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,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,也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,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。也推荐几篇文章:

  1.     Maven介绍及安装和在eclipse中的配置
  2.     Eclipse中使用Maven创建基本的web项目
  3.     Eclipse搭建Maven工程集成Spring4MVC
  4.     Eclipse搭建Maven工程集成Spring4+MVC+Hibernate5
  5.     JPA规范介绍及实例(Java数据持久化解决方案)

    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:

    001

    勾选为简单的工程(Create a simple project),Next:

    002

    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:

    003

    这是得到的工程目录结构是这样的:

    004

    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...:

    005

    在右边,我们勾选Dynamic Web Module(动态网页),然后点OK:

    006

    这时会多出一个WebContent目录:

    007

    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:

    008

    这时,就可以右键工程,Run On Server了,可以看下效果:

    10

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:

    11

    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:009

    这时候就可以运行测试了,效果如下:

    12

    13

    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:

    14

    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:

18

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:

    15

    16

17

    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+"%")!


源码:

    github地址:https://github.com/anxpp/SpringMVC-SpringDataJpa-Hibernate-Demo

    本地下载:SpringMVC + Spring Data JPA + Hibernate

    CSDN下载(不需要积分):http://download.csdn.net/download/anxpp/9520498