oracle中读写blob字段的问题

    LOB?型分?BLOB和CLOB??：BLOB即二?制大型?像（Binary Large Object），?用於存?非文本的字?流??（如程序、?像、影音等）。而CLOB，即字符型大型?像（Character Large Object），??字符集相?，?於存?文本型的??（如?史?案、大部?著作等）。

下面以程序?例?明通?JDBC操?Oracle???LOB?型字段的??情?。

先建立如下????用的???表，Power Designer PD模型如下：

 

建表SQL?句?：

CREATE TABLE TEST_CLOB ( ID NUMBER(3), CLOBCOL CLOB)

CREATE TABLE TEST_BLOB ( ID NUMBER(3), BLOBCOL BLOB)

一、 CLOB?象的存取

1、往???中插入一?新的CLOB?像

public static void clobInsert(String infile) throws Exception

{

/* ?定不自?提交 */

boolean defaultCommit = conn.getAutoCommit();

conn.setAutoCommit(false);

try {

/* 插入一?空的CLOB?像 */

stmt.executeUpdate("INSERT INTO TEST_CLOB VALUES ('111', EMPTY_CLOB())");

/* 查?此CLOB?象??定 */

ResultSet rs = stmt.executeQuery("SELECT CLOBCOL FROM TEST_CLOB WHERE ID='111' FOR UPDATE");

while (rs.next()) {

/* 取出此CLOB?像 */

oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");

/* 向CLOB?像中?入?? */

BufferedWriter out = new BufferedWriter(clob.getCharacterOutputStream());

BufferedReader in = new BufferedReader(new FileReader(infile));

int c;

while ((c=in.read())!=-1) {

out.write(c);

}

in.close();

out.close();

}

/* 正式提交 */

conn.commit();

} catch (Exception ex) {

/* 出?回? */

conn.rollback();

throw ex;

}

/* 恢?原提交?? */

conn.setAutoCommit(defaultCommit);

}

2、修改CLOB?像（是在原CLOB?像基?上?行覆?式的修改）

public static void clobModify(String infile) throws Exception

{

/* ?定不自?提交 */

boolean defaultCommit = conn.getAutoCommit();

conn.setAutoCommit(false);

try {

/* 查?CLOB?象??定 */

ResultSet rs = stmt.executeQuery("SELECT CLOBCOL FROM TEST_CLOB WHERE ID='111' FOR UPDATE");

while (rs.next()) {

/* ?取此CLOB?像 */

oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");

/* ?行覆?式修改 */

BufferedWriter out = new BufferedWriter(clob.getCharacterOutputStream());

BufferedReader in = new BufferedReader(new FileReader(infile));

int c;

while ((c=in.read())!=-1) {

out.write(c);

}

in.close();

out.close();

}

/* 正式提交 */

conn.commit();

} catch (Exception ex) {

/* 出?回? */

conn.rollback();

throw ex;

}

/* 恢?原提交?? */

conn.setAutoCommit(defaultCommit);

}

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