完全解读JAVA完全控制Oracle中BLOB、CLOB.doc

网络上很多关于JAVA对Oracle中BLOB、CLOB类型字段的操作说明，有的不够全面，有的不够准确，甚至有的简直就是胡说八道。最近的项目正巧用到了这方面的知识，在这里做个总结。环境：Database: Oracle 9iApp Server: BEA Weblogic 8.14表结构：CREATE TABLE TESTBLOB (ID Int, NAME Varchar2(20), BLOBATTR Blob)CREATE TABLE TESTBLOB (ID Int, NAME Varchar2(20), CLOBATTR Clob)JAVA可以通过JDBC，也可以通过JNDI访问并操作数据库，这两种方式的具体操作存在着一些差异，由于通过App Server的数据库连接池JNDI获得的数据库连接提供的java.sql.Blob和java.sql.Clob实现类与JDBC方式提供的不同，因此在入库操作的时候需要分别对待；出库操作没有这种差异，因此不用单独对待。一、BLOB操作1、入库（1）JDBC方式 /通过JDBC获得数据库连接 Class.forName(oracle.jdbc.driver.OracleDriver); Connection con = DriverManager.getConnection(jdbc:oracle:thin:localhost:1521:testdb, test, test); con.setAutoCommit(false); Statement st = con.createStatement(); /插入一个空对象empty_blob() st.executeUpdate(insert into TESTBLOB (ID, NAME, BLOBATTR) values (1, thename, empty_blob(); /锁定数据行进行更新，注意“for update”语句 ResultSet rs = st.executeQuery(select BLOBATTR from TESTBLOB where ID=1 for update); if (rs.next() /得到java.sql.Blob对象后强制转换为oracle.sql.BLOB oracle.sql.BLOB blob = (oracle.sql.BLOB) rs.getBlob(BLOBATTR); OutputStream outStream = blob.getBinaryOutputStream(); /data是传入的byte数组，定义：byte data outStream.write(data, 0, data.length); outStream.flush(); outStream.close(); mit(); con.close();（2）JNDI方式 /通过JNDI获得数据库连接 Context context = new InitialContext(); ds = (DataSource) context.lookup(ORA_JNDI); Connection con = ds.getConnection(); con.setAutoCommit(false); Statement st = con.createStatement(); /插入一个空对象empty_blob() st.executeUpdate(insert into TESTBLOB (ID, NAME, BLOBATTR) values (1, thename, empty_blob(); /锁定数据行进行更新，注意“for update”语句 ResultSet rs = st.executeQuery(select BLOBATTR from TESTBLOB where ID=1 for update); if (rs.next() /得到java.sql.Blob对象后强制转换为weblogic.jdbc.vendor.oracle.OracleThinBlob（不同的App Server对应的可能会不同） weblogic.jdbc.vendor.oracle.OracleThinBlob blob = (weblogic.jdbc.vendor.oracle.OracleThinBlob) rs.getBlob(BLOBATTR); OutputStream outStream = blob.getBinaryOutputStream(); /data是传入的byte数组，定义：byte data outStream.write(data, 0, data.length); outStream.flush(); outStream.close(); mit(); con.close();2、出库 /获得数据库连接 Connection con = ConnectionFactory.getConnection(); con.setAutoCommit(false); Statement st = con.createStatement(); /不需要“for update” ResultSet rs = st.executeQuery(select BLOBATTR from TESTBLOB where ID=1); if (rs.next() java.sql.Blob blob = rs.getBlob(BLOBATTR); InputStream inStream = blob.getBinaryStream(); /data是读出并需要返回的数据，类型是byte data = new byteinput.available(); inStream.read(data); inStream.close(); inStream.close(); mit(); con.close();二、CLOB操作1、入库（1）JDBC方式 /通过JDBC获得数据库连接 Class.forName(oracle.jdbc.driver.OracleDriver); Connection con = DriverManager.getConnection(jdbc:oracle:thin:localhost:1521:testdb, test, test); con.setAutoCommit(false); Statement st = con.createStatement(); /插入一个空对象empty_clob() st.executeUpdate(insert into TESTCLOB (ID, NAME, CLOBATTR) values (1, thename, empty_clob(); /锁定数据行进行更新，注意“for update”语句 ResultSet rs = st.executeQuery(select CLOBATTR from TESTCLOB where ID=1 for update); if (rs.next() /得到java.sql.Clob对象后强制转换为oracle.sql.CLOB oracle.sql.CLOB clob = (oracle.sql.CLOB) rs.getClob(CLOBATTR); Writer outStream = clob.getCharacterOutputStream(); /data是传入的字符串，定义：String data char c = data.toCharArray(); outStream.write(c, 0, c.length); outStream.flush(); outStream.close(); mit(); con.close();（2）JNDI方式 /通过JNDI获得数据库连接 Context context = new InitialContext(); ds = (DataSource) context.lookup(ORA_JNDI); Connection con = ds.getConnection(); con.setAutoCommit(false); Statement st = con.createStatement(); /插入一个空对象empty_clob() st.executeUpdate(insert into TESTCLOB (ID, NAME, CLOBATTR) values (1, thename, empty_clob(); /锁定数据行进行更新，注意“for update”语句 ResultSet rs = st.executeQuery(select CLOBATTR from TESTCLOB where ID=1 for update); if (rs.next() /得到java.sql.Clob对象后强制转换为weblogic.jdbc.vendor.oracle.OracleThinClob（不同的App Server对应的可能会不同） weblogic.jdbc.vendor.oracle.OracleThinClob clob = (weblogic.jdbc.vendor.oracle.OracleThinClob) rs.getClob(CLOBATTR); Writer outStream = clob.getCharacterOutputStream(); /data是传入的字符串，定义：String data char c = data.toCharArray(); outStream.write(c, 0, c.length); outStream.flush(); outStream.close(); mit(); con.close();2、出库 /获得数据库连接 Connection con = ConnectionFactory.getConnection(); con.setAutoCommit(false); Statement st = con.createStatement(); /不需要“for update” ResultSet rs = st.executeQuery(select CLOBATTR from TESTCLOB where ID=1); if (rs.next() java.sql.Clob clob = rs.getClob(CLOBATTR); Reader inStream = clob.getCharacterStream(); char c = new char(int) clob.length(); inStream.read(c); /data是读出并需要返回的数据，类型是String data = new St