XML配置
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd">
<util:properties id="mongoProperties" location="file:///storage/local.properties" />
<bean id="mongoService" class="com.business.persist.MongoService"></bean>
</beans>
和MongoService看起来像
@Service
public class MongoService {
@Value("#{mongoProperties[host]}")
private String host;
@Value("#{mongoProperties[port]}")
private int port;
@Value("#{mongoProperties[database]}")
private String database;
private Mongo mongo;
private static final Logger LOGGER = LoggerFactory.getLogger(MongoService.class);
public MongoService() throws UnknownHostException {
LOGGER.info("host=" + host + ", port=" + port + ", database=" + database);
mongo = new Mongo(host, port);
}
public void putDocument(@Nonnull final DBObject document) {
LOGGER.info("inserting document - " + document.toString());
mongo.getDB(database).getCollection(getCollectionName(document)).insert(document, WriteConcern.SAFE);
}
我写我的MongoServiceTest为
public class MongoServiceTest {
@Autowired
private MongoService mongoService;
public MongoServiceTest() throws UnknownHostException {
mongoRule = new MongoRule();
}
@Test
public void testMongoService() {
final DBObject document = DBContract.getUniqueQuery("001");
document.put(DBContract.RVARIABLES, "values");
document.put(DBContract.PVARIABLES, "values");
mongoService.putDocument(document);
}
我认为测试失败
12:37:25.224 [main] INFO c.s.business.persist.MongoService - host=null, port=0, database=null
java.lang.NullPointerException
at com.business.persist.MongoServiceTest.testMongoService(MongoServiceTest.java:40)
这意味着Bean无法从local.properties中读取值
local.properties
### === MongoDB interaction === ###
host="127.0.0.1"
port=27017
database=contract
我该如何解决?
更新
即使在为字段创建了setters / getters之后,似乎也没有读取这些值。我现在真的很笨。
更新01
在添加init()方法并将其添加到bean之后,它的stil不起作用。我什至都看不到日志消息
XML格式
<bean id="mongoService" class="com.business.persist.MongoService" init-method="init"></bean>
MongoService
@Service
public class MongoService {
@Value("#{mongoProperties['host']}")
private String host;
@Value("#{mongoProperties['port']}")
private int port;
@Value("#{mongoProperties['database']}")
private String database;
private Mongo mongo;
private static final Logger LOGGER = LoggerFactory.getLogger(MongoService.class);
public MongoService() {}
public void init() throws UnknownHostException {
LOGGER.info("host=" + host + ", port=" + port + ", database=" + database);
mongo = new Mongo(host, port);
}
public void putDocument(@Nonnull final DBObject document) {
LOGGER.info("inserting document - " + document.toString());
mongo.getDB(database).getCollection(getCollectionName(document)).insert(document, WriteConcern.SAFE);
}
我该如何调试这个问题?
非常感谢!
最佳答案
我在这里看到一个问题,您正在实例化MongoService
构造函数中的Mongo类,但是此时您的属性尚未基于local.properties
文件注入,因此host,port和database的值将为空那里。
相反,您可以做的是不实例化Service构造函数中的Mongo类,让属性按照您执行的方式注入到MongoService中,然后将其创建为init方法的一部分,该方法在设置属性后被调用:
在MongoService中:
public void init(){
mongo = new Mongo(host, port);
}
并在您的bean配置中:
<bean id="mongoService" class="com.business.persist.MongoService" init-method="init"></bean>
关于java - Spring:使用@Value注释时,Bean无法从外部属性文件中读取值,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/11268049/