java - JTDS 未连接到正确的数据库

Question

我正在使用 JTDS 连接到 MS SQL Server。与数据库的连接没有问题，但是当我尝试执行语句时，出现数据库“java”不存在异常。

连接字符串:

conn = DriverManager.getConnection("jdbc:jtds:sqlserver://localhost;DatabaseName=MyDatabase;user=testuser;password=testpassword");

尝试执行脚本:

private void runStatement(String scriptLocation) {
    if(scriptLocation == null) {
        return;
    }

    try {
        InputStream is = getClass().getClassLoader().getResourceAsStream(scriptLocation);
        String query = is.toString();
        is.close();

        Statement stmt = conn.createStatement();
        stmt.executeQuery(query);
    } catch(IOException | SQLException ex) {
        log.warning(ex.getMessage());
    }
}

堆栈跟踪:

WARNING: Database 'java' does not exist. Make sure that the name is entered correctly.
java.sql.SQLException: Database 'java' does not exist. Make sure that the name is entered correctly.
    at net.sourceforge.jtds.jdbc.SQLDiagnostic.addDiagnostic(SQLDiagnostic.java:372)
    at net.sourceforge.jtds.jdbc.TdsCore.tdsErrorToken(TdsCore.java:2988)
    at net.sourceforge.jtds.jdbc.TdsCore.nextToken(TdsCore.java:2421)
    at net.sourceforge.jtds.jdbc.TdsCore.getMoreResults(TdsCore.java:671)
    at net.sourceforge.jtds.jdbc.JtdsStatement.executeSQLQuery(JtdsStatement.java:505)
    at net.sourceforge.jtds.jdbc.JtdsStatement.executeQuery(JtdsStatement.java:1427)
    at com.exampe.MyJTDSConnection.runStatement(MyJTDSConnection.java:238)
    at com.exampe.MyJTDSConnection.loadPageTitle(MyJTDSConnection.java:208)
    at com.exampe.MyJTDSConnection.runTesting(MyJTDSConnection.java:69)
    at com.exampe.SeleniumTesting.runTest(SeleniumTesting.java:59)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    ...

Answer 1

正如您问题的评论中所提到的，将 .toString() 方法应用于 InputStream 对象不会读取 InputStream。相反，它只返回对象本身的字符串表示形式，而不是对象包含的内容。

例如，我的 Java 项目有一个名为“script.sql”的资源文件，其中包含:

SELECT @@VERSION

以下代码比较了仅对对象执行 .toString() 与使用 Apache Commons IO 的结果实际上将读取InputStream到字符串中:

package resourceTest;

import java.io.InputStream;
import org.apache.commons.io.IOUtils;

public class ResourceTestMain {

    public static void main(String[] args) {
        try (InputStream is = ResourceTestMain.class.getClassLoader().getResourceAsStream("resources/script.sql")) {
            String toStringValue = is.toString();
            String contents = IOUtils.toString(is, "UTF-8");
            is.close();
            System.out.println("is.toString() returned:");
            System.out.println("    " + toStringValue);
            System.out.println();
            System.out.println("IOUtils.toString(is, \"UTF-8\") returned:");
            System.out.println("    " + contents);
        } catch (Exception e) {
            e.printStackTrace(System.out);
        }
    }

}

结果是:

is.toString() returned:
    java.io.BufferedInputStream@804a77

IOUtils.toString(is, "UTF-8") returned:
    SELECT @@VERSION