JDBC操作LOB
时间：2021-07-01 10:21:17
帮助过：30人阅读
Blob：是指二进制大对象也就是英文Binary Large Object的所写，是用来存储大量二进制数据。
Clob：是指大字符对象也就是英文Character Large Object的所写，用来存储大量文本数据。
一：操作CLOB
(1)数据库表结构如下：
create table CLOB_TEST(
ID VARCHAR2(5) not null,
CONTENT CLOB
)
(2)插入CLOB
方法一：第一步插入一个空值，第二步锁住此行，更新clob字段
public static void insertClob(Connection conn,String data) throws Exception{
//这句话如没有，9i的驱动下会报 java.sql.SQLException: ORA-01002: 读取违反顺序 的异常。
conn.setAutoCommit(false);
//插入一个空CLOB
String insertSql = "insert into clob_test(id,content) values(‘1‘,empty_clob())";
PreparedStatement stmt = conn.prepareStatement(insertSql);
stmt.executeUpdate();
stmt.close();
// 查询插入的空CLOB 并 lock this line
String selectSql = "select content from clob_test where id = ‘1‘ for update";
PreparedStatement pstmt = conn.prepareStatement(selectSql);
ResultSet rs = pstmt.executeQuery();
if(rs.next()){
oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob(1);
//为CLOB写信息
BufferedWriter out = new BufferedWriter(clob.getCharacterOutputStream());
BufferedReader in = new BufferedReader(new FileReader(data));
int c;
while ((c=in.read())!=-1) {
out.write(c);
}
in.close();
out.close();
}
conn.commit();
pstmt.close();
}
注：此方法在jdk1.4、jdk50、jdk6.0和Oracle9i、Oracle10g、Oracle11g驱动下测试通过！
方法二：通过setString方法
public static void insertClob(Connection conn,String data) throws Exception{
String insertSql = "insert into clob_test(id,content) values(‘1‘,?)";
PreparedStatement stmt = conn.prepareStatement(insertSql);
stmt.setString(1, data);
stmt.executeUpdate();
stmt.close();
conn.close();
}
注：由于在Oracle9i的驱动下，setString 有2000字符长度的限制，故这个方法只适合Oracle10g以上的驱动（Oracle11g驱动+JDK6.0也测试通过）。
方法三：通过setClob方法
public static void insertClob(Connection conn,String filePath) throws Exception{
String insertSql = "insert into clob_test(id,content) values(‘1‘,?)";
PreparedStatement stmt = conn.prepareStatement(insertSql);
stmt.setClob(1, new FileReader(filePath));
stmt.executeUpdate();
stmt.close();
conn.commit();
}
注：由于setClob(int parameterIndex, Reader reader)这个方法是JDBC4.0规范刚加的内容，是以流的方式为CLOB赋值的。并且Oracle9i驱动、Oracle10g驱动、JDK1.4、JDK1.5是基于JDBC3.0规范的，只有Oracle11g驱动+JDK6.0才是基于JDBC4.0规范的，所以目前这个方法只适合Oracle11g驱动（ojdbc6.jar）+JDK6.0！
(3)读取CLOB
方法一：
public static String readClob(Connection conn) throws Exception{
PreparedStatement stmt = conn.prepareStatement("select * from clob_test where id = ‘1‘");
ResultSet rs = stmt.executeQuery();
String str="";
StringBuffer sb = new StringBuffer("");
while(rs.next()){
Clob clob = rs.getClob("content");
Reader is = clob.getCharacterStream();
BufferedReader br = new BufferedReader(is);
str = br.readLine();
while (str != null){
sb.append(str);
str = br.readLine();
}
}
return sb.toString();
}
方法二：
public static String readClob(Connection conn) throws Exception{
PreparedStatement stmt = conn.prepareStatement("select * from clob_test where id = ‘1‘");
ResultSet rs = stmt.executeQuery();
String str="";
while(rs.next()){
str = rs.getString("content");
}
return str;
}
注：由于在Oracle9i的驱动下，rs.getString 返回为null，所以此方法只适合Oracle10g及其以上驱动。
二：操作BLOB
(1)数据库表结构如下：
create table BLOB_TEST(
ID VARCHAR2(5) not null,
CONTENT BLOB
)
(2)插入BLOB
方法一：第一步插入一个空值，第二步锁住此行，更新blob字段
public static void writeBlob(Connection con,String filePath) throws Exception{
FileInputStream fis = null;
PreparedStatement psm = null;
File file = new File(filePath);
psm = con.prepareStatement("insert into blob_test(id,content) values(‘2‘,empty_blob())");
psm.executeUpdate();
psm = con.prepareStatement("select content from blob_test where id =‘2‘ for update");
ResultSet rs = psm.executeQuery();
if(rs.next()){
oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob(1);
FileInputStream fin = new FileInputStream(file);
OutputStream out = blob.getBinaryOutputStream();
int count = -1, total = 0;
byte[] data = new byte[blob.getBufferSize()];
while ((count = fin.read(data)) != -1){
out.write(data, 0, count);
}
out.flush();
out.close();
}
}
方法二：通过setBinaryStream方法
public static void writeBlob(Connection con,String filePath) throws Exception{
FileInputStream fis = null;
PreparedStatement psm = null;
File file = new File(filePath);
try {
fis = new FileInputStream(file);
psm = con.prepareStatement("insert into blob_test(id,content) values(‘2‘,?)");
psm.setBinaryStream(1, fis, fis.available());
psm.executeUpdate();
}finally{
if(fis != null) fis.close();
psm.close();
con.close();
}
}
方法三：通过setBlob(int parameterIndex, InputStream inputStream)方法
public static void writeBlob(Connection con,String filePath) throws Exception{
FileInputStream fis = null;
PreparedStatement psm = null;
File file = new File(filePath);
try {
fis = new FileInputStream(file);
psm = con.prepareStatement("insert into blob_test(id,content) values(‘2‘,?)");
psm.setBlob(1, fis);
psm.executeUpdate();
}finally{
if(fis != null)
fis.close();
psm.close();
con.close();
}
}
注：由于setBlob(int parameterIndex, InputStream inputStream)这个方法是JDBC4.0规范刚加的内容，是以流的方式为BLOB赋值的。并且Oracle9i驱动、Oracle10g驱动、JDK1.4、JDK1.5是基于JDBC3.0规范的，只有Oracle11g驱动+JDK6.0才是基于JDBC4.0规范的，所以目前这个方法只适合Oracle11g驱动（ojdbc6.jar）+JDK6.0！
(3)读取BLOB
public static void readBlob(Connection con,String outFilePath){
Statement sm = null;
ResultSet rs = null;
try {
sm = con.createStatement();
rs = sm.executeQuery("select * from blob_test where id = 2");
if(rs.next()){
Blob blob = rs.getBlob("content");
File file = new File(outFilePath);
FileOutputStream sout = new FileOutputStream(file);
InputStream in = blob.getBinaryStream();//获取BLOB数据的输入数据流
//经BLOB输入数据流读取数据，并将其写入文件
byte[] b = new byte[256];
int off = 0;
int len = b.length;
for (int i = in.read(b); i != -1;) {
sout.write(b);
i = in.read(b);
}
sout.close();
rs.close();
sm.close();
con.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
版权声明：本文为博主原创文章，未经博主允许不得转载。
JDBC操作LOB
标签：oracle jdbc lob clob blob
