14、JDBCに基づくBaseDaoの実現

1、jdbc.propertiesのプロファイルは次のとおりです.

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost/bjsxteasyui
username=root
password=root

2、BaseDao.java

public interface BaseDao<Entity> {

	
	void save(Entity obj) throws Exception ; 
	
	void update (Entity obj) throws Exception; 
	
	void delete(int id) throws Exception; 
	
	List<Entity> findAll() throws Exception;
	
	Entity findById( int id) throws Exception;
	
	
}

3、BaseDaoImpl.java

/**
 * jdbc   ： 1        2 sql 3 preparedstatemenet
 *
 * @param <Entity>
 */
public class BaseDaoImpl<Entity> implements BaseDao<Entity>{

	//public 
	protected Class clazz ;
	

	public BaseDaoImpl(){

		//System.out.println(this.getClass());
		ParameterizedType pt = (ParameterizedType) this.getClass().getGenericSuperclass();
		//           
		clazz = (Class)pt.getActualTypeArguments()[0];
		System.out.println(clazz);
	}
	
	
	
	/**
	 *     
	 */
	public void save(Entity obj) throws Exception {
		
		//obj.getSimpleName();
		Connection conn = DBUtils.createConn();
		String sql = "insert into " + clazz.getSimpleName() + " values(null ";
		//             
		Field[] fs = clazz.getDeclaredFields();
		//System.out.println(fs.length);
		
		for (int i = 1; i < fs.length; i++) {
			sql += ",? " ;
		}
		sql = sql + ")";
		System.out.println(sql);
		
		//     
		PreparedStatement ps = DBUtils.getPs(conn, sql);
		
		//ps.setString(1, user.getName());
		
		for (int i = 1; i < fs.length; i++) {
			//       
			String MethodName = "get" +Character.toUpperCase(fs[i].getName().charAt(0)) + fs[i].getName().substring(1) ;
			Method m = clazz.getMethod(MethodName);
			ps.setObject(i, m.invoke(obj));
		}
		ps.executeUpdate();
		DBUtils.close(ps);
		DBUtils.close(conn);
		
	}
	
	/**
	 *     
	 */
	public void update(Entity obj) throws Exception {

			Connection conn = DBUtils.createConn();
			// update user set name = ? , age = ? where id = ?
			String sql = " update " + clazz.getSimpleName() + " set  ";
			Field[] fs = clazz.getDeclaredFields();
			for (int i = 1; i < fs.length; i++) {
				sql += fs[i].getName() + "=?,";
			}
			sql = sql.substring(0, sql.length()-1) + " where id = ? ";
			
			PreparedStatement ps = DBUtils.getPs(conn, sql);
			
			for (int i = 1; i < fs.length; i++) {
				String methodName = "get" + Character.toUpperCase(fs[i].getName().charAt(0)) + fs[i].getName().substring(1);
				Method m  = clazz.getMethod(methodName);
				ps.setObject(i, m.invoke(obj));// user.getName();
			}
			Method m2 = clazz.getMethod("getId");
			ps.setInt(fs.length,(Integer)m2.invoke(obj));
			
			ps.executeUpdate();
			DBUtils.close(ps);
			DBUtils.close(conn);			
			
	}

	/**
	 *     id     
	 */
	public Entity findById(int id) throws Exception {
		Connection conn = DBUtils.createConn();
		String sql = " select * from  " + clazz.getSimpleName() +  " where id = " + id ;
		PreparedStatement ps = DBUtils.getPs(conn, sql);
		ResultSet rs = ps.executeQuery();
		Entity entity =  (Entity) clazz.newInstance();
		if(rs.next()){
			Field[]  fs = clazz.getDeclaredFields();
			for (int i = 0; i < fs.length; i++) {
				
				String methodName = "set" + Character.toUpperCase(fs[i].getName().charAt(0)) + fs[i].getName().substring(1);
				Method m = clazz.getDeclaredMethod(methodName, fs[i].getType());
				m.invoke(entity, rs.getObject(fs[i].getName()));
			}
		}
		DBUtils.close(rs);
		DBUtils.close(ps);
		DBUtils.close(conn);
		return entity;
	}

	/**
	 *     
	 */
	public List<Entity> findAll() throws Exception {
		Connection conn = DBUtils.createConn();
		String sql =" select * from " + clazz.getSimpleName();
		PreparedStatement ps = DBUtils.getPs(conn, sql);
		
		List<Entity> list = new ArrayList<Entity>();
		
		ResultSet rs =  ps.executeQuery();
		
		while(rs.next()){
			Entity entity = (Entity)clazz.newInstance();
			
			Field[] fs = clazz.getDeclaredFields();
			for (int i = 0; i < fs.length; i++) {
				String methodName = "set"+ Character.toUpperCase(fs[i].getName().charAt(0)) + fs[i].getName().substring(1);
				Method m = clazz.getMethod(methodName, fs[i].getType());
				m.invoke(entity, rs.getObject(fs[i].getName()));
			}
			
			list.add(entity);
		}
		DBUtils.close(rs);
		DBUtils.close(ps);
		DBUtils.close(conn);
		return list;
	}

	/**
	 *     
	 */
	public void delete(int id) throws Exception {
			Connection conn = DBUtils.createConn();
			String sql = " delete from " + clazz.getSimpleName() + " where id =" +id;
			PreparedStatement ps = DBUtils.getPs(conn, sql);
			ps.executeUpdate(sql);
			DBUtils.close(ps);
			DBUtils.close(conn);	
	}


	
	/**
	 *            
	 * @param sql
	 * @param params
	 * @return
	 */
	public  List<Entity> queryListForParams(String sql,Object[] params ) throws Exception{
		Connection conn  = DBUtils.createConn();
		PreparedStatement ps = null;
		ResultSet rs = null;
		List list = new ArrayList();
		try {
			//   statement  (   sql)
			ps = conn.prepareStatement(sql); // select * from org where id = ? and name = ?  [1 , z3]
			if(params!=null){
				for(int i=0;i<params.length;i++){
					ps.setObject(i+1, params[i]);
				}
			}
			Field[] fs = clazz.getDeclaredFields();
			rs = ps.executeQuery();
			while(rs.next()){
				Object obj = clazz.getConstructor().newInstance();
				for(int i = 0 ; i <fs.length;i++ ){
					String methodName = "set" +fs[i].getName().substring(0, 1).toUpperCase()+fs[i].getName().substring(1);
					Method m = clazz.getMethod(methodName, fs[i].getType());			
					Object value = rs.getObject(fs[i].getName());  
					m.invoke(obj, value); 
				}
				list.add(obj);
			}				

		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			DBUtils.close(rs);
			DBUtils.close(ps);
			DBUtils.close(conn);
		}
		return list;
	}		
	
	
}

4、DButils.java

public class DBUtils {
	
	private static Properties props = new Properties();
	
	static{
		InputStream is = null;
		
		is = DBUtils.class.getClassLoader().getResourceAsStream("jdbc.properties");
		try {
			props.load(is);
		} catch (IOException e) {
			e.printStackTrace();
		} finally{
			if(is!=null){
				try {
					is.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		
	}
	
	
		
	//    
	public static Connection createConn(){
		Connection conn = null; 
		try {
			Class.forName((String)props.get("driver"));
			//ip   +      
			conn = DriverManager.getConnection((String)props.get("url"), (String)props.get("username"), (String)props.get("password"));
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}
	
	//    
	public static PreparedStatement getPs(Connection conn , String sql){
		PreparedStatement ps = null; 
		try {
			ps = conn.prepareStatement(sql);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return ps ; 
	}

	public static void close(Connection conn){
			if(conn != null){
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
	}
	
	public static void close(ResultSet rs){
		if(rs != null){
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
	
	public static void close(PreparedStatement ps){
		if(ps != null){
			try {
				ps.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
		
}

5、UserDao.java

public interface UserDao extends BaseDao<<span style="font-family: Arial, Helvetica, sans-serif;">User</span><span style="font-family: Arial, Helvetica, sans-serif;">> {</span>

}

6、UserDaoImpl.java

public class UserDaoImpl extends BaseDaoImpl<User> implements UserDao {
    //         

}