PreparedStatement操作blob类型的变量

1. PreparedStatement可以操作Blob类型的变量

写入操作的方法：setBolb(InputStream is)
读取操作的方法：
Blob blob = getBlob(int index);
InputStream is = blob.getBinaryStream();

2. 具体实现insert

//向数据表customers中插入Blob类型的字段
	@Test
	public void testInsert() throws Exception{
        //1.与数据库建立连接
		Connection conn = JDBCUtils.getConnection();
        //2.预编译sql语句返回PreparedStatement的对象
		String sql = "insert into customers(name,email,birth,photo)values(?,?,?,?)";
		//3.填充占位符
		PreparedStatement ps = conn.prepareStatement(sql);
		
		ps.setObject(1,"袁浩");
		ps.setObject(2, "yuan@qq.com");
		ps.setObject(3,"1992-09-08");
		FileInputStream is = new FileInputStream(new File("girl.jpg"));
		ps.setBlob(4, is);
		//4.执行
		ps.execute();
		
		JDBCUtils.closeResource(conn, ps);
		
	}

3. 具体的query

//查询数据表customers中Blob类型的字段
	@Test
	public void testQuery(){
		Connection conn = null;
		PreparedStatement ps = null;
		InputStream is = null;
		FileOutputStream fos = null;
		ResultSet rs = null;
		try {
			//1.与数据库建立连接
			conn = JDBCUtils.getConnection();
            //2.预编译sql语句返回PreparedStatement的对象
			String sql = "select id,name,email,birth,photo from customers where id = ?";
			ps = conn.prepareStatement(sql);
            //3. 填充占位符
			ps.setInt(1, 21);
            //4.执行并返回结果集
			rs = ps.executeQuery();
			if(rs.next()){
	//			方式一：
	//			int id = rs.getInt(1);
	//			String name = rs.getString(2);
	//			String email = rs.getString(3);
	//			Date birth = rs.getDate(4);
				//方式二：
				int id = rs.getInt("id");
				String name = rs.getString("name");
				String email = rs.getString("email");
				Date birth = rs.getDate("birth");
				
				Customer cust = new Customer(id, name, email, birth);
				System.out.println(cust);
				
				//将Blob类型的字段下载下来，以文件的方式保存在本地
				Blob photo = rs.getBlob("photo");
				is = photo.getBinaryStream();
				fos = new FileOutputStream("zhangyuhao.jpg");
				byte[] buffer = new byte[1024];
				int len;
				while((len = is.read(buffer)) != -1){
					fos.write(buffer, 0, len);
				}
				
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			
			try {
				if(is != null)
					is.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
			
			try {
				if(fos != null)
					fos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
			
			JDBCUtils.closeResource(conn, ps, rs);
		}
		
		
	}

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