DBUtils - 应用实例

本章提供了有关如何使用DBUtils库创建简单JDBC应用程序的示例。这将向您展示如何打开数据库连接，执行SQL查询以及显示输出。

将以下示例复制并粘贴到MainApp.java中，按如下所示进行编译和运行-

MainApp.java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.ResultSetHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;

public class MainApp {
   //JDBC 驱动程序名称和数据库 URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost:3306/emp";

   //数据库帐号密码
   static final String USER = "root";
   static final String PASS = "admin";

   public static void main(String[] args) throws SQLException {
      Connection conn = null;
      QueryRunner queryRunner = new QueryRunner();
      
      //第一步：注册JDBC驱动
      DbUtils.loadDriver(JDBC_DRIVER);

      //第二步：打开连接
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL, USER, PASS);

      //第三步：创建一个 ResultSet Handler 来处理 Employee Bean
      ResultSetHandler<Employee> resultHandler = new BeanHandler<Employee>(Employee.class);

      try {
         Employee emp = queryRunner.query(conn, "SELECT * FROM employees WHERE first=?",
            resultHandler, "Sumit");
         //显示信息
         System.out.print("ID: " + emp.getId());
         System.out.print(", Age: " + emp.getAge());
         System.out.print(", First: " + emp.getFirst());
         System.out.println(", Last: " + emp.getLast());
      } finally {
         DbUtils.close(conn);
      }              
   }
}

Employee.java

public class Employee {
   private int id;
   private int age;
   private String first;
   private String last;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public int getAge() {
      return age;
   }
   public void setAge(int age) {
      this.age = age;
   }
   public String getFirst() {
      return first;
   }
   public void setFirst(String first) {
      this.first = first;
   }
   public String getLast() {
      return last;
   }
   public void setLast(String last) {
      this.last = last;
   }
}

现在让无涯教程编译以上示例，如下所示:

C:\>javac MainApp.java Employee.java
C:\>

当您运行 MainApp 时，它会产生以下输出-

C:\>java MainApp
Connecting to database...
ID: 103, Age: 28, First: Sumit, Last: Learnfk
C:\>