java - 将 SQL 数据库中的表值插入到 ArrayList

Question

我正在尝试将我的数据库中的一些值插入到 ArrayList 中。我猜 showMeeting() 方法有问题。希望你们能理解从控制台获得的一些消息。

public ArrayList<String> showMeeting() {

    ArrayList<String> output = new ArrayList<String>();
    try {
        Class.forName(driverName).newInstance();
        con = DriverManager.getConnection(url + dbName, userName, password);
        try {
            Statement st = con.createStatement();
            String meetID = "SELECT meetID FROM Meeting";
            ResultSet rs = st.executeQuery(meetID);
            while(rs.next()){
                output.add(rs.toString());
            }
        } catch (SQLException s) {
            System.out.println("Wrong sql-query");
        }
        con.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return output;
}
public static void main(String[] args) {
    InteractWithDatabase2 test = new InteractWithDatabase2();
    ArrayList<String> meetID = test.showMeeting();
    String meetings = "";
    for (int i = 0; i <meetID.size(); i++) {
        meetings += meetID.get(i) + "\n";
    }
    System.out.println(meetings);

}

当我尝试在 Eclipse 中运行它时，我收到以下消息:

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:169) at no.ntnu.fp.model.InteractWithDatabase2.visMoter(InteractWithDatabase2.java:107) at no.ntnu.fp.model.InteractWithDatabase2.main(InteractWithDatabase2.java:127)

Answer 1

您的代码似乎没有任何问题，您只是在类路径中缺少 mysql 连接器 .jar。

可以从the download page下载或者通过 Maven:

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.15</version>
</dependency>