JDBC操做DB2 Clob、Blob字段的Bug探究

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。有興趣的博友能夠嘗試嘗試，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。