java - 如何在java中检查getBytes(coloulm name)是否包含空值

Question

我想检查以下语句是否为空

byte[] imageBytes = rs.getBytes("doctimg");

我的代码是......

while(rs.next() ) {
    JsonObject row = new JsonObject();      

    /*Want  to Check this 
    byte[] imageBytes = rs.getBytes("doctimg");
    null or not*/
    byte[] imageBytes = rs.getBytes("doctimg");
    String imageBase64 = DatatypeConverter.printBase64Binary(imageBytes);

    row.add("doctId",new JsonPrimitive(""+rs.getString("doctId")));
    row.add("deptId",new JsonPrimitive(""+rs.getString("deptId")));


    row.addProperty("img", imageBase64);

    data.add(row);
}

Answer 1

您可以使用wasNull()方法:

byte[] imageBytes = rs.getBytes("doctimg");
if (rs.wasNull()) {
    System.out.println("It was null!"); // or some more robust treatment
} else {
    // Wasn't null, let's use it
    String imageBase64 = DatatypeConverter.printBase64Binary(imageBytes);
}