JDBC操作DB2 Clob、Blob字段的Bug探究

JDBC操作DB2 Clob、Blob字段的Bug探究

J2EE的开发之路布满了陷阱，相信很多人都深有体会。

IBM的东西就是傻大笨粗，巨难用！！！
最近再用JDBC操作DB2的Clob和Blob时候出现了些问题：
我用的是DB2 V9安装程序自带的驱动，相传DB2驱动很多，这个最常用，也是最规范一个。

我用的驱动名字如下：
db2jcc.jar
db2jcc_license_cisuz.jar
db2jcc_license_cu.jar

Clob出现的问题：写入Clob没有问题，读取出问题。
Blob出现的问题：都写通常情况下没有问题。但当同时写入Data和Blob字段时候，会出问题。（一个例子中遇到的，不足以给出肯定结果）。

抛出的异常代码如下：
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)
......

为测试搭建环境：

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 '年检_个体';
COMMENT ON ZFZVF.NJ_GT (
ID IS 'ID',
ZTBS IS '主体BS',
NJBS IS '年检BS',
ND IS '年度',
NJNR IS '年检内容',
SJC IS '时间戳' );
COMMIT;

例子如下：

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";

/**
* 获取数据库连接Connection
*
* @return 数据库连接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;
}

/**
* 测试连接
*/
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();
}
}
}

/**
* 插入文件测试
*/
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();
}
}
}

/**
* 查询DB2 Clob测试 ,会抛出异常
*/
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();
}
}
}

/**
* 查询DB2 Blob测试
*/
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();
}
}
}

/**
* 查询DB2 Clob测试 ,会抛出异常
*/
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();

}
}

一一运行各个测试方法，可以看到操作Clob时候抛出了异常。

由于DB2驱动比较多，而一般都用测试用的这个驱动做开发，因此我也没有尝试用别的驱动了。对于这个问题，我自己用Blob来存储本应用Clob来处理的字段，也就是将原Clob定义为Blob，通过Blob来操作。具体代码就不赘述了。

由于大量使用Blob，又从中发现个问题，就是日期和Blob同时插入时会出一些问题。有兴趣的博友可以尝试尝试，最近很忙，也没有那么精力去细究。希望IBM能尽快解决这些问题。