上一章展示了如何使用MyBatis对表进行读取操作。本章将告诉你如何在一个表中使用MyBatis更新记录。
我们已经在MySQL下有EMPLOYEE表：
1 CREATE TABLE EMPLOYEE ( 2 id INT NOT NULL auto_increment, 3 first_name VARCHAR(20) default NULL, 4 last_name VARCHAR(20) default NULL, 5 salary INT default NULL, 6 PRIMARY KEY (id) 7 );
此表有如下只有一条记录：
1 mysql> select * from EMPLOYEE; 2 +----+------------+-----------+--------+ 3 | id | first_name | last_name | salary | 4 +----+------------+-----------+--------+ 5 | 1 | Zara | Ali | 5000 | 6 +----+------------+-----------+--------+ 7 1 row in set (0.00 sec)
Employee POJO 类:
要执行UDPATE操作，需要修改Employee.java文件，如下所示：
1 public class Employee {
2 private int id;
3 private String first_name;
4 private String last_name;
5 private int salary;
6
7 /* Define constructors for the Employee class. */
8 public Employee() {}
9
10 public Employee(String fname, String lname, int salary) {
11 this.first_name = fname;
12 this.last_name = lname;
13 this.salary = salary;
14 }
15
16 /* Here are the required method definitions */
17 public int getId() {
18 return id;
19 }
20 public void setId(int id) {
21 this.id = id;
22 }
23 public String getFirstName() {
24 return first_name;
25 }
26 public void setFirstName(String fname) {
27 this.first_name = fname;
28 }
29 public String getLastName() {
30 return last_name;
31 }
32 public void setlastName(String lname) {
33 this.last_name = lname;
34 }
35 public int getSalary() {
36 return salary;
37 }
38 public void setSalary(int salary) {
39 this.salary = salary;
40 }
41
42 } /* End of Employee */
Employee.xml 文件:
要定义使用iBATIS SQL映射语句，我们想补充的<Update>标签Employee.xml文件，这个标签定义中，我们会定义将用于在IbatisUpdate.java文件的数据库执行SQL UPDATE查询的“id”。
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE sqlMap 3 PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN" 4 "http://ibatis.apache.org/dtd/sql-map-2.dtd"> 5 6 <sqlMap namespace="Employee"> 7 <insert id="insert" parameterClass="Employee"> 8 INSERT INTO EMPLOYEE(first_name, last_name, salary) 9 values (#first_name#, #last_name#, #salary#) 10 11 <selectKey resultClass="int" keyProperty="id"> 12 select last_insert_id() as id 13 </selectKey> 14 15 </insert> 16 17 <select id="getAll" resultClass="Employee"> 18 SELECT * FROM EMPLOYEE 19 </select> 20 21 <update id="update" parameterClass="Employee"> 22 UPDATE EMPLOYEE 23 SET first_name = #first_name# 24 WHERE id = #id# 25 </update> 26 </sqlMap>
IbatisUpdate.java 文件:
文件将应用程序级别的逻辑来更新记录到Employee表：
1 import com.ibatis.common.resources.Resources;
2 import com.ibatis.sqlmap.client.SqlMapClient;
3 import com.ibatis.sqlmap.client.SqlMapClientBuilder;
4 import java.io.*;
5 import java.sql.SQLException;
6 import java.util.*;
7
8 public class IbatisUpdate{
9 public static void main(String[] args)
10 throws IOException,SQLException{
11 Reader rd = Resources.getResourceAsReader("SqlMapConfig.xml");
12 SqlMapClient smc = SqlMapClientBuilder.buildSqlMapClient(rd);
13
14 /* This would update one record in Employee table. */
15 System.out.println("Going to update record.....");
16 Employee rec = new Employee();
17 rec.setId(1);
18 rec.setFirstName( "Roma");
19 smc.update("Employee.update", rec );
20 System.out.println("Record updated Successfully ");
21
22 System.out.println("Going to read records.....");
23 List <Employee> ems = (List<Employee>)
24 smc.queryForList("Employee.getAll", null);
25 Employee em = null;
26 for (Employee e : ems) {
27 System.out.print(" " + e.getId());
28 System.out.print(" " + e.getFirstName());
29 System.out.print(" " + e.getLastName());
30 System.out.print(" " + e.getSalary());
31 em = e;
32 System.out.println("");
33 }
34
35 System.out.println("Records Read Successfully ");
36
37 }
38 }
编译和运行：
下面是步骤来编译并运行上述软件。请确保您已在进行的编译和执行之前，适当地设置PATH和CLASSPATH。
- 创建Employee.xml如上所示。
- 创建Employee.java如上图所示，并编译它。
- 创建IbatisUpdate.java如上图所示，并编译它。
- 执行IbatisUpdate二进制文件来运行程序。
得到下面的结果，并创建纪录在EMPLOYEE表进行更新和更高版本相同的记录将从EMPLOYEE表中读出。
1 Going to update record..... 2 Record updated Successfully 3 Going to read records..... 4 1 Roma Ali 5000 5 Records Read Successfully
系列文章：
MyBatis知多少（13）MyBatis如何解决数据库的常见问题
时间： 2024-08-24 18:27:06