java 大字符串转为二进制流存入CLOB字段 JDBC方法

Posted 2023-05-04

String s = "大字符串";
byte[] bt = new byte[s.length()];
bt = dbField.getFieldValue().toString().getBytes();
ByteArrayInputStream iis = new ByteArrayInputStream(bt);
pstmt.setBinaryStream(i + 1, iis,bt.length);
这个方法看似正确啊，为什么不行啊。oracle报错，说不能更新这个字段值为NULL，意思就是转二进制没转明白，sql不好使。大侠们谁遇到过这个问题，帮帮我
提问时候写错了，程序中是s.getBytes().length，可是不行

我以前写程序发现：
oracle的数据库BLOB不能用来存储字符，改用NCLOB就OK了。

BLOB：用来存储无结构的二进制数据
CLOB：存储单字节字符数据。（别用来存中文喔。。。）
NCLOB：用来存储定宽多字节字符数据。 参考技术A 使用java.sql.Clob类型 参考技术B dbField.getFieldValue().toString().getBytes();
上面这个值有吗？取到了吗？
下面是我以前一个项目的

InputStream pic = new FileInputStream(dto.get(i).getLibPic());

sql = "INSERT INTO piclib (name,pic,sign,remark) VALUES (?,?,?,?)";

pstmt = con.prepareStatement(sql);
pstmt.setString(1, dto.get(i).getName());
pstmt.setBinaryStream(2,pic,(int)dto.get(i).getLibPic().length());本回答被提问者和网友采纳

如何将二进制文件存入Oracle数据库中

参考技术A 先把文件读取到内存，再以二进制格式保持到数据库中的大字段中（clob或clob）。
写大对象。

Java code

public static void main(String[] args)
// TODO Auto-generated method stub
Connection conn = null;
Statement stat = null;
ResultSet rs = null;
OutputStream os = null;
FileInputStream fis = null;
int bs = 0;
try
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:oraDB","bigfou","---");
conn.setAutoCommit(false);
stat = conn.createStatement();
stat.executeUpdate("insert into t_video(id,video) values(1,empty_blob())");

rs = stat.executeQuery("select video from t_video where id = 1");
rs.next();
oracle.sql.BLOB blo = (oracle.sql.BLOB)rs.getBlob(1);
os = blo.getBinaryOutputStream();
bs = blo.getBufferSize();
fis = new FileInputStream("D:\\Temp\\MPlayer-CVS-20040808-K&K\\mplayer.exe");
byte[] buf = new byte[bs];
int length = 0;

while(true)

length = fis.read(buf);
if(length == -1) break;
os.write(buf,0,length);


os.close();
os = null;
fis.close();
fis = null;
conn.commit();
conn.setAutoCommit(true);
conn.close();
catch(Exception ex)
ex.printStackTrace();



读大对象

Java code

InputStream is = null;
FileOutputStream fos = null;
byte[] buf = null;
int bs = 0;

try
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:oraDB","bigfou","-");
conn.setAutoCommit(false);
stat = conn.createStatement();

rs = stat.executeQuery("select video from t_video where id = 1");
rs.next();
oracle.sql.BLOB blo = (oracle.sql.BLOB)rs.getBlob(1);
bs = blo.getBufferSize();
buf = new byte[bs];
int length = 0;
is = blo.getBinaryStream();
fos = new FileOutputStream("d:\\test.exe");

while(true)
length = is.read(buf);
if(length == -1) break;
fos.write(buf,0,length);


fos.close();
fos = null;
is.close();
is = null;
conn.commit();
conn.setAutoCommit(true);
conn.close();
...