Oracle中三种上载文件技术

核心提示： 三、通过JDBC实现文件上载和下载通过把文件上载到BLOB或CLOB列实现文件上载，但此法不支持客户端文件上载，Oracle中三种上载文件技术(6)，所以局限性很大，通过JDBC实现的下载功能也只是在服务器的本地下载（下载程序没有列出），所以这种方法仅作为一项技术参考可以，没有太大实用价值

三、通过JDBC实现文件上载和下载

通过把文件上载到BLOB或CLOB列实现文件上载，但此法不支持客户端文件上载，所以局限性很大，通过JDBC实现的下载功能也只是在服务器的本地下载（下载程序没有列出），所以这种方法仅作为一项技术参考可以，没有太大实用价值。

Blob_in_stream.jsp程序如下：

＜%@ page session="true" language="java" %＞
＜html＞
＜head＞
＜meta http-equiv="Content-Type" content="text/HTML;charset=gb2312"＞
＜title＞jdbc upload and download blob＜/title＞
＜/head＞
＜body＞
＜FORM action="blob_w_stream.jsp" method="POST"＞
＜p＞文件 File to upload:＜INPUT type="file" name="up_file"＞＜br＞
＜p＞＜INPUT type="submit"＞
＜/FORM＞
＜/body＞
＜/html＞

Blob_w_stream.jsp程序如下：

＜%@ page session="true" language="java" contentType="text/html; charset=gb2312"%＞
＜%@ page import="java.sql.*"%＞
＜%@ page import="java.io.*"%＞
＜%@ page import="oracle.jdbc.driver.*" %＞
＜%@ page import="oracle.sql.*" %＞
＜html＞
＜head＞
＜meta http-equiv="Content-Type" content="text/HTML;charset=gb2312"＞
＜title＞jdbc upload and download blob＜/title＞
＜/head＞
＜body＞
＜%
String uploadfile=request.getParameter("up_file");
//Input form don't have ENCTYPE="multipart/form-data" clause,else input
//file name will NULL!Get file name from input form.
File binaryFile = new File(uploadfile);
Reader char_stream = clobtext.getCharacterStream();
char [] char_array = new char [length];
int chars_read = char_stream.read (char_array, 0, length);
out.println(char_array);
out.println();
out.write();
Inputstream asciiChar_stream = clobtext.getAsciiStream();
byte[] asciiChar_array = new byte[length];
int asciiChar_read = asciiChar_stream.read(asciiChar_array,0,length);
//Or File binaryFile = new File("c:\\cf\\a.doc"); point to c:\cf\a.doc.
FileInputStream instream = new FileInputStream(binaryFile);
%＞
＜p＞file name is :＜%=uploadfile%＞
＜%
Class.forName("oracle.jdbc.OracleDriver").newInstance();
String connStr="jdbc:oracle:thin:@db92:1521:cf92";
String user="zy";
String password="zy";
Connection conn = DriverManager.getConnection(connStr,user,password);
conn.setAutoCommit(false);
Statement stmt=conn.createStatement();
stmt.execute("UPDATE ZY.BLOB_TABLE SET DATA = EMPTY_BLOB() WHERE FILENAME='Concepts.pdf'");
conn.commit();
//must null the blob data column,else if size of inserting file less than
//existing blob file,then new insert file format error occur!New blob file don't
//overwrite old blob column data!
String cmd = "SELECT DATA FROM ZY.BLOB_TABLE WHERE FILENAME='Concepts.pdf' for update";
ResultSet rset = stmt.executeQuery(cmd);
BLOB blob;
rset.next();//must.else occur error "don't call ResultSet.next()"
blob = ((OracleResultSet)rset).getBLOB(1);
//must explicit!dont locate in logical block.for example,locate in IF...ITEN.
OutputStream outstream = blob.getBinaryOutputStream();
int size = blob.getBufferSize();
%＞
＜p＞buffer size is :＜%=size%＞
＜%
byte[] buffer = new byte[102400];
//Or direct 102400 instead of variable size!
//Performance tips!size=24396.
int length = -1;
while ((length = instream.read(buffer)) != -1)
outstream.write(buffer, 0, length);
instream.close();
outstream.close();
conn.commit();//must explicit commit!If BFILE,then auto commit.
conn.close();
%＞
＜p＞Upload file is down!
＜/body＞
＜/html＞