详解jdbc实现对CLOB和BLOB数据类型的操作
1、 读取操作
CLOB
//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 String(c); inStream.close(); } inStream.close(); con.commit(); con.close();
BLOB
//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 byte[input.available()];
inStream.read(data);
inStream.close();
}
inStream.close();
con.commit();
con.close();
2、写入操作
CLOB
//获得数据库连接
Connection con = ConnectionFactory.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();
con.commit();
con.close();
BLOB
//获得数据库连接
Connection con = ConnectionFactory.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();
con.commit();
con.close();
3、读写CLOB/BLOB数据到文件
TNS：
# tnsnames.ora Network Configuration File: d:\oracle\product\10.2.0\client_1\NETWORK\ADMIN\tnsnames.ora # Generated by Oracle configuration tools. ORADB = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.100)(PORT = 1521)) ) (CONNECT_DATA = (SID = ORCL) ) ) MYORCL = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.100)(PORT = 1521)) ) (CONNECT_DATA = (SERVICE_NAME = myorcl) ) )
Table：
create table TEST_ORALOB ( ID VARCHAR2(20), TSBLOB BLOB not null, TSCLOB CLOB not null )
测试代码：
package lavasoft.oralob.common;
import oracle.sql.BLOB;
import java.io.*;
import java.sql.*;
/**
* JDBC读写Oracle10g的CLOB、BLOB
*
*/
public class TestOraLob {
public static void main(String[] args) {
insertBlob();
queryBlob();
}
public static void insertBlob() {
Connection conn = DBToolkit.getConnection();
PreparedStatement ps = null;
try {
String sql = "insert into test_oralob (ID, TSBLOB, TSCLOB) values (?, ?, ?)";
ps = conn.prepareStatement(sql);
ps.setString(1, "100");
//设置二进制BLOB参数
File file_blob = new File("C:\\a.jpg");
InputStream in = new BufferedInputStream(new FileInputStream(file_blob));
ps.setBinaryStream(2, in, (int) file_blob.length());
//设置二进制CLOB参数
File file_clob = new File("c:\\a.txt");
InputStreamReader reader = new InputStreamReader(new FileInputStream(file_clob));
ps.setCharacterStream(3, reader, (int) file_clob.length());
ps.executeUpdate();
in.close();
} catch (IOException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBToolkit.closeConnection(conn);
}
}
public static void queryBlob() {
Connection conn = DBToolkit.getConnection();
PreparedStatement ps = null;
Statement stmt = null;
ResultSet rs = null;
try {
String sql = "select TSBLOB from TEST_ORALOB where id ='100'";
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
if (rs.next()) {
//读取Oracle的BLOB字段
InputStream in = rs.getBinaryStream(1);
File file = new File("c:\\a1.jpg");
OutputStream out = new BufferedOutputStream(new FileOutputStream(file));
byte[] buff1 = new byte[1024];
for (int i = 0; (i = in.read(buff1)) > 0;) {
out.write(buff1, 0, i);
}
out.flush();
out.close();
in.close();
//读取Oracle的CLOB字段
char[] buff2 = new char[1024];
File file_clob = new File("c:\\a1.txt");
OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(file_clob));
Reader reader = rs.getCharacterStream(1);
for (int i = 0; (i = reader.read(buff2)) > 0;) {
writer.write(buff2, 0, i);
}
writer.flush();
writer.close();
reader.close();
}
rs.close();
stmt.close();
} catch (IOException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
DBToolkit.closeConnection(conn);
}
}
}
注：如果是具体的字符串写入CLOB字段，简化写法：
//设置二进制CLOB参数
String xxx = "abcdefg";
ps.setCharacterStream(3, new StringReader(xxx), xxx.getBytes("GBK").length);
ps.executeUpdate();
in.close();
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