Oracle中三种上载文件技术(三)

王朝oracle·作者佚名  2008-05-19
窄屏简体版  字體: |||超大  

第三种方式: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>

 
 
 
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