Spring JdbcTemplate - 插入blob并返回生成的密钥 [英] Spring JdbcTemplate - Insert blob and return generated key

问题描述

从Spring JDBC文档中，我知道如何使用JdbcTemplate插入blob

From the Spring JDBC documentation, I know how to insert a blob using JdbcTemplate

final File blobIn = new File("spring2004.jpg");
final InputStream blobIs = new FileInputStream(blobIn);
jdbcTemplate.execute(
  "INSERT INTO lob_table (id, a_blob) VALUES (?, ?)",
  new AbstractLobCreatingPreparedStatementCallback(lobhandler) {                         
      protected void setValues(PreparedStatement ps, LobCreator lobCreator) 
          throws SQLException {
        ps.setLong(1, 1L);
        lobCreator.setBlobAsBinaryStream(ps, 2, blobIs, (int)blobIn.length());           
      }
  }
);
blobIs.close();

还有如何检索新插入行的生成密钥：

KeyHolder keyHolder = new GeneratedKeyHolder();
jdbcTemplate.update(
    new PreparedStatementCreator() {
        public PreparedStatement createPreparedStatement(Connection connection) throws SQLException {
            PreparedStatement ps =
                connection.prepareStatement(INSERT_SQL, new String[] {"id"});
            ps.setString(1, name);
            return ps;
        }
    },
    keyHolder);

// keyHolder.getKey() now contains the generated key

是有没有办法把两者结合起来？

Is there a way I could combine the two?

推荐答案

我来这里寻找相同的答案，但对接受的内容不满意。所以我做了一些挖掘并提出了我在Oracle 10g和Spring 3.0中测试过的解决方案

I came here looking for the same answer, but wasn't satisfied with what was accepted. So I did a little digging around and came up with this solution that I've tested in Oracle 10g and Spring 3.0

public Long save(final byte[] blob) {
  KeyHolder keyHolder = new GeneratedKeyHolder();
  String sql = "insert into blobtest (myblob) values (?)"; //requires auto increment column based on triggers
  getSimpleJdbcTemplate().getJdbcOperations().update(new AbstractLobPreparedStatementCreator(lobHandler, sql, "ID") {
    @Override
    protected void setValues(PreparedStatement ps, LobCreator lobCreator) throws SQLException, DataAccessException {
      lobCreator.setBlobAsBytes(ps, 1, blob);
    }
  }, keyHolder);

  Long newId = keyHolder.getKey().longValue();
  return newId;
}

这还需要以下抽象类，部分基于Spring的AbstractLobCreatingPreparedStatementCallback

this also requires the following abstract class, based in part on Spring's AbstractLobCreatingPreparedStatementCallback

public abstract class AbstractLobPreparedStatementCreator implements PreparedStatementCreator {
  private final LobHandler lobHandler;
  private final String sql;
  private final String keyColumn;
  public AbstractLobPreparedStatementCreator(LobHandler lobHandler, String sql, String keyColumn) {
    this.lobHandler = lobHandler;
    this.sql = sql;
    this.keyColumn = keyColumn;
  }
  public PreparedStatement createPreparedStatement(Connection con) throws SQLException {
    PreparedStatement ps = con.prepareStatement(sql, new String[] { keyColumn });
    LobCreator lobCreator = this.lobHandler.getLobCreator();
    setValues(ps, lobCreator);
    return ps;
  }
  protected abstract void setValues(PreparedStatement ps, LobCreator lobCreator) throws SQLException, DataAccessException;
}

此外，您在Oracle中创建的表应具有自动递增的列使用序列和触发器的id。触发器是必要的，因为否则你必须使用Spring的NamedParameterJdbcOperations（在SQL中执行sequence.nextval），它似乎不支持KeyHolder（我用它来检索自动生成id）。有关详细信息，请参阅此博客文章（而非我的博客）： http://www.lifeaftercoffee.com/2006/02/17/how-to-create-auto-increment-columns-in-oracle/

Also, the table you create in Oracle should have an auto-incremented column for the id using a sequence and trigger. The trigger is necessary because otherwise you'd have to use Spring's NamedParameterJdbcOperations (to do the sequence.nextval in your SQL) which doesn't seem to have support for KeyHolder (which I use to retrieve the auto-gen id). See this blog post (not my blog) for more info: http://www.lifeaftercoffee.com/2006/02/17/how-to-create-auto-increment-columns-in-oracle/

create table blobtest (
id number primary key,
myblob blob);

create sequence blobseq start with 1 increment by 1;

CREATE OR REPLACE TRIGGER blob_trigger
BEFORE INSERT
ON blobtest
REFERENCING NEW AS NEW
FOR EACH ROW
BEGIN
SELECT blobseq.nextval INTO :NEW.ID FROM dual;
end;
/

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