java - 无法将 blob 转换为字符串，SQLite+java

Question

我使用以下代码从 SQLite 数据库检索数据。数据库的第 4 列将字符串存储为 BLOB。现在我需要取回该字符串值。但是 Blob blob = exe.getBlob("col_4"); 给了我一个异常 未由 SQLite JDBC 驱动程序实现。我该如何解决这个问题？

Connection c = null;
Statement stm = null;

String db = "C:\\Users\\Asus™\\Desktop\\New folder (2)\\tempo.db";
try {
    Class.forName("org.sqlite.JDBC");
    c = DriverManager.getConnection("jdbc:sqlite:" + db);
    c.setAutoCommit(false);

    System.out.println("DB opened successfully !");

    stm = c.createStatement();
    int rc = 0;
    try (ResultSet exe = stm.executeQuery("SELECT * FROM tblTest;")) {
        while (exe.next()) {
            Blob blob = exe.getBlob("col_4");
            String password = new String(blob.getBytes(1, (int) blob.length()));

            System.out.println(password
                    + exe.getString("col_1") + "\t"
                    + exe.getString("col_2") + "\t"
                    + exe.getString("col_3") + "\t"
                    + password
            );
            rc++;
        }
        System.out.println(rc++);
    }
    stm.close();
} catch (ClassNotFoundException ex) {
    Logger.getLogger(SQLiteBrowser.class.getName()).log(Level.SEVERE, null, ex);
} catch (SQLException ex) {
    Logger.getLogger(SQLiteBrowser.class.getName()).log(Level.SEVERE, null, ex);

}

异常:

java.sql.SQLException: not implemented by SQLite JDBC driver
       at org.sqlite.jdbc4.JDBC4ResultSet.unused(JDBC4ResultSet.java:320)
       at org.sqlite.jdbc4.JDBC4ResultSet.getBlob(JDBC4ResultSet.java:345)
       at sqlite.SQLiteBrowser.jButton1ActionPerformed(SQLiteBrowser.java:256)
       at sqlite.SQLiteBrowser.access$000(SQLiteBrowser.java:29)
       at sqlite.SQLiteBrowser$1.actionPerformed(SQLiteBrowser.java:76)
       at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
       at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
       at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
       at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
       at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
       at java.awt.Component.processMouseEvent(Component.java:6525)
       at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)

Answer 1

看来，该 JDBC 库实现不支持 ResultSet#getBlob 方法(由于 sources ， JDBC4ResultSet 未实现它)。您可以尝试使用 ResultSet#getBytes 代替:

byte[] bytes = exe.getBytes("col_4");
String password = new String(bytes);