java - 连接到 DB java - 导入 java sql 连接与同一文件中定义的类型冲突

Question

我尝试使用 jdbc 连接到数据库，但是 import java.sql.Connection;

旁边仍然有错误

The import java sql connection conflicts with a type defined in the same file

我将 mysql-connector-java-5.1.40-bin.jar 保存在 Apache Tomcat 库中。

这是我的代码:

package demo;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class Connect
 */
@WebServlet("/Connect")
public class Connection extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public Connection() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        PrintWriter out = response.getWriter();

        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            out.println("Can't load database driver");
            //e.printStackTrace();
            String strClassPath = System.getProperty("java.class.path");

            System.out.println("Classpath is " + strClassPath);
            return;
        }

        Connection conn = null;

        try {
            conn = DriverManager.getConnection(
                    "jdbc:mysql://localhost:3306/webshop", "root", "root");
        } catch (SQLException e) {
            out.println("Can't connect to database.");
            return;
        }

        out.println("Connected to database.");

        try {
            conn.close();
        } catch (SQLException e) {

        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

}

Answer 1

这是因为您的类也被命名为 Connection，因此在创建对象时产生了冲突。

产生冲突的行如下:

Connection conn = null; 

您可以按如下方式修改:

java.sql.Connection conn = null;

或者，将您的类重命名为 DBConnection 或其他名称。