spring data jpa 搭建 从最基本的Java工程搭建SpringMVC+SpringDataJPA+Hibernate
anxpp 人气:0本文会介绍从一个最基本的java工程,到Web工程,到集成Spring、SpringMVC、SpringDataJPA+Hibernate。
平时我们可能是通过一个模板搭建一个工程,或者是直接导入一个项目,而本文选择从最基本的java工程开始,目的是为了展示更多原理。
当然,我们还是从一个最基本的Maven工程开始,其实普通的非Maven工程,搭建过程几乎是一模一样的,只是Jar包需要我们手动的添加到工程中,而Maven工程就只是修改配置文件即可。
下面就正式开始。
1、基于Maven(如果不使用Maven也可以用传统的工程)创建最基本的Java工程
新建工程,选择Maven Project,Next:
勾选为简单的工程(Create a simple project),Next:
Group id为你的域名反序,通常跟工程源码的包名对应,Artifact id为这个Group id中工程的唯一名,根据你的爱好,怎么填都行,然后Finish:
这是得到的工程目录结构是这样的:
pom.xml就是Maven的核心文件。
2、将工程设置为动态网页模式
接下来就将工程转换为Web工程,右键打开工程属性,如图,点击左边菜单中的Project Facets,然后点击Convert to faceted from...:
在右边,我们勾选Dynamic Web Module(动态网页),然后点OK:
这时会多出一个WebContent目录:
在WEB-INF目录下,添加web.xml文件,内如如下:
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <display-name>SpringDataJPA</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> </web-app>
然后添加一个欢迎页index.html:
<html> <head> </head> <body> <h1>Hello Word!</h1> </body> </html>
这时目录结构如下:
这时,就可以右键工程,Run On Server了,可以看下效果:
3、集成Spring+SpringMVC
新建包,并添加一些接口和类(具体代码后面会列出来),包结构如图:
需要添加jar包,直接修改pom文件即可,如果为普通工程,按pom.xml中的jar包,添加到工程中即可。
首先添加使用的spring版本,方便统一管理,然后再添加所有需要的jar包,下面把此处需要的所有jar包添加进来,完成后的pom.xml如下:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.anxpp</groupId> <artifactId>SpringDataJPA</artifactId> <version>0.0.1-SNAPSHOT</version> <properties> <!-- spring版本号 --> <spring.version>4.2.5.RELEASE</spring.version> </properties> <dependencies> <!-- spring核心包 --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aop</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-jpa</artifactId> <version>1.10.1.RELEASE</version> </dependency> </dependencies> </project>
在WEB-INF目录下添加Spring配置文件applicationContext.xml,并添加如下内容:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd"> <!-- 开启IOC注解扫描 --> <context:component-scan base-package="com.anxpp.demo" /> <!-- 开启MVC注解扫描 --> <mvc:annotation-driven /> </beans>
修改web.xml,将spring添加进去:
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> <display-name>SpringDataJPA</display-name> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <context-param> <param-name>contextConfigLocation</param-name> <param-value>WEB-INF/applicationContext.xml</param-value> </context-param> <servlet> <servlet-name>springmvc</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet </servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath*:springmvc-servlet.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>springmvc</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> </web-app>
下面开始编写代码,注意注解不要忘记写,在本小节开始部分已经给出了包的层次结构。
实体User:
package com.anxpp.demo.core.entity; public class User { private Integer id; private String name; public User(Integer id, String name) { this.id = id; this.name = name; } public Integer getId() { return id; } public void setId(Integer 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; } }
dao层接口UserDao:
package com.anxpp.demo.core.dao; import com.anxpp.demo.core.entity.User; public interface UserDao { User getUser(Integer id,String name); }
dao层实现UserDaoImpl:
package com.anxpp.demo.core.dao.impl; import org.springframework.stereotype.Repository; import com.anxpp.demo.core.dao.UserDao; import com.anxpp.demo.core.entity.User; @Repository public class UserDaoImpl implements UserDao{ @Override public User getUser(Integer id, String name) { return new User(id, name); } }
service层接口UserService:
package com.anxpp.demo.core.service; import com.anxpp.demo.core.entity.User; public interface UserService { User getUser(Integer id, String name); }
service层实现:
package com.anxpp.demo.core.service.impl; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.anxpp.demo.core.dao.UserDao; import com.anxpp.demo.core.entity.User; import com.anxpp.demo.core.service.UserService; @Service public class UserServiceImpl implements UserService{ @Autowired UserDao userDao; @Override public User getUser(Integer id, String name) { return userDao.getUser(id, name); } }
controller层DemoController:
package com.anxpp.demo.controller; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody; import com.anxpp.demo.core.service.UserService; @Controller @RequestMapping("/") public class demoController { @Autowired UserService userService; @RequestMapping("/") @ResponseBody public String index(){ return "index"; } @RequestMapping("/getuser") @ResponseBody public String getUser(Integer id, String name){ return userService.getUser(id, name).toString(); } }
这是还不能直接Run On Server,因为jar包不会被一同发布,我们需要如下配置:
右键工程选择属性,按下图配置:
这时候就可以运行测试了,效果如下:
到这里,我们还没有操作数据库的。
4、添加返回Json格式数据支持
现在,我们常使用json作为数据传输的格式,下面就为SpringMVC添加返回json的支持
首先添加jar包:
<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.5.0</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.5.0</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.5.0</version> </dependency>
然后改写getUser()方法如下:
@RequestMapping("/getuser") @ResponseBody public Map<String, Object> getUser(Integer id, String name){ Map<String, Object> map = new HashMap<String, Object>(); map.put("state", "success"); map.put("data", userService.getUser(id, name)); return map; }
重新运行后访问效果如下:
此时,就可以返回json数据了。
5、配置静态资源访问
通常情况下,WEB-INF目录下的资源,我们是无法直接访问的,如果我们的网站是html+ajax构成的,那么就可以在WEB-INF之外新建html的目录,并为web.xml配置默认的过滤器,不过注意要放到SpingMVC过滤器之前:
<servlet-mapping> <servlet-name>default</servlet-name> <url-pattern>*.html</url-pattern> </servlet-mapping>
如果一定要访问WEB-INF目录内的资源,通过查阅Spring官方文档,发现有两种方式
1、手写一个资源映射器:
@Configuration @EnableWebMvc public class WebConfig extends WebMvcConfigurerAdapter { @Override public void addResourceHandlers(ResourceHandlerRegistry registry) { registry.addResourceHandler("/resources/**") .addResourceLocations("/public-resources/") .setCacheControl(CacheControl.maxAge(1, TimeUnit.HOURS).cachePublic()); } }
可以看到,还可以设置缓存时间的,而更简单的方式,就是xml配置:
<mvc:resources mapping="/resources/**" location="/public-resources/"> <mvc:cache-control max-age="3600" cache-public="true"/> </mvc:resources>
也可以加上下面的这个:
<!-- 对静态资源文件的访问,将无法mapping到Controller的path交给default servlet handler处理--> <mvc:default-servlet-handler />
6、乱码解决
我们通常使用ajax提交请求,但也常用地址栏直接测试。请求提交分get和post。
使用post提交请求是,一般是不会出现中文乱码的,但是如果确实出现了乱码,可以通过在web.xml添加一个编码过滤器解决:
<filter> <filter-name>CharacterEncoding</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>CharacterEncoding</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>
上面只能解决post的中文乱码,对于get(含浏览器地址栏直接提交方式),我们需要修改tomcat配置,在conf目录下的server.xml中找到并如下修改:
<Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443" URIEncoding="UTF-8"/>
如果我们只是测试,项目并没有部署,可以直接在eclipse中的server下,找到server.xml,做出上面一样的改动即可:
7、整合SpringDataJPA+Hibernate
你可以通过这篇文字了解JPA:JPA规范介绍及实例(Java数据持久化解决方案)
SpringDataJPA也正是这样一种轻量级的解决方案,而首选的Hibernate就实现了JPA。
首先还是jar包,SpringDataJPA的jar包,在之前整合Spring时已经一并加入,下面是Hibernate(和mysql驱动)的jar包.
<!-- hibernate --> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>${hibernate.version}</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-ehcache</artifactId> <version>${hibernate.version}</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-entitymanager</artifactId> <version>${hibernate.version}</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-c3p0</artifactId> <version>${hibernate.version}</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.9</version> </dependency>
统一管理的版本为:
<!-- hibernate 版本号 --> <hibernate.version>5.1.0.Final</hibernate.version>
添加Jpa的配置文件persistence.xml到META-INF目录下,本文介绍时数据库使用MySQL。并添加如下内容:
<?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="demo" transaction-type="RESOURCE_LOCAL"> <!-- provider>org.eclipse.persistence.jpa.PersistenceProvider</provider --> <provider>org.hibernate.ejb.HibernatePersistence</provider> <class>com.ninelephas.meerkat.pojo.User</class> <!-- MYSql 的连接 --> <properties> <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" /> <property name="hibernate.connection.url" value="jdbc:mysql://127.0.0.1:3306/demo?createDatabaseIfNotExist=true" /> <property name="hibernate.connection.username" value="root" /> <property name="hibernate.connection.password" value="root" /> <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" /> </properties> </persistence-unit> </persistence>
Spring配置文件applicationContext.xml中增加JPA支持后的完整内容:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:jpa="http://www.springframework.org/schema/data/jpa" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd"> <!-- 开启IOC注解扫描 --> <context:component-scan base-package="com.anxpp.demo" /> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="generateDdl" value="true" /> <property name="database" value="MYSQL" /> </bean> </property> <property name="persistenceUnitName" value="demo" /> </bean> <!-- 开启MVC注解扫描 --> <mvc:annotation-driven /> <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver"> <property name="viewResolvers"> <list> <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="prefix" value="/WEB-INF/view/" /> <property name="suffix" value=".html" /> </bean> </list> </property> <!-- 用于将对象转换为 JSON --> <property name="defaultViews"> <list> <bean class="org.springframework.web.servlet.view.json.MappingJackson2JsonView" /> </list> </property> </bean> <!-- 对静态资源文件的访问,将无法mapping到Controller的path交给default servlet handler处理 --> <mvc:default-servlet-handler /> <!-- 配置事务管理器 --> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> <!-- 启用 annotation事务 --> <tx:annotation-driven transaction-manager="transactionManager" /> <!-- 配置Spring Data JPA扫描目录 --> <jpa:repositories base-package="com.anxpp.demo" /> </beans>
修改实体:
package com.anxpp.demo.core.entity; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table public class User { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Integer id; private String name; public User() { } public User(String name) { this.name = name; } public Integer getId() { return id; } public void setId(Integer 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; } }
可以删掉dao层实现了,我们记住将dao层接口继承自强大的JpaRepository:
public interface UserDao extends JpaRepository<User, Serializable>{ User findById(Integer id); }
是不是看上去特别简洁,而且都不需要写实现的,SpringDataJPA会自动帮我们完成。
修改service层接口:
package com.anxpp.demo.core.service; import java.util.List; import com.anxpp.demo.core.entity.User; public interface UserService { User findById(Integer id); User save(String name); List<User> findAll(); }
修改service层实现:
package com.anxpp.demo.core.service.impl; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.anxpp.demo.core.dao.UserDao; import com.anxpp.demo.core.entity.User; import com.anxpp.demo.core.service.UserService; @Service public class UserServiceImpl implements UserService{ @Autowired UserDao userDao; @Override public User findById(Integer id) { return userDao.findById(id); } @Override public User save(String name) { return userDao.save(new User(name)); } @Override public List<User> findAll() { return userDao.findAll(); } }
修改controller,提供多个测试接口:
package com.anxpp.demo.controller; import java.util.HashMap; import java.util.Map; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody; import com.anxpp.demo.core.service.UserService; @Controller @RequestMapping("/") public class demoController { @Autowired UserService userService; @RequestMapping("/") @ResponseBody public String index(){ return "index"; } @RequestMapping("/info") public String info(){ return "info"; } @RequestMapping("/findall") @ResponseBody public Map<String, Object> getUser(){ Map<String, Object> map = new HashMap<String, Object>(); map.put("state", "success"); map.put("data", userService.findAll()); return map; } @RequestMapping("/findbyid") @ResponseBody public Map<String, Object> findById(Integer id){ Map<String, Object> map = new HashMap<String, Object>(); map.put("state", "success"); map.put("data", userService.findById(id)); return map; } @RequestMapping("/add") @ResponseBody public Map<String, Object> save(String name){ Map<String, Object> map = new HashMap<String, Object>(); map.put("state", "success"); map.put("data", userService.save(name)); return map; } }
运行效果:
那么,如果需要添加一个查找id大于指定值的指定姓氏的数据呢?
如果是SQL,我们会这样写(?表示参数):
SELECT * FROM user WHERE id>? AND name like '?%';
但是这里,我们连SQL(或者HQL)都可以不用写,直接在dao层接口添加一个方法即可:
List<User> findByIdGreaterThanAndNameLike(Integer id,String name);
你不需要怀疑,上面的方法执行偏偏就是能成功(注意:service实现的使用,调用该方法记得name+"%")!
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