在Eclipse中生成java代码？

Question

Does anyone know what approach one can take to automatically generate Java source code, from for example an xml or json file, in eclipse?

One great example of what I am thinking of doing is what Google Android sdk does: they have an R class generated automatically from the resources .

Every time a resource file is saved in Eclipse R class is automatically regenerated.

UPDATE: Example: In the text (xml or json file) I have the following:

 <tags>
     <tag id="ALPHA">
         <description>The first alpha tag.</description>
         <value>231232</value>
     </tag>
     <tag id="BETA">
         <description>This is the beta tag.</description>
         <value>231232</value>
     </tag>

Then in my generated java class, say RI would have something like:

R.tags.ids.ALPHA //refers to an enum value for example
R.tags.values.ALPHA //refers to final int with avlue 231232
R.tags.descriptions.ALPHA //refers to the String with description

Thanks!

Answer 1

The way I do it is that I have an XSLT file that simply transforms my xml-data (in my case a protocol specification) to java source code. This XSLT-transformation can easily be done in an ANT-task which could be included in the build-chain in eclipse.

Perhaps there is a plugin for this particular task.

Some useful links:

• XSLT tutorial
• Ant: Performing XSLT Tranformations
• Using Ant to Auto-Build in Eclipse

Answer 2

I'm adding another answer based on your comments and also because I don't really recommend doing this outside of Google Android Resource SDK. Google is basically using a hierarchy of static classes (singletons) for their resources. You need to make your XSLT generate static member variables instead of getters and setters.

I basically took my old answer and changed it to static for all member variables. You have to be very careful doing this because I have seen so many bugs with incorrect use of the "static" modifier.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="text" />
    <xsl:template match="/" priority="100">
    public class <xsl:value-of select="name(node())" /> {
        <xsl:apply-templates  select="child::node()" />
    }
    </xsl:template>
    <xsl:template match="/*/*">
        public static String <xsl:value-of select="name()" />;
        public static String get<xsl:value-of select="name()" /> {
            return <xsl:value-of select=" name()" />;
        }

        public void static set<xsl:value-of select="name()" />(String value) {
            <xsl:value-of select="name()" /> = value;
        }
    </xsl:template>
</xsl:stylesheet>

If you process with this example XML:

<?xml version="1.0" encoding="UTF-8"?>
<Human>
    <EyeColor>brown</EyeColor>
    <HairColor>brown</HairColor>
</Human>

You get something like: public class Human {

    public static String EyeColor;

    public static String getEyeColor {
        return EyeColor;
    }

    public static void setEyeColor(String value) {
        this.EyeColor = value;
    }


    public static String HairColor;
    public static String getHairColor {
        return HairColor;
    }

    public static void setHairColor(String value) {
        this.HairColor = value;
    }


}

Answer 3

Well Eclipse Modelling Framework (EMF) is meant for the application you are looking forward to. I assume you have a model and you want to convert it into code. Very specific hint I can give is JET (Java Emitter template) you can refer here for more details.

Also the newer framework XPand introduced by eclipse,

Revolving around the abstract syntax-development components are model-transformation tech- nologies. 1. model-to-text (Java Emitter Templates [JET] and Xpand) 2. model-to-model (QVT and ATL)

Here model refers to XML-XSLT / UML (Rational rose) model.

Answer 4

Take a look at XDoclet . Its an extensible open source code generation engine for Java.

EDIT: As bozho points out, XDoclet has mostly been replaced by annotations: Annotations vs. XDoclet

Do any java libraries use annotations for code generation?

Answer 5

From XML to JAVA and vice Versa I highly recommend JAXB.

You can generate Java source code from Schema's using JAXB 2.0 or greater. Or you can generate Schemas from Java.

You can also easily make JAXB generate/consume JSON using Jettison.

You can also have JAXB generate POJO's in a Martin Fowler Fluent Style or a whole bunch of different ways using its plugin system.

EDIT based on your comments: Have XSLT generate your JAXB POJO:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="text" />
    <xsl:template match="/" priority="100">
    import javax.xml.bind.annotation.XmlRootElement;

    @XmlRootElement(name="Human")
    public class <xsl:value-of select="name(node())" /> {
        <xsl:apply-templates  select="child::node()" />
    }
    </xsl:template>
    <xsl:template match="/*/*">
        private String <xsl:value-of select="name()" />;
        public String get<xsl:value-of select="name()" /> {
            return <xsl:value-of select=" name()" />;
        }

        public void set<xsl:value-of select="name()" />(String value) {
            this.<xsl:value-of select="name()" /> = value;
        }
    </xsl:template>
</xsl:stylesheet>

If you process with this example XML:

<?xml version="1.0" encoding="UTF-8"?>
<Human>
    <EyeColor>brown</EyeColor>
    <HairColor>brown</HairColor>
</Human>

You get something like:

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="Human")
public class Human {


    private String EyeColor;
    public String getEyeColor {
        return EyeColor;
    }

    public void setEyeColor(String value) {
        this.EyeColor = value;
    }


    private String HairColor;
    public String getHairColor {
        return HairColor;
    }

    public void setHairColor(String value) {
        this.HairColor = value;
    }


}

Answer 6

您可以查看Eclipse建模项目的模型到文本组件 。

Answer 7

是的，您可以使用xml文件来创建它。创建您自己的xml文件模板，然后使用preferences-java-code template-import选择该文件，您可以使用该模板。