(1)不通数据库中对应clob,blob的类型如下：
二、jdbc操作clob(以oracle为例)
首先操作clob/blob不像操作varchar类型那样简单，插入步骤一般分为两步：第一步插入一个空值，第二步锁住此行，更新clob/blob字段。
//插入空值
conn.setAutoCommit(false);
String sql = "INSERT INTO T_FILE(NAME, FILE_CONTENT) VALUES ('Jambhala', EMPTY_CLOB())";
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.executeUpdate();
//锁住此行
String sql_lockstr = "SELECT FILE_CONTENT FROM T_FILE WHERE NAME='Jambhala' FOR UPDATE";
pstmt = conn.prepareStatement(sql_lockstr);
ResultSet rs = pstmt.executeQuery();
oracle.sql.Clob clob = (oracle.sql.Clob)rs.getClob(1);
java.io.OutputStream writer = clob.getAsciiOutputStream();
byte[] temp = newFileContent.getBytes();
writer.write(temp);
writer.flush();
writer.close();
pstmt.close();
读取内容：
oracle.sql.Clob clob = rs.getClob("FILE_CONTENT");
if(clob != null){
Reader is = clob.getCharacterStream();
BufferedReader br = new BufferedReader(is);
String s = br.readLine();
while(s != null){
content += s+"<br>";
s = br.readLine();
}
}
三、jdbc操作blob
conn.setAutoCommit(false);
String sql = "INSERT INTO T_PHOTO(NAME, PHOTO) VALUES ('Jambhala', EMPTY_BLOB())";
pstmt = conn.prepareStatement(sql);
pstmt = conn.executeUpdate();
sql = "SELECT PHOTO FROM T_PHOTO WHERE NAME='Jambhala'";
pstmt = conn.prepareStatement(sql);
rs = pstmt.executeQuery(sql);
if(rs.next()){
oracle.sql.Blob blob = (oracle.sql.Blob)rs.getBlob(1);
}
//write to a file
File file=new File("C:\\test.rar");
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){
total += count;
out.write(data, 0, count);
}
四、hibernate处理clob
MyFile file = new MyFile();
file.setName("Jambhala");
file.setContent(Hibernate.createClob(""));
session.save(file);
session.flush();
session.refresh(file, LockMode.UPGRADE);
oracle.sql.Clob clob = (oracle.sql.Clob)file.getContent();
Writer pw = clob.getCharacterOutputStream();
pw.write(longText); //写入长文本
pw.close();
session.close();五、使用hibernate处理blob
原理基本相同：
Photo photo = new Photo();
photo.setName("Jambhala");
photo.setPhoto(Hibernate.createBlob(""));
session.save(photo);
session.flush();
session.refresh(photo, LockMode.UPGRADE); //锁住此对象
oracle.sql.Blob blob = photo.getPhoto(); //取得此blob的指针
OutputStream out = blob.getBinaryOutputStream();
//写入一个文件
File f = new File("C:\\test.rar");
FileInputStream fin = new FileInputStream(f);
int count=-1,total=0;
byte[] data = new byte[(int)fin.available()];
out.write(data);
fin.close();
out.close();
session.flush();
String DRIVER = "oracle.jdbc.driver.OracleDriver";
//Oracle连接用URL
private static final String URL = "jdbc:oracle:thin:@testora:1521:orac";
//用户名
private static final String USER = "scott";
//密码
private static final String PASSWORD = "pswd";
//数据库连接
private static Connection conn = null;
//SQL语句对象
private static Statement stmt = null;
//@roseuid 3EDA089E02BC
public LobPros(){}
//往数据库中插入一个新的Clob对象
//@param infile 数据文件
//@throws java.lang.Exception
//@roseuid 3EDA089E02BC
public static void clobInsert(String infile) throws Exception {
//设定不自动提交
boolean defaultCommit = conn.getAutoCommit();
conn.setAutoCommit(false);
try{
//插入一个空的Clob对象
stmt.executeUpdate("INSERT INTO TEST_CLOB VALUES ('111', EMPTY_CLOB())");
//查询此Clob对象并锁定
ResultSet rs = stmt.executeQuery("SELECT CLOBCOL FROM TEST_CLOB WHERE ID='111' FOR UPDATE");
while(rs.next()){
//取出此Clob对象
oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");
//向Clob对象中写入数据
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 e){
//出错回滚
conn.rollback();
throw e;
}
//恢复原提交状态
conn.setAutoCommit(defaultCommit);
}
//修改Clob对象(是在原Clob对象基础上进行覆盖式的修改)
//@param infile 数据文件
//@throws java.lang.Exception
//@roseuid 3EDA089E02BC
public static void clobModify(String infile) throws Exception {
//设定不自动提交
boolean defaultCommit = conn.getAutoCommit();
conn.setAutoCommit(false);
try{
//查询Clob对象并锁定
ResultSet rs = stmt.executeQuery("SELECT CLOBCOL FROM TEST_CLOB WHERE ID='111' FOR UPDATE");
while(rs.next()){
//获取此Clob对象
oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");
//进行覆盖式修改
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 e){
//出错回滚
conn.rollback();
throw e;
}
//恢复原提交状态
conn.setAutoCommit(defaultCommit);
}
//替换CLOB对象（将原CLOB对象清除，换成一个全新的CLOB对象
//@param infile 数据文件
//@throws java.lang.Exception
//@roseuid 3EDA04BF01E1
public static void clobReplace(String infile) throws Exception {
//设定不自动提交
boolean defaultCommit = conn.getAutoCommit();
conn.setAutoCommit(false);
try{
//清空原CLOB对象
stmt.executeUpdate("UPDATE TEST_CLOB SET CLOBCOL=EMPTY_CLOB() WHERE ID='111'");
//查询CLOB对象并锁定
ResultSet rs = stmt.executeQuery("SELECT CLOBCOL FROM TEST_CLOB WHERE ID='111' FOR UPDATE");
while (rs.next()) {
//获取此CLOB对象
oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");
//更新数据
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 e){
//出错回滚
conn.rollback();
throw e;
}
//恢复原提交状态
conn.setAutoCommit(defaultCommit);
}
//CLOB对象读取
//@param outfile 输出文件名
//@throws java.lang.Exception
//@roseuid 3EDA04D80116
public static void clobRead(String outfile) throws Exception {
//设定不自动提交
boolean defaultCommit = conn.getAutoCommit();
conn.setAutoCommit(false);
try{
//查询CLOB对象
ResultSet rs = stmt.executeQuery("SELECT * FROM TEST_CLOB WHERE ID='111'");
while (rs.next()) {
//获取CLOB对象
oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");
//以字符形式输出
BufferedReader in = new BufferedReader(clob.getCharacterStream());
BufferedWriter out = new BufferedWriter(new FileWriter(outfile));
int c;
while ((c=in.read())!=-1) {
out.write(c);
}
out.close();
in.close();
}
}catch(Exception e){
conn.rollback();
throw e;
}
//恢复原提交状态
conn.setAutoCommit(defaultCommit);
}
//向数据库中插入一个新的BLOB对象
//@param infile 数据文件
//@throws java.lang.Exception
//@roseuid 3EDA04E300F6
public static void blobInsert(String infile) throws Exception {
//设定不自动提交
boolean defaultCommit = conn.getAutoCommit();
conn.setAutoCommit(false);
try {
//插入一个空的BLOB对象
stmt.executeUpdate("INSERT INTO TEST_BLOB VALUES ('222', EMPTY_BLOB())");
//查询此BLOB对象并锁定
ResultSet rs = stmt.executeQuery("SELECT BLOBCOL FROM TEST_BLOB WHERE ID='222' FOR UPDATE");
while (rs.next()) {
//取出此BLOB对象
oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob("BLOBCOL");
//向BLOB对象中写入数据
BufferedOutputStream out = new BufferedOutputStream(blob.getBinaryOutputStream());
BufferedInputStream in = new BufferedInputStream(new FileInputStream(infile));
int c;
while ((c=in.read())!=-1) {
out.write(c);
}
in.close();
out.close();
}
//正式提交
conn.commit();
} catch (Exception e) {
//出错回滚
conn.rollback();
throw e;
}
//恢复原提交状态
conn.setAutoCommit(defaultCommit);
}
//修改BLOB对象（是在原BLOB对象基础上进行覆盖式的修改）
//@param infile 数据文件
//@throws java.lang.Exception
//@roseuid 3EDA04E90106
public static void blobModify(String infile) throws Exception {
//设定不自动提交
boolean defaultCommit = conn.getAutoCommit();
conn.setAutoCommit(false);
try {
//查询BLOB对象并锁定
ResultSet rs = stmt.executeQuery("SELECT BLOBCOL FROM TEST_BLOB WHERE ID='222' FOR UPDATE");
while (rs.next()) {
//取出此BLOB对象
oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob("BLOBCOL");
//向BLOB对象中写入数据
BufferedOutputStream out = new BufferedOutputStream(blob.getBinaryOutputStream());
BufferedInputStream in = new BufferedInputStream(new FileInputStream(infile));
int c;
while ((c=in.read())!=-1) {
out.write(c);
}
in.close();
out.close();
}
//正式提交
conn.commit();
} catch (Exception e) {
//出错回滚
conn.rollback();
throw e;
}
//恢复原提交状态
conn.setAutoCommit(defaultCommit);
}
//替换BLOB对象（将原BLOB对象清除，换成一个全新的BLOB对象）
//@param infile 数据文件
//@throws java.lang.Exception
//@roseuid 3EDA0505000C
public static void blobReplace(String infile) throws Exception {
//设定不自动提交
boolean defaultCommit = conn.getAutoCommit();
conn.setAutoCommit(false);
try {
//清空原BLOB对象
stmt.executeUpdate("UPDATE TEST_BLOB SET BLOBCOL=EMPTY_BLOB() WHERE ID='222'");
//查询此BLOB对象并锁定
ResultSet rs = stmt.executeQuery("SELECT BLOBCOL FROM TEST_BLOB WHERE ID='222' FOR UPDATE");
while (rs.next()) {
//取出此BLOB对象
oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob("BLOBCOL");
//向BLOB对象中写入数据
BufferedOutputStream out = new BufferedOutputStream(blob.getBinaryOutputStream());
BufferedInputStream in = new BufferedInputStream(new FileInputStream(infile));
int c;
while ((c=in.read())!=-1) {
out.write(c);
}
in.close();
out.close();
}
//正式提交
conn.commit();
} catch (Exception e) {
//出错回滚
conn.rollback();
throw e;
}
//恢复原提交状态
conn.setAutoCommit(defaultCommit);
}
//BLOB对象读取
//@param outfile 输出文件名
//@throws java.lang.Exception
//@roseuid 3EDA050B003B
public static void blobRead(String outfile) throws Exception {
//设定不自动提交
boolean defaultCommit = conn.getAutoCommit();
conn.setAutoCommit(false);
try {
//查询BLOB对象
ResultSet rs = stmt.executeQuery("SELECT BLOBCOL FROM TEST_BLOB WHERE ID='222'");
while (rs.next()) {
//取出此BLOB对象
oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob("BLOBCOL");
//以二进制形式输出
BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outfile));
BufferedInputStream in = new BufferedInputStream(blob.getBinaryStream());
int c;
while ((c=in.read())!=-1) {
out.write(c);
}
in.close();
out.close();
}
//正式提交
conn.commit();
} catch (Exception e) {
//出错回滚
conn.rollback();
throw e;
}
//恢复原提交状态
conn.setAutoCommit(defaultCommit);
}
//建立测试用表格
//@throws Exception
public static void createTables() throws Exception {
try {
stmt.executeUpdate("CREATE TABLE TEST_CLOB (ID NUMBER(3), CLOBCOL CLOB)");
stmt.executeUpdate("CREATE TABLE TEST_BLOB (ID NUMBER(3), BLOBCOL BLOB)");
} catch (Exception e) { }
}
//@param args - 命令行参数
//@throws java.lang.Exception
//@roseuid 3EDA052002AC
public static void main(String[] args) throws Exception {
//装载驱动,建立数据库连接
Class.forName(DRIVER);
conn = DriverManager.getConnection(URL,USER,PASSWORD);
stmt = conn.createStatement();
//建立测试表格
createTables();
//CLOB对象插入测试
clobInsert("c:/clobInsert.txt");
clobRead("c:/clobInsert.out");
//CLOB对象修改测试
clobModify("c:/clobModify.txt");
clobRead("c:/clobModify.out");
//CLOB对象替换测试
clobReplace("c:/clobReplace.txt");
clobRead("c:/clobReplace.out");
//BLOB对象插入测试
blobInsert("c:/blobInsert.doc");
blobRead("c:/blobInsert.out");
//BLOB对象修改测试
blobModify("c:/blobModify.doc");
blobRead("c:/blobModify.out");
//BLOB对象替换测试
blobReplace("c:/blobReplace.doc");
blobRead("c:/bolbReplace.out");
//关闭资源退出
conn.close();
System.exit(0);
}