如何修复 "import com.dyuproject cannot be resolved" 错误

Question

我是 Java 的新手，尤其是 Maven 的新手，尤其是 protostuff 项目 (protostuff website). I need to use protostuff to serialize/deserialize XML to google's protobuf format. I tried using the protobuf-java-format package, but there's a documented error in deserialization that is a show-stopper for me (issue 37)。

到目前为止，我已经完成了以下工作：

已下载 protostuff-1.3.1 并解压缩。
运行 mvn integration-test、mvn install 和 mvn package 所有步骤都成功了。
然后我创建了一个新的 maven 项目并包含了一个原型 here

然后我按照 aforementioned link 中的描述在原型上修改了我的 pom.xml 和运行 protostuff:compile，生成了以下 Person.java 文件

// Generated by http://code.google.com/p/protostuff/ ... DO NOT EDIT!
// Generated from foo.proto

package com.example.foo;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import com.dyuproject.protostuff.ByteString;
import com.dyuproject.protostuff.GraphIOUtil;
import com.dyuproject.protostuff.Input;
import com.dyuproject.protostuff.Message;
import com.dyuproject.protostuff.Output;
import com.dyuproject.protostuff.Schema;
import com.dyuproject.protostuff.UninitializedMessageException;

public final class Person implements Externalizable, Message<Person>, Schema<Person>
{
    public enum Gender implements com.dyuproject.protostuff.EnumLite<Gender>
    {
        MALE(1),
        FEMALE(2);

        public final int number;

        private Gender (int number)
        {
            this.number = number;
        }

        public int getNumber()
        {
            return number;
        }

        public static Gender valueOf(int number)
        {
            switch(number) 
            {
                case 1: return MALE;
                case 2: return FEMALE;
                default: return null;
            }
        }
    }


    public static Schema<Person> getSchema()
    {
        return DEFAULT_INSTANCE;
    }

    public static Person getDefaultInstance()
    {
        return DEFAULT_INSTANCE;
    }

    static final Person DEFAULT_INSTANCE = new Person();

    static final String DEFAULT_MOTTO = ByteString.stringDefaultValue("When the cat is away, the mouse is alone!");
    static final Gender DEFAULT_GENDER = Gender.MALE;

    private Integer id;
    private String name;
    private String motto = DEFAULT_MOTTO;
    private Gender gender;

    public Person()
    {

    }

    public Person(
        Integer id
    )
    {
        this.id = id;
    }

    // getters and setters

    // id

    public Integer getId()
    {
        return id;
    }

    public void setId(Integer id)
    {
        this.id = id;
    }

    // name

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    // motto

    public String getMotto()
    {
        return motto;
    }

    public void setMotto(String motto)
    {
        this.motto = motto;
    }

    // gender

    public Gender getGender()
    {
        return gender == null ? Gender.MALE : gender;
    }

    public void setGender(Gender gender)
    {
        this.gender = gender;
    }

    // java serialization

    public void readExternal(ObjectInput in) throws IOException
    {
        GraphIOUtil.mergeDelimitedFrom(in, this, this);
    }

    public void writeExternal(ObjectOutput out) throws IOException
    {
        GraphIOUtil.writeDelimitedTo(out, this, this);
    }

    // message method

    public Schema<Person> cachedSchema()
    {
        return this;
    }

    // schema methods

    public Person newMessage()
    {
        return new Person();
    }

    public Class<Person> typeClass()
    {
        return Person.class;
    }

    public String messageName()
    {
        return Person.class.getSimpleName();
    }

    public String messageFullName()
    {
        return Person.class.getName();
    }

    public boolean isInitialized(Person message)
    {
        return 
            message.id != null;
    }

    public void mergeFrom(Input input, Person message) throws IOException
    {
        for(int number = input.readFieldNumber(this);; number = input.readFieldNumber(this))
        {
            switch(number)
            {
                case 0:
                    return;
                case 1:
                    message.id = input.readInt32();
                    break;
                case 2:
                    message.name = input.readString();
                    break;
                case 3:
                    message.motto = input.readString();
                    break;
                case 4:
                    message.gender = Gender.valueOf(input.readEnum());
                    break;
                default:
                    input.handleUnknownField(number, this);
            }   
        }
    }


    public void writeTo(Output output, Person message) throws IOException
    {
        if(message.id == null)
            throw new UninitializedMessageException(message);
        output.writeInt32(1, message.id, false);

        if(message.name != null)
            output.writeString(2, message.name, false);

        if(message.motto != null && message.motto != DEFAULT_MOTTO)
            output.writeString(3, message.motto, false);

        if(message.gender != null)
             output.writeEnum(4, message.gender.number, false);
    }

    public String getFieldName(int number)
    {
        switch(number)
        {
            case 1: return "id";
            case 2: return "name";
            case 3: return "motto";
            case 4: return "gender";
            default: return null;
        }
    }

    public int getFieldNumber(String name)
    {
        final Integer number = __fieldMap.get(name);
        return number == null ? 0 : number.intValue();
    }

    private static final java.util.HashMap<String,Integer> __fieldMap = new java.util.HashMap<String,Integer>();
    static
    {
        __fieldMap.put("id", 1);
        __fieldMap.put("name", 2);
        __fieldMap.put("motto", 3);
        __fieldMap.put("gender", 4);
    }

}

我正在 Eclipse（Luna 版本）中构建整个项目，它为上述文件提供了错误 "import com.dyuproject cannot be resolved"。我不明白为什么它会给出错误或如何 find/install 包以便 Eclipse 可以看到它。 Maven 应该有 built/provided 吗？

我在 VirtualBox VM 上运行 CentOS 6.4 版（最终版）：

uname -a Linux localhost.localdomain 2.6.32-358.18.1.el6.x86_64 #1 SMP Wed Aug 28 17:19:38 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux `

Answer 1

看起来您使用的 protostuff-core 和 protostuff-maven-plugin 版本不兼容。

从 1.1 版本开始，protostuff 使用包 io.protostuff 而不是 com.dyuproject.protostuff。 Protostuff 依赖版本和 protostuff maven 插件版本应该相等（1.3.5 是最新版本）。

Here是使用protostuff-maven-plugin进行代码生成的maven工程示例

如何修复 "import com.dyuproject cannot be resolved" 错误

How to fix "import com.dyuproject cannot be resolved" error

java

protocol-buffers

maven

protostuff