远程JodConverter服务调用报NullPointerException问题求助

将LibreOffice服务部署至公网服务器并开放端口后，项目调用远程JodConverter服务的execute方法时触发NullPointerException，本地部署服务时一切正常，怀疑文件传输环节存在问题，相关信息如下：

错误日志 #

2023-11-09 17:27:58.675 ERROR 15750 --- [ter-poolentry-0] o.j.remote.task.RemoteConversionTask     : Remote conversion failed.

java.lang.NullPointerException: null
    at java.base/java.util.Objects.requireNonNull(Objects.java:221) ~[na:na]
    at org.jodconverter.remote.task.RemoteConversionTask.execute(RemoteConversionTask.java:135) ~[jodconverter-remote-4.3.0.jar:4.3.0]
    at org.jodconverter.remote.office.RemoteOfficeManagerPoolEntry.doExecute(RemoteOfficeManagerPoolEntry.java:306) ~[jodconverter-remote-4.3.0.jar:4.3.0]
    at org.jodconverter.core.office.AbstractOfficeManagerPoolEntry.lambda$execute$0(AbstractOfficeManagerPoolEntry.java:83) ~[jodconverter-core-4.3.0.jar:4.3.0]
    at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264) ~[na:na]
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java) ~[na:na]
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
    at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

org.jodconverter.core.office.OfficeException: Remote conversion failed
    at org.jodconverter.remote.task.RemoteConversionTask.execute(RemoteConversionTask.java:153)
    at org.jodconverter.remote.office.RemoteOfficeManagerPoolEntry.doExecute(RemoteOfficeManagerPoolEntry.java:306)
    at org.jodconverter.core.office.AbstractOfficeManagerPoolEntry.lambda$execute$0(AbstractOfficeManagerPoolEntry.java:83)
    at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.NullPointerException
    at java.base/java.util.Objects.requireNonNull(Objects.java:221)
    at org.jodconverter.remote.task.RemoteConversionTask.execute(RemoteConversionTask.java:135)
    ... 7 more
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.alibaba.fastjson2.util.JDKUtils (file:/Users/jayleonc/Developer/Environment/apache-maven-3.8.4/maven-repo/com/alibaba/fastjson2/fastjson2/2.0.17/fastjson2-2.0.17.jar) to constructor java.lang.invoke.MethodHandles$Lookup(java.lang.Class,int)
WARNING: Please consider reporting this to the maintainers of com.alibaba.fastjson2.util.JDKUtils
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

配置信息 #

jodconverter.
  remote.
    url: http://xxx.xx.xx.xxx:9980
  local: # office-home: /Applications/LibreOffice.app/Contents/
    # office-home: /Applications/LibreOffice.app/Contents/
    enabled: false

配置类代码 #

package com.xxx.supt.infra.config;

import org.jodconverter.core.DocumentConverter;
import org.jodconverter.core.office.OfficeManager;
import org.jodconverter.remote.RemoteConverter;
import org.jodconverter.remote.office.RemoteOfficeManager;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class LibreofficeConfig {

    @Value("${jodconverter.remote.url:''}")
    private String jodconverterUrl;

    @Bean(
        initMethod = "start",
        destroyMethod = "stop"
    )
    public OfficeManager officeManager() {
        RemoteOfficeManager.Builder builder = RemoteOfficeManager.builder();
        builder.urlConnection(jodconverterUrl);
        builder.poolSize(10);
        builder.taskExecutionTimeout(60000L);
        builder.taskQueueTimeout(60000L);
        return builder.build();
    }

    @Bean
    @ConditionalOnMissingBean
    @ConditionalOnBean({OfficeManager.class})
    public DocumentConverter jodConverter(OfficeManager officeManager) {
        return RemoteConverter.make(officeManager);
    }

}

转换方法代码 #

public void convertToPdfAndOutput(File file) throws IOException, OfficeException {
        File tempFile = File.createTempFile("temp", ".pdf");
        converter.convert(file).to(tempFile).execute();
        outputToResponse(tempFile, "application/pdf");
    }

调试converter.convert(file).to(tempFile).execute();时触发错误，需排查问题并解决。

核心问题定位 #

从报错栈看，NPE发生在RemoteConversionTask.java:135，结合JodConverter 4.3.0源码，这一行是处理远程请求响应时发现响应对象为null，主要原因集中在配置解析错误、网络连通性异常或远程服务未正常启动。

具体修复步骤 #

1. 修正YAML配置格式 #

你的配置文件存在格式错误，YAML要求层级用冒号+空格分隔，不能用点号换行，否则Spring无法正确解析jodconverter.remote.url，导致连接地址为空。

修正后的配置：

jodconverter:
  remote:
    url: http://xxx.xx.xx.xxx:9980
  local:
    enabled: false

2. 验证网络与远程服务状态 #

• 在项目部署机器执行curl http://xxx.xx.xx.xxx:9980，检查是否能正常访问远程服务
• 确认公网服务器的防火墙/安全组已开放9980端口，允许项目机器的IP访问
• 查看远程LibreOffice服务日志，确认服务无启动异常，能正常接收请求

3. 优化配置类的参数校验 #

配置类中@Value的默认值为空字符串，可能导致无效连接，建议移除默认值并增加非空校验：

package com.xxx.supt.infra.config;

import org.jodconverter.core.DocumentConverter;
import org.jodconverter.core.office.OfficeManager;
import org.jodconverter.remote.RemoteConverter;
import org.jodconverter.remote.office.RemoteOfficeManager;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.util.Assert;

@Configuration
public class LibreofficeConfig {

    @Value("${jodconverter.remote.url}")
    private String jodconverterUrl;

    @Bean(
        initMethod = "start",
        destroyMethod = "stop"
    )
    public OfficeManager officeManager() {
        // 增加非空校验，避免无效连接
        Assert.notNull(jodconverterUrl, "jodconverter.remote.url 必须配置");
        RemoteOfficeManager.Builder builder = RemoteOfficeManager.builder();
        builder.urlConnection(jodconverterUrl);
        builder.poolSize(10);
        builder.taskExecutionTimeout(60000L);
        builder.taskQueueTimeout(60000L);
        return builder.build();
    }

    @Bean
    @ConditionalOnMissingBean
    @ConditionalOnBean({OfficeManager.class})
    public DocumentConverter jodConverter(OfficeManager officeManager) {
        return RemoteConverter.make(officeManager);
    }

}

4. 验证文件与服务权限 #

• 确认项目机器上的源文件file存在且有可读权限
• 检查远程服务器的临时目录（LibreOffice转换时会用到）是否有可写权限
• 在远程服务器直接用LibreOffice命令行转换文件，验证服务本身功能正常：

  libreoffice --headless --convert-to pdf /path/to/test/file.docx
  

内容的提问来源于stack exchange，提问作者Jayleonc