maven（04）--一个简单的项目
简单介绍
一个maven项目，使用hibernate框架，实现向mysql数据库中添加和获取操作，其他操作也是类似
如果你没有hibernate，那么也不要紧，这里主要介绍如何在一个maven项目中引入框架
项目流程
1、新建一个maven项目，项目命名为maven-ch04
2、添加相关依赖，如junit、hibernate、mysql驱动、log4j
pom.xml文件添加以下依赖（如果你是第一次加这些依赖，那么需要等一会，这时候IDEA会下载一些相关文件）
如果你不知道如何查找依赖，可以查看maven（02）
<dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.10</version> <scope>test</scope> </dependency> <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core --> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>5.2.10.Final</version> </dependency> <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.38</version> </dependency> <!-- https://mvnrepository.com/artifact/log4j/log4j --> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency> </dependencies>
3、在mysql数据可以新建一个数据库，名称为maven
4、新建实体类User（注意新建包）
package com.simfg.maven.model; /** * Created by SimFG on 2017/5/14. */ public class User { private int id; private String name; private String password; public User() { } public User(String name, String password) { this.name = name; this.password = password; } 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; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
5、在resources文件夹下新建hibernate.cfg.xml（如果没有resource文件夹，则在src下新建；注意修改mysql连接密码；如果你新建数据库名称不为maven，那么你也需要修改连接连接数据库名称）
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- 连接数据库 --> <property name="connection.username">root</property> <!-- mysql的连接密码 --> <property name="connection.password">xxxxx</property> <property name="connection.driver_class">com.mysql.jdbc.Driver</property> <property name="connection.url">jdbc:mysql:///maven?characterEncoding=UTF8&userSSL=true</property> <!-- 配置hibernate的信息 --> <!-- hibernate所使用的数据库方言 --> <property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property> <!-- 执行操作控制台是否打印sql --> <property name="show_sql">true</property> <!-- 格式化sql语句 --> <property name="format_sql">true</property> <!-- 指定自动生成策略 --> <property name="hbm2ddl.auto">update</property> <!-- 指定关联的.hbm.xml --> <mapping resource="com/simfg/maven/model/User.hbm.xml"/> </session-factory> </hibernate-configuration>
6、在该目录下新建一个log4j.properties，内容如下
如果你想详细了解log4j如何配置，可以参照log4j详解
log4j.rootLogger=WARN, stdout, R log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.layout=org.apache.log4j.PatternLayout # Pattern to output the caller's file name and line number. log4j.appender.stdout.layout.ConversionPattern=%d [%t] %-5p %c - %m%n log4j.appender.R=org.apache.log4j.RollingFileAppender log4j.appender.R.File=example.log log4j.appender.R.MaxFileSize=100KB # Keep one backup file log4j.appender.R.MaxBackupIndex=1 log4j.appender.R.layout=org.apache.log4j.PatternLayout log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n # Print only messages of level WARN or above in the package com.foo. log4j.logger.com.foo=WARN
7、在User.java这个文件的同一目录下新建一个User.hbm.xml文件（注意修改class标签中name属性，改成你自己命名的包）
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping > <class name="com.simfg.maven.model.User" table="USER"> <id name="id" type="java.lang.Integer"> <column name="ID" /> <generator class="native" /> </id> <property name="name" type="java.lang.String"> <column name="NAME" /> </property> <property name="password" type="java.lang.String"> <column name="PASSWORD" /> </property> </class> </hibernate-mapping>
8、编写一个HibernateUtil.java文件，注意建立相应的包
package com.simfg.maven.util; import com.simfg.maven.model.User; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.boot.Metadata; import org.hibernate.boot.MetadataSources; import org.hibernate.boot.model.naming.ImplicitNamingStrategyComponentPathImpl; import org.hibernate.boot.registry.StandardServiceRegistry; import org.hibernate.boot.registry.StandardServiceRegistryBuilder; /** * Created by SimFG on 2017/5/14. */ public class HibernateUtil { private static Session session; private static Transaction transaction; private static SessionFactory sessionFactory; public static void startup(){ // 1:创建一个sessionFactory对象 StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder().configure().build(); Metadata metadata = new MetadataSources(standardRegistry).getMetadataBuilder() .applyImplicitNamingStrategy(ImplicitNamingStrategyComponentPathImpl.INSTANCE).build(); sessionFactory = metadata.getSessionFactoryBuilder().build(); // 2:创建一个session对象 session = sessionFactory.openSession(); // 3:开启事务 transaction = session.beginTransaction(); } private static void closeup(){ // 5:提交事务 transaction.commit(); // 6:关闭session session.close(); // 7:关闭sessionFactory sessionFactory.close(); } public static void hibernateSave(User user) throws Exception { startup(); session.save(user); closeup(); } public static User hibernateQuery(){ startup(); String sql = "FROM User u WHERE u.name = ?"; User user = (User) session.createQuery(sql).setParameter(0,"sim").uniqueResult(); closeup(); return user; } }
9、编写一个DAO，即UserDao.java
package com.simfg.maven.dao; import com.simfg.maven.model.User; import com.simfg.maven.util.HibernateUtil; /** * Created by SimFG on 2017/5/14. */ public class UserDao{ public void addUser() { try { HibernateUtil.hibernateSave(new User("sim","123456")); } catch (Exception e) { e.printStackTrace(); } } public User loadByUsername() { return HibernateUtil.hibernateQuery(); } }
10、测试，在test中新建一个TestUserDao.java
import com.simfg.maven.dao.UserDao; import com.simfg.maven.model.User; import org.junit.Before; import org.junit.Test; /** * Created by SimFG on 2017/5/14. */ public class TestUserDao { private UserDao userDao; @Before public void setup() { userDao = new UserDao(); } @Test public void add(){ userDao.addUser(); System.out.println(userDao.loadByUsername().getName()); } }
运行add，结果如下图
如果你运行项目出现xxx.hbm.xml未找到
在pom.xml文件加一下代码
<build> <resources> <resource> <directory>src/main/java</directory> <includes> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.xml</include> <include>**/*.properties</include> </includes> </resource> </resources> </build>
