How to easily load a XML-based Config File into a Java Class?

问题

I've got a simple java class that looks something like this:

public class Skin implements Serializable {

    public String scoreFontName = "TahomaBold";
    ...
    public int scoreFontHeight = 20;
    ...
    public int blockSize = 16;
            ...

    public int[] nextBlockX = {205, 205, 205, 205};
            ...
    public String backgroundFile = "back.bmp";
            ... 
}

I'd like to read this information from a simple XML file that looks something like this:

<xml>
    <skin>
        <scoreFontName>"Tahoma Bold"</scoreFontName>
        ...
        <scoreFontHeight>20</scoreFontHeight>
        ...
        <blockSize>16</blockSize>
        ...
        <nextBlockX>
             <0>205</0>
             <1>205</1>
             <2>205</2>
             <3>205</3>
        <nextBlockX>
        ....
        <backgroundFile>"back.bmp"</backgroundFile>
        ...
     <skin>
 </xml>

Is there an easy way to inject the information from the xml file directly into the variable names rather than having to parse it manually? I don't mind using an external library.

Any help is appreciated.

回答1:

XStream is really great library for just this.

http://x-stream.github.io/

You can set up aliases for your class and even custom data formats to make the XML file more readable.

回答2:

Alternatives to the already mentioned solutions (XStream and Apache Commons Digester) would be Java's own JAXB for a comparable general approach, or solutions more tailored towards configuration like Apache Commons Configuration or Java's Preferences API.

回答3:

I would actually recommend Apache Digester, since if your classes are beans, it will just handle reading the XML into them.

回答4:

You can also use Spring - although it may be a bit of overkill for one class if its for a mobile game!

回答5:

I've recently started using Simple http://simple.sourceforge.net/ for XML to object mapping. It uses annotations within the class similarly to method I use in C# and is nice and clean. You can also break up the file into multiple classes and loading saving is a simple one liner.

In your case the Class structure would look like.

import org.simpleframework.xml.Element;
import org.simpleframework.xml.Root;

@Root (Name="skin")
public class Skin {

    @Element(name="scoreFontName")  // name param not needed if class field is the same as the xml (element) value
    private String scoreFontName 

    @Element
    private int scoreFontHeight 

    @Element
    private int blockSize 

    @ElementArray
    private int[] nextBlockX 

    @Element    
    private String backgroundFile 

    // getters
}

Note one difference is that your array will be saved like this

<nextBlockX>
     <int>205</int>
     <int>205</int>
     <int>205</int>
     <int>205</int>
<nextBlockX>

But you you have the option of adding (entry="myName") to the annotation in which came the XML will be saved down like this

<nextBlockX>
     <myName>205</myName>
     <myName>205</myName>
     <myName>205</myName>
     <myName>205</myName>
<nextBlockX>

But the end result is the same once it's loaded into the array.

回答6:

Use JAXB. It is included in the JDK starting with Java 1.6.

来源：https://stackoverflow.com/questions/501325/how-to-easily-load-a-xml-based-config-file-into-a-java-class

标签

java

xml

code-injection