Ibatis 简明教程

iBATIS - Update Operation

在上一章中，我们讨论了如何使用 iBATIS 对表执行 READ 操作。本章将解释如何使用 iBATIS 更新表中的记录。

We discussed, in the last chapter, how to perform READ operation on a table using iBATIS. This chapter explains how you can update records in a table using iBATIS.

我们在 MySQL 中有以下“员工”表——

We have the following EMPLOYEE table in MySQL −

CREATE TABLE EMPLOYEE (
   id INT NOT NULL auto_increment,
   first_name VARCHAR(20) default NULL,
   last_name  VARCHAR(20) default NULL,
   salary     INT  default NULL,
   PRIMARY KEY (id)
);

此表仅有一个记录，如下所示 -

This table has only one record as follows −

mysql> select * from EMPLOYEE;
+----+------------+-----------+--------+
| id | first_name | last_name | salary |
+----+------------+-----------+--------+
|  1 | Zara       | Ali       |   5000 |
+----+------------+-----------+--------+
1 row in set (0.00 sec)

Employee POJO Class

要执行 udpate 操作，您需要如下修改 Employee.java 文件 -

To perform udpate operation, you would need to modify Employee.java file as follows −

public class Employee {
   private int id;
   private String first_name;
   private String last_name;
   private int salary;

   /* Define constructors for the Employee class. */
   public Employee() {}

   public Employee(String fname, String lname, int salary) {
      this.first_name = fname;
      this.last_name = lname;
      this.salary = salary;
   }

   /* Here are the required method definitions */
   public int getId() {
      return id;
   }

   public void setId(int id) {
      this.id = id;
   }

   public String getFirstName() {
      return first_name;
   }

   public void setFirstName(String fname) {
      this.first_name = fname;
   }

   public String getLastName() {
      return last_name;
   }
   public void setlastName(String lname) {
      this.last_name = lname;
   }

   public int getSalary() {
      return salary;
   }

   public void setSalary(int salary) {
      this.salary = salary;
   }

} /* End of Employee */

Employee.xml File

要使用 iBATIS 定义 SQL 映射语句，我们将在 Employee.xml 中添加 <update> 标签，并且在此标签定义内，我们将定义一个“id”，该 id 将在 IbatisUpdate.java 文件中用于对数据库执行 SQL UPDATE 查询。

To define SQL mapping statement using iBATIS, we would add <update> tag in Employee.xml and inside this tag definition, we would define an "id" which will be used in IbatisUpdate.java file for executing SQL UPDATE query on database.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN" "http://ibatis.apache.org/dtd/sql-map-2.dtd">

<sqlMap namespace="Employee">

   <insert id="insert" parameterClass="Employee">
      INSERT INTO EMPLOYEE(first_name, last_name, salary)
      values (#first_name#, #last_name#, #salary#)

      <selectKey resultClass="int" keyProperty="id">
         select last_insert_id() as id
      </selectKey>
   </insert>

   <select id="getAll" resultClass="Employee">
      SELECT * FROM EMPLOYEE
   </select>

   <update id="update" parameterClass="Employee">
      UPDATE EMPLOYEE
      SET    first_name = #first_name#
      WHERE  id = #id#
   </update>

</sqlMap>

IbatisUpdate.java File

这个文件具有将记录更新到 Employee 表中的应用程序级逻辑 -

This file has application level logic to update records into the Employee table −

import com.ibatis.common.resources.Resources;
import com.ibatis.sqlmap.client.SqlMapClient;
import com.ibatis.sqlmap.client.SqlMapClientBuilder;

import java.io.*;
import java.sql.SQLException;
import java.util.*;

public class IbatisUpdate{
   public static void main(String[] args)
   throws IOException,SQLException{
      Reader rd = Resources.getResourceAsReader("SqlMapConfig.xml");
      SqlMapClient smc = SqlMapClientBuilder.buildSqlMapClient(rd);

      /* This would update one record in Employee table. */
      System.out.println("Going to update record.....");
      Employee rec = new Employee();
      rec.setId(1);
      rec.setFirstName( "Roma");
      smc.update("Employee.update", rec );
      System.out.println("Record updated Successfully ");

      System.out.println("Going to read records.....");
      List <Employee> ems = (List<Employee>)
         smc.queryForList("Employee.getAll", null);
      Employee em = null;

      for (Employee e : ems) {
         System.out.print("  " + e.getId());
         System.out.print("  " + e.getFirstName());
         System.out.print("  " + e.getLastName());
         System.out.print("  " + e.getSalary());
         em = e;
         System.out.println("");
      }

      System.out.println("Records Read Successfully ");
   }
}

Compilation and Run

以下是如何编译和运行上述软件的步骤。在继续编译和执行之前，请确保已正确设置 PATH 和 CLASSPATH。

Here are the steps to compile and run the above-mentioned software. Make sure you have set PATH and CLASSPATH appropriately before proceeding for compilation and execution.

Create Employee.xml as shown above.
Create Employee.java as shown above and compile it.
Create IbatisUpdate.java as shown above and compile it.
Execute IbatisUpdate binary to run the program.

您会得到以下结果，并且会更新 EMPLOYEE 表中的一条记录，然后从 EMPLOYEE 表中读取同一条记录。

You would get following result, and a record would be updated in EMPLOYEE table and later, the same record would be read from the EMPLOYEE table.

Going to update record.....
Record updated Successfully
Going to read records.....
   1  Roma  Ali  5000
Records Read Successfully