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在J2EE领域，Hibernate与Mybatis是大家常用的持久层框架，它们各有特点，在持久层框架中处于领导地位。
本文主要介绍Mybatis（对于较小型的系统，特别是报表较多的系统，个人偏向Mybatis），对于它，个人比较喜欢的是：
不喜欢的是：
本文主要介绍Mybatis的搭建，是学习Mybatis过程后整理的札记，其中包括“单独搭建Mybaits”和常用的“Mybatis与Spring的整合”。
一、数据库的准备
因为Mybatis是持久层框架，毫无疑问，是需要操作数据库的。所以，在搭建之前，我们需要先创建一个简单的表。
create table T_USER_TEST_1407 ( USERNAME VARCHAR2(255), PASSWORD VARCHAR2(255) )
插入一些数据，以作查询的测试。
insert into T_USER_TEST_1407 (USERNAME, PASSWORD) values (‘nick‘, ‘Optimistic,Confident,Love - 1‘);
二、单独搭建Mybaits
1）环境准备、版本说明
此工程使用JDK1.6 + mybatis-3.2.4 + Oracle11g。
新建一个Web工程，由于只构建Mybatis，只引用Mybatis和Oracle JDBC驱动包
2）程序的搭建
首先，我们将数据源等配置信息放在一个xml，让Mybatis可以根据这个信息去连接数据库、管理事务。
目前我们可只关注environments节点，此节点是用于配置数据源、事务管理的 。
其他的节点，如typeAliases、mappers，是用于注册一些信息的，后面会陆续提到。
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE configuration 3 PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-config.dtd"> 5 6 <configuration> 7 8 <!-- Register Alias --> 9 <typeAliases> 10 <typeAlias alias="user" type="com.nicchagil.mybatisonly.bean.User" /> 11 </typeAliases> 12 13 <!-- Data Source --> 14 <environments default="development"> 15 <environment id="development"> 16 <transactionManager type="JDBC" /> 17 <dataSource type="POOLED"> 18 <property name="driver" value="oracle.jdbc.driver.OracleDriver" /> 19 <property name="url" value="jdbc:oracle:thin:@xxx.xxx.xxx.xxx:xxxx:xxxxxx" /> 20 <property name="username" value="xxxx" /> 21 <property name="password" value="xxxx" /> 22 </dataSource> 23 </environment> 24 </environments> 25 26 <!-- Register Mapper --> 27 <mappers> 28 <!-- SQL Mapper --> 29 <mapper resource="com/nicchagil/mybatisonly/mapper/sqlxml/UserMapper.xml" /> 30 </mappers> 31 32 </configuration>
既然有了配置的xml，下一步就需要让Mybatis加载它了。
package com.nicchagil.mybatisonly; import java.io.IOException; import java.io.InputStream; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import com.nicchagil.mybatisonly.bean.User; import com.nicchagil.mybatisonly.mapper.UserMapper; public class Call { public static SqlSessionFactory sqlSessionFactory = null; public static void main(String[] args) throws IOException { // Query User /* kickStartMybatis(); queryUser("nick"); */ // Inser User kickStartMybatis(); insertUser("user004", "hello world."); } public static void kickStartMybatis() throws IOException { String resource = "com/nicchagil/mybatisonly/mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } /** * Query User * @param username * @return */ public static User queryUser(String username) { User user = null; SqlSession session = sqlSessionFactory.openSession(); try { /* Un-recommended Method */ /* user = (User)session.selectOne("com.nicchagil.mybatisonly.mapper.UserMapper.queryUser", username); */ /* Recommended Method */ UserMapper userMapper = session.getMapper(UserMapper.class); user = userMapper.queryUser(username); System.out.println("username - " + user.getUsername() + " , password - " + user.getPassword()); } finally { session.close(); } return user; } /** * Insert User * @param username * @param password */ public static void insertUser(String username, String password) { SqlSession session = sqlSessionFactory.openSession(); try { UserMapper userMapper = session.getMapper(UserMapper.class); User user = new User(); user.setUsername(username); user.setPassword(password); userMapper.insertUser(user); // Flushes batch statements and commits database connection. // Note that database connection will not be committed if no updates/deletes/inserts were called. session.commit(); System.out.println("username - " + user.getUsername() + " , password - " + user.getPassword()); } catch (Exception e) { session.rollback(); e.printStackTrace(); //TODO Print the exception logs //TODO Prompts fail to execute for user } finally { session.close(); } } /** * Insert User * @param username * @param password */ public static void insertUserBySQL(String username, String password) { SqlSession session = sqlSessionFactory.openSession(); try { User user = new User(); user.setUsername(username); user.setPassword(password); session.insert("com.nicchagil.mybatisonly.mapper.UserMapper.insertUser", user); // Flushes batch statements and commits database connection. // Note that database connection will not be committed if no updates/deletes/inserts were called. session.commit(); } catch (Exception e) { session.rollback(); e.printStackTrace(); //TODO Print the exception logs //TODO Prompts fail to execute for user } finally { session.close(); } } }
UserMapper是一个DAO的接口，是定义作哪些数据库操作的。
1 package com.nicchagil.mybatisonly.mapper; 2 3 import com.nicchagil.mybatisonly.bean.User; 4 5 public interface UserMapper { 6 7 public User queryUser(String username); 8 9 }
UserMapper只是供调用的接口，那么具体的实现逻辑在哪里呢？
我们可见UserMaper.xml，它定义的SQL就是用于定义UserMapper接口的实现。我们需在mybatis-config.xml注册UserMaper.xml，可见mybatis-config.xml的mappers节点。
<?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="com.nicchagil.mybatisonly.mapper.UserMapper"> <select id="queryUser" resultType="user"> select * from t_user_test_1407 t where t.username = #{username} </select> <insert id="insertUser" parameterType="user"> INSERT INTO t_user_test_1407 T (T.USERNAME, T.PASSWORD) VALUES (#{username}, #{password}) </insert> </mapper>
而com.nicchagil.mybatisonly.bean.User是实体类，用于装载数据。
1 package com.nicchagil.mybatisonly.bean; 2 3 public class User { 4 5 private String username; 6 private String password; 7 8 public String getUsername() { 9 return username; 10 } 11 12 public void setUsername(String username) { 13 this.username = username; 14 } 15 16 public String getPassword() { 17 return password; 18 } 19 20 public void setPassword(String password) { 21 this.password = password; 22 } 23 24 @Override 25 public int hashCode() { 26 final int prime = 31; 27 int result = 1; 28 result = prime * result 29 + ((password == null) ? 0 : password.hashCode()); 30 result = prime * result 31 + ((username == null) ? 0 : username.hashCode()); 32 return result; 33 } 34 35 @Override 36 public boolean equals(Object obj) { 37 if (this == obj) 38 return true; 39 if (obj == null) 40 return false; 41 if (getClass() != obj.getClass()) 42 return false; 43 User other = (User) obj; 44 if (password == null) { 45 if (other.password != null) 46 return false; 47 } else if (!password.equals(other.password)) 48 return false; 49 if (username == null) { 50 if (other.username != null) 51 return false; 52 } else if (!username.equals(other.username)) 53 return false; 54 return true; 55 } 56 57 }
最后，我们运行Call.java，将能成功查询、插入数据库。我们可通过打印的信息和查询数据库，以查看是否成功查询、插入数据。
3）事务说明
对于数据库有写操作的应用程序，一般来说，事务是不可或缺的一部分。因为未使用其他框架，这里使用编程式事务，即使用SqlSession.commit()和SqlSession.rollback()方法，可见Call.java。
Flushes batch statements and commits database connection. Note that database connection will not be committed if no updates/deletes/inserts were called. To force the commit call SqlSession.commit(boolean)
单独搭建Mybaits完毕！
二、 Mybatis与Spring的整合
一个项目中，单独使用Mybatis的情况并不多；更多的情况下，我们需要将Mybatis与其他框架进行整合，以便更好地使用。比如Mybatis + Spring，就是一个流行的整合组合。
1）环境准备、版本说明
本次用Mybatis3 + Spring3进行整合。注意，并不包含MVC框架的配置，因为本文的目的是学习Mybatis，所以尽量不引用其他框架，以避免影响代码的理解。
需引入的类库详情如下:
<dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>3.2.10.RELEASE</version> </dependency> <dependency> <groupId>org.springframework.webflow</groupId> <artifactId>spring-webflow</artifactId> <version>2.4.0.RELEASE</version> </dependency> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-oracle</artifactId> <version>1.0.0.RELEASE</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.2.4</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> <version>1.2.2</version> </dependency> </dependencies>
2）程序的搭建
首先，我们在Spring中配置关于Mybatis数据源的信息。
这里以applicationContext-mybatis.xml来体现，配置了如下信息：
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <!-- JDBC Data Source --> <!-- <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource" > <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" /> <property name="url" value="jdbc:oracle:thin:@hostname:port:sid" /> <property name="username" value="username" /> <property name="password" value="password" /> </bean> --> <!-- JNDI Data Source --> <bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean"> <property name="jndiName"> <value>JNDI_TEST_DB</value> </property> </bean> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="mapperLocations"> <list> <value>classpath:com/nicchagil/mybatis3spring3intg/mapper/sqlxml/*_mapper.xml</value> <value>classpath:com/nicchagil/mybatis3spring3intg/bean/resultmapxml/*_resultmap.xml</value> </list> </property> <property name="typeAliasesPackage" value="com.nicchagil.mybatis3spring3intg.bean" /> </bean> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.nicchagil.mybatis3spring3intg.mapper" /> <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" /> </bean> </beans>
除了Mybatis的信息，还有一些Spring的信息需要配置：
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd"> <context:component-scan base-package="com.nicchagil.mybatis3spring3intg" /> <!-- Transaction Support --> <tx:annotation-driven transaction-manager="transactionManager" /> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource" /> </bean> <bean id="SpringContextUtil" class="com.nicchagil.util.SpringContextUtil"/> </beans>
众所周知，以上是Spring的配置文件，那么我们需要告诉应用程序“这些配置文件在哪里”，所以我们需要在web.xml中告诉应用程序。另外，此web.xml注册了一个Servlet，用于接收页面的请求。
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> <display-name>mybatis3spring3Intg</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath*:config/applicationContext*.xml</param-value> </context-param> <servlet> <description></description> <display-name>UserServlet</display-name> <servlet-name>UserServlet</servlet-name> <servlet-class>com.nicchagil.mybatis3spring3intg.servlet.UserServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>UserServlet</servlet-name> <url-pattern>/UserServlet</url-pattern> </servlet-mapping> </web-app>
我们还需要定义Mapper的接口，即DAO接口。此处的Mapper的接口，我们已经在applicationContext-mybatis.xml中注册为指定路径下自动扫描。
package com.nicchagil.mybatis3spring3intg.mapper; import com.nicchagil.mybatis3spring3intg.bean.User; public interface UserMapper { public User find(String username); public void save(User user); }
而Mapper的实现是如何的呢？
Mybatis会帮我们实现，我们只需要通过user_mapper.xml文件告诉Mybatis对应的SQL，此处的mapper文件，已经在applicationContext-mybatis.xml中注册为指定路径下自动扫描。
<?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="com.nicchagil.mybatis3spring3intg.mapper.UserMapper"> <select id="find" resultType="user" resultMap="userResultMap"> select * from t_user_test_1407 t where t.username = #{username} </select> <insert id="save" parameterType="user"> INSERT INTO t_user_test_1407 T (T.USERNAME, T.PASSWORD) VALUES (#{username}, #{password}) </insert> </mapper>
可以看到，Mapper和SQL配置文件中都引用到了实体类，我们也需要定义。此处的实体类，已经在applicationContext-mybatis.xml中注册为指定路径下自动扫描。
package com.nicchagil.mybatis3spring3intg.bean; public class User { private String username; private String password; private String childhoodName; 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 getChildhoodName() { return childhoodName; } public void setChildhoodName(String childhoodName) { this.childhoodName = childhoodName; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((childhoodName == null) ? 0 : childhoodName.hashCode()); result = prime * result + ((password == null) ? 0 : password.hashCode()); result = prime * result + ((username == null) ? 0 : username.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; User other = (User) obj; if (childhoodName == null) { if (other.childhoodName != null) return false; } else if (!childhoodName.equals(other.childhoodName)) return false; if (password == null) { if (other.password != null) return false; } else if (!password.equals(other.password)) return false; if (username == null) { if (other.username != null) return false; } else if (!username.equals(other.username)) return false; return true; } }
实体的属性与DB的字段之间的映射/匹配，我们需要定义一下。此处的resultmap.xml文件已经在applicationContext-mybatis.xml中注册为指定路径下自动扫描。
<?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="com.nicchagil.mybatis3spring3intg.mapper.UserMapper"> <resultMap type="user" id="userResultMap"> <result property="username" column="USERNAME" /> <result property="password" column="PASSWORD" /> <result property="childhoodName" column="USERNAME" /> </resultMap> </mapper>
完成了DAO，那么接着写Service。
首先一个Service的接口。
package com.nicchagil.mybatis3spring3intg.service; import com.nicchagil.mybatis3spring3intg.bean.User; public interface UserService { public User query(String username); public void save(User user); public void testTransaction(User user1, User user2); }
Service的实现类如下，这里只简单地测试查询、保存、事务是否能正常处理。
package com.nicchagil.mybatis3spring3intg.service.impl; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Transactional; import com.nicchagil.mybatis3spring3intg.bean.User; import com.nicchagil.mybatis3spring3intg.mapper.UserMapper; import com.nicchagil.mybatis3spring3intg.service.UserService; @Service public class UserServiceImpl implements UserService { @Autowired private UserMapper mapper; @Override public User query(String username) { return mapper.find(username); } @Override public void save(User user) { mapper.save(user); } @Override @Transactional public void testTransaction(User user1, User user2) { mapper.save(user1); // Code a NullPointerException to test transaction setting String str = null; str.charAt(0); mapper.save(user2); } }
由于没有整合MVC框架，此处由一个Servlet(此Servlet已于web.xml中注册）获取页面请求并调用Service，
那么如何在Servlet中获得Spring IOC管理下Service的bean呢？这里借助SpringContextUtil（implements ApplicationContextAware），此SpringContextUtil于以上提及的applicationContext.xml中注册。
package com.nicchagil.mybatis3spring3intg.servlet; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.nicchagil.mybatis3spring3intg.bean.User; import com.nicchagil.mybatis3spring3intg.service.UserService; import com.nicchagil.util.SpringContextUtil; /** * Servlet implementation class UserServlet */ public class UserServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public UserServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String action = request.getParameter("action"); UserService service = (UserService)SpringContextUtil.getBean("userServiceImpl"); if ("find".equals(action)) { User user = service.query(request.getParameter("username")); System.out.println(user.getUsername() + " - " + user.getPassword() + " - " + user.getChildhoodName()); } if ("save".equals(action)) { User user = new User(); user.setUsername(request.getParameter("username")); user.setPassword(request.getParameter("password")); service.save(user); System.out.println(user.getUsername() + " - " + user.getPassword()); } if ("testTransaction".equals(action)) { User user1 = new User(); user1.setUsername(request.getParameter("username")); user1.setPassword(request.getParameter("password")); User user2 = new User(); user2.setUsername(request.getParameter("username") + " - Double"); user2.setPassword(request.getParameter("password") + " - Double"); service.testTransaction(user1, user2); System.out.println(user1.getUsername() + " - " + user1.getPassword()); System.out.println(user2.getUsername() + " - " + user2.getPassword()); } } }
package com.nicchagil.util; import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; public class SpringContextUtil implements ApplicationContextAware { private static ApplicationContext applicationContext = null; @Override public void setApplicationContext(ApplicationContext ac) throws BeansException { applicationContext = ac; } public static ApplicationContext getApplicationContext() { return applicationContext; } public static Object getBean(String beanName) { return applicationContext.getBean(beanName); } public static boolean containsBean(String beanName) { return applicationContext.containsBean(beanName); } }
几乎大功告成。
这里写了些触发测试的页面，执行结果可通过“查看控制台”或“查询数据库”获得。哈哈！~~
导航页
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> </head> <body> <a href="find.html">find</a> <br/> <a href="save.html">save</a> <br/> <a href="testTransaction.html">testTransaction</a> </body> </html>
输入username查询记录的触发页面
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> </head> <body> <form action="UserServlet"> <input type="hidden" name="action" value="find"> <input type="text" name="username"> <input type="submit"> </form> </body> </html>
保存页面
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> </head> <body> <body> <form action="UserServlet"> <input type="hidden" name="action" value="save"> <input type="text" name="username"> <input type="password" name="password"> <input type="submit"> </form> </body> </body> </html>
测试事务的触发页面
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> </head> <body> <body> <form action="UserServlet"> <input type="hidden" name="action" value="testTransaction"> <input type="text" name="username"> <input type="password" name="password"> <input type="submit"> </form> </body> </body> </html>
大功告成！！
由“单独搭建Mybatis”到“Mybatis与Spring的整合/集成”,布布扣,bubuko.com
由“单独搭建Mybatis”到“Mybatis与Spring的整合/集成”
标签：des style blog http color java 使用 os
原文地址：http://www.cnblogs.com/nick-huang/p/3838326.html
