JDBC-可调用语句对象例子

下面的例子演示如何使用可调用语句和getEmpName() MySQL存储过程：

确保在EMP数据库中创建这个存储过程。你可以使用MySQL查询浏览器完成。

DELIMITER $$

DROP PROCEDURE IF EXISTS `EMP`.`getEmpName` $$
CREATE PROCEDURE `EMP`.`getEmpName`
   (IN EMP_ID INT, OUT EMP_FIRST VARCHAR(255))
BEGIN
   SELECT first INTO EMP_FIRST
   FROM Employees
   WHERE ID = EMP_ID;
END $$

DELIMITER ;

示例代码基于之前设置的环境和数据库编写。

复制粘贴代码到JDBCExample.java，编译运行如下：

//STEP 1. Import required packages
import java.sql.*;

public class JDBCExample {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; 
   static final String DB_URL = "jdbc:mysql://localhost/EMP";

   //  Database credentials
   static final String USER = "username";
   static final String PASS = "password";
  
   public static void main(String[] args) {
   Connection conn = null;
   CallableStatement 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...");
      String sql = "{call getEmpName (?, ?)}";
      stmt = conn.prepareCall(sql);
     
      //Bind IN parameter first, then bind OUT parameter
      int empID = 102;
      stmt.setInt(1, empID); // This would set ID as 102
      // Because second parameter is OUT so register it
      stmt.registerOutParameter(2, java.sql.Types.VARCHAR);
     
      //Use execute method to run stored procedure.
      System.out.println("Executing stored procedure..." );
      stmt.execute();

      //Retrieve employee name with getXXX method
      String empName = stmt.getString(2);
      System.out.println("Emp Name with ID:" +
               empID + " is " + empName);
      stmt.close();
      conn.close();
   }catch(SQLException se){
      //Handle errors for JDBC
      se.printStackTrace();
   }catch(Exception e){
      //Handle errors for Class.forName
      e.printStackTrace();
   }finally{
      //finally block used to close resources
      try{
         if(stmt!=null)
            stmt.close();
      }catch(SQLException se2){
      }// nothing we can do
      try{
         if(conn!=null)
            conn.close();
      }catch(SQLException se){
         se.printStackTrace();
      }//end finally try
   }//end try
   System.out.println("Goodbye!");
}//end main
}//end JDBCExample

让我们编译以上代码如下：

C:>javac JDBCExample.java
C:>

当你运行JDBCExample的时候，产生如下输出：

C:>java JDBCExample
Connecting to database...
Creating statement...
Executing stored procedure...
Emp Name with ID:102 is Zaid
Goodbye!
C:>