Java：iBatis简单入门

简介: 

jar包

普通的javaBean: domain.User

与bean对应的SQL映射文件: maps/User.xml

iBatis需要的配置文件: SqlMapConfig.xml

加载iBatis配置文件SqlMapConfig.xml是相对于class loader所在目录的相对路径. 如在Web程序中，例如Tomcat下时，class loader所对应的目录是WEB-INF/classes目录. 如在普通的单机运用程序中，class loader对应的目录是编译生成class的bin目录(把src和bin分开存放时).

1. 需要的jar包(暂且先用下面的，可到http://www.javaeye.com/topic/26433示例中一起下载):

commons-dbcp.jar, commons-logging-api.jar, commons-logging.jar, commons-pool.jar, 

hsqldb.jar, ibatis-common-2.jar, ibatis-dao-2.jar, ibatis-sqlmap-2.jar,

mysql-connector-java-3.1.12-bin.jar

2. 类User:

package domain;

public class User {

    private int id;

    private String name;

    public User() {}

    public User(String name) { this(0, name); }

    public User(int id, String name) {

        this.id = id;

        this.name = name;

    }

    public int getId() { return id; }

    public void setId(int id) { this.id = id; }

    public String getName() { return name; }

    public void setName(String name) { this.name = name; }

    @Override

    public String toString() { return "ID: " + id + ", Name: " + name; }

}

3. User.xml映射文件:

<?xml version="1.0" encoding="UTF-8"?> 

<!DOCTYPE sqlMap PUBLIC

    "-//iBATIS.com//DTD SQL Map 2.0//EN"

    "http://www.ibatis.com/dtd/sql-map-2.dtd">

<sqlMap namespace="User">

    <!-- 设置本映射中的别名: 方便使用 -->

    <typeAlias alias="user" type="domain.User" />

    <typeAlias alias="string" type="java.lang.String" />

    <typeAlias alias="integer" type="java.lang.Integer" />

    

    <!-- 增删查改的Statement配置 -->

    <select id="getAllUsers" resultClass="user"><![CDATA[

        SELECT id, name FROM user ORDER BY id

    ]]></select>

    

    <select id="getUser" resultClass="user" parameterClass="integer"><![CDATA[

        SELECT id, name FROM user WHERE id=#id#

    ]]></select>

    

    <update id="updateUser" parameterClass="user"><![CDATA[

        UPDATE user SET name=#name# WHERE id=#id#

    ]]></update>

    

    <insert id="insertUser" parameterClass="user"><![CDATA[

        INSERT INTO user (name) VALUES (#name#)

    ]]></insert>

    

    <delete id="deleteUser" parameterClass="integer"><![CDATA[

        DELETE FROM user WHERE id=#id#

    ]]></delete>

</sqlMap>

4. iBatis需要的配置文件:

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE sqlMapConfig 

    PUBLIC "-//iBATIS.com//DTD SQL Map Config 2.0//EN" 

    "http://www.ibatis.com/dtd/sql-map-config-2.dtd">

<sqlMapConfig>

    <settings cacheModelsEnabled="true" enhancementEnabled="true"

        lazyLoadingEnabled="true" errorTracingEnabled="true" maxRequests="32"

        maxSessions="10" maxTransactions="5" useStatementNamespaces="false" />

    <transactionManager type="JDBC">

        <dataSource type="SIMPLE">

            <!-- JDBC连接需要的配置 -->

            <property name="JDBC.Driver" value="com.mysql.jdbc.Driver" />

            <property name="JDBC.ConnectionURL"

                value="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8" />

            <property name="JDBC.Username" value="root" />

            <property name="JDBC.Password" value="" />

            

            <!-- 连接池配置 -->

            <property name="Pool.MaximumActiveConnections" value="10" />

            <property name="Pool.MaximumIdleConnections" value="5" />

            <property name="Pool.MaximumCheckoutTime" value="120000" />

            <property name="Pool.TimeToWait" value="500" />

            <property name="Pool.PingQuery" value="select 1 from sample" />

            <property name="Pool.PingEnabled" value="false" />

            <property name="Pool.PingConnectionsOlderThan" value="1" />

            <property name="Pool.PingConnectionsNotUsedFor" value="1" />

        </dataSource>

    </transactionManager>

    <!-- 映射文件 -->

    <sqlMap resource="maps/User.xml" />

</sqlMapConfig>

5. 使用iBatis访问数据库:

package test;

import java.io.IOException;

import java.io.Reader;

import java.util.List;

import com.ibatis.common.resources.Resources;

import com.ibatis.sqlmap.client.SqlMapClient;

import com.ibatis.sqlmap.client.SqlMapClientBuilder;

import domain.User;

public class Test {

    public static enum Mode {

        INSERT, UPDATE, DELETE

    }

    public void update(Object arg, Mode mode) {

        SqlMapClient smc = null;

        

        try {

            smc = getSqlMapClient();

            smc.startTransaction();

            switch (mode) {

            case INSERT: smc.insert("insertUser", arg); break;

            case UPDATE: smc.update("updateUser", arg); break;

            case DELETE: smc.delete("deleteUser", arg); break;

            }

            smc.commitTransaction();

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            endTransaction(smc);

        }

    }

    public void listUsers() {

        SqlMapClient smc = null;

        try {

            smc = getSqlMapClient();

            smc.startTransaction();

            List users = smc.queryForList("getAllUsers", null);

            System.out.println(users);

            smc.commitTransaction();

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            endTransaction(smc);

        }

    }

    public User selectUser(int id) {

        User user = null;

        SqlMapClient smc = null;

        try {

            smc = getSqlMapClient();

            smc.startTransaction();

            user = (User) smc.queryForObject("getUser", id);

            smc.commitTransaction();

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            endTransaction(smc);

        }

        return user;

    }

    // ////////////////////////////////////////////////////////////////////////

    // Don't care

    // ////////////////////////////////////////////////////////////////////////

    private SqlMapClient getSqlMapClient() throws IOException {

        // 初始化ibatis, 获得一个SqlMapClient对象

        String resource = "SqlMapConfig.xml";

        Reader reader = Resources.getResourceAsReader(resource);

        return SqlMapClientBuilder.buildSqlMapClient(reader);

    }

    private void endTransaction(SqlMapClient smc) {

        if (smc == null) { return; }

        try {

            smc.endTransaction();

        } catch (Exception e2) {

            e2.printStackTrace();

        }

    }

    public static void main(String[] args) {

        Test t = new Test();

        t.listUsers();

        User user = new User("Biao");

        user = t.selectUser(7);

        user.setName("Biao 黄河");

        t.update(user, Mode.UPDATE);

        // t.update(user, Mode.INSERT);

        // t.update(Integer.valueOf(7), Mode.DELETE);

        t.listUsers();

    }

}