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MyBatis知多少（22）MyBatis删除操作

2015-07-29 20:18 453 查看

本节从表中使用MyBatis删除记录。

我们已经在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)
);

假设这个表是有两条记录如下：

mysql> select * from EMPLOYEE;
+----+------------+-----------+--------+
| id | first_name | last_name | salary |
+----+------------+-----------+--------+
|  1 | Zara       | Ali       |   5000 |
|  2 | Roma       | Ali       |   3000 |
+----+------------+-----------+--------+
2 row in set (0.00 sec)

Employee POJO 类:

要执行删除操作，就需要修改Employee.java文件。

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 文件:

要定义使用MyBatis SQL映射语句中，我们将增加<Delete>键标签Employee.xml文件，这个标签定义中，我们会定义将用于在IbatisDelete.java文件执行SQL DELETE查询数据库的“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>

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

<delete id="delete" parameterClass="int">
DELETE FROM EMPLOYEE
WHERE  id = #id#
</delete>

</sqlMap>

IbatisDelete.java 文件:

文件将应用程序级别的逻辑从Employee表中删除记录：

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

/* This would delete one record in Employee table. */
System.out.println("Going to delete record.....");
int id = 1;

smc.delete("Employee.delete", id );
System.out.println("Record deleted 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 ");

}
}

编译和运行：

下面是步骤来编译并运行上述软件。请确保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IbatisDelete.java如上图所示，并编译它。

执行IbatisDelete二进制文件来运行程序。

得到以下结果，ID=1将在EMPLOYEE表中被删除，并读取EMPLOYEE表中的一条记录。

Going to delete record.....
Record deleted Successfully
Going to read records.....
2  Roma  Ali  3000
Records Read Successfully

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