iBATIS讀取操作

上一章展示了如何使用iBATIS執(zhí)行創(chuàng)建操作表。本章將告訴你如何使用iBATIS來讀取表。

我們已經(jīng)在MySQL下有EMPLOYEE表：

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)
);

此表有如下只有一條記錄：

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

Employee POJO 類:

要執(zhí)行讀操作，我們將修改Employee類中Employee.java文件，如下所示：

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 method definitions */
  public int getId() {
    return id;
  }
  public String getFirstName() {
    return first_name;
  }
  public String getLastName() {
    return last_name;
  }
  public int getSalary() {
    return salary;
  }
} /* End of Employee */

Employee.xml 文件:

要定義使用iBATIS SQL映射語句，我們將增加<select>標(biāo)記在Employee.xml文件，這個(gè)標(biāo)簽定義中，我們會(huì)定義將用于在IbatisRead.java文件的數(shù)據(jù)庫執(zhí)行SQL SELECT查詢的“id”。

<?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>
</sqlMap>

在這里，我們沒有使用WHERE子句和SQL SELECT語句。后續(xù)章節(jié)將演示如何用WHERE和SELECT語句子句，以及如何將值傳遞到WHERE子句。

IbatisRead.java 文件:

該文件將應(yīng)用程序級(jí)別的邏輯從雇員Employee表中讀出記錄：

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

   /* This would read all records from the Employee table. */
   System.out.println(上一篇：iBATIS刪除操作下一篇：ibatis