利用mybatis怎么将表与对象进行关联

发布时间：2020-12-03 16:46:06 来源：亿速云阅读：290 作者：Leah 栏目：编程语言

本篇文章给大家分享的是有关利用mybatis怎么将表与对象进行关联，小编觉得挺实用的，因此分享给大家学习，希望大家阅读完这篇文章后可以有所收获，话不多说，跟着小编一起来看看吧。

所需要用到的其他工具或技术:

项目管理工具 : Maven

测试运行工具 : Junit

数据库 : Derby

Maven Dependencies:

<dependencies> 
    <dependency> 
      <groupId>org.mybatis</groupId> 
      <artifactId>mybatis</artifactId> 
      <version>3.2.7</version> 
    </dependency> 
    <dependency> 
      <groupId>junit</groupId> 
      <artifactId>junit</artifactId> 
      <version>4.9</version> 
      <scope>test</scope> 
    </dependency> 
    <dependency> 
      <groupId>org.apache.derby</groupId> 
      <artifactId>derby</artifactId> 
      <version>10.10.2.0</version> 
    </dependency> 
    <dependency> 
      <groupId>org.apache.derby</groupId> 
      <artifactId>derbyclient</artifactId> 
      <version>10.10.2.0</version> 
    </dependency> 
  </dependencies>

SQL 建表及数据插入（新建一个USER_TEST_TB_RELATIONSHIP表，然后CopyUSER_TEST_TB的数据，Derby不支持表结构中列名的修改，只能这么做了）:

CREATE TABLE USER_TEST_TB_RELATIONSHIP( 
USER_ID INT PRIMARY KEY,   
USER_USERNAME VARCHAR(20) NOT NULL,   
USER_PASSWORD VARCHAR(20) NOT NULL,   
USER_NICKNAME VARCHAR(20) NOT NULL   
); 
 INSERT INTO USER_TEST_TB_RELATIONSHIP(USER_ID,USER_USERNAME,USER_PASSWORD,USER_NICKNAME) SELECT ID,USERNAME,PASSWORD,NICKNAME FROM USER_TEST_TB;

Mybatis配置文件 src/main/resource源目录下

test-mybatis-configuration.xml

<&#63;xml version="1.0" encoding="UTF-8" &#63;>  
<!DOCTYPE configuration  
 PUBLIC "-//mybatis.org//DTD Config 3.0//EN"  
 "http://mybatis.org/dtd/mybatis-3-config.dtd"> 
<configuration> 
  <properties> 
    <property name="driver" value="org.apache.derby.jdbc.ClientDriver" /> 
    <property name="url"       value="jdbc:derby://localhost:1527/bjpowernode;create=true" /> 
  </properties> 
  <environments default="development"> 
    <environment id="development"> 
      <transactionManager type="JDBC" /> 
      <dataSource type="POOLED"> 
        <property name="driver" value="${driver}" /> 
        <property name="url" value="${url}" /> 
      </dataSource> 
    </environment> 
  </environments> 
  <mappers> 
    <mapper resource="com/bjpowernode/practice/UserMapper.xml" />
  </mappers> 
</configuration>

User.java对象类(src/main/java/com/bjpowernode/practice目录下)

package com.bjpowernode.practice; 
public class User 
{ 
  private Integer id; 
  private String username; 
  private String password; 
  private String nickname; 
  public Integer getId() 
  { 
    return id; 
  } 
  public void setId(Integer id) 
  { 
    this.id = id; 
  } 
  public String getUsername() 
  { 
    return username; 
  } 
  public void setUsername(String username) 
  { 
    this.username = username; 
  } 
  public String getPassword() 
  { 
    return password; 
  } 
  public void setPassword(String password) 
  { 
    this.password = password; 
  } 
  public String getNickname() 
  { 
    return nickname; 
  } 
  public void setNickname(String nickname) 
  { 
    this.nickname = nickname; 
  } 
}

UserMapper.xml Mapper文件（src/main/java/com.bjpowernode.practice目录下）

<&#63;xml version="1.0" encoding="UTF-8" &#63;>  
<!DOCTYPE mapper  
 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"  
 "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 
<mapper namespace="com.bjpowernode.practice.UserMapper">  
  <!-- 对象属性和表字段的对应 --> 
  <resultMap id="userResultMap" type="com.bjpowernode.practice.User"> 
    <result property="id" column="USER_ID"/> 
    <result property="username" column="USER_USERNAME"/> 
    <result property="password" column="USER_PASSWORD"/> 
    <result property="nickname" column="USER_NICKNAME"/> 
  </resultMap>    
  <select id="getUser" resultMap="userResultMap"> 
    select * 
    from USER_TEST_TB_RELATIONSHIP 
  </select> 
</mapper>

UserMapper.java Mapper类（src/main/java/com.bjpowernode.practice目录下）

package com.bjpowernode.practice;  
import java.util.List;  
public interface UserMapper 
{ 
  public List<User> getUser(); 
}

测试类TestMyBatis.Java（src/test/java/com.bjpowernode.practice目录下）

package com.bjpowernode.practice; 
import java.io.InputStream; 
import java.text.MessageFormat; 
import java.util.List; 
import org.apache.ibatis.session.SqlSession; 
import org.apache.ibatis.session.SqlSessionFactory; 
import org.apache.ibatis.session.SqlSessionFactoryBuilder; 
import org.junit.Before; 
import org.junit.Test; 
public class TestMyBatis 
{ 
  private String source; 
  private InputStream inputStream; 
  private SqlSessionFactory sqlSessionFactory; 
  @Before 
  public void setUp() 
  { 
    /** 
     * 准备Mybatis运行环境 
     */ 
    source = "test-mybatis-configuration.xml"; 
    inputStream = TestMyBatis.class.getClassLoader().getResourceAsStream(source); 
    sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); 
  } 
  @Test 
  public void testGet() 
  { 
    try 
    { 
      // 获取Session连接 
      SqlSession session = sqlSessionFactory.openSession(); 
      // 获取Mapper 
      UserMapper userMapper = session.getMapper(UserMapper.class); 
      // 显示User信息 
      System.out.println("Test Get start..."); 
      this.printUsers(userMapper.getUser()); 
      System.out.println("Test Get finished..."); 
    } 
    catch (Exception e) 
    { 
      e.printStackTrace(); 
    } 
  } 
  /** 
   * 
   * 打印用户信息到控制台 
   * 
   * @param users 
   */ 
  private void printUsers(final List<User> users) 
  { 
    int count = 0; 
    for (User user : users) 
    { 
      System.out.println(MessageFormat.format("==User[{0}]=================", ++count)); 
      System.out.println("User Id: " + user.getId()); 
      System.out.println("User UserName: " + user.getUsername()); 
      System.out.println("User Password: " + user.getPassword()); 
      System.out.println("User nickname: " + user.getNickname()); 
    } 
  } 
}

以上就是利用mybatis怎么将表与对象进行关联，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注亿速云行业资讯频道。

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