Struts 2.1.6 精简实例系列教程(3)：新闻管理Model层的开发（整合iBatis）
本期开始讲Model层的开发，整合iBatis框架，iBatis是Apache旗下Java数据持久层的框架，跟Hibernate是同一类型的框架。大家可到它的官方网站去下载http://ibatis.apache.org/java.cgi，如下图：
我这里下载的是当前最新版本iBatis 2.3.4 , 下载之后，解压包是这样的：
我们在lib目录下，找到“ibatis-2.3.4.726.jar”文件，加入到我们项目的lib目录下，就行。在这里，我们先说下怎么学习这个iBatis框架：上图中，有个simple_example的文件夹，它里面就包含了一个超级简单且容易理解的例子，大家可以去学习一下。By the way，如果你学过Hibernate的话，你会发觉iBatis要比Hibernate好学很多。关于Hibernate和iBatis的争论，网上有很多，大家有兴趣可以去了解一下。
好，我们先建立数据库和设计数据库吧。我这项目用的是MySQL 5.0。生成数据库和数据表的SQL语句如下：
create database simpledb;
create table article
(
??? ID int auto_increment not null primary key,
??? TITLE varchar(25),
??? AUTHOR varchar(25),
??? CONTENT text,
??? PUBTIME date
);
?
这是我们常见的新闻表及其中的字段。
接下来，写一个与表对应的新闻类，Article.java，这个其实是POJO类，代码如下：
package?cn.simple.pojo;import?java.util.Date;
public?class?Article?
{
????????private?int?id;????private?String?title;????private?String?author;????private?String?content;????private?Date?pubtime;????
????/**?*//***********getter和setter方法***********/????public?int?getId()?{????????return?id;
????}????public?void?setId(int?id)?{????????this.id?=?id;????}????public?String?getTitle()?{????????return?title;????}????public?void?setTitle(String?title)?{????????this.title?=?title;????}????public?String?getAuthor()?{????????return?author;????}????public?void?setAuthor(String?author)?{????????this.author?=?author;????}????public?String?getContent()?{????????return?content;????}????public?void?setContent(String?content)?{????????this.content?=?content;????}????public?Date?getPubtime()?{????????return?pubtime;????}????public?void?setPubtime(Date?pubtime)?{????????this.pubtime?=?pubtime;????}????
} ?
有了数据表和实体类，现在来写两者之间映射的配置文件Article.xml。代码如下：
<?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?namespace="Article">????<!--?Use?type?aliases?to?avoid?typing?the?full?classname?every?time.?-->????<typeAlias?alias="Article"?type="cn.simple.pojo.Article"?/>????<!--????????Result?maps?describe?the?mapping?between?the?columns?returned?from?a????????query,?and?the?class?properties.?A?result?map?isn't?necessary?if?the????????columns?(or?aliases)?match?to?the?properties?exactly.????-->????<resultMap?id="ArticleResult"?class="Article">????????<result?property="id"?column="ID"?/>????????<result?property="title"?column="TITLE"/>????????<result?property="author"?column="AUTHOR"/>????????<result?property="content"?column="CONTENT"/>????????<result?property="pubtime"?column="PUBTIME"/>????</resultMap>????<!--????????Select?with?no?parameters?using?the?result?map?for?Account?class.????-->????<select?id="selectAllArticles"?resultMap="ArticleResult">????????select?*?from?article??????</select>????<!--????????A?simpler?select?example?without?the?result?map.?Note?the?aliases?to????????match?the?properties?of?the?target?result?class.????-->????<select?id="selectArticleById"?parameterClass="int"?resultClass="Article">????????select????????ID?as?id,????????TITLE?as?title,????????AUTHOR?as?author,????????CONTENT?as?content,????????PUBTIME?as?pubtime????????from?Article????????where?ID=#id#??</select>????<!--?Insert?example,?using?the?Account?parameter?class?-->????<insert?id="insertArticle"?parameterClass="Article">????????insert?into?article?(????????????TITLE,????????????AUTHOR,????????????CONTENT,????????????PUBTIME????????)?values?(????????????#title#,????????????#author#,????????????#content#,????????????#pubtime#????????)??</insert>????<!--?Update?example,?using?the?Account?parameter?class?-->????<update?id="updateArticle"?parameterClass="Article">????????update?article?set????????TITLE?=?#title#,????????AUTHOR?=?#author#,????????CONTENT?=?#content#,????????PUBTIME?=?#pubtime#????????where????????ID?=?#id#??</update>????<!--?Delete?example,?using?an?integer?as?the?parameter?class?-->????<delete?id="deleteArticleById"?parameterClass="int">????????delete?from?article?where?ID?=?#id#??</delete></sqlMap> ?
大家不要觉得这个映射文件很复杂，其实，这挺容易理解的，如果大家赖得写的话，可复制iBatis自带的simple_example下的例子的映射文件，然后修改一下就行。
有了表、实体类、表与实体之间的映射文件，之后，该做什么呢？学过Hibernate的朋友会想到那个数据库连接信息的配置文件，当然，iBatis也需要类似的文件，即SqlMapConfig.xml，代码如下：
<?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>??<!--?Configure?a?built-in?transaction?manager.??If?you're?using?an????????app?server,?you?probably?want?to?use?its?transaction?manager????????and?a?managed?datasource?-->??<transactionManager?type="JDBC"?commitRequired="false">????<dataSource?type="SIMPLE">??????<property?name="JDBC.Driver"?value="com.mysql.jdbc.Driver"/>??????<property?name="JDBC.ConnectionURL"?value="jdbc:mysql://localhost:3306/simpledb"/>??????<property?name="JDBC.Username"?value="root"/>??????<property?name="JDBC.Password"?value="root"/>????</dataSource>??</transactionManager>??<!--?List?the?SQL?Map?XML?files.?They?can?be?loaded?from?the????????classpath,?as?they?are?here?(com.domain.data)?-->??<sqlMap?resource="cn/simple/pojo/Article.xml"/>??<!--?List?more?here??<sqlMap?resource="com/mydomain/data/Order.xml"/>??<sqlMap?resource="com/mydomain/data/Documents.xml"/>??--></sqlMapConfig> ?
一看这代码，也有点复杂，我的说法同上，大不了COPY，再略作修改，呵呵
好了，来写我们的业务逻辑层：
package?cn.simple.manager;import?java.io.IOException;import?java.io.Reader;import?java.sql.SQLException;import?java.util.List;import?cn.simple.pojo.Article;import?com.ibatis.common.resources.Resources;import?com.ibatis.sqlmap.client.SqlMapClient;import?com.ibatis.sqlmap.client.SqlMapClientBuilder;public?class?ArticleManager?{????/**?*//**?????*?SqlMapClient?instances?are?thread?safe,?so?you?only?need?one.?In?this?????*?case,?we'll?use?a?static?singleton.?So?sue?me.?;-)?????*/????private?static?SqlMapClient?sqlMapper;????/**?*//**?????*?It's?not?a?good?idea?to?put?code?that?can?fail?in?a?class?initializer,?????*?but?for?sake?of?argument,?here's?how?you?configure?an?SQL?Map.?????*/????static?{????????try?{????????????Reader?reader?=?Resources.getResourceAsReader("SqlMapConfig.xml");????????????sqlMapper?=?SqlMapClientBuilder.buildSqlMapClient(reader);????????????reader.close();????????}?catch?(IOException?e)?{????????????//?Fail?fast.????????????throw?new?RuntimeException(????????????????????"Something?bad?happened?while?building?the?SqlMapClient?instance."????????????????????????????+?e,?e);????????}????}????/**?*//**?????*?查询列表?????*?@return?????*?@throws?SQLException?????*/????public?static?List<Article>?selectAllArticles()?throws?SQLException?{????????return?sqlMapper.queryForList("selectAllArticles");????}????????/**?*//**?????*?插入数据?????*?@param?article?????*?@throws?SQLException?????*/????public?static?void?insertArticle(Article?article)?throws?SQLException?{????????sqlMapper.insert("insertArticle",?article);????}????????/**?*//**?????*?更新数据?????*?@param?article?????*?@throws?SQLException?????*/????public?static?void?updateArticle(Article?article)?throws?SQLException?{????????sqlMapper.update("updateArticle",?article);????}?
本文转自我的JavaEE技术博客http://www.blogjava.net/rongxh7/,转载请注明出处!谢谢!
1 楼 rtsbtx 2009-08-21 我是一个新手，想问一下，这里如果要设计DAO层的话应该怎么改呢~~？ 2 楼 SeanHe 2009-08-22 如果你使用SPRING的话，spring帮你把IBATIS做封装，使用起来也很方便。印象中spring的例子里有对iBATIS整合的例子 3 楼 wenxiang_tune 2009-08-26 小例子不能说明大问题。。。LZ的配置方法Hibernate已经实现的很好了，而且Hibernate有很多种可选方案 4 楼 快乐让让 2009-12-21 没用呀，随便下个IBATIS的快速应用就有你所说的一切了，而且还比你说的详细。。。 5 楼 ckn126 2010-05-13 我问一下 如果 B对象包含在A中 如果我想用查询A时候，把B对象一起封装进去 ，这个在hibernate之中是使用component 那么 ibatis中如何处理对象的包含关系。。。 6 楼 everher 2010-05-17 我现在就在用ibatis，但是用ibatis作为持久层有一个比较大的缺点，即：代码生成工具很难使用，而且效果不好。