Xembly学习(二):Xembly脚本基本语法与几个XML生成实例
Xembly学习(二):Xembly脚本基本语法与几个XML生成实例
北风其凉 发表于2年前
Xembly学习(二):Xembly脚本基本语法与几个XML生成实例
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腾讯云 十分钟定制你的第一个小程序>>>   

摘要: Xembly是一个类似汇编语言的命令式语言,可以用来操作XML文档。

Xembly是一个类似汇编语言的命令式语言,可以用来操作XML文档。本文给出了Xembly从下载、编译、运行示例的详细方法。我电脑中的操作系统为 Windows7家庭普通版(Service Pack 1),JDK版本为jdk1.8,Eclipse版本为Luna Service Release 1 (4.4.1)。

Xembly的下载、编译步骤,可以参考我的上一篇Blog:

http://my.oschina.net/Tsybius2014/blog/614784

一、Xembly的语法

Xembly是一种命令式语言,它的语法类似于汇编语法,下面列出了Xembly的命令

1、ADD:在当前节点下新增一个新节点,游标(cursor)同时跟进到该节点

2、ADDIF:在当前节点下如果不存在指定名称的节点则新增一个新节点,游标同时跟进到该节点,本语句对大小写敏感

3、SET:使用指定文本修改节点值,不改变游标位置

4、XSET:使用指定XPath表达式修改节点值,不改变游标位置

5、ATTR:设置属性

6、UP:将游标移动到上级节点

7、XPATH:移动游标到指定XPath表达式位置

8、REMOVE:移除当前节点,并将游标重新指向父节点

9、STRICT:检查当前节点下的节点数是否与指定数字相符,不相符则提示异常,本语句不改变指针位置

10、PI:添加XML首部处理指令(processing instruction)

11、PUSH:将当前位置压入栈中

12、POP:从堆栈中取出第一个位置并跳转到该位置

13、NS:为指定节点添加命名空间

详情可见页面 https://github.com/yegor256/xembly 下Readme.MD文件的描述

二、执行Xembly脚本

为了执行Xembly脚本,我写了一个Java程序,代码如下:

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

import org.xembly.Directives;
import org.xembly.Xembler;

public class XemblyTester {
    public static void main(String[] args) {

        String scriptPath = "C:\\Users\\Tsybius\\Desktop\\XemblyScript\\America.xembly";
        String outputPath = "C:\\Users\\Tsybius\\Desktop\\XemblyScript\\America.xml";

        GenXmlByXembly(scriptPath, outputPath);
    }

    public static void GenXmlByXembly(String scriptPath, String outputPath) {
        try {
            String script = ""; // 用来保存每行读取的内容
            StringBuilder buffer = new StringBuilder();
            InputStream is = new FileInputStream(scriptPath);
            String line;
            BufferedReader reader = new BufferedReader(
                new InputStreamReader(is));
            line = reader.readLine();
            while (line != null) {
                buffer.append(line);
                buffer.append("\n");
                line = reader.readLine();
            }
            script = buffer.toString();
            reader.close();
            is.close();

            System.out.println("读取到Xembly代码");
            System.out.println(script);

            String xml = new Xembler(new Directives(script)).xml();

            System.out.println("生成的XML文件");
            System.out.println(xml);
            
            BufferedWriter bufferedWriter  = null;
            File file = new File(outputPath);
            bufferedWriter = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), "UTF-8"));
            bufferedWriter.append(xml);
            bufferedWriter.flush();
            bufferedWriter.close();
            
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

其中scriptPath变量用于指定Xembly脚本的路径,outputPath变量用于指定生成后的XML保存到的路径

三、示例1:生成法国国旗的SVG图像

法国国旗是三色旗,它的SVG图像比较容易绘制,它的绘制脚本France.xembly如下:

ADD "svg";
ATTR "xmlns", "http://www.w3.org/2000/svg";
ATTR "width", "900";
ATTR "height", "600";
ADD "rect";
ATTR "width", "900";
ATTR "height", "600";
ATTR "fill", "#ED2939";
UP;
ADD "rect";
ATTR "width", "600";
ATTR "height", "600";
ATTR "fill", "#fff";
UP;
ADD "rect";
ATTR "width", "300";
ATTR "height", "600";
ATTR "fill", "#002395";

生成的SVG文件France.svg如下:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" height="600" width="900">
<rect fill="#ED2939" height="600" width="900"/>
<rect fill="#fff" height="600" width="600"/>
<rect fill="#002395" height="600" width="300"/>
</svg>

将生成的SVG文件用浏览器打开,就可以看到效果了。本文中的列举的5个国旗的SVG文件,都参考了Wikipedia上各国国旗的SVG文件。

四、示例2:生成俄罗斯国旗的SVG图像

俄罗斯国旗也是三色旗,它的SVG图像绘制方法与法国国旗类似,脚本Russia.xembly如下:

ADD "svg";
ATTR "xmlns", "http://www.w3.org/2000/svg";
ATTR "viewBox", "0 0 9 6";
ATTR "width", "900";
ATTR "height", "600";
ADD "rect";
ATTR "fill", "#fff";
ATTR "width", "9";
ATTR "height", "3";
UP;
ADD "rect";
ATTR "fill", "#d52b1e";
ATTR "y", "3";
ATTR "width", "9";
ATTR "height", "3";
UP;
ADD "rect";
ATTR "fill", "#0039a6";
ATTR "y", "2";
ATTR "width", "9";
ATTR "height", "2";

生成的SVG文件Russia.svg如下:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" height="600" viewBox="0 0 9 6" width="900">
<rect fill="#fff" height="3" width="9"/>
<rect fill="#d52b1e" height="3" width="9" y="3"/>
<rect fill="#0039a6" height="2" width="9" y="2"/>
</svg>

五、示例3:生成中国国旗的SVG图像

中国国旗是五星红旗,需要绘制五颗不同角度的星星,脚本China.xembly如下:

ADD "svg";
ATTR "xmlns", "http://www.w3.org/2000/svg";
ATTR "xmlns:xlink", "http://www.w3.org/1999/xlink";
ATTR "width", "900";
ATTR "height", "600";
ATTR "viewBox", "0 0 30 20";
PUSH;
ADD "defs";
ADD "path";
ATTR "id", "s";
ATTR "d", "M0,-1 0.587785,0.809017 -0.951057,-0.309017H0.951057L-0.587785,0.809017z";
ATTR "fill", "#ffde00";
POP;
ADD "rect";
ATTR "width", "30";
ATTR "height", "20";
ATTR "fill", "#de2910";
UP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "transform", "translate(5,5) scale(3)";
UP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "transform", "translate(10,2) rotate(23.036243)";
UP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "transform", "translate(12,4) rotate(45.869898)";
UP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "transform", "translate(12,7) rotate(69.945396)";
UP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "transform", "translate(10,9) rotate(20.659808)";

生成的SVG文件China.svg如下:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" height="600" viewBox="0 0 30 20" width="900">
<defs>
<path d="M0,-1 0.587785,0.809017 -0.951057,-0.309017H0.951057L-0.587785,0.809017z" fill="#ffde00" id="s"/>
</defs>
<rect fill="#de2910" height="20" width="30"/>
<use transform="translate(5,5) scale(3)" xlink:href="#s"/>
<use transform="translate(10,2) rotate(23.036243)" xlink:href="#s"/>
<use transform="translate(12,4) rotate(45.869898)" xlink:href="#s"/>
<use transform="translate(12,7) rotate(69.945396)" xlink:href="#s"/>
<use transform="translate(10,9) rotate(20.659808)" xlink:href="#s"/>
</svg>

六、示例4:生成英国国旗的SVG图像

英国国旗是米字旗,需要建立一个clipPath,然后按照蓝底背景、白色斜十字、红色斜十字、白色十字、红色十字的顺序绘制,脚本Bratain.xembly如下:

ADD "svg";
ATTR "xmlns", "http://www.w3.org/2000/svg";
ATTR "viewBox", "0 0 60 30";
ATTR "width", "1200";
ATTR "height", "600";
PUSH;
ADD "clipPath";
ATTR "id", "t";
ADD "path";
ATTR "d", "M30,15 h30 v15 z v15 h-30 z h-30 v-15 z v-15 h30 z";
POP;
ADD "path";
ATTR "d", "M0,0 v30 h60 v-30 z";
ATTR "fill", "#00247d";
UP;
ADD "path";
ATTR "d", "M0,0 L60,30 M60,0 L0,30";
ATTR "stroke", "#fff";
ATTR "stroke-width", "6";
UP;
ADD "path";
ATTR "d", "M0,0 L60,30 M60,0 L0,30";
ATTR "clip-path", "url(#t)";
ATTR "stroke", "#cf142b";
ATTR "stroke-width", "4";
UP;
ADD "path";
ATTR "d", "M30,0 v30 M0,15 h60";
ATTR "stroke", "#fff";
ATTR "stroke-width", "10";
UP;
ADD "path";
ATTR "d", "M30,0 v30 M0,15 h60";
ATTR "stroke", "#cf142b";
ATTR "stroke-width", "6";

生成的SVG文件Britain.svg如下:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" height="600" viewBox="0 0 60 30" width="1200">
<clipPath id="t">
<path d="M30,15 h30 v15 z v15 h-30 z h-30 v-15 z v-15 h30 z"/>
</clipPath>
<path d="M0,0 v30 h60 v-30 z" fill="#00247d"/>
<path d="M0,0 L60,30 M60,0 L0,30" stroke="#fff" stroke-width="6"/>
<path clip-path="url(#t)" d="M0,0 L60,30 M60,0 L0,30" stroke="#cf142b" stroke-width="4"/>
<path d="M30,0 v30 M0,15 h60" stroke="#fff" stroke-width="10"/>
<path d="M30,0 v30 M0,15 h60" stroke="#cf142b" stroke-width="6"/>
</svg>

七、示例5:生成美国国旗的SVG图像

美国的星条旗较难绘制,最难的部分在于左上角的51颗星星,脚本America.xembly如下:

ADD "svg";
ATTR "xmlns", "http://www.w3.org/2000/svg";
ATTR "xmlns:xlink", "http://www.w3.org/1999/xlink";
ATTR "width", "1235";
ATTR "height", "650";
ATTR "viewBox", "0 0 7410 3900";
ADD "rect";
ATTR "width", "7410";
ATTR "height", "3900";
ATTR "fill", "#b22234";
UP;
ADD "path";
ATTR "d", "M0,450H7410m0,600H0m0,600H7410m0,600H0m0,600H7410m0,600H0";
ATTR "stroke", "#fff";
ATTR "stroke-width", "300";
UP;
ADD "rect";
ATTR "width", "2964";
ATTR "height", "2100";
ATTR "fill", "#3c3b6e";
UP;
ADD "g";
ATTR "fill", "#fff";
PUSH;
ADD "g";
ATTR "id", "s18";
PUSH;
ADD "g";
ATTR "id", "s9";
PUSH;
ADD "g";
ATTR "id", "s5";
PUSH;
ADD "g";
ATTR "id", "s4";
ADD "path";
ATTR "id", "s";
ATTR "d", "M247,90 317.534230,307.082039 132.873218,172.917961H361.126782L176.465770,307.082039z";
UP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "y", "420";
UP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "y", "840";
UP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "y", "1260";
POP;
ADD "use";
ATTR "xlink:href", "#s";
ATTR "y", "1680";
POP;
ADD "use";
ATTR "xlink:href", "#s4";
ATTR "x", "247";
ATTR "y", "210";
POP;
ADD "use";
ATTR "xlink:href", "#s9";
ATTR "x", "494";
POP;
ADD "use";
ATTR "xlink:href", "#s18";
ATTR "x", "988";
UP;
ADD "use";
ATTR "xlink:href", "#s9";
ATTR "x", "1976";
UP;
ADD "use";
ATTR "xlink:href", "#s5";
ATTR "x", "2470";

生成的SVG文件America.svg如下:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" height="650" viewBox="0 0 7410 3900" width="1235">
<rect fill="#b22234" height="3900" width="7410"/>
<path d="M0,450H7410m0,600H0m0,600H7410m0,600H0m0,600H7410m0,600H0" stroke="#fff" stroke-width="300"/>
<rect fill="#3c3b6e" height="2100" width="2964"/>
<g fill="#fff">
<g id="s18">
<g id="s9">
<g id="s5">
<g id="s4">
<path d="M247,90 317.534230,307.082039 132.873218,172.917961H361.126782L176.465770,307.082039z" id="s"/>
<use xlink:href="#s" y="420"/>
<use xlink:href="#s" y="840"/>
<use xlink:href="#s" y="1260"/>
</g>
<use xlink:href="#s" y="1680"/>
</g>
<use x="247" xlink:href="#s4" y="210"/>
</g>
<use x="494" xlink:href="#s9"/>
</g>
<use x="988" xlink:href="#s18"/>
<use x="1976" xlink:href="#s9"/>
<use x="2470" xlink:href="#s5"/>
</g>
</svg>

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