JAVA操作数据库一（Spring data jpa)

总的来说，JAVA操作数据库还是相当方便的。

首先是核心配置文件daoContext.xml

<?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:jdbc="http://www.springframework.org/schema/jdbc"   xmlns:c="http://www.springframework.org/schema/c"   xmlns:context="http://www.springframework.org/schema/context"   xmlns:p="http://www.springframework.org/schema/p"   xmlns:jpa="http://www.springframework.org/schema/data/jpa"   xsi:schemaLocation="http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsdhttp://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.0.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd"><jpa:repositories base-package="db,service" /><bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"  p:dataSource-ref="dataSource"  p:persistenceUnitName="mypersistest"  p:packagesToScan="entity"  p:jpaVendorAdapter-ref="jpaVendorAdapter"/><bean id="jpaVendorAdapter" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"><property name="database" value="ORACLE" /><property name="showSql" value="true" /><property name="generateDdl" value="true" /></bean><bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"/><!-- PropertyPlaceholderConfigurer是一个容器后处理器，它会读取属性文件信息，并将这些信息设置成Spring配置文件的数据。 --><bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"><property name="locations"><list><value>classpath:my.properties</value><!-- 如果有多个属性文件,依次在下面列出来 --><!--value>dbconn.properties</value--></list></property></bean><!-- Simple implementation of the standard JDBC DataSource interface,       configuring the plain old JDBC DriverManager via bean properties --><bean id="dataSource" class="oracle.jdbc.pool.OracleDataSource"><property name="URL" value="${url}" /><property name="user" value="${username}" /><property name="password" value="${password}" /><property name="implicitCachingEnabled" value="true"/><property name="fastConnectionFailoverEnabled" value="true"/></bean></beans>

my.properties里面的内容非常简单

driverClassName=oracle.jdbc.driver.OracleDriverurl=jdbc:oracle:thin:@127.0.0.1:1521:orclusername=mynamepassword=mypassword

然后我们需要一个实体类，就是数据库的表名，我叫做MyEntity，代码如下

import javax.persistence.*;import java.math.BigDecimal;@Entitypublic class MyEntity {    @Id    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "prooduct_id_seq")    @SequenceGenerator(name="prooduct_id_seq", sequenceName = "PRODUCT_ID_SEQ", allocationSize = 100)    private Integer id;    @Version    private Integer version;    private String testString;    private BigDecimal testNumber;    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public Integer getVersion() {        return version;    }    public void setVersion(Integer version) {        this.version = version;    }    public String getTestString() {        return testString;    }    public void setTestString(String testString) {        this.testString = testString;    }    public BigDecimal getTestNumber() {        return testNumber;    }    public void setTestNumber(BigDecimal testNumber) {        this.testNumber = testNumber;    }}

有了表。我们还需要对表的操作。

这就更加简单了

public interface MyEntityRepository extends JpaRepository<MyEntity, Long> {

//里面可以写各种复杂函数。暂时我们就先用一些基本的操作，所以无需写任何代码}

最后在我们的服务类中进行测试

public class MyService {    @Autowired    MyEntityRepository myEntityRepository;    public String processCommand(String anything)    {        String str = "hello";        List<MyEntity> myEntityList = myEntityRepository.findAll();        return str;    }}

一切OK。成功拿到了表里数据（表里的数据可以用工具直接写入数据库）

真的是太轻松了。都没几行代码。如果有人设计好了数据库，用Hibernate是可以直接生成MyEntity的类，也是说。对数据库进行操作，基本不用写啥代码，增删改查都有了。

最后补下缺失的代码

import net.sf.json.JSONObject;import org.springframework.web.bind.annotation.*;import org.springframework.web.context.ContextLoader;import org.springframework.web.context.WebApplicationContext;import org.springframework.web.servlet.config.annotation.EnableWebMvc;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import service.MyService;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpSession;@RestController@EnableWebMvc@RequestMapping(value = "mytest")public class MyController {    public MyController() {        wac = ContextLoader.getCurrentWebApplicationContext();    }    WebApplicationContext wac;    private static final Logger logger = LoggerFactory.getLogger(MyController.class);    @RequestMapping(value = "/{anything}",  method = RequestMethod.POST, produces="application/json;charset=UTF-8")    public Object myServiceControl(HttpServletRequest request, HttpSession session, @PathVariable String anything)    {        String jsonRet = "hello";        logger.info(request.getMethod());        logger.info("anything is " + anything ) ;        try{            MyService  myService = (MyService)wac.getBean("myService");            jsonRet = myService.processCommand(anything);        }catch(Exception e){            JSONObject jsonObject = new JSONObject();            e.printStackTrace();            jsonObject.put("result" , "-1");            jsonObject.put("desc" , e.toString());            return jsonObject.toString();        }        logger.info("end");        logger.info(jsonRet);        return jsonRet;    }}

pom.xml

<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/maven-v4_0_0.xsd">  <modelVersion>4.0.0</modelVersion>  <groupId>TestDataBaseGroup2</groupId>  <artifactId>TestDataBaseArt2</artifactId>  <packaging>war</packaging>  <version>1.0-SNAPSHOT</version>  <name>TestDataBaseArt Maven Webapp</name>  <url>http://maven.apache.org</url>  <dependencies>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>4.12</version>      <scope>test</scope>    </dependency>    <!-- oracle -->    <dependency>      <groupId>com.oracle</groupId>      <artifactId>ojdbc6</artifactId>      <version>11.2.0</version>    </dependency>    <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->    <dependency>      <groupId>mysql</groupId>      <artifactId>mysql-connector-java</artifactId>      <version>6.0.5</version>    </dependency>    <!-- spring -->    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-webmvc</artifactId>      <version>4.3.4.RELEASE</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-orm</artifactId>      <version>4.3.4.RELEASE</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-aspects</artifactId>      <version>4.3.4.RELEASE</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-test</artifactId>      <version>4.3.4.RELEASE</version>    </dependency>    <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-context</artifactId>      <version>4.3.4.RELEASE</version>    </dependency>    <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-jpa -->    <dependency>      <groupId>org.springframework.data</groupId>      <artifactId>spring-data-jpa</artifactId>      <version>1.10.6.RELEASE</version>    </dependency>    <!-- https://mvnrepository.com/artifact/org.springframework.session/spring-session -->    <dependency>      <groupId>org.springframework.session</groupId>      <artifactId>spring-session</artifactId>      <version>1.2.2.RELEASE</version>    </dependency>    <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-elasticsearch -->    <dependency>      <groupId>org.springframework.data</groupId>      <artifactId>spring-data-elasticsearch</artifactId>      <version>2.0.5.RELEASE</version>    </dependency>    <!-- hibernate -->    <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->    <dependency>      <groupId>org.hibernate</groupId>      <artifactId>hibernate-core</artifactId>      <version>5.2.5.Final</version>    </dependency>    <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-c3p0 -->    <dependency>      <groupId>org.hibernate</groupId>      <artifactId>hibernate-c3p0</artifactId>      <version>5.2.5.Final</version>    </dependency>    <!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic -->    <dependency>      <groupId>ch.qos.logback</groupId>      <artifactId>logback-classic</artifactId>      <version>1.1.8</version>    </dependency>    <!-- servlet -->    <dependency>      <groupId>javax.servlet</groupId>      <artifactId>servlet-api</artifactId>      <version>2.5</version>    </dependency>    <dependency>      <groupId>javax.servlet</groupId>      <artifactId>jstl</artifactId>      <version>1.2</version>    </dependency>    <!-- https://mvnrepository.com/artifact/javax.inject/javax.inject -->    <dependency>      <groupId>javax.inject</groupId>      <artifactId>javax.inject</artifactId>      <version>1</version>    </dependency>    <!-- https://mvnrepository.com/artifact/com.h2database/h2 -->    <dependency>      <groupId>com.h2database</groupId>      <artifactId>h2</artifactId>      <version>1.4.193</version>    </dependency>    <!-- json -->    <dependency>      <groupId>net.sf.json-lib</groupId>      <artifactId>json-lib</artifactId>      <version>2.3</version>      <classifier>jdk15</classifier>    </dependency>  </dependencies>  <build>    <finalName>OnlyMyTest</finalName>  </build></project>

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"        xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"        version="3.1">  <display-name>Archetype Created Web Application</display-name>  <listener>    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>  </listener>  <context-param>    <param-name>contextConfigLocation</param-name>    <param-value>classpath:applicationContext.xml,classpath:daoContext.xml</param-value>  </context-param>  <servlet>    <servlet-name>mvc-dispatcher</servlet-name>    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>    <init-param>      <param-name>contextConfigLocation</param-name>      <param-value>classpath:mvc-dispatcher-servlet.xml</param-value>    </init-param>    <load-on-startup>1</load-on-startup>  </servlet>  <servlet-mapping>    <servlet-name>mvc-dispatcher</servlet-name>    <url-pattern>/</url-pattern>  </servlet-mapping></web-app>

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   xmlns="http://www.springframework.org/schema/beans"   xmlns:p="http://www.springframework.org/schema/p"   xmlns:c="http://www.springframework.org/schema/c"   xmlns:tx="http://www.springframework.org/schema/tx"   xmlns:task="http://www.springframework.org/schema/task"   xmlns:aop="http://www.springframework.org/schema/aop"   xmlns:context="http://www.springframework.org/schema/context"   xsi:schemaLocation="http://www.springframework.org/schema/beans      http://www.springframework.org/schema/beans/spring-beans-4.0.xsd   http://www.springframework.org/schema/tx   http://www.springframework.org/schema/tx/spring-tx-4.0.xsd   http://www.springframework.org/schema/aop   http://www.springframework.org/schema/aop/spring-aop-4.0.xsd   http://www.springframework.org/schema/task       http://www.springframework.org/schema/task/spring-task-3.1.xsd        http://www.springframework.org/schema/context        http://www.springframework.org/schema/context/spring-context.xsd"><!-- 定义Service组件，并将DAO组件注入Service组件 --><bean id="myService" class="service.MyService"/><context:annotation-config /></beans>