FactoryBean的兩種實現方法（以Mybatis中的SqlSessionFactory爲例)

在spring中，FactoryBean用於構造複雜的對象，如Connection,SqlSession等，本文以構建SqlSession爲例

首先準備如下代碼：

數據庫配置文件：databases.properties

#連接設置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/test?useSSL=true
username=root
password=xxxxxxxx
#<!-- 初始化連接 -->
initialSize=10
#最大連接數量
maxActive=50
#<!-- 最小空閒連接 -->
minIdle=5
#<!-- 超時等待時間以毫秒爲單位 60000毫秒/1000等於60秒 -->
maxWait=5000

一個Entity:StudentInfo.java

package org.example.entity;


import java.sql.Date;

public class StudentInfo {

    private String student_id;
    private String student_name;
    private String student_major;
    private String student_gender;
    private java.sql.Date student_birthday;

    public StudentInfo() {
    }

    public StudentInfo(String student_id, String student_name, String student_major, String student_gender, Date student_birthday) {
        this.student_id = student_id;
        this.student_name = student_name;
        this.student_major = student_major;
        this.student_gender = student_gender;
        this.student_birthday = student_birthday;
    }

    @Override
    public String toString() {
        return "StudentInfo{" +
                "student_id='" + student_id + '\'' +
                ", student_name='" + student_name + '\'' +
                ", student_major='" + student_major + '\'' +
                ", student_gender='" + student_gender + '\'' +
                ", student_birthday=" + student_birthday +
                '}';
    }

    public String getStudent_id() {
        return student_id;
    }

    public void setStudent_id(String student_id) {
        this.student_id = student_id;
    }

    public String getStudent_name() {
        return student_name;
    }

    public void setStudent_name(String student_name) {
        this.student_name = student_name;
    }

    public String getStudent_major() {
        return student_major;
    }

    public void setStudent_major(String student_major) {
        this.student_major = student_major;
    }

    public String getStudent_gender() {
        return student_gender;
    }

    public void setStudent_gender(String student_gender) {
        this.student_gender = student_gender;
    }

    public Date getStudent_birthday() {
        return student_birthday;
    }

    public void setStudent_birthday(Date student_birthday) {
        this.student_birthday = student_birthday;
    }


}

StduentInfo對應的dao層接口：StudentDao.java

package org.example.dao;

import org.example.entity.StudentInfo;

import java.util.List;

public interface StudentDao {
    /**
     * 根據id查詢用戶信息
     *
     * @param id
     * @return
     */
    public StudentInfo queryStudentById(String id);

    /**
     * 查詢所有用戶信息
     *
     * @return
     */
    public List<StudentInfo> queryStudentAll();

    /**
     * 新增用戶
     *
     * @param studentInfo
     */
    public void insertUser(StudentInfo studentInfo);

    /**
     * 更新用戶信息
     *
     * @param studentInfo
     */
    public void updateStudent(StudentInfo studentInfo);

    /**
     * 根據id刪除用戶信息
     *
     * @param id
     */
    public void deleteStudent(String id);
}

StudentDao.java的mybatis的映射：StudentDaoMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.example.dao.StudentDao">

    <select id="queryStudentById" resultType="org.example.entity.StudentInfo">
        SELECT *
        FROM test.student_info
        WHERE student_id = #{student_id};
    </select>

    <select id="queryStudentAll" resultType="org.example.entity.StudentInfo">
        SELECT *
        FROM test.student_info;
    </select>

    <insert id="insertUser" parameterType="org.example.entity.StudentInfo">
        INSERT INTO test.student_info (student_id, student_name, student_major, student_gender, student_birthday)
        VALUES (#{student_id}, #{student_name}, #{student_major}, #{student_gender}, #{student_birthday});
    </insert>

    <update id="updateStudent" parameterType="org.example.entity.StudentInfo">
        UPDATE test.student_info
        SET student_id=#{student_id},
        student_name=#{student_name},
        <if test="student_major!=null">student_major=#{student_major},</if>
        student_gender=#{student_gender},
        student_birthday=#{student_birthday}
        WHERE student_id = #{student_id};
    </update>

    <delete id="deleteStudent">
        DELETE
        FROM test.student_info
        WHERE student_id = #{student_id};
    </delete>

</mapper>

最後就是MyBatis的配置文件:mybatis-config.xml(將mapper添加其中)

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!-- 根標籤 -->
<configuration>
    <properties resource="mybatis/database.properties"/>

    <!-- 環境，可以配置多個，default：指定採用哪個環境 -->
    <environments default="test">
        <!-- id：唯一標識 -->
        <environment id="test">
            <!-- 事務管理器，JDBC類型的事務管理器 -->
            <transactionManager type="JDBC"/>
            <!-- 數據源，池類型的數據源 -->
            <dataSource type="POOLED">
                <property name="driver" value="${driverClassName}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>

    <!--    Mapper配置-->
    <mappers>
        <mapper resource="mybatis/mapper/StudentDaoMapper.xml"/>
    </mappers>
</configuration>

經過以上準備，我們現在就可以通過mybatis-config.xml來獲取SqlSessionFactory對象了

方法一：實現FactoryBean接口

新建SqlSessionFactoryBean.java ,使其實現FactoryBean接口

package org.example.factoryBean;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.springframework.beans.factory.FactoryBean;

import java.io.InputStream;

/**
 * 生產SqlSessionFactory對象
 */
public class SqlSessionFactoryBean implements FactoryBean<SqlSessionFactory> {
    //完成複雜對象的生產，並返回該對象
    @Override
    public SqlSessionFactory getObject() throws Exception {
        InputStream inputStream= Resources.getResourceAsStream("mybatis/mybatis-config.xml");
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        return sqlSessionFactory;
    }

    //返回複雜對象的類對象
    @Override
    public Class<?> getObjectType() {
        return SqlSessionFactory.class;
    }

    //控制複雜對象的創建模式,（返回true爲單例模式，返回false爲多例（原型）模式）
    @Override
    public boolean isSingleton() {
        return true;
    }
}

在applicationContext.xml中配置如下<bean>

即可在工廠中獲取該對象

方法二：靜態工廠方法

修改對象SqlSessionFactoryBean.java

package org.example.factoryBean;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.InputStream;

/**
 * 生產SqlSessionFactory對象
 */
public class SqlSessionFactoryBean {
    //完成複雜對象的生產，並返回該對象
    public static SqlSessionFactory getObject() throws Exception {
        InputStream inputStream = Resources.getResourceAsStream("mybatis/mybatis-config.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        return sqlSessionFactory;
    }
}

在applicationContext.xml中配置如下<bean>

 

謝謝觀看！