Oracle中blob类型的读取
虽然用blob的情况不多，但是还是得了解一下，网上看得有点乱，而且没有看到从数据读blob的。在此总结一下：
数据库中的建表语句如下：
Sql代码
create table blogtest(id number primary key,name varchar2(20),picture
blob);
Java代码
package August;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class OracleBlobTest {
public static void main(String[] args) {
}
public static void readBlob() {
try {
Class.forName(\"oracle.jdbc.driver.OracleDriver\");
Connection conn = DriverManager.getConnection(
\"jdbc:oracle:thin:@127.0.0.1:1521/july\
\"snaillocke\");
Statement st = conn.createStatement();
PreparedStatement ps = conn.prepareStatement(\"select * from
BLOBTEST where id = ?\");
ps.setInt(1, 1);
ResultSet rs = ps.executeQuery();
rs.next();
oracle.sql.BLOB imgBlob = (oracle.sql.BLOB) rs.getBlob(3);
// 将二进制数据写入BLOB
try{
FileOutputStream outStream = new
FileOutputStream(\"D:/oracleback.png\");
InputStream inStream = imgBlob.getBinaryStream();
byte[] buf = new byte[10240];
int len;
while ((len = inStream.read(buf)) > 0) {
outStream.write(buf, 0, len);
}
inStream.close();
outStream.close();
}catch(Exception e) {
e.printStackTrace();
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void writeBlob() {
try {
Class.forName(\"oracle.jdbc.driver.OracleDriver\");
Connection conn = DriverManager.getConnection(
\"jdbc:oracle:thin:@127.0.0.1:1521/july\
\"snaillocke\");
Statement st = conn.createStatement();
// 插入一个空对象empty_blob()
// 锁定数据行进行更新，注意“for update”语句
PreparedStatement ps = conn.prepareStatement(\"insert into
BLOBTEST (ID, NAME, PICTURE) values (1,'fang.jpg',?)\");
// 通过ORALCE.SQL.BLOB/CLOB.EMPTY_LOB()构造空BLOB/CLOB对
象
ps.setBlob(1, oracle.sql.BLOB.empty_lob());
ps.execute();
ps.close();
// 再次对读出BLOB/CLOB句柄
ps = conn
.prepareStatement(\"SELECT * FROM BLOBTEST WHERE
ID=? FOR UPDATE\");
ps.setInt(1, 1);
ResultSet rs = ps.executeQuery();
rs.next();
oracle.sql.BLOB imgBlob = (oracle.sql.BLOB) rs.getBlob(3);
// 将二进制数据写入BLOB
try{
FileInputStream inStream = new FileInputStream(\"D:/My
Pictures/oracle.png\");
OutputStream outStream = imgBlob.getBinaryOutputStream();
byte[] buf = new byte[10240];
int len;
while ((len = inStream.read(buf)) > 0) {
outStream.write(buf, 0, len);
}
inStream.close();
outStream.close();
}catch(Exception e) {
e.printStackTrace();
}
// 再将Blob字段更新到数据库
ps = conn
.prepareStatement(\" update BLOBTEST set PICTURE=?\");
ps.setBlob(1, imgBlob);
ps.executeUpdate();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
