ssm框架學習---mybatis學習檔案結構和程式碼示例
阿新 • • 發佈：2019-02-18
準備工作：mybatis的jar包，資料庫的驅動包，日誌log4j和單元測試的包
開發模式：（1）基於原始dao開發，需要編寫dao介面和dao介面的實現類
（2）基於mapper開發，只需編寫dao介面，但是需要遵守一定規範（對映檔案的名稱空間為dao介面全限定名，介面中的方法，引數型別和返回型別和對映檔案中statement語句輸入引數和輸出引數相對應，注意返回結果為集合比較特殊）
框架的結構：（1）SqlMapConfig.xml(Mybatis的全域性配置檔案，配置資料來源、事務、快取等mybatis執行環境)，配置對映檔案UserMapper.xml,xxxMapper.xml
（2）SqlSessionFactory（會話工廠）用來建立SqlSession
（3）SqlSession (會話)操作資料庫（curd）操作
（4）Executor（執行器）Sqlsession內部通過執行器來操作資料庫
（5）mapped statement(底層封裝物件) 對操作資料庫儲存封裝，包括sql語句，輸入引數、輸出結果型別
工程結構如下：
兩種方式我都寫了，所以這裡會有連個xml對映檔案，並且會有dao和mapper的包，實際開發選擇其中一種（推薦mapper）
首先這裡給出db.properties和log4j.properties這兩個檔案
db.properties
jdbc.driver =com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=admin這裡需要注意一下，在我們開發過程，要使用debug模式# Global logging configuration #\u5728\u5f00\u53d1\u73af\u5883\u4e0b\u65e5\u5fd7\u7ea7\u522b\u8981\u8bbe\u7f6e\u6210DEBUG\uff0c\u751f\u4ea7\u73af\u5883\u8bbe\u7f6e\u6210info\u6216error log4j.rootLogger=DEBUG, stdout # Console output... log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
sqlmapconfig.xml主要放mybatis的配置檔案如下，主要包括二個部分，第一部分為配置資料來源，第二部分為對映檔案配置
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!-- 載入資料庫的配置檔案 -->
<properties resource="db.properties">
<!-- 這中間還可以配置一些其他的屬性，載入時先載入然後再載入外部的配置 -->
</properties>
<!-- 配置資料庫環境 -->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="sqlmap/User.xml"/>
<mapper resource="sqlmap/UserMapper.xml"/>
<!-- 使用批量匯入的方式，需要注意使用mapper代理，並且xml檔案和mapper介面放在同一目錄中-->
</mappers>
</configuration>user.xml
<?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">
<!-- 名稱空間對於使用mapper代理方式很重要 -->
<mapper namespace="test">
<select id="selectUserById" parameterType="int" resultType="com.zcj.po.User">
select * from userinfo where id=#{id}
</select>
</mapper><?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">
<!-- 名稱空間對於使用mapper代理方式很重要 -->
<mapper namespace="com.zcj.mapper.UserMapper">
<select id="selectUserById" parameterType="int" resultType="com.zcj.po.User">
select * from userinfo where id=#{id}
</select>
</mapper>UserDao.java
package com.zcj.dao;
import com.zcj.po.User;
public interface UserDao {
public User selectUserById(int id);
}
package com.zcj.dao;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import com.zcj.po.User;
public class UserDaoImp implements UserDao {
private SqlSessionFactory sqlSessionFactory;
public UserDaoImp(SqlSessionFactory sqlSessionFactory){
this.sqlSessionFactory=sqlSessionFactory;
}
public User selectUserById(int id) {
// TODO Auto-generated method stub
SqlSession sqlSession= sqlSessionFactory.openSession();
User user = sqlSession.selectOne("test.selectUserById",id);
return user;
}
}UserMapper.java
package com.zcj.mapper;
import com.zcj.po.User;
public interface UserMapper {
public User selectUserById(int id);
}mapper方式的測試：
package com.zcj.mapper;
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 org.junit.Before;
import org.junit.Test;
import com.zcj.po.User;
public class UserMapperTest {
private SqlSessionFactory sqlSessionFactory;
@Before
public void setUp() throws Exception {
String resource ="mybatis/SqlMapConfig.xml";
InputStream inputStream =Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void testSelectUserById() {
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user=userMapper.selectUserById(1);
System.out.println(user);
}
}dao方式的測試類似，只需要把sessionFactory傳給dao的構造方法的引數就可以獲取sqlsession了
package com.zcj.dao;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;
import com.zcj.po.User;
public class UserDaoImpTest {
private SqlSessionFactory sqlSessionFactory;
@Before
public void setUp() throws Exception {
String resource ="mybatis/SqlMapConfig.xml";
InputStream inputStream =Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void testSelectUserById() {
UserDaoImp userDaoImp = new UserDaoImp(sqlSessionFactory);
User user=userDaoImp.selectUserById(1);
System.out.println(user);
}
}
User.java
package com.zcj.po;
public class User {
private int id;
private String username;
private String password;
private String sex;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
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 getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
@Override
public String toString() {
return "User [id=" + id + ", password=" + password + ", sex=" + sex
+ ", username=" + username + "]";
}
}
首先需要準備jar包，然後編寫一個配置檔案generator.xml,這裡使用一個方法執行它對應檔案如下：
generator.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
"http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
<context id="testTables" targetRuntime="MyBatis3">
<commentGenerator>
<!-- 是否去除自動生成的註釋 true：是 ： false:否 -->
<property name="suppressAllComments" value="true" />
</commentGenerator>
<!--資料庫連線的資訊：驅動類、連線地址、使用者名稱、密碼 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/mybatis" userId="root"
password="admin">
</jdbcConnection>
<!-- 預設false，把JDBC DECIMAL 和 NUMERIC 型別解析為 Integer，為 true時把JDBC DECIMAL 和
NUMERIC 型別解析為java.math.BigDecimal -->
<javaTypeResolver>
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<!-- targetProject:生成PO類的位置 -->
<javaModelGenerator targetPackage="com.zcj.ssm.po"
targetProject=".\src">
<!-- enableSubPackages:是否讓schema作為包的字尾 -->
<property name="enableSubPackages" value="false" />
<!-- 從資料庫返回的值被清理前後的空格 -->
<property name="trimStrings" value="true" />
</javaModelGenerator>
<!-- targetProject:mapper對映檔案生成的位置 -->
<sqlMapGenerator targetPackage="com.zcj.ssm.mapper"
targetProject=".\src">
<!-- enableSubPackages:是否讓schema作為包的字尾 -->
<property name="enableSubPackages" value="false" />
</sqlMapGenerator>
<!-- targetPackage：mapper介面生成的位置 -->
<javaClientGenerator type="XMLMAPPER"
targetPackage="com.zcj.ssm.mapper"
targetProject=".\src">
<!-- enableSubPackages:是否讓schema作為包的字尾 -->
<property name="enableSubPackages" value="false" />
</javaClientGenerator>
<!-- 指定資料庫表 -->
<table tableName="userinfo" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
<!-- <table schema="" tableName="sys_user"></table>
<table schema="" tableName="sys_role"></table>
<table schema="" tableName="sys_permission"></table>
<table schema="" tableName="sys_user_role"></table>
<table schema="" tableName="sys_role_permission"></table> -->
<!-- 有些表的欄位需要指定java型別
<table schema="" tableName="">
<columnOverride column="" javaType="" />
</table> -->
</context>
</generatorConfiguration>
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.exception.XMLParserException;
import org.mybatis.generator.internal.DefaultShellCallback;
public class GeneratorSqlmap {
public void generator() throws Exception{
List<String> warnings = new ArrayList<String>();
boolean overwrite = true;
//
File configFile = new File("generatorConfig.xml");
ConfigurationParser cp = new ConfigurationParser(warnings);
Configuration config = cp.parseConfiguration(configFile);
DefaultShellCallback callback = new DefaultShellCallback(overwrite);
MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config,
callback, warnings);
myBatisGenerator.generate(null);
}
public static void main(String[] args) throws Exception {
try {
GeneratorSqlmap generatorSqlmap = new GeneratorSqlmap();
generatorSqlmap.generator();
} catch (Exception e) {
e.printStackTrace();
}
}
}