java常用方法

1.读取oracle blob类型

private byte[] readBlob(Object obj) {
byte[] data = null;
InputStream inStream = null;
java.sql.Blob blob = (Blob) obj;
try {
inStream = blob.getBinaryStream();
long nLen = blob.length();
int nSize = (int) nLen;
// System.out.println("img data size is :" + nSize);
data = new byte[nSize];
inStream.read(data);
return data ;
} catch (Exception e) {
System.out.println(e.getMessage());
return null;
} finally {
try {
if (inStream != null) {
inStream.close();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

2.写oracle blob列

public void updateBlobFile(String id, byte[] data) throws IOException,
SQLException {
Connection conn = null;
PreparedStatement preparedStatement1 = null;
PreparedStatement preparedStatement2 = null;
ResultSet rs = null;
oracle.sql.BLOB blob = null;
OutputStream outStream=null;
try {
conn = db.getConnection();
conn.setAutoCommit(false);

String updateEmptySql = "update table1 t set t.attachFile=empty_blob() where t.id=?";
preparedStatement1 = conn.prepareStatement(updateEmptySql);
preparedStatement1.setString(1, id);
preparedStatement1.executeUpdate();
// 获取空BLOB字段，并获取更新锁
String getEmpty = "select t.attachFile from table1 t where t.id= ? for update ";
preparedStatement2 = conn.prepareStatement(getEmpty);
preparedStatement2.setString(1, id);
rs = preparedStatement2.executeQuery();
if (rs.next()) {
blob = (oracle.sql.BLOB) rs.getBlob(1);
}
outStream = blob.getBinaryOutputStream();
outStream.write(data, 0, data.length);
outStream.flush();
conn.commit();
} catch (SQLException e) {
conn.rollback();
throw e;
} finally {
if (outStream != null) {
outStream.close();
}
if (preparedStatement1 != null) {
preparedStatement1.close();
}
if (preparedStatement2 != null) {
preparedStatement2.close();
}
if (conn != null) {
conn.close();
}
}
}

3.读oracle clob 类型

private String readClob(Object obj) {
Reader inStream = null;
try {
java.sql.Clob clob = (java.sql.Clob) obj;
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
String data = new String(c);
return data;
} catch (Exception e) {
System.out.println("获取Clob数据失败,原因:" + e.getMessage());
return "";
} finally {
try {
if (inStream != null) {
inStream.close();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

4.写oracle clob 类型

public void updateClob(String id, String data) throws IOException,
SQLException {
Connection conn = null;
PreparedStatement preparedStatement1 = null;
PreparedStatement preparedStatement2 = null;
ResultSet rs = null;
oracle.sql.CLOB clob = null;
OutputStream outStream=null;
try {
conn = db.getConnection();
conn.setAutoCommit(false);

String updateEmptySql = "update table1 t set t.content_clob=empty_clob() where t.id=?";
preparedStatement1 = conn.prepareStatement(updateEmptySql);
preparedStatement1.setString(1, id);
preparedStatement1.executeUpdate();
// 获取空BLOB字段，并获取更新锁
String getEmpty = "select t.content_clob from table1 t where t.id= ? for update ";
preparedStatement2 = conn.prepareStatement(getEmpty);
preparedStatement2.setString(1, id);
rs = preparedStatement2.executeQuery();
if (rs.next()) {
clob = (oracle.sql.CLOB) rs.getBlob(1);

Writer outStream = clob.getCharacterOutputStream();
char[] c = data.toCharArray();
outStream.write(c, 0, c.length);
}
outStream.flush();
conn.commit();
} catch (SQLException e) {
conn.rollback();
throw e;
} finally {
if (outStream != null) {
outStream.close();
}
if (preparedStatement1 != null) {
preparedStatement1.close();
}
if (preparedStatement2 != null) {
preparedStatement2.close();
}
if (conn != null) {
conn.close();
}
}
}