无法使用jdbc驱动程序连接mysql

Question

我有一个java文件hello.java，它有一个JDBC连接，在运行它时，我得到错误(Ubuntu 18.04 LTS):

javac hello.java
java hello
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at hello.main(hello.java:22)
Goodbye!

当我尝试使用类路径时，它给出:

javac -cp /usr/share/java/mysql-connector-java-8.0.23.jar hello.java
java -cp /usr/share/java/mysql-connector-java-8.0.23.jar hello
Error: Could not find or load main class hello

我还尝试了mysql-connector-java-5.1.45.jar，还是同样的问题。

，java -version给出:

openjdk version "1.8.0_282"
OpenJDK Runtime Environment (build 1.8.0_282-8u282-b08-0ubuntu1~18.04-b08)
OpenJDK 64-Bit Server VM (build 25.282-b08, mixed mode)

我尝试了以下问题:

1. ClassNotFoundException com.mysql.jdbc.Driver
2. . lang。ClassNotFoundException: com.mysql.jdbc.Driver在导入库
后出现错误如何修复"java.lang.ClassNotFoundException: com.mysql.jdbc"。将驱动程序添加到构建路径并使用Class.forName()注册;
3. . lang。ClassNotFoundException: com.mysql.jdbc.Driver in Eclipse

但没有得到满意的结果。有人知道怎么解决这个问题吗?

这是我的代码，hello.java:

//STEP 1. Import required packages 
import java.sql.*; 
public class hello { 
// JDBC driver name and database URL 
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; 
static final String DB_URL = "jdbc:mysql://localhost/data"; 
// Database credentials 
static final String USER = "newuser"; 
static final String PASS = "password"; 
public static void main(String[] args) { 
Connection conn = null; 
Statement stmt = null; 
try{ 
//STEP 2: Register JDBC driver 
Class.forName("com.mysql.jdbc.Driver"); 
//STEP 3: Open a connection System.out.println("Connecting to database..."); 
conn = DriverManager.getConnection(DB_URL,USER,PASS); 
//STEP 4: Execute a query 
System.out.println("Creating statement..."); 
stmt = conn.createStatement(); 
String sql; 
sql = "SELECT * from temp"; 
ResultSet rs = stmt.executeQuery(sql); 
//STEP 5: Extract data from result set 
while(rs.next()){ 
//Retrieve by column name 
int id = rs.getInt("id"); 
int age = rs.getInt("age"); 
String first = rs.getString("first"); 
String last = rs.getString("last"); 
//Display values System.out.print("ID: " + id); 
System.out.print(", Age: " + age); 
System.out.print(", First: " + first); 
System.out.println(", Last: " + last); 
} 
//STEP 6: Clean-up environment 
rs.close(); 
stmt.close(); 
conn.close(); 
}catch(Exception e){ 
//Handle errors for JDBC 
e.printStackTrace(); 
} finally{ 
//finally block used to close resources 
try{ 
if(stmt!=null) {
stmt.close(); 
}
}catch(SQLException se){ 
// nothing we can do 
se.printStackTrace(); 
}
try{ 
if(conn!=null) conn.close();
}catch(SQLException se){ 
se.printStackTrace(); 
}
System.out.println("Goodbye!"); 
}//end main 
}//end FirstExample
} 

Answer 1

你必须这样做。

javac hello.java
java -cp .:/usr/share/java/mysql-connector-java-8.0.23.jar hello

在这里阅读的。