iBATIS介绍.doc

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-77版本。1、 创建新的项目，并引入jar包a) ibatis-77.jarb) mysql驱动2、 在类路径中提供ibatis的配置文件：sqlMapConfig.xml 3、创建实体类：User.javapackage 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;4、创建针对User对象的CRUD的xml映射配置:User.xml select * from t_user select * from t_user where id=#id# insert into t_user values ( null,#username#,#password# ) update t_user set username = #username#,password=#password# where id=#id# delete from t_user where id=#id# 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 mon.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; i10; 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 mon.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; How To如何获得刚插入记录的自增长ID值？ insert into t_user values ( null,#username#,#password# ) SELECT IDENTITY AS ID User user = new User();user.setUsername(张三);user.setPassword(张三密码);/如果主键是自动生成的，则其返回值可以通过标签来设置/如果不通过标签来设置，则返回值为空！/中的keyProperty，是指定User中的id属性，当调用结束之后，/user对象的id值和insert方法的返回值都是这条记录的ID值！Object obj = sqlMapper.insert(insertUser, user);parameterClass的使用 insert into t_user values ( null,#username#,#password# ) SELECT IDENTITY AS ID insert into t_user values ( null,#username#,#password# ) SELECT IDENTITY AS ID insertUser使用了parameterClass，所以必需传入User类型的对象User user = new User();user.setUsername(张三);user.setPassword(张三密码);/传递进去的对象，必须是User类型Object obj = sqlMapper.insert(insertUser, user);insertUser2没有使用parameterClass，所以可以传入任意具有相应属性值的对象JustAnObject anobj = new JustAnObject();anobj.setUsername(用户名);anobj.setPassword(用户密码);/如果没有指定parameterClass属性，则任何一个具有相应属性值/的对象都可以被传递进去Object obj = sqlMapper.insert(insertUser2, anobj);parameterMap的使用 insert into t_user values ( null,?,? ) SELECT IDENTITY AS ID parameterMap用于传入参数，以便匹配SQL语句中的?号User user = new User();user.setUsername(张三dd);user.setPassword(张三密码dd);Object obj = sqlMapper.insert(insertUser, user);利用parameterMap，可以定义参数对象的属性如何映射到SQL查询语句的动态参数上，注意parameterMap中标签的先后顺序不能颠倒！如何将查询结果映射到不同的对象？(resultClass的使用) select username as prop1, password as prop2 from t_user where id=#value# /查找t_user表，将其结果映射到一个属性名不同的对象中！OtherObject obj = (OtherObject)sqlMapper.queryForObject(selectUserForOtherObject, 1);System.out.println(obj.getProp1()+,+obj.getProp2();如何将查询结果集映射到不同的对象？(resultMap的基本使用) select username, password from t_user where id=#value# /查找t_user表，将其结果映射到一个属性名不同的对象中！OtherObject obj = (OtherObject)sqlMapper.queryForObject(selectUserForOtherObject2, 17);System.out.println(obj.getProp1()+,+obj.getProp2();如何将查询结果集映射为xml格式的数据？ select * from t_user where id=#value# select * from t_user /查找t_user表，将其结果映射到xml！/返回值是xml形式的字符串Object obj = (Object)sqlMapper.queryForObject(selectXmlData, 1);System.out.println(obj);/查找t_user表，将其结果映射到xml！List list = (List)sqlMapper.queryForList(selectXmlDatas);System.out.println(list);如何用Map类型的对象作为传入参数？ insert into t_user values ( null,#username#,#password# ) Map user = new TreeMap();user.put(username, Map用户);user.put(password, Map用户密码);sqlMapper.insert(insertUser,user);如何将查询结果集的元素转换为Map类型的对象？ select * from t_user List list = (List)sqlMapper.queryForList(selectMapUsers);System.out.println(list);for (Iterator iter = list.iterator(); iter.hasNext();) Map map = (Map) iter.next();/可在此输出map的数据关联数据的存取（一对多，从多查询一）学生和班级Student类public class Student private int id;private String name;private String sex;private Classes classes;public int getId() return id;public void setId(int id) this.id = id;public String getName() return name;public void setName(String name) = name;public String getSex() return sex;public void setSex(String sex) this.sex = sex;public Classes getClasses() return classes;public void setClasses(Classes classes) this.classes = classes;Classes类public class Classes private int id;private String cname;public int getId() return id;public void setId(int id) this.id = id;public String getCname() return cname;public void setCname(String cname) ame = cname;第一种方法，通过命别名Student的xml文件insert into t_student values (null,#name#,#sex#,#classes.id#),s.sex,s.cid as classes.id,ame as amefrom t_student s,t_classes cwhere s.cid = c.id and s.id = #id#Classes的xml文件insert into t_classes values (null,#cname#)select identity as id测试public class ClassesAnStudentTest extends TestCase public void testSaveClassesAndStudent() 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();Classes c1 = new Classes();c1.setCname(测试班级);sqlMapper.insert(saveClasses, c1);Student s1 = new Student();s1.setName(学生+new Random().nextInt(9999);s1.setSex(男);s1.setClasses(c1);sqlMapper.insert(saveStudent, s1);public void testFindStudent() 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();Student s = (Student)sqlMapper.queryForObject(findStudent, 1);System.out.println(s.getName()+属于班级：+s.getClasses().getCname();第二种方法，通过第二条查询语句Classes的xml文件insert into t_classes values (null,#cname#)select identity as idselect * from t_classes where id = #cid#Student的xml文件insert into t_student values (null,#name#,#sex#,#classes.id#)select*from t_studentwhere id = #id#关联数据的存取（一对多，从一查询多）Student类public class Student private int id;private String name;private String sex;private Classes classes;Classes类public class Classes private int id;private String cname;private Set students;Student的xml文件insert into t_student values (null,#name#,#sex#,#classes.id#)select*from t_studentwhere id = #id#select * from t_student where cid = #cid#Classes的xml文件insert into t_classes values (null,#cname#)select identity as idselect * from t_classes where id = #cid#select * from t_classes where id = #id#关联数据的存取（双向）启用懒加载，双向中用List，不用Set，否则会有异常Student类public class Student private int id;private String name;private String sex;private Classes classes;Classes类public class Classes private int id;private String cname;private List students;iBATIS主配置文件，启用懒加载 Student的xml文件insert into t_student values (null,#name#,#sex#,#classes.id#)select*from t_studentwhere id = #id#select * from t_student where cid = #cid#Classes的xml文件insert into t_classes values (null,#cname#)select identity as id!- select * from t_classes where id = #cid