JDBC操做DB2 Clob、Blob字段的Bug探究

J2EE的開發之路佈滿了陷阱，相信不少人都深有體會。

IBM的東西就是傻大笨粗，巨難用！！！

最近再用JDBC操做DB2的Clob和Blob時候出現了些問題：

我用的是DB2 V9安裝程序自帶的驅動，相傳DB2驅動不少，這個最經常使用，也是最規範一個。

我用的驅動名字以下：

db2jcc.jar
db2jcc_license_cisuz.jar
db2jcc_license_cu.jar

Clob出現的問題：寫入Clob沒有問題，讀取出問題。

Blob出現的問題：都寫一般狀況下沒有問題。但當同時寫入Data和Blob字段時候，會出問題。（一個例子中遇到的，不足以給出確定結果）。

拋出的異常代碼以下：
com.ibm.db2.jcc.c.SqlException
at com.ibm.db2.jcc.c.ec.<init>(ec.java:183)
at com.ibm.db2.jcc.b.d.b(d.java:1328)
at com.ibm.db2.jcc.c.s.a(s.java:748)
at com.ibm.db2.jcc.c.s.U(s.java:1393)
at com.ibm.db2.jcc.c.wf.getClob(wf.java:914)
......

爲測試搭建環境：

CREATE

TABLE

ZFZVF.T_LOB (

NAME

VARCHAR

(24),
TXT CLOB(2M) LOGGED

NOT

COMPACT,
IMG BLOB(2M) LOGGED

NOT

COMPACT
);

DROP

TABLE

ZFZVF.NJ_GT;

COMMIT

;

CREATE

TABLE

ZFZVF.NJ_GT (
ID

BIGINT

,
ZTBS

BIGINT

,
NJBS

BIGINT

,
ND

VARCHAR

(4),
NJNR BLOB(2M) LOGGED

NOT

COMPACT,
SJC

TIMESTAMP

);

COMMIT

;
COMMENT

ON

TABLE

ZFZVF.NJ_GT

IS

'年檢_個體'

;
COMMENT

ON

ZFZVF.NJ_GT (
ID

IS

'ID'

,
ZTBS

IS

'主體BS'

,
NJBS

IS

'年檢BS'

,
ND

IS

'年度'

,
NJNR

IS

'年檢內容'

,
SJC

IS

'時間戳'

);

COMMIT

;

例子以下：

package

lob;

import

java.io.*;

import

java.sql.*;

/**
* DB2 Clob、Blob Bug探究
* File:

TestLob4DB2

.java
* User: leizhimin
* Date: 2008-3-3 8:56:00
*/

public

class

TestLob4DB2{

public

static

final

String url =

"jdbc:db2:

//127.0.0.1:50000/zfzvf";

public

static

final

String username =

"zfzvf"

;

public

static

final

String password =

"zfzvfdb2"

;

public

static

final

String driverClassName =

"com.ibm.db2.jcc.DB2Driver"

;

/**
* 獲取數據庫鏈接Connection
*
* @return 數據庫鏈接Connection
*/

public

static

Connection makeConnection() {
Connection conn =

null

;

try

{
Class.forName(driverClassName);
}

catch

(ClassNotFoundException e) {
e.printStackTrace();
}

try

{
conn = DriverManager.getConnection(url, username, password);
}

catch

(SQLException e) {
e.printStackTrace();
}

return

conn;
}

/**
* 測試鏈接
*/

public

static

void

testConnection() {
Connection conn = makeConnection();

try

{
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(

"SELECT * FROM ZFZVF.DM_HYML"

);

while

(rs.next()) {
String s1 = rs.getString(1);
String s2 = rs.getString(2);
System.out.println(s1 + s2);
}
rs.close();
stmt.close();
}

catch

(SQLException e) {
e.printStackTrace();
}

finally

{

try

{
conn.close();
}

catch

(SQLException e) {
e.printStackTrace();
}
}
}

/**
* 插入文件測試
*/

public

static

void

testInsertlob() {
Connection conn = makeConnection();

try

{
conn.setAutoCommit(

false

);
File txtFile =

new

File(

"C:\\txt.txt"

);
File imgFile =

new

File(

"C:\\img.png"

);

int

txt_len = (

int

) txtFile.length();

int

img_len = (

int

) imgFile.length();

try

{
InputStream fis1 =

new

FileInputStream(txtFile);
InputStream fis2 =

new

FileInputStream(imgFile);
PreparedStatement pstmt = conn.prepareStatement(

"INSERT INTO ZFZVF.T_LOB(NAME,TXT,IMG) VALUES('G',?,?)"

);
pstmt.setAsciiStream(1, fis1, txt_len);
pstmt.setBinaryStream(2, fis2, img_len);
pstmt.executeUpdate();
conn.commit();
}

catch

(FileNotFoundException e) {
e.printStackTrace();
}
}

catch

(SQLException e) {
e.printStackTrace();
}

finally

{

try

{
conn.close();
}

catch

(SQLException e) {
e.printStackTrace();
}
}
}

/**
* 查詢DB2 Clob測試 ,會拋出異常
*/

public

static

void

testQueryLob() {
Connection conn = makeConnection();

try

{
conn.setAutoCommit(

true

);
PreparedStatement stmt = conn.prepareStatement(

"SELECT TXT,IMG FROM ZFZVF.T_LOB"

);
ResultSet rs = stmt.executeQuery();

while

(rs.next()) {
Clob clob = rs.getClob(

"TXT"

);
Blob blob = rs.getBlob(

"IMG"

);
InputStreamReader ir = (InputStreamReader) clob.getCharacterStream();
File fileOutput =

new

File(

"C:\\txt_1.txt"

);
FileOutputStream fo =

new

FileOutputStream(fileOutput);

int

c;

while

((c = ir.read()) != -1) {
fo.write(c);

break

;
}
fo.close();
}
}

catch

(SQLException e) {
e.printStackTrace();
}

catch

(IOException e) {
e.printStackTrace();
}

finally

{

try

{
conn.close();
}

catch

(SQLException e) {
e.printStackTrace();
}
}
}

/**
* 查詢DB2 Blob測試
*/

public

static

void

testBlobQuery() {
Connection conn = makeConnection();

try

{
conn.setAutoCommit(

true

);
PreparedStatement stmt = conn.prepareStatement(

"SELECT img FROM ZFZVF.T_LOB"

);
ResultSet rs = stmt.executeQuery();

int

i = 0;

while

(rs.next()) {
Blob blob = rs.getBlob(1);
InputStream inputStream = blob.getBinaryStream();
File fileOutput =

new

File(

"c:\\str_x"

+ i +

".txt"

);
FileOutputStream fo =

new

FileOutputStream(fileOutput);

int

c;

while

((c = inputStream.read()) != -1)
fo.write(c);
fo.close();
System.out.println(

"Blob "

+ i +

" retrieved!!"

);
i++;
}
}

catch

(SQLException e) {

}

catch

(FileNotFoundException e) {
e.printStackTrace();
}

catch

(IOException e) {
e.printStackTrace();
}

finally

{

try

{
conn.close();
}

catch

(SQLException e) {
e.printStackTrace();
}
}
}

/**
* 查詢DB2 Clob測試 ,會拋出異常
*/

public

static

void

testClobQuery() {
Connection conn = makeConnection();

try

{
conn.setAutoCommit(

false

);
PreparedStatement stmt = conn.prepareStatement(

"SELECT TXT FROM ZFZVF.T_LOB"

);
ResultSet rs = stmt.executeQuery();
conn.commit();

while

(rs.next()) {
Clob clob = rs.getClob(1);
InputStream is = clob.getAsciiStream();
File fileOutput =

new

File(

"C:\\ttttt.txt"

);
FileOutputStream fo =

new

FileOutputStream(fileOutput);

int

c;

while

((c = is.read()) != -1)
fo.write(c);
fo.close();

break

;
}
}

catch

(SQLException e) {
e.printStackTrace();

//To change body of catch statement use File | Settings | File Templates.

}

catch

(FileNotFoundException e) {
e.printStackTrace();

//To change body of catch statement use File | Settings | File Templates.

}

catch

(IOException e) {
e.printStackTrace();

//To change body of catch statement use File | Settings | File Templates.

}

finally

{

try

{
conn.close();
}

catch

(SQLException e) {
e.printStackTrace();
}
}

}

public

static

void

main(String args[]) {
testConnection();
testInsertlob();

// testQueryLob();

testBlobQuery();
testClobQuery();

}
}

一一運行各個測試方法，能夠看到操做Clob時候拋出了異常。

因爲DB2驅動比較多，而通常都用測試用的這個驅動作開發，所以我也沒有嘗試用別的驅動了。對於這個問題，我本身用Blob來存儲本應用Clob來處理的字段，也就是將原Clob定義爲Blob，經過Blob來操做。具體代碼就不贅述了。

因爲大量使用Blob，又從中發現個問題，就是日期和Blob同時插入時會出一些問題。有興趣的朋友能夠嘗試嘗試，最近很忙，也沒有那麼精力去細究。但願IBM能儘快解決這些問題。