| Log for SQL (PL/SQL 개발환경에서 로그 정보 확인하기) (0) | 2011.03.15 |
|---|---|
| CLOB 파일 다루기 예제 (0) | 2011.01.11 |
| Heap Dump 분석을 통한 Perm Area Memory Leak 원인 진단 (0) | 2010.12.14 |
| Java ARchives (JAR) (0) | 2010.11.17 |
| Multifile storage with Zip (ZIP으로 여러 파일 저장하기) (0) | 2010.11.17 |
| CLOB 파일 다루기 예제 (0) | 2011.01.11 |
|---|---|
| FILE을 CLOB에 INSERT하고, 반대로 컬럼을 읽어 FILE로 WRITE하는 JDBC PROGRAM 예제 (JDBC 8.1 이상 (0) | 2011.01.07 |
| Java ARchives (JAR) (0) | 2010.11.17 |
| Multifile storage with Zip (ZIP으로 여러 파일 저장하기) (0) | 2010.11.17 |
| 자바 간단한 GZIP 압축 예제 (0) | 2010.11.17 |
The Zip format is also used in the JAR (Java ARchive) file format, which is a way to collect a group of files into a single compressed file, just like Zip. However, like everything else in Java, JAR files are cross-platform, so you don’t need to worry about
JAR files are particularly helpful when you deal with the Internet. Before JAR files, your Web browser would have to make repeated requests of a Web server in order to download all of the files that make up an applet. In addition, each of these files was uncompressed. By combining all of the files for a particular applet into a single JAR file, only one server request is necessary and the transfer is faster because of compression. And each entry in a JAR file can be digitally signed for security (see Chapter 14 for an example of signing).
A JAR file consists of a single file containing a collection of zipped files along with a “manifest” that describes them. (You can create your own manifest file; otherwise, the jar program will do it for you.) You can find out more about JAR manifests in the
The jar utility that comes with Sun’s JDK automatically compresses the files of your choice. You invoke it on the command line:
jar [options] destination [manifest] inputfile(s)
The options are simply a collection of letters (no hyphen or any other indicator is necessary). Unix/Linux users will note the similarity to the tar options. These are:
|
c |
Creates a new or empty archive. |
|
t |
Lists the table of contents. |
|
x |
Extracts all files. |
|
x file |
Extracts the named file. |
|
f |
Says: “I’m going to give you the name of the file.” If you don’t use this, jar assumes that its input will come from standard input, or, if it is creating a file, its output will go to standard output. |
|
m |
Says that the first argument will be the name of the user-created manifest file. |
|
v |
Generates verbose output describing what jar is doing. |
|
0 |
Only store the files; doesn’t compress the files (use to create a JAR file that you can put in your classpath). |
|
M |
Don’t automatically create a manifest file. |
If a subdirectory is included in the files to be put into the JAR file, that subdirectory is automatically added, including all of its subdirectories, etc. Path information is also preserved.
Here are some typical ways to invoke jar:
jar cf myJarFile.jar *.class
This creates a JAR file called myJarFile.jar that contains all of the class files in the current directory, along with an automatically generated manifest file.
jar cmf myJarFile.jar myManifestFile.mf *.class
Like the previous example, but adding a user-created manifest file called myManifestFile.mf.
jar tf myJarFile.jar
Produces a table of contents of the files in myJarFile.jar.
jar tvf myJarFile.jar
Adds the “verbose” flag to give more detailed information about the files in myJarFile.jar.
jar cvf myApp.jar audio classes image
Assuming audio, classes, and image are subdirectories, this combines all of the subdirectories into the file myApp.jar. The “verbose” flag is also included to give extra feedback while the jar program is working.
If you create a JAR file using the 0 (zero) option, that file can be placed in your CLASSPATH:
CLASSPATH="lib1.jar;lib2.jar;"
Then Java can search lib1.jar and lib2.jar for class files.
The jar tool isn’t as useful as a zip utility. For example, you can’t add or update files to an existing JAR file; you can create JAR files only from scratch. Also, you can’t move files into a JAR file, erasing them as they are moved. However, a JAR file created on one platform will be transparently readable by the jar tool on any other platform (a problem that sometimes plagues zip utilities).
As you will see in Chapter 14, JAR files are also used to
출처 : http://www.linuxtopia.org/online_books/programming_books/thinking_in_java/TIJ314_034.htm
| FILE을 CLOB에 INSERT하고, 반대로 컬럼을 읽어 FILE로 WRITE하는 JDBC PROGRAM 예제 (JDBC 8.1 이상 (0) | 2011.01.07 |
|---|---|
| Heap Dump 분석을 통한 Perm Area Memory Leak 원인 진단 (0) | 2010.12.14 |
| Multifile storage with Zip (ZIP으로 여러 파일 저장하기) (0) | 2010.11.17 |
| 자바 간단한 GZIP 압축 예제 (0) | 2010.11.17 |
| 자바 파일 압축 (0) | 2010.11.17 |
The library that supports the Zip format is much more extensive. With it you can easily store multiple files, and there’s even a separate class to make the process of reading a
//: c12:ZipCompress.java // Uses Zipcompression tocompress any // number of files given on the command line. // {Args: ZipCompress.java} // {Clean: test.zip} import com.bruceeckel.simpletest.*; import java.io.*; import java.util.*; import java.util.zip.*; public class ZipCompress { private static Test monitor = new Test(); // Throw exceptions to console: public static void main(String[] args) throws IOException { FileOutputStream f = new FileOutputStream("test.zip"); CheckedOutputStream csum = new CheckedOutputStream(f, new Adler32()); ZipOutputStream zos = new ZipOutputStream(csum); BufferedOutputStream out = new BufferedOutputStream(zos); zos.setComment("A test of Java Zipping"); // No corresponding getComment(), though. for(int i = 0; i < args.length; i++) { System.out.println("Writing file " + args[i]); BufferedReader in = new BufferedReader(new FileReader(args[i])); zos.putNextEntry(new ZipEntry(args[i])); int c; while((c = in.read()) != -1) out.write(c); in.close(); } out.close(); // Checksum valid only after the file has been closed! System.out.println("Checksum: " + csum.getChecksum().getValue()); // Now extract the files: System.out.println("Reading file"); FileInputStream fi = new FileInputStream("test.zip"); CheckedInputStream csumi = new CheckedInputStream(fi, new Adler32()); ZipInputStream in2 = new ZipInputStream(csumi); BufferedInputStream bis = new BufferedInputStream(in2); ZipEntry ze; while((ze = in2.getNextEntry()) != null) { System.out.println("Reading file " + ze); int x; while((x = bis.read()) != -1) System.out.write(x); } if(args.length == 1) monitor.expect(new String[] { "Writing file " + args[0], "%% Checksum: \\d+", "Reading file", "Reading file " + args[0]}, args[0]); System.out.println("Checksum: " + csumi.getChecksum().getValue()); bis.close(); // Alternative way to open and readzip files : ZipFile zf = new ZipFile("test.zip"); Enumeration e = zf.entries(); while(e.hasMoreElements()) { ZipEntry ze2 = (ZipEntry)e.nextElement(); System.out.println("File: " + ze2); // ... and extract the data as before } if(args.length == 1) monitor.expect(new String[] { "%% Checksum: \\d+", "File: " + args[0] }); } } ///:~
For each file to add to the archive, you must call putNextEntry( ) and pass it a ZipEntry object. The ZipEntry object contains an extensive interface that allows you to get and set all the data available on that particular entry in your Zip file: name,
To extract files, ZipInputStream has a getNextEntry( ) method that returns the next ZipEntry if there is one. As a more succinct alternative, you can read the file using a ZipFile object, which has a method entries( ) to return an Enumeration to the ZipEntries.
In order to read the checksum, you must somehow have access to the associated Checksum object. Here, a reference to the CheckedOutputStream and CheckedInputStream objects is retained, but you could also just hold onto a reference to the Checksum object.
A baffling method in Zip streams is setComment( ). As shown in ZipCompress.java, you can set a comment when you’re writing a file, but there’s no way to recover the comment in the ZipInputStream. Comments appear to be supported fully on an entry-by-entry basis only via ZipEntry.
Of course, you are not limited to files when using the GZIP or Zip libraries—you can compress anything, including data to be sent through a network connection.
출처 : http://www.linuxtopia.org/online_books/programming_books/thinking_in_java/TIJ314_033.htm
| Heap Dump 분석을 통한 Perm Area Memory Leak 원인 진단 (0) | 2010.12.14 |
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| Java ARchives (JAR) (0) | 2010.11.17 |
| 자바 간단한 GZIP 압축 예제 (0) | 2010.11.17 |
| 자바 파일 압축 (0) | 2010.11.17 |
| JAVA File Locking(자바 파일 잠금) (0) | 2010.11.17 |
The GZIP interface is simple and thus is probably more appropriate when you have a single stream of data that you want to compress (rather than a container of dissimilar pieces of data). Here’s an example that compresses a single file:
setup.exe
ha36.jar//: c12:GZIPcompress.java
// {Args: GZIPcompress.java}
// {Clean: test.gz}
import com.bruceeckel.simpletest.*;
import java.io.*;
import java.util.zip.*;
public class GZIPcompress {
private static Test monitor = new Test();
// Throw exceptions to console:
public static void main(String[] args)
throws IOException {
if(args.length == 0) {
System.out.println(
"Usage: \nGZIPcompress file\n" +
"\tUses GZIP compression to compress " +
"the file to test.gz");
System.exit(1);
}
BufferedReader in = new BufferedReader(
new FileReader(args[0]));
BufferedOutputStream out = new BufferedOutputStream(
new GZIPOutputStream(
new FileOutputStream("test.gz")));
System.out.println("Writing file");
int c;
while((c = in.read()) != -1)
out.write(c);
in.close();
out.close();
System.out.println("Reading file");
BufferedReader in2 = new BufferedReader(
new InputStreamReader(new GZIPInputStream(
new FileInputStream("test.gz"))));
String s;
while((s = in2.readLine()) != null)
System.out.println(s);
monitor.expect(new String[] {
"Writing file",
"Reading file"
}, args[0]);
}
} ///:~
The use of the compression classes is straightforward; you simply wrap your output stream in a GZIPOutputStream or ZipOutputStream, and your input stream in a GZIPInputStream or ZipInputStream. All else is ordinary I/O reading and writing. This is an example of mixing the char-oriented streams with the byte-oriented streams; in uses the Reader classes, whereas GZIPOutputStream’s constructor can accept only an OutputStream object, not a Writer object. When the file is opened, the GZIPInputStream is converted to a Reader.
출처 : http://www.linuxtopia.org/
| Java ARchives (JAR) (0) | 2010.11.17 |
|---|---|
| Multifile storage with Zip (ZIP으로 여러 파일 저장하기) (0) | 2010.11.17 |
| 자바 파일 압축 (0) | 2010.11.17 |
| JAVA File Locking(자바 파일 잠금) (0) | 2010.11.17 |
| 자바 메모리를 사용한 큰 파일 조작하기 (0) | 2010.11.17 |
The Java I/O library contains classes to support reading and writing streams in a
These classes are not derived from the Reader and Writer classes, but instead are part of the InputStream and OutputStream hierarchies. This is because the compression library works with bytes, not characters. However, you might sometimes be forced to mix the two types of streams. (Remember that you can use InputStreamReader and OutputStreamWriter to provide easy conversion between one type and another.)
|
Function | |
|---|---|
|
CheckedInputStream |
GetCheckSum( ) produces checksum for any InputStream (not just decompression). |
|
CheckedOutputStream |
GetCheckSum( ) produces checksum for any OutputStream (not just compression). |
|
DeflaterOutputStream |
Base class for compression classes. |
|
ZipOutputStream |
A DeflaterOutputStream that |
|
GZIPOutputStream |
A DeflaterOutputStream that compresses data into the GZIP file format. |
|
InflaterInputStream |
Base class for decompression classes. |
|
ZipInputStream |
An InflaterInputStream that decompresses data that has been stored in the Zip file format. |
|
GZIPInputStream |
An InflaterInputStream that decompresses data that has been stored in the GZIP file format. |
| Multifile storage with Zip (ZIP으로 여러 파일 저장하기) (0) | 2010.11.17 |
|---|---|
| 자바 간단한 GZIP 압축 예제 (0) | 2010.11.17 |
| JAVA File Locking(자바 파일 잠금) (0) | 2010.11.17 |
| 자바 메모리를 사용한 큰 파일 조작하기 (0) | 2010.11.17 |
| 다수의 JAR파일들 중, 특정 Class 찾기 (0) | 2010.01.11 |
File locking, introduced in
Here is a simple example of file locking.
//: c12:FileLocking.java
// {Clean: file.txt}
import java.io.FileOutputStream;
import java.nio.channels.*;
public class FileLocking {
public static void main(String[] args) throws Exception {
FileOutputStream fos= new FileOutputStream("file.txt");
FileLock fl = fos.getChannel().tryLock();
if(fl != null) {
System.out.println("Locked File");
Thread.sleep(100);
fl.release();
System.out.println("Released Lock");
}
fos.close();
}
} ///:~
You get a FileLock on the entire file by calling either tryLock( ) or lock( ) on a FileChannel. (SocketChannel, DatagramChannel, and ServerSocketChannel do not need locking since they are inherently single-process entities; you don’t generally share a network socket between two processes.) tryLock( ) is non-blocking. It tries to grab the lock, but if it cannot (when some other process already holds the same lock and it is not shared), it simply returns from the method call. lock( ) blocks until the lock is acquired, or the thread that invoked lock( ) is interrupted, or the channel on which the lock( ) method is called is closed. A lock is released using FileLock.release( ).
It is also possible to lock a part of the file by using
tryLock(long position, long size, boolean shared)
or
lock(long position, long size, boolean shared)
which locks the region (size - position). The third argument specifies whether this lock is shared.
Although the zero-argument locking methods adapt to changes in the size of a file, locks with a fixed size do not change if the file size changes. If a lock is acquired for a region from position to position+size and the file increases beyond position+size, then the section beyond position+size is not locked. The zero-argument locking methods lock the entire file, even if it grows.
Support for exclusive or shared locks must be provided by the underlying operating system. If the operating system does not support shared locks and a request is made for one, an exclusive lock is used instead. The type of lock (shared or exclusive) can be queried using FileLock.isShared( ).
As mentioned earlier, file mapping is typically used for very large files. One thing that you may need to do with such a large file is to lock portions of it so that other processes may modify unlocked parts of the file. This is something that happens, for example, with a database, so that it can be available to many users at once.
Here’s an example that has two threads, each of which locks a distinct portion of a file:
//: c12:LockingMappedFiles.java
// Locking portions of a mapped file.
// {RunByHand}
// {Clean: test.dat}
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
public class LockingMappedFiles {
static final int LENGTH = 0x8FFFFFF; // 128 Mb
static FileChannel fc;
public static void main(String[] args) throws Exception {
fc =
new RandomAccessFile("test.dat", "rw").getChannel();
MappedByteBuffer out =
fc.map(FileChannel.MapMode.READ_WRITE, 0, LENGTH);
for(int i = 0; i < LENGTH; i++)
out.put((byte)'x');
new LockAndModify(out, 0, 0 + LENGTH/3);
new LockAndModify(out, LENGTH/2, LENGTH/2 + LENGTH/4);
}
private static class LockAndModify extends Thread {
private ByteBuffer buff;
private int start, end;
LockAndModify(ByteBuffer mbb, int start, int end) {
this.start = start;
this.end = end;
mbb.limit(end);
mbb.position(start);
buff = mbb.slice();
start();
}
public void run() {
try {
// Exclusive lock with no overlap:
FileLock fl = fc.lock(start, end, false);
System.out.println("Locked: "+ start +" to "+ end);
// Perform modification:
while(buff.position() < buff.limit() - 1)
buff.put((byte)(buff.get() + 1));
fl.release();
System.out.println("Released: "+start+" to "+ end);
} catch(IOException e) {
throw new RuntimeException(e);
}
}
}
} ///:~
The LockAndModify thread class sets up the buffer region and creates a slice( ) to be modified, and in run( ), the lock is acquired on the file channel (you can’t acquire a lock on the buffer—only the channel). The call to lock( ) is very similar to acquiring a threading lock on an object—you now have a “critical section” with exclusive access to that portion of the file.
The locks are automatically released when the JVM exits, or the channel on which it was acquired is closed, but you can also explicitly call release( ) on the FileLock object, as shown here.
출처 : http://www.linuxtopia.org/
| 자바 간단한 GZIP 압축 예제 (0) | 2010.11.17 |
|---|---|
| 자바 파일 압축 (0) | 2010.11.17 |
| 자바 메모리를 사용한 큰 파일 조작하기 (0) | 2010.11.17 |
| 다수의 JAR파일들 중, 특정 Class 찾기 (0) | 2010.01.11 |
| Java를 이용한 CLOB, BLOB 조작법J (0) | 2009.12.23 |
Memory-mapped files allow you to create and modify files that are too big to bring into
//: c12:LargeMappedFiles.java
// Creating a very large file using mapping.
// {RunByHand}
// {Clean: test.dat}
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
public class LargeMappedFiles {
static int length = 0x8FFFFFF; // 128 Mb
public static void main(String[] args) throws Exception {
MappedByteBuffer out =
new RandomAccessFile("test.dat", "rw").getChannel()
.map(FileChannel.MapMode.READ_WRITE, 0, length);
for(int i = 0; i < length; i++)
out.put((byte)'x');
System.out.println("Finished writing");
for(int i = length/2; i < length/2 + 6; i++)
System.out.print((char)out.get(i));
}
} ///:~
To do both writing and reading, we start with a RandomAccessFile, get a channel for that file, and then call map( ) to produce a MappedByteBuffer, which is a particular kind of direct buffer. Note that you must specify the starting point and the length of the region that you want to map in the file; this means that you have the option to map smaller regions of a large file.
MappedByteBuffer is inherited from ByteBuffer, so it has all of ByteBuffer’s methods. Only the very simple uses of put( ) and get( ) are shown here, but you can also use things like asCharBuffer( ), etc.
The file created with the preceding program is 128 MB long, which is probably larger than the space your OS will allow. The file appears to be accessible all at once because only portions of it are brought into memory, and other parts are swapped out. This way a very large file (up to 2 GB) can easily be modified. Note that the file-mapping facilities of the underlying operating system are used to maximize performance.
Although the performance of “old” stream I/O has been improved by implementing it with nio, mapped file access tends to be dramatically faster. This program does a simple performance comparison:
//: c12:MappedIO.java
// {Clean: temp.tmp}
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
public class MappedIO {
private static int numOfInts = 4000000;
private static int numOfUbuffInts = 200000;
private abstract static class Tester {
private String name;
public Tester(String name) { this.name = name; }
public long runTest() {
System.out.print(name + ": ");
try {
long startTime = System.currentTimeMillis();
test();
long endTime = System.currentTimeMillis();
return (endTime - startTime);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
public abstract void test() throws IOException;
}
private static Tester[] tests = {
new Tester("Stream Write") {
public void test() throws IOException {
DataOutputStream dos = new DataOutputStream(
new BufferedOutputStream(
new FileOutputStream(new File("temp.tmp"))));
for(int i = 0; i < numOfInts; i++)
dos.writeInt(i);
dos.close();
}
},
new Tester("Mapped Write") {
public void test() throws IOException {
FileChannel fc =
new RandomAccessFile("temp.tmp", "rw")
.getChannel();
IntBuffer ib = fc.map(
FileChannel.MapMode.READ_WRITE, 0, fc.size())
.asIntBuffer();
for(int i = 0; i < numOfInts; i++)
ib.put(i);
fc.close();
}
},
new Tester("Stream Read") {
public void test() throws IOException {
DataInputStream dis = new DataInputStream(
new BufferedInputStream(
new FileInputStream("temp.tmp")));
for(int i = 0; i < numOfInts; i++)
dis.readInt();
dis.close();
}
},
new Tester("Mapped Read") {
public void test() throws IOException {
FileChannel fc = new FileInputStream(
new File("temp.tmp")).getChannel();
IntBuffer ib = fc.map(
FileChannel.MapMode.READ_ONLY, 0, fc.size())
.asIntBuffer();
while(ib.hasRemaining())
ib.get();
fc.close();
}
},
new Tester("Stream Read/Write") {
public void test() throws IOException {
RandomAccessFile raf = new RandomAccessFile(
new File("temp.tmp"), "rw");
raf.writeInt(1);
for(int i = 0; i < numOfUbuffInts; i++) {
raf.seek(raf.length() - 4);
raf.writeInt(raf.readInt());
}
raf.close();
}
},
new Tester("Mapped Read/Write") {
public void test() throws IOException {
FileChannel fc = new RandomAccessFile(
new File("temp.tmp"), "rw").getChannel();
IntBuffer ib = fc.map(
FileChannel.MapMode.READ_WRITE, 0, fc.size())
.asIntBuffer();
ib.put(0);
for(int i = 1; i < numOfUbuffInts; i++)
ib.put(ib.get(i - 1));
fc.close();
}
}
};
public static void main(String[] args) {
for(int i = 0; i < tests.length; i++)
System.out.println(tests[i].runTest());
}
} ///:~
As seen in earlier examples in this book, runTest( ) is the Template Method that provides the testing framework for various implementations of test( ) defined in anonymous inner subclasses. Each of these subclasses perform one kind of test, so the test( ) methods also give you a prototype for performing the various I/O activities.
Although a mapped write would seem to use a FileOutputStream, all output in file mapping must use a RandomAccessFile, just as read/write does in the preceding code.
Here’s the output from one run:
Stream Write: 1719 Mapped Write: 359 Stream Read: 750 Mapped Read: 125 Stream Read/Write: 5188 Mapped Read/Write: 16
Note that the test( ) methods include the time for initialization of the various I/O objects, so even though the setup for mapped files can be expensive, the overall gain compared to stream I/O is significant.
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| 자바 파일 압축 (0) | 2010.11.17 |
|---|---|
| JAVA File Locking(자바 파일 잠금) (0) | 2010.11.17 |
| 다수의 JAR파일들 중, 특정 Class 찾기 (0) | 2010.01.11 |
| Java를 이용한 CLOB, BLOB 조작법J (0) | 2009.12.23 |
| [Tip] 오라클 CLOB 데이터 입출력 (0) | 2009.12.23 |
|
#!/bin/ksh
# ############[ Useage ]############
if [ $# -lt 1 ]; then echo "Usage: $0 찾을Class명" exit 0 fi for file in $(ls -1 *.jar) do echo "[ $file ]" jar tvf $file | grep $1 done |
| JAVA File Locking(자바 파일 잠금) (0) | 2010.11.17 |
|---|---|
| 자바 메모리를 사용한 큰 파일 조작하기 (0) | 2010.11.17 |
| Java를 이용한 CLOB, BLOB 조작법J (0) | 2009.12.23 |
| [Tip] 오라클 CLOB 데이터 입출력 (0) | 2009.12.23 |
| JAVA Decompiler (이클립스에 추가하기) (0) | 2009.07.02 |
1) import 시켜야할 API
① oracle.sql.BLOB
② oracle.sql.CLOB
③ oracle.jdbc.driver.OracleResultSet
2) CLOB
① DB에 CLOB 데이터형 쓰기
// UPDATE 또는 INSERT 명령으로 DB 에 공간 확보
String query = "UPDATE TABLE SET CLOB_DATA = EMPTY_CLOB() " ;
stmt.executeUpdate(query);
// 그런 다음 다시 요놈을 다시 SELECT
query = "SELECT CLOB_DATA FROM TABLE WHERE ~ " ;
stmt = dbConn.createStatement();
rs = stmt.executeQuery(query);
if(rs.next()) {
CLOB clob = null;
Writer writer = null;
Reader src = null;
char[] buffer = null;
int read = 0;
clob = ((OracleResultSet)rs).getCLOB(1);
writer = clob.getCharacterOutputStream();
// str -> DB에 넣을 내용
src = new CharArrayReader(str.toCharArray());
buffer = new char[1024];
read = 0;
while ( (read = src.read(buffer,0,1024)) != -1) {
writer.write(buffer, 0, read); // write clob.
}
src.close();
writer.close();
}
dbConn.commit();
dbConn.setAutoCommit(true);
② DB에서 CLOB 데이터형 읽기
// SELECT
String query = "SELECT CLOB_DATA FROM TABLE WHERE ~ " ;
stmt = dbConn.createStatement();
rs = stmt.executeQuery(query);
if(rs.next()) {
StringBuffer output = new StringBuffer();
Reader input = rs.getCharacterStream("CLOB_DATA");
char[] buffer = new char[1024];
int byteRead = 0;
while((byteRead=input.read(buffer,0,1024))!=-1){
output.append(buffer,0,byteRead);
}
// contents -> CLOB 데이터가 저장될 String
String contents = output.toString();
}
dbConn.commit();
dbConn.setAutoCommit(true);
3) BLOB
① DB에 BLOB 데이터형 쓰기
// UPDATE 또는 INSERT 명령으로 DB 에 공간 확보
String query = "UPDATE TABLE SET BLOB_DATA = EMPTY_BLOB() " ;
stmt.executeUpdate(query);
// 그런 다음 다시 요놈을 다시 SELECT
query = "SELECT BLOB_DATA FROM TABLE WHERE ~ " ;
stmt = dbConn.createStatement();
rs = stmt.executeQuery(query);
if(rs.next()) {
BLOB blob = null;
BufferedOutputStream out = null;
BufferedInputStream in = null;
byte[] buf = null;
int bytesRead= 0;
blob = ((OracleResultSet)rs).getBLOB(1);
out = new BufferedOutputStream(blob.getBinaryOutputStream());
// str -> DB에 넣을 내용
in = new BufferedInputStream(new StringBufferInputStream(str));
int nFileSize = (int)str.length();
buf = new byte[nFileSize];
while ((bytesRead = in.read(buf)) != -1){
out.write(buf, 0, bytesRead);
}
in.close();
out.close();
}
dbConn.commit();
dbConn.setAutoCommit(true);
② DB에서 BLOB 데이터형 읽기
// SELECT
String query = "SELECT CLOB_DATA FROM TABLE WHERE ~ " ;
stmt = dbConn.createStatement();
rs = stmt.executeQuery(query);
if(rs.next()) {
BLOB blob = ((OracleResultSet)rs).getBLOB(1);
BufferedInputStream in = new BufferedInputStream(blob.getBinaryStream());
int nFileSize = (int)blob.length();
byte[] buf = new byte [nFileSize];
int nReadSize = in.read(buf, 0, nFileSize);
in.close();
// contents -> BLOB 데이터가 저장될 String
String contents = new String(buf);
}
dbConn.commit();
dbConn.setAutoCommit(true);
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