Question

我一直试图让这个例子让activejdbc工作无济于事。我的数据库中有表格来使用这段代码，这就是它在我的编辑器中打开时的样子（intellij）：

我删除了一些未被此代码使用的表，因为它只是为了测试不同的项目，而这些表对于这个问题并不重要。

我正在尝试运行的代码如下：

package activejdbc.examples.simple;

import org.javalite.activejdbc.Base;
import org.javalite.activejdbc.DB;
import org.postgresql.Driver;

public class Main {

public static void main(String[] args) {
    try {

        System.out.println(Class.forName("org.postgresql.Driver"));


    } catch (ClassNotFoundException e) {

        System.out.println("Where is your PostgreSQL JDBC Driver? "
                + "Include in your library path!");
        e.printStackTrace();
        return;

    }
    Base.open("org.postgresql.Driver", "jdbc:postgresql://<ip>:<port>/<database_name>", "<database_user>", "<password>");

    Person director  = new Person();
    director.set("name", "Steven Spielberg");
    director.saveIt();

    director.add(new Movie("Saving private Ryan", 1998));
    director.add(new Movie("Jaws", 1982));
    director.getAll(Movie.class).forEach(System.out::println);

    Base.close();
    }
}

根据http://javalite.io/activejdbc#supported-databases

对象（Movie，MoviesPeople，Person）都是空类

这会在运行时出现以下错误：

Connected to the target VM, address: '127.0.0.1:42363', transport: 'socket'
class org.postgresql.Driver
Exception in thread "main" org.javalite.activejdbc.InitException: java.lang.NullPointerException
    at org.javalite.activejdbc.Registry.init(Registry.java:154)
    at org.javalite.activejdbc.Registry.getMetaModel(Registry.java:103)
    at org.javalite.activejdbc.ModelDelegate.metaModelOf(ModelDelegate.java:289)
    at org.javalite.activejdbc.Model.<init>(Model.java:79)
    at activejdbc.examples.simple.Person.<init>(Person.java:10)
    at activejdbc.examples.simple.Main.main(Main.java:25)
Caused by: java.lang.NullPointerException
    at org.postgresql.jdbc2.AbstractJdbc2DatabaseMetaData.getColumns(AbstractJdbc2DatabaseMetaData.java:2502)
    at org.postgresql.jdbc4.AbstractJdbc4DatabaseMetaData.getColumns(AbstractJdbc4DatabaseMetaData.java:99)
    at org.javalite.activejdbc.Registry.fetchMetaParams(Registry.java:198)
    at org.javalite.activejdbc.Registry.init(Registry.java:138)
    ... 5 more
Disconnected from the target VM, address: '127.0.0.1:42363', transport: 'socket'

似乎永远不会建立数据库连接，并且无法从activejdbc创建/调用对象。但我不知道这里出了什么问题，我觉得它应该有效，我知道我的数据库使用的url是正确的，因为它在我的编辑器中可以连接到数据库。而且司机显然在那里工作，因为我的检查不会失败。有什么建议吗？

PS：这是我的pom.xml，如果这有助于解决这个问题：

<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>com.heroku.sample</groupId>
<artifactId>webappRunnerSample</artifactId>
<version>1.0-SNAPSHOT</version>
<name>webappRunnerSample Maven Webapp</name>
<packaging>war</packaging>
<url>http://maven.apache.org</url>
<properties>
    <activejdbc.version>2.1-SNAPSHOT</activejdbc.version>
    <environments>development.test,development</environments>
</properties>
<build>
    <finalName>webappRunnerSample</finalName>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.6.0</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.javalite</groupId>
            <artifactId>activejdbc-instrumentation</artifactId>
            <version>2.0</version>
            <executions>
                <execution>
                    <phase>process-classes</phase>
                    <goals>
                        <goal>instrument</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
        <plugin>
            <groupId>org.javalite</groupId>
            <artifactId>db-migrator-maven-plugin</artifactId>
            <version>2.0</version>
            <configuration>
                <configFile>
                    ${project.basedir}/src/main/resources/database.properties
                </configFile>
                <environments>${environments}</environments>
            </configuration>
            <executions>
                <execution>
                    <id>dev_migrations</id>
                    <phase>validate</phase>
                    <goals>
                        <goal>migrate</goal>
                    </goals>
                </execution>
            </executions>
            <dependencies>
                <dependency>
                    <groupId>postgresql</groupId>
                    <artifactId>postgresql</artifactId>
                    <version>9.1-901-1.jdbc4</version>
                </dependency>
                <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
                    <version>5.1.34</version>
                </dependency>
            </dependencies>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>2.18.1</version>
            <configuration>
                <reportFormat>brief</reportFormat>
                <trimStackTrace>true</trimStackTrace>
                <useFile>false</useFile>
                <includes>
                    <include>**/*Spec*.java</include>
                    <include>**/*Test*.java</include>
                </includes>
                <excludes>
                    <exclude>**/helpers/*</exclude>
                    <exclude>**/*$*</exclude>
                </excludes>

            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-dependency-plugin</artifactId>
            <version>2.3</version>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>copy</goal>
                    </goals>
                    <configuration>
                        <artifactItems>
                            <artifactItem>
                                <groupId>com.github.jsimone</groupId>
                                <artifactId>webapp-runner</artifactId>
                                <version>7.0.22</version>
                                <destFileName>webapp-runner.jar</destFileName>
                            </artifactItem>
                        </artifactItems>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>
<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.javalite</groupId>
        <artifactId>activejdbc</artifactId>
        <version>2.0</version>
        <exclusions>
            <exclusion>
                <groupId>opensymphony</groupId>
                <artifactId>oscache</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <version>9.1-901-1.jdbc4</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.34</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>1.8.0-beta1</version>
    </dependency>
    <dependency>
        <groupId>org.codehaus.groovy</groupId>
        <artifactId>groovy</artifactId>
        <version>1.8.3</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.2.3</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.containers</groupId>
        <artifactId>jersey-container-servlet</artifactId>
        <version>2.25.1</version>
    </dependency>

    <dependency>
        <groupId>org.glassfish</groupId>
        <artifactId>javax.json</artifactId>
        <version>1.0.2</version>
    </dependency>

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
        <scope>provided</scope>
    </dependency>

    <dependency>
        <groupId>com.sun.xml.ws</groupId>
        <artifactId>jaxws-rt</artifactId>
        <version>2.2.8</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-core</artifactId>
        <version>2.2.7</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.stream.buffer</groupId>
        <artifactId>streambuffer</artifactId>
        <version>1.5.3</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-impl</artifactId>
        <version>2.2.7</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.ws</groupId>
        <artifactId>policy</artifactId>
        <version>2.3.1</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.gmbal</groupId>
        <artifactId>gmbal-api-only</artifactId>
        <version>3.2.0-b003</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.ha</groupId>
        <artifactId>ha-api</artifactId>
        <version>3.1.9</version>
    </dependency>
</dependencies>
<repositories>
    <repository>
        <id>snapshots1</id>
        <name>JavaLite Snapshots1</name>
        <url>http://repo.javalite.io/</url>
        <snapshots>
            <enabled>true</enabled>
            <updatePolicy>always</updatePolicy>
            <checksumPolicy>warn</checksumPolicy>
        </snapshots>
    </repository>
</repositories>
<pluginRepositories>
    <pluginRepository>
        <id>snapshots2</id>
        <name>JavaLite Snapshots2</name>
        <url>http://repo.javalite.io/</url>
        <snapshots>
            <enabled>true</enabled>
            <updatePolicy>always</updatePolicy>
            <checksumPolicy>warn</checksumPolicy>
        </snapshots>
    </pluginRepository>
</pluginRepositories>

Answer 1

尝试更新的PostgreSQL驱动程序。这是Maven的定义：

SELECT winner
FROM nobel_win
WHERE (SUBJECT='Physics' AND Year=1970 )
OR (SUBJECT='Economics' AND Year=1971);

|        winner |
|---------------|
| Hannes Alfven |
|    Louis Neel |
| Simon Kuznets |

activejdbc的Postgres驱动程序不断抛出nullpointers

1 个答案: