介绍
iBATIS是以SQL为中心的持久化层框架。能支持懒加载、关联查询、继承等特性。
iBATIS不同于一般的OR映射框架。OR映射框架,将数据库表、字段等映射到类、属性,那是一种元数据(meta-data)映射。iBATIS则是将SQL查询的参数和结果集映射到类。
所以,iBATIS做的是SQL Mapping的工作。
它把SQL语句看成输入以及输出,结果集就是输出,而where后面的条件参数则是输入。iBATIS能将输入的普通POJO对象、Map、XML等映射到SQL的条件参数上,同时也可以将查询结果映射到普通POJO对象(集合)、Map、XML等上面。
iBATIS使用xml文件来映射这些输入以及输出。
简单示例
基于ibatis-2.3.0.677版本。
创建新的项目,并引入jar包
ibatis-2.3.0.677.jar
mysql驱动
在类路径中提供ibatis的配置文件: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>
- <transactionManager type="JDBC" commitRequired="false">
- <dataSource type="SIMPLE">
- <property name="JDBC.Driver" value="com.mysql.jdbc.Driver"/>
- <property name="JDBC.ConnectionURL" value="jdbc:mysql://127.0.0.1/ibatis"/>
- <property name="JDBC.Username" value="root"/>
- <property name="JDBC.Password" value="mysql"/>
- </dataSource>
- </transactionManager>
- <sqlMap resource="com/bjsxt/crm/model/User.xml"/>
- </sqlMapConfig>
<?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> <transactionManager type="JDBC" commitRequired="false"> <dataSource type="SIMPLE"> <property name="JDBC.Driver" value="com.mysql.jdbc.Driver"/> <property name="JDBC.ConnectionURL" value="jdbc:mysql://127.0.0.1/ibatis"/> <property name="JDBC.Username" value="root"/> <property name="JDBC.Password" value="mysql"/> </dataSource> </transactionManager> <sqlMap resource="com/bjsxt/crm/model/User.xml"/> </sqlMapConfig>
3、创建实体类:User.java
- package com.bjsxt.crm.model;
- public class User {
- private int id;
- private String username;
- private String password;
- public int getId() {
- return id;
- }
- public void setId(int id) {
- this.id = id;
- }
- public String getPassword() {
- return password;
- }
- public void setPassword(String password) {
- this.password = password;
- }
- public String getUsername() {
- return username;
- }
- public void setUsername(String username) {
- this.username = username;
- }
- }
package com.bjsxt.crm.model; public class User { private int id; private String username; private String password; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } }
创建针对User对象的CRUD的xml映射配置:User.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>
- <!-- Use type aliases to avoid typing the full classname every time. -->
- <!--定义一个实体类型,要写全包和类名在下面的CRUD操作中可以引用 -->
- <typeAlias alias="User" type="com.bjsxt.crm.model.User"/>
- <!-- Select with no parameters using the result map for Account class. -->
- <!-- resultClass:所定义的语句的返回值类型-->
- <select id="selectAllUsers" resultClass="User">
- select * from t_user
- </select>
- <!--parameterClass:要传递进来的参数类型 -->
- <select id="selectUser" resultClass="User" parameterClass="int">
- select * from t_user where id=#id#
- </select>
- <!--parameterClass:把一个类做为参数传递进来-->
- <!--sql语句中#中间的值必须在传递进来的这个类的属性中有才能赋值 -->
- <insert id="insertUser" parameterClass="User">
- insert into t_user values (
- null,#username#,#password#
- )
- </insert>
- <update id="updateUser" parameterClass="User">
- update t_user set username = #username#,password=#password#
- where id=#id#
- </update>
- <delete id="deleteUser" parameterClass="int">
- delete from t_user where id=#id#
- </delete>
- </sqlMap>
<?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> <!-- Use type aliases to avoid typing the full classname every time. --> <!--定义一个实体类型,要写全包和类名在下面的CRUD操作中可以引用 --> <typeAlias alias="User" type="com.bjsxt.crm.model.User"/> <!-- Select with no parameters using the result map for Account class. --> <!-- resultClass:所定义的语句的返回值类型--> <select id="selectAllUsers" resultClass="User"> select * from t_user </select> <!--parameterClass:要传递进来的参数类型 --> <select id="selectUser" resultClass="User" parameterClass="int"> select * from t_user where id=#id# </select> <!--parameterClass:把一个类做为参数传递进来--> <!--sql语句中#中间的值必须在传递进来的这个类的属性中有才能赋值 --> <insert id="insertUser" parameterClass="User"> insert into t_user values ( null,#username#,#password# ) </insert> <update id="updateUser" parameterClass="User"> update t_user set username = #username#,password=#password# where id=#id# </update> <delete id="deleteUser" parameterClass="int"> delete from t_user where id=#id# </delete> </sqlMap>
5、创建测试程序测试:
- package com.bjsxt.crm.model;
- import java.io.Reader;
- import java.util.Iterator;
- import java.util.List;
- import com.ibatis.common.resources.Resources;
- import com.ibatis.sqlmap.client.SqlMapClient;
- import com.ibatis.sqlmap.client.SqlMapClientBuilder;
- /**
- * 最简单的形式!
- * @author Lee
- *
- */
- public class UserTest {
- /**
- * @param args
- */
- public static void main(String[] args) throws Exception{
- //从配置文件中得到SqlMapClient对象
- Reader reader = Resources.getResourceAsReader("sqlMapConfig.xml");
- SqlMapClient sqlMapper = SqlMapClientBuilder.buildSqlMapClient(reader);
- reader.close();
- //创建用户数据
- for(int i=0; i<10; i++){
- User user = new User();
- user.setUsername("用户"+i);
- user.setPassword("密码"+i);
- sqlMapper.insert("insertUser", user);
- }
- //查询用户数据
- List users = sqlMapper.queryForList("selectAllUsers");
- for (Iterator iter = users.iterator(); iter.hasNext();) {
- User user = (User) iter.next();
- System.out.println(user.getUsername());
- }
- //查询特定用户的数据
- User user = (User)sqlMapper.queryForObject("selectUser", 1);
- System.out.println("用户【id="+1+"】的名称是:"+user.getUsername());
- //更新用户的信息
- user = new User();
- user.setId(3);
- user.setUsername("更改之后的用户名称");
- user.setPassword("密码被更改");
- sqlMapper.update("updateUser", user);
- //删除用户的信息
- sqlMapper.delete("deleteUser", 6);
- }
- }
package com.bjsxt.crm.model; import java.io.Reader; import java.util.Iterator; import java.util.List; import com.ibatis.common.resources.Resources; import com.ibatis.sqlmap.client.SqlMapClient; import com.ibatis.sqlmap.client.SqlMapClientBuilder; /** * 最简单的形式! * @author Lee * */ public class UserTest { /** * @param args */ public static void main(String[] args) throws Exception{ //从配置文件中得到SqlMapClient对象 Reader reader = Resources.getResourceAsReader("sqlMapConfig.xml"); SqlMapClient sqlMapper = SqlMapClientBuilder.buildSqlMapClient(reader); reader.close(); //创建用户数据 for(int i=0; i<10; i++){ User user = new User(); user.setUsername("用户"+i); user.setPassword("密码"+i); sqlMapper.insert("insertUser", user); } //查询用户数据 List users = sqlMapper.queryForList("selectAllUsers"); for (Iterator iter = users.iterator(); iter.hasNext();) { User user = (User) iter.next(); System.out.println(user.getUsername()); } //查询特定用户的数据 User user = (User)sqlMapper.queryForObject("selectUser", 1); System.out.println("用户【id="+1+"】的名称是:"+user.getUsername()); //更新用户的信息 user = new User(); user.setId(3); user.setUsername("更改之后的用户名称"); user.setPassword("密码被更改"); sqlMapper.update("updateUser", user); //删除用户的信息 sqlMapper.delete("deleteUser", 6); } }
SqlMapClient对象
这个对象是iBatis操作数据库的接口(执行CRUD等操作),它也可以执行事务管理等操作。这个类是我们使用iBATIS的最主要的类。它是线程安全的。通常,将它定义为单例。(与
- hibernate中sessionFactory的定义类似)。如:
- import java.io.Reader;
- import com.ibatis.common.resources.Resources;
- import com.ibatis.sqlmap.client.SqlMapClient;
- import com.ibatis.sqlmap.client.SqlMapClientBuilder;
- public class IbatisSQLMapConfig {
- private static final SqlMapClient sqlMap;
- //在静态区块中初试化返回
- static {
- try {
- //声明配置文件的名称(映射文件被定义在其中)
- String resource = "sql_map_config.xml";
- //利用工具类Resources来读取到配置文件
- Reader reader = Resources.getResourceAsReader(resource);
- //创建SqlMapClient接口的变量实例
- sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);
- } catch (Exception e) {
- e.printStackTrace();
- throw new RuntimeException(
- "Error initializing MyAppSqlConfig class. Cause: " + e);
- }
- }
- public static SqlMapClient getSqlMapInstance() {
- //提供静态方法返回静态区块中得到的SqlMapClient
- return sqlMap;
- }
- }
hibernate中sessionFactory的定义类似)。如: import java.io.Reader; import com.ibatis.common.resources.Resources; import com.ibatis.sqlmap.client.SqlMapClient; import com.ibatis.sqlmap.client.SqlMapClientBuilder; public class IbatisSQLMapConfig { private static final SqlMapClient sqlMap; //在静态区块中初试化返回 static { try { //声明配置文件的名称(映射文件被定义在其中) String resource = "sql_map_config.xml"; //利用工具类Resources来读取到配置文件 Reader reader = Resources.getResourceAsReader(resource); //创建SqlMapClient接口的变量实例 sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException( "Error initializing MyAppSqlConfig class. Cause: " + e); } } public static SqlMapClient getSqlMapInstance() { //提供静态方法返回静态区块中得到的SqlMapClient return sqlMap; } }
上面相当于是对SqlMapClient的一个简单的封装,在用junit进行单元测试的时候,为了防止重复的写代码获取SqlMapClient对象,我们进行一个简单的封装