JDBC CallableStatement实例

以下是使用CallableStatement以及MySQL存储过程:getEmpName()的示例 -

确保已经在EMP数据库中创建了getEmpName()存储过程，可以使用MySQL查询来创建 -

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 ;

查询emp数据库的所有存储过程，如下语句 -

mysql>  select `name` from mysql.proc where db = 'emp' and `type` = 'PROCEDURE';
+------------+
| name       |
+------------+
| getEmpName |
+------------+
1 row in set (0.00 sec)

此示例代码是基于前面章节中完成的环境和数据库设置编写的。复制以下示例代码到JDBCCallableStatement.java中编译，并运行如下 -

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

public class JDBCCallableStatement {
   // 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 = "root";
   static final String PASS = "123456";

   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

现在编译上面例子中的代码，如下 -

F:\worksp\jdbc>
F:\worksp\jdbc>javac -Djava.ext.dirs=F:\worksp\jdbc\libs JDBCCallableStatement.java

运行JDBCCallableStatement时，会产生以下结果 -

F:\worksp\jdbc>java -Djava.ext.dirs=F:\worksp\jdbc\libs JDBCCallableStatement
Connecting to database...
Wed May 31 03:49:50 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
Creating statement...
Executing stored procedure...
Emp Name with ID:102 is Xueyou
Goodbye!

F:\worksp\jdbc>