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ibatis 入门



iBatis 简介:

iBatis apache 的一个开源项目,一个O/R Mapping 解决方案,iBatis 最大的特点就是小巧,上手很快。如果不需要太多复杂的功能,iBatis 是能够满足你的要求又足够灵活的最简单的解决方案,现在的iBatis 已经改名为Mybatis 了。

官网为:http://www.mybatis.org/

搭建iBatis 开发环境:

1 、导入相关的jar 包,ibatis-2.3.0.677.jarmysql-connector-java-5.1.6-bin.jar

2 、编写配置文件:

  Jdbc 连接的属性文件  (eg:SqlMap.properties)

  总配置文件 (SqlMapConfig.xml)

  关于每个实体的映射文件(Map 文件) (eg:Student.xml)

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本文以 对学生Student的 增删改查为例

Demo:

工程目录:

数据库结构截图:


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1. Student.java

package com.ibatis.entity;

import java.sql.Date;

public class Student {
	// 注意这里需要保证有一个无参构造方法,因为包括Hibernate在内的映射都是使用反射的,如果没有无参构造可能会出现问题 
	private int id;
	private String name;
	private Date birth;
	private float score;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Date getBirth() {
		return birth;
	}
	public void setBirth(Date birth) {
		this.birth = birth;
	}
	public float getScore() {
		return score;
	}
	public void setScore(float score) {
		this.score = score;
	}
	
	@Override
	public String toString() {
		return "Student [id=" + id + ", name=" + name + ", birth=" + birth
				+ ", score=" + score + "]";
	}
	
	
	

}

2. SqlMap.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mydb
username=root
password=123456

3. Student.xml

<?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>
	<!-- 通过typeAlias使得我们在下面使用Student实体类的时候不需要写包名 -->
	<typeAlias alias="Student" type="com.ibatis.entity.Student" />

	<!-- 这样以后改了sql,就不需要去改java代码了 -->
	<!-- id表示select里的sql语句,resultClass表示返回结果的类型 -->
	<select id="selectAllStudent" resultClass="Student">
		select * from
		tbl_student
	</select>

	<!-- parameterClass表示参数的内容 -->
	<!-- #表示这是一个外部调用的需要传进的参数,可以理解为占位符 -->
	<select id="selectStudentById" parameterClass="int" resultClass="Student">
		select * from tbl_student where id=#id#
	</select>

	<!-- 注意这里的resultClass类型,使用Student类型取决于queryForList还是queryForObject -->
	<select id="selectStudentByName" parameterClass="String"
		resultClass="Student">
		select name,birth,score from tbl_student where name like
		‘%$name$%‘
	</select>

	<insert id="addStudent" parameterClass="Student">
		insert into
		tbl_student(name,birth,score) values
		(#name#,#birth#,#score#);
		<selectKey resultClass="int" keyProperty="id">
			select @@identity as inserted
			<!-- 这里需要说明一下不同的数据库主键的生成,对各自的数据库有不同的方式: -->
			<!-- mysql:SELECT LAST_INSERT_ID() AS VALUE -->
			<!-- mssql:select @@IDENTITY as value -->
			<!-- oracle:SELECT STOCKIDSEQUENCE.NEXTVAL AS VALUE FROM DUAL -->
			<!-- 还有一点需要注意的是不同的数据库生产商生成主键的方式不一样,有些是预先生成 (pre-generate)主键的,如Oracle和PostgreSQL。 
				有些是事后生成(post-generate)主键的,如MySQL和SQL Server 所以如果是Oracle数据库,则需要将selectKey写在insert之前 -->
		</selectKey>
	</insert>

	<delete id="deleteStudentById" parameterClass="int">
		<!-- #id#里的id可以随意取,但是上面的insert则会有影响,因为上面的name会从Student里的属性里去查找 -->
		<!-- 我们也可以这样理解,如果有#占位符,则ibatis会调用parameterClass里的属性去赋值 -->
		delete from tbl_student where id=#id#
	</delete>

	<update id="updateStudent" parameterClass="Student">
		update tbl_student set
		name=#name#,birth=#birth#,score=#score# where id=#id#
	</update>

</sqlMap>

4. SqlMapConfig.xml

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

<sqlMapConfig>
	<!-- 引用JDBC属性的配置文件 -->
	<properties resource="com/ibatis/SqlMap.properties" />
	<!-- 使用JDBC的事务管理 -->
	<transactionManager type="JDBC">
		<!-- 数据源 -->
		<dataSource type="SIMPLE">
			<property name="JDBC.Driver" value=http://www.mamicode.com/"${driver}" />>

5. StudentDao.java

package com.ibatis.dao;

import java.util.List;

import com.ibatis.entity.Student;
public interface StudentDao {

	/**
	 * 添加学生信息
	 * 
	 * @param student
	 *            学生实体
	 * @return 返回是否添加成功
	 */
	public boolean addStudent(Student student);

	/**
	 * 根据学生id删除学生信息
	 * 
	 * @param id
	 *            学生id
	 * @return 删除是否成功
	 */
	public boolean deleteStudentById(int id);

	/**
	 * 更新学生信息
	 * 
	 * @param student
	 *            学生实体
	 * @return 更新是否成功
	 */
	public boolean updateStudent(Student student);

	/**
	 * 查询全部学生信息
	 * 
	 * @return 返回学生列表
	 */
	public List<Student> selectAllStudent();

	/**
	 * 根据学生姓名模糊查询学生信息
	 * 
	 * @param name
	 *            学生姓名
	 * @return 学生信息列表
	 */
	public List<Student> selectStudentByName(String name);

	/**
	 * 根据学生id查询学生信息
	 * 
	 * @param id
	 *            学生id
	 * @return 学生对象
	 */
	public Student selectStudentById(int id);

}


6. StudentDaoImpl.java

package com.ibatis.daoimpl;
import java.io.IOException;
import java.io.Reader;
import java.sql.SQLException;
import java.util.List;
import com.ibatis.dao.StudentDao;
import com.ibatis.entity.Student;


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

public class StudentDaoImpl implements StudentDao {

	
	private static SqlMapClient sqlMapClient = null;

	// 读取配置文件
		static {
			try {
				Reader reader = Resources
						.getResourceAsReader("com/ibatis/SqlMapConfig.xml");
				sqlMapClient = SqlMapClientBuilder.buildSqlMapClient(reader);
				reader.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

		public boolean addStudent(Student student) {
			Object object = null;
			boolean flag = false;
			try {
				object = sqlMapClient.insert("addStudent", student);
				System.out.println("添加学生信息的返回值:" + object);
			} catch (SQLException e) {
				e.printStackTrace();
			}
			if (object != null) {
				flag = true;
			}
			return flag;
		}

		public boolean deleteStudentById(int id) {
			boolean flag = false;
			Object object = null;
			try {
				object = sqlMapClient.delete("deleteStudentById", id);
				System.out.println("删除学生信息的返回值:" + object + ",这里返回的是影响的行数");
			} catch (SQLException e) {
				e.printStackTrace();
			}
			if (object != null) {
				flag = true;

			}
			return flag;

		}

		public boolean updateStudent(Student student) {
			boolean flag = false;
			Object object = false;
			try {
				object = sqlMapClient.update("updateStudent", student);
				System.out.println("更新学生信息的返回值:" + object + ",返回影响的行数");
			} catch (SQLException e) {
				e.printStackTrace();
			}
			if (object != null) {
				flag = true;
			}
			return flag;
		}

		public List<Student> selectAllStudent() {
			List<Student> students = null;
			try {
				students = sqlMapClient.queryForList("selectAllStudent");
			} catch (SQLException e) {
				e.printStackTrace();
			}
			return students;
		}

		public List<Student> selectStudentByName(String name) {
			List<Student> students = null;
			try {
				students = sqlMapClient.queryForList("selectStudentByName",name);
			} catch (SQLException e) {
				e.printStackTrace();
			}
			return students;
		}

		public Student selectStudentById(int id) {
			Student student = null;
			try {
				student = (Student) sqlMapClient.queryForObject(
						"selectStudentById", id);
			} catch (SQLException e) {
				e.printStackTrace();
			}
			return student;
		}

}


7. TestIbatis.java

package com.ibatis.test;
import java.sql.Date;
import java.util.List;

import com.ibatis.daoimpl.StudentDaoImpl;
import com.ibatis.entity.Student;


public class TestIbatis {

	public static void main(String[] args) {
		StudentDaoImpl studentDaoImpl = new StudentDaoImpl();

		System.out.println("测试插入");
		Student addStudent = new Student();
		addStudent.setName("李四");
		addStudent.setBirth(Date.valueOf("2011-09-02"));
		addStudent.setScore(88);
		System.out.println(studentDaoImpl.addStudent(addStudent));

		System.out.println("测试根据id查询");
		System.out.println(studentDaoImpl.selectStudentById(1));

		System.out.println("测试模糊查询");
		List<Student> mohuLists = studentDaoImpl.selectStudentByName("李");
		for (Student student : mohuLists) {
			System.out.println(student);
		}

		System.out.println("测试查询所有");
		List<Student> students = studentDaoImpl.selectAllStudent();
		for (Student student : students) {
			System.out.println(student);
		}

		System.out.println("根据id删除学生信息");
		System.out.println(studentDaoImpl.deleteStudentById(1));

		System.out.println("测试更新学生信息");
		Student updateStudent = new Student();
		updateStudent.setId(1);
		updateStudent.setName("李四1");
		updateStudent.setBirth(Date.valueOf("2011-08-07"));
		updateStudent.setScore(21);
		System.out.println(studentDaoImpl.updateStudent(updateStudent));

	}
}

iBatis 的优缺点:

优点:

1、 减少代码量,简单;

2、 性能增强;

3、 Sql语句与程序代码分离;

4、 增强了移植性;

缺点:

1、 Hibernate 相比,sql 需要自己写;

2、 参数数量只能有一个,多个参数时不太方便;