自动装配变量为空 [重复]

Question

这个问题在这里已经有了答案：

为什么我的 Spring @Autowired 字段为空？ (22 个回答)

2年前关闭。

在我的应用程序中，我有自动装配的 dataSource 对象，该对象返回 null。 该对象正在 DAO 类中使用。

Application Flow -> 1.OAConsumer.java开始执行 2.调用service.java 3.调用KafkaDAOImpl类中的insertOffset

用于 eclispe Oxygen 的 IDE。 下面的代码和错误详细信息。

显示错误

java.lang.NullPointerException
    at com.oa.dao.KafkaOffsetDAOImpl.insertOffset(KafkaOffsetDAOImpl.java:36)
    at com.oa.services.Service.savePayload(Service.java:54)
    at com.oa.consumer.OAConsumer.orderConsumer(OAConsumer.java:30)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:170)
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:120)
    at org.springframework.kafka.listener.adapter.HandlerAdapter.invoke(HandlerAdapter.java:48)
    at org.springframework.kafka.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:283)
    at org.springframework.kafka.listener.adapter.BatchMessagingMessageListenerAdapter.invoke(BatchMessagingMessageListenerAdapter.java:146)
    at org.springframework.kafka.listener.adapter.BatchMessagingMessageListenerAdapter.onMessage(BatchMessagingMessageListenerAdapter.java:138)
    at org.springframework.kafka.listener.adapter.BatchMessagingMessageListenerAdapter.onMessage(BatchMessagingMessageListenerAdapter.java:59)
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.doInvokeBatchOnMessage(KafkaMessageListenerContainer.java:1052)
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.invokeBatchOnMessage(KafkaMessageListenerContainer.java:1036)
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.doInvokeBatchListener(KafkaMessageListenerContainer.java:998)
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.invokeBatchListener(KafkaMessageListenerContainer.java:938)
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.invokeListener(KafkaMessageListenerContainer.java:921)
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.pollAndInvoke(KafkaMessageListenerContainer.java:740)
    at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.run(KafkaMessageListenerContainer.java:689)
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

KafkaOffsetDAOImpl.java

package com.oa.dao;

import java.sql.Connection;
import java.util.HashMap;
import java.util.Map;

import javax.sql.DataSource;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
import org.springframework.jdbc.core.namedparam.SqlParameterSource;
import org.springframework.jdbc.core.simple.SimpleJdbcCall;
import org.springframework.jdbc.datasource.DriverManagerDataSource;

import com.oa.model.KafkaOffsetRecord;


public class KafkaOffsetDAOImpl implements KafkaOffsetDAO {

//  @Autowired
//  JdbcTemplate jdbcTemplate;
    
    @Autowired
    DataSource dataSource;

@Override
public boolean insertOffset(KafkaOffsetRecord offsetRecord) {
    
    boolean status=false;
    
    try(Connection connection =dataSource.getConnection()){
    
    if(connection.isValid(10000))
        status= true;
    }catch (Exception e) {
        e.printStackTrace();
        
    }
    
    
    return false;
}

配置文件

package com.oa.config;

import java.sql.SQLException;

import javax.sql.DataSource;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;


@Configuration
public class OracleConfig {
    

    private static final Logger logger = LoggerFactory.getLogger(OracleConfig.class);

    @Value("${spring.datasource.url}")
    private String url;

    @Value("${spring.datasource.username}")
    private String username;

    @Value("${spring.datasource.password}")
    private String password;

    @Value("${spring.datasource.driver-class-name}")
    private String driverClassName;

    @Value("${spring.datasource.maximumPoolSize}")
    private int maxPoolSize;
    
    @Value("${spring.datasource.minimumIdle}")
    private int minIdle;
    
    @Value("${spring.datasource.connectionTimeout}")
    private long connTimeOut;
    
    @Value("${spring.datasource.idleTimeout}")
    private long idleTimeout;
//
    /**
     * See <a href="http://google.com">http://www.baeldung.com/hikaricp</a>
     */
    @Bean
    public HikariDataSource dataSource() {

        HikariConfig hikariConfig = new HikariConfig();
        hikariConfig.setDriverClassName(driverClassName);
        hikariConfig.setUsername(username);
        hikariConfig.setPassword(password);
        hikariConfig.setJdbcUrl(url);
        hikariConfig.setMaximumPoolSize(maxPoolSize);
        hikariConfig.setConnectionTimeout(connTimeOut);
        hikariConfig.setMinimumIdle(minIdle);
        hikariConfig.setIdleTimeout(idleTimeout);

        HikariDataSource hikariDataSource = new HikariDataSource(hikariConfig);

        if (hikariDataSource.isRunning()) {
            logger.info("------> Oracle DB connection created successfully.");
        }

        return hikariDataSource;

    }

消费者.java

package com.oa.consumer;

import java.util.List;

import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.kafka.support.Acknowledgment;
import org.springframework.kafka.support.KafkaHeaders;
import org.springframework.messaging.handler.annotation.Header;
import org.springframework.messaging.handler.annotation.Payload;

import com.oa.services.OrderService;

public class OAConsumer {

    private static final Logger LOGGER = LoggerFactory.getLogger(OAConsumer.class);

    @KafkaListener(topics = "**removed**", groupId = "**removed**")
    public void orderConsumer(List<ConsumerRecord<String, String>> records, Acknowledgment acknowledgment) {

        LOGGER.debug("START :: orderConsumer");
        OrderService orderService = new OrderService();
        try {

            for (ConsumerRecord<String, String> record : records) {
                LOGGER.debug("Processing Offset Order :: offset={} :: partitionId={} :: topicName={}", record.offset(),
                        record.partition(), record.topic());
                orderService.savePayload(record);
                
            }

            acknowledgment.acknowledge();
            LOGGER.debug("END :: orderConsumer:: Acknowledged");
        } catch (Exception exception) {
            
            exception.printStackTrace();
            LOGGER.error(exception.getMessage());
        }
    }

服务.java

package com.oa.services;

import java.io.IOException;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.oa.dao.KafkaOffsetDAO;
import com.oa.dao.KafkaOffsetDAOImpl;
import com.oa.model.KafkaOffsetRecord;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

public class Service {

    private static final Logger LOGGER = LoggerFactory.getLogger(Service.class);

    public Boolean checkOAEligible(String message, long offset, String topic) throws IOException {

        
        return true;
    }

    public Boolean savePayload(ConsumerRecord<String, String> record) {
        
        LOGGER.debug("START:: saveOrderPayload ::offset= {} :: topic= {}", record.offset(), record.topic());
        
        Boolean status = false;
        KafkaOffsetDAO dao = new KafkaOffsetDAOImpl();
        
        try {
            if (checkOAEligible(record.value(), record.offset(), record.topic())) {

                KafkaOffsetRecord kafkaOffsetRecord= new KafkaOffsetRecord(record);
                
                status = dao.insertOffset(kafkaOffsetRecord);
                                

            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        LOGGER.debug("END:: saveOrderPayload :: offset={} :: topic={} , status={}", record.offset(), record.topic(), status);
        return status;

    }
}

KafkaOffsetRecord

包 com.oa.model;

导入 org.apache.kafka.clients.consumer.ConsumerRecord；

公共类 KafkaOffsetRecord {

long offsetId;
String jsonMsg;
String kafkaSourceType;
int partitionId;
String kafkaTopicName;


public KafkaOffsetRecord() {
    
}

public KafkaOffsetRecord(ConsumerRecord<String, String> consumerRecord) {
    offsetId = consumerRecord.offset();
    jsonMsg = consumerRecord.value();
    partitionId=consumerRecord.partition();
    kafkaTopicName= consumerRecord.topic();
    kafkaSourceType = "TEST";
    
}

public long getOffsetId() {
    return offsetId;
}

public String getJsonMsg() {
    return jsonMsg;
}

public String getKafkaSourceType() {
    return kafkaSourceType;
}

public int getPartitionId() {
    return partitionId;
}

public String getKafkaTopicName() {
    return kafkaTopicName;
}

public void setOffsetId(long offsetId) {
    this.offsetId = offsetId;
}

public void setJsonMsg(String jsonMsg) {
    this.jsonMsg = jsonMsg;
}

public void setKafkaSourceType(String kafkaSourceType) {
    this.kafkaSourceType = kafkaSourceType;
}

public void setPartitionId(int partitionId) {
    this.partitionId = partitionId;
}

public void setKafkaTopicName(String kafkaTopicName) {
    this.kafkaTopicName = kafkaTopicName;
}

}

应用程序属性

spring.datasource.url=jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(LOAD_BALANCE=ON)(FAILOVER=OFF)(ADDRESS=(PROTOCOL=TCP)(HOST=**removed**)(PORT=**removed**))(ADDRESS=(PROTOCOL=TCP)(HOST=**removed**)(PORT=**removed**)))(CONNECT_DATA=(SERVICE_NAME=**removed**)(SERVER=DEDICATED)))
spring.datasource.driver-class-name=oracle.jdbc.OracleDriver
spring.datasource.username=**removed**
spring.datasource.password=**removed**
spring.datasource.type=oracle.jdbc.pool.OracleDataSource
spring.datasource.maximumPoolSize=20
spring.datasource.minimumIdle=5
spring.datasource.connectionTimeout=30000
spring.datasource.idleTimeout=1500000

Answer 1

使用构造函数注入，当你使用它时

public class KafkaOffsetDAOImpl implements KafkaOffsetDAO {


    private final DataSource dataSource;

    @Autowired
    KafkaOffsetDAOImpl(final Datasource datasrouce) {
       this.dataSource = dataSource;
    }

通过这种方式，您可以确定，该弹簧会创建自动装配的字段并将其注入。