微服務作為Java技術圈最火的技術架構，所以核心SpringBoot作為最基礎單元值得我們好好研究。

PG作為數據庫圈最全面的數據庫，有著全站型數據庫之稱。

在下面這篇文章中，我將介紹如何使用SpringBoot2.0+SpringDataJPA+PostgreSQL構建一個。

我們將使用到如下技術和工具：

首先我們創建一個SpringBoot+SpringDataJPA（先使用H2內存數據庫構建）

1.項目目錄

2. Maven構建

pom.xml 文件中的依賴

<code>
<project>         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
\t\t http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelversion>4.0.0/<modelversion>

    <artifactid>spring-data-jpa/<artifactid>
    <packaging>jar/<packaging>
    <name>Spring Boot Spring Data JPA/<name>
    <version>1.0/<version>

    <parent>
        <groupid>org.springframework.boot/<groupid>
        <artifactid>spring-boot-starter-parent/<artifactid>
        <version>2.1.2.RELEASE/<version>
    /<parent>

    <properties>
        <java.version>1.8/<java.version>
        <downloadsources>true/<downloadsources>
        <downloadjavadocs>true/<downloadjavadocs>
    /<properties>

    <dependencies>

        
        <dependency>
            <groupid>org.springframework.boot/<groupid>
            <artifactid>spring-boot-starter-data-jpa/<artifactid>
        /<dependency>

        
        <dependency>
            <groupid>com.h2database/<groupid>
            <artifactid>h2/<artifactid>
        /<dependency>

        <dependency>
            <groupid>org.springframework.boot/<groupid>
            <artifactid>spring-boot-starter-test/<artifactid>
            <scope>test/<scope> 

        /<dependency>

    /<dependencies>

    <build>
        <plugins>

            <plugin>
                <groupid>org.springframework.boot/<groupid>
                <artifactid>spring-boot-maven-plugin/<artifactid>
            /<plugin>

            <plugin>
                <groupid>org.apache.maven.plugins/<groupid>
                <artifactid>maven-surefire-plugin/<artifactid>
                <version>2.22.0/<version>
            /<plugin>

        /<plugins>

    /<build>
/<project>/<code>

3. 構建Spring Data JPA

Book.java

<code>package com.mkyong;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class Book {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String name;

    public Book() {
    }

    public Book(String name) {
        this.name = name;
    }

    //getters, setters, toString... 

}
複製/<code>

BookRepository.java

<code>package com.mkyong;

import org.springframework.data.repository.CrudRepository;

import java.util.List;

public interface BookRepository extends CrudRepository<book> {

    List<book> findByName(String name);
/<book>/<book>/<code>

4. @SpringBootApplication啟動

4.1啟動Spring Boot，將3本書插入H2數據庫，然後測試該find()方法。

StartApplication.java

<code>package com.mkyong;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class StartApplication implements CommandLineRunner {

    private static final Logger log = LoggerFactory.getLogger(StartApplication.class);

    @Autowired
    private BookRepository repository;

    public static void main(String[] args) {
        SpringApplication.run(StartApplication.class, args);
    }

    @Override
    public void run(String... args) {

        log.info("StartApplication..."); 


        repository.save(new Book("Java"));
        repository.save(new Book("Node"));
        repository.save(new Book("Python"));

        System.out.println("\\nfindAll()");
        repository.findAll().forEach(x -> System.out.println(x));

        System.out.println("\\nfindById(1L)");
        repository.findById(1l).ifPresent(x -> System.out.println(x));

        System.out.println("\\nfindByName('Node')");
        repository.findByName("Node").forEach(x -> System.out.println(x));

    }

}/<code>

5. 使用HikariCP連接池

默認情況下，Spring Boot 2使用HikariCP作為默認連接池。

5.1啟用com.zaxxer調試的日誌記錄級別，它將打印出默認的HikariCP配置。

application.properties

<code>logging.level.org.springframework=INFO
logging.level.com.mkyong=INFO
logging.level.com.zaxxer=DEBUG
logging.level.root=ERROR/<code>

5.2運行Spring Boot，查看日誌：

<code>DEBUG com.zaxxer.hikari.HikariConfig - Driver class org.h2.Driver found in Thread context class loader jdk.internal.loader.ClassLoaders$AppClassLoader@28c97a5
DEBUG com.zaxxer.hikari.HikariConfig - HikariPool-1 - configuration:
DEBUG com.zaxxer.hikari.HikariConfig - allowPoolSuspension.............false
DEBUG com.zaxxer.hikari.HikariConfig - autoCommit......................true
DEBUG com.zaxxer.hikari.HikariConfig - catalog.........................none
DEBUG com.zaxxer.hikari.HikariConfig - connectionInitSql...............none
DEBUG com.zaxxer.hikari.HikariConfig - connectionTestQuery.............none
DEBUG com.zaxxer.hikari.HikariConfig - connectionTimeout...............30000
DEBUG com.zaxxer.hikari.HikariConfig - dataSource......................none
DEBUG com.zaxxer.hikari.HikariConfig - dataSourceClassName.............none
DEBUG com.zaxxer.hikari.HikariConfig - dataSourceJNDI..................none
DEBUG com.zaxxer.hikari.HikariConfig - dataSourceProperties............{password=<masked>} 

DEBUG com.zaxxer.hikari.HikariConfig - driverClassName................."org.h2.Driver"
DEBUG com.zaxxer.hikari.HikariConfig - healthCheckProperties...........{}
DEBUG com.zaxxer.hikari.HikariConfig - healthCheckRegistry.............none
DEBUG com.zaxxer.hikari.HikariConfig - idleTimeout.....................600000
DEBUG com.zaxxer.hikari.HikariConfig - initializationFailTimeout.......1
DEBUG com.zaxxer.hikari.HikariConfig - isolateInternalQueries..........false
DEBUG com.zaxxer.hikari.HikariConfig - jdbcUrl.........................jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
DEBUG com.zaxxer.hikari.HikariConfig - leakDetectionThreshold..........0
DEBUG com.zaxxer.hikari.HikariConfig - maxLifetime.....................1800000
DEBUG com.zaxxer.hikari.HikariConfig - maximumPoolSize.................10
DEBUG com.zaxxer.hikari.HikariConfig - metricRegistry..................none
DEBUG com.zaxxer.hikari.HikariConfig - metricsTrackerFactory...........none
DEBUG com.zaxxer.hikari.HikariConfig - minimumIdle.....................10
DEBUG com.zaxxer.hikari.HikariConfig - password........................<masked>
DEBUG com.zaxxer.hikari.HikariConfig - poolName........................"HikariPool-1"
DEBUG com.zaxxer.hikari.HikariConfig - readOnly........................false
DEBUG com.zaxxer.hikari.HikariConfig - registerMbeans..................false
DEBUG com.zaxxer.hikari.HikariConfig - scheduledExecutor...............none
DEBUG com.zaxxer.hikari.HikariConfig - schema..........................none
DEBUG com.zaxxer.hikari.HikariConfig - threadFactory...................internal
DEBUG com.zaxxer.hikari.HikariConfig - transactionIsolation............default
DEBUG com.zaxxer.hikari.HikariConfig - username........................"sa"
DEBUG com.zaxxer.hikari.HikariConfig - validationTimeout...............5000
INFO  com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Starting...
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn0: url=jdbc:h2:mem:testdb user=SA
INFO  com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Start completed.
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Pool stats (total=1, active=0, idle=1, waiting=0)
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn1: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn2: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn3: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn4: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn5: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn6: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn7: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn8: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn9: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - After adding stats (total=10, active=0, idle=10, waiting=0)
複製/<masked>/<masked>/<code>

5.2我們可以使用spring.datasource.hikari.*覆蓋默認設置。

application.properties

<code>logging.level.org.springframework=INFO
logging.level.com.mkyong=INFO
logging.level.com.zaxxer=DEBUG
logging.level.root=ERROR

spring.datasource.hikari.connectionTimeout=20000 

spring.datasource.hikari.maximumPoolSize=5
spring.datasource.hikari.poolName=HikariPoolZZZ
複製/<code>

6.單元測試

6.1 @DataJpaTest並TestEntityManager測試一個Spring數據JPA存儲庫。

BookRepositoryTest.java

<code>package com.mkyong;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager;
import org.springframework.test.context.junit4.SpringRunner;

import java.util.List;

import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.Assert.assertEquals;

@RunWith(SpringRunner.class)
@DataJpaTest
public class BookRepositoryTest {

    @Autowired
    private TestEntityManager entityManager;

    @Autowired
    private BookRepository repository;

    @Test
    public void testFindByName() {

        entityManager.persist(new Book("C++"));

        List<book> books = repository.findByName("C++");
        assertEquals(1, books.size());

        assertThat(books).extracting(Book::getName).containsOnly("C++");

    }

}
複製/<book>/<code>

7.演示

<code>$ mvn spring-boot:run

INFO  com.mkyong.StartApplication - Started StartApplication in 2.79 seconds (JVM running for 10.883)
INFO  com.mkyong.StartApplication - StartApplication...

findAll()
DEBUG com.zaxxer.hikari.pool.PoolBase - HikariPoolZZZ - Reset (readOnly) on connection conn0: url=jdbc:h2:mem:testdb user=SA
Book{id=1, name='Java'}
Book{id=2, name='Node'}
Book{id=3, name='Python'}

findById(1L)
DEBUG com.zaxxer.hikari.pool.PoolBase - HikariPoolZZZ - Reset (readOnly) on connection conn0: url=jdbc:h2:mem:testdb user=SA
Book{id=1, name='Java'}

findByName('Node')
Book{id=2, name='Node'}/<code>

到這裡構建一個SpringBoot+SpringDataJPA的框架已經完成，但是這裡使用的H2內存數據庫，下面我們要將H2數據庫轉換成PostgreSQL數據庫。

pom.xml修改添加

<code>\t<dependency>
\t\t<groupid>org.postgresql/<groupid>
\t\t<artifactid>postgresql/<artifactid>
\t/<dependency>/<code>

1. Maven

pom.xml

<code>
<project>         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
\t\t http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelversion>4.0.0/<modelversion>

    <artifactid>spring-boot-data-jpa/<artifactid>
    <packaging>jar/<packaging>
    <name>Spring Boot Spring Data JPA/<name>
    <version>1.0/<version>

    <parent>
        <groupid>org.springframework.boot/<groupid>
        <artifactid>spring-boot-starter-parent/<artifactid>
        <version>2.1.2.RELEASE/<version>
    /<parent>

    <properties>
        <java.version>1.8/<java.version>
        <downloadsources>true/<downloadsources>
        <downloadjavadocs>true/<downloadjavadocs>
    /<properties>

    <dependencies>

        
        <dependency>
            <groupid>org.springframework.boot/<groupid>
            <artifactid>spring-boot-starter-data-jpa/<artifactid>
        /<dependency>

         

        <dependency>
            <groupid>org.postgresql/<groupid>
            <artifactid>postgresql/<artifactid>
        /<dependency>

        <dependency>
            <groupid>org.springframework.boot/<groupid>
            <artifactid>spring-boot-starter-test/<artifactid>
            <scope>test/<scope>
        /<dependency>

    /<dependencies>

    <build>
        <plugins>

            <plugin>
                <groupid>org.springframework.boot/<groupid>
                <artifactid>spring-boot-maven-plugin/<artifactid>
            /<plugin>

            <plugin>
                <groupid>org.apache.maven.plugins/<groupid>
                <artifactid>maven-surefire-plugin/<artifactid>
                <version>2.22.0/<version>
            /<plugin>

        /<plugins>

    /<build>
/<project>/<code>

2. 配置 PostgreSQL數據庫

application.properties

<code>## default connection pool
spring.datasource.hikari.connectionTimeout=20000
spring.datasource.hikari.maximumPoolSize=5

## PostgreSQL
spring.datasource.url=jdbc:postgresql://localhost:5432/postgres
spring.datasource.username=postgres
spring.datasource.password=password

#drop n create table again, good for testing, comment this in production
spring.jpa.hibernate.ddl-auto=create/<code>

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關鍵字: PostgreSQL 數據庫 XML