field field : columnFields) { String filedName; if (field.getAnnotation(DbFiled.class) != null) { filedName = field.getAnnotation(DbFiled.class).value(); } else { filedName = field.getName(); } if (columnName.equals(filedName)) { cacheMap.put(columnName, field); } } } } catch (Exception e) { } finally { cursor.close(); } } public abstract String createDataBase(); @Override public Long inserrt(T entity) { Map
         
           map = getValues(entity); ContentValues contentvalues = getContentValues(map); Long result = sqLiteDatabase.insert(tableName, null, contentvalues); return result; } /** * 返回ContentValues * @param map key是数据库的字段名称,Value是需要插入的值 * @return ContentValues */ private ContentValues getContentValues(Map
          
            map) { ContentValues contentvalues = new ContentValues(); Set keys = map.keySet(); Iterator iterator = keys.iterator(); while (iterator.hasNext()) { String key = (String) iterator.next(); String value = map.get(key); if (value != null) { contentvalues.put(key, value); } } return contentvalues; } /** * 将表对象的的field值取出,作为Value * 将field对象的数据库字段名取出,作为Key * @param entity 表对象(User) * @return Map */ public Map getValues(T entity) { HashMap
           
             result = new HashMap<>(); Iterator fieldsIterator = cacheMap.values().iterator(); while (fieldsIterator.hasNext()) { Field colmunToFiled = (Field) fieldsIterator.next(); String cacheKey = null; String cacheValue = null; if (colmunToFiled.getAnnotation(DbFiled.class) != null) { cacheKey = colmunToFiled.getAnnotation(DbFiled.class).value(); } else { cacheKey = colmunToFiled.getName(); } try { if (null == colmunToFiled.get(entity)) { continue; } cacheValue = colmunToFiled.get(entity).toString(); } catch (Exception e) { e.printStackTrace(); } result.put(cacheKey, cacheValue); } return result; } @Override public int update(T entity, T where) { int result = -1; Map values = getValues(entity); Condition condition = new Condition(getValues(where)); result = sqLiteDatabase.update(tableName, getContentValues(values), condition.whereClauser, condition.WhereArgs); return result; }}
           
          
         
        
       
      
     
    
   

/** * 用于拼接查询语句 */public class Condition {
       public String whereClauser;    public String[] WhereArgs;    public Condition(Map
   
     map) {        ArrayList list = new ArrayList();        StringBuilder stringBuilder = new StringBuilder();        stringBuilder.append(" 1=1 ");        Set keys = map.keySet();        Iterator iterator = keys.iterator();        while (iterator.hasNext()) {            String key = (String) iterator.next();            String value = map.get(key);            if (null != value) {                stringBuilder.append(" and " + key + " =? ");                list.add(value);            }        }        this.whereClauser = stringBuilder.toString();        this.WhereArgs = (String[]) list.toArray(new String[list.size()]);    }}
   

public class MainActivity extends AppCompatActivity {
       BaseDao baseDao;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        baseDao = DaoManagerFactory.instance().getDataHelper(UserDao.class, User.class);    }    public void insert(View view) {        User user = new User();        user.setName("李四");        user.setPassword("123456");        baseDao.inserrt(user);    }}

/** * 工厂类 */public class DaoManagerFactory {
       private String path;    private static DaoManagerFactory instance = new DaoManagerFactory(new File(Environment.getExternalStorageDirectory(), "ligic.db"));    private SQLiteDatabase sqLiteDatabase;    private DaoManagerFactory(File file) {        this.path = file.getAbsolutePath();        openDataBase();    }    private void openDataBase() {        this.sqLiteDatabase = SQLiteDatabase.openOrCreateDatabase(path, null);    }    public synchronized 
   
     T getDataHelper(Class
    
      clazz, Class
     
       entityClass) {
  //回过头细看        T baseDao = null;        try {            baseDao = clazz.newInstance();            baseDao.init(entityClass, sqLiteDatabase);        } catch (InstantiationException e) {            e.printStackTrace();        } catch (IllegalAccessException e) {            e.printStackTrace();        }        return baseDao;    }    public static DaoManagerFactory instance() {        return instance;    }}