From edc66d76afac8800d1f4c773876b1ba1865c8159 Mon Sep 17 00:00:00 2001 From: Kazuki Shimizu Date: Wed, 6 May 2015 03:24:48 +0900 Subject: [PATCH] Improve description of DefaultLobHandler in reference manual Issue: SPR-12985 --- src/asciidoc/data-access.adoc | 42 ++++++++++++++++++++++++----------- 1 file changed, 29 insertions(+), 13 deletions(-) diff --git a/src/asciidoc/data-access.adoc b/src/asciidoc/data-access.adoc index eef3d6898d..f591156606 100644 --- a/src/asciidoc/data-access.adoc +++ b/src/asciidoc/data-access.adoc @@ -4355,23 +4355,24 @@ You can provide SQL type information in several ways: [[jdbc-lob]] ==== Handling BLOB and CLOB objects -You can store images, other binary objects, and large chunks of text. These large object -are called BLOB for binary data and CLOB for character data. In Spring you can handle -these large objects by using the JdbcTemplate directly and also when using the higher -abstractions provided by RDBMS Objects and the `SimpleJdbc` classes. All of these -approaches use an implementation of the `LobHandler` interface for the actual management -of the LOB data. The `LobHandler` provides access to a `LobCreator` class, through the -`getLobCreator` method, used for creating new LOB objects to be inserted. +You can store images, other binary data, and large chunks of text in the database. These +large objects are called BLOBs (Binary Large OBject) for binary data and CLOBs (Character +Large OBject) for character data. In Spring you can handle these large objects by using +the `JdbcTemplate` directly and also when using the higher abstractions provided by RDBMS +Objects and the `SimpleJdbc` classes. All of these approaches use an implementation of +the `LobHandler` interface for the actual management of the LOB (Large OBject) data. The +`LobHandler` provides access to a `LobCreator` class, through the `getLobCreator` method, +used for creating new LOB objects to be inserted. The `LobCreator/LobHandler` provides the following support for LOB input and output: * BLOB -* byte[] -- getBlobAsBytes and setBlobAsBytes -* InputStream -- getBlobAsBinaryStream and setBlobAsBinaryStream +** `byte[]` -- `getBlobAsBytes` and `setBlobAsBytes` +** `InputStream` -- `getBlobAsBinaryStream` and `setBlobAsBinaryStream` * CLOB -* String -- getClobAsString and setClobAsString -* InputStream -- getClobAsAsciiStream and setClobAsAsciiStream -* Reader -- getClobAsCharacterStream and setClobAsCharacterStream +** `String` -- `getClobAsString` and `setClobAsString` +** `InputStream` -- `getClobAsAsciiStream` and `setClobAsAsciiStream` +** `Reader` -- `getClobAsCharacterStream` and `setClobAsCharacterStream` The next example shows how to create and insert a BLOB. Later you will see how to read it back from the database. @@ -4407,10 +4408,25 @@ dependency injection. clobReader.close(); ---- -<1> Pass in the lobHandler that in this example is a plain `DefaultLobHandler` +<1> Pass in the `lobHandler` that in this example is a plain `DefaultLobHandler`. <2> Using the method `setClobAsCharacterStream`, pass in the contents of the CLOB. <3> Using the method `setBlobAsBinaryStream`, pass in the contents of the BLOB. + +[NOTE] +==== +If you invoke the `setBlobAsBinaryStream`, `setClobAsAsciiStream`, or +`setClobAsCharacterStream` method on the `LobCreator` returned from +`DefaultLobHandler.getLobCreator()`, you can optionally specify a negative value for the +`contentLength` argument. If the specified content length is negative, the +`DefaultLobHandler` will use the JDBC 4.0 variants of the set-stream methods without a +length parameter; otherwise, it will pass the specified length on to the driver. + +Consult the documentation for the JDBC driver in use to verify support for streaming a +LOB without providing the content length. +==== + + Now it's time to read the LOB data from the database. Again, you use a `JdbcTemplate` with the same instance variable `lobHandler` and a reference to a `DefaultLobHandler`.