如何写自己的Ant Task?

首先，要写出自己的Ant Task是一件非常简单的事情，有了心里的这层藐视之后，做起事来就容易多了！
说说我做这个Ant Task的背景，随着部门框架的推广，支持国际化是一个严肃的问题，我们选择了utf-8作为UNICODE字符集的编码形式，因此现有项目必须经过一些转换的处理，自然，Ant是首选工具。
可以看一个完整的build.xml:

<? xml version = " 1.0 " encoding = " UTF-8 " ?>

< project default = " main " basedir = " . " >
     < property name = " jsp.dir " value = " organtype " />
     < property name = " lib.dir " value = " bin " />
     < path id = " classpath " >
         < fileset dir = " ${lib.dir} " >
             < include name = " **/*.jar " />
         </ fileset >
         < pathelement path = " bin " />
     </ path >
     
     < target name = " replace " description = " 将GBK,gb2312换成UTF-8 " >
         < replace dir = " ${jsp.dir} " token = " GBK " value = " UTF-8 " />
         < replace dir = " ${jsp.dir} " token = " gb2312 " value = " UTF-8 " />
     </ target >

     
     < target name = " init-tasks " description = " ==> 生成代码前的初始化工作 " >
         < taskdef name = " gbk2utf8 " classname = " org.loushang.bsp.util.GBK2UTF8 " >
             < classpath refid = " classpath " />
         </ taskdef >
     </ target >

     
     < target name = " convert " description = " 改变文件的编码格式 " depends = " init-tasks " >
         < gbk2utf8 destDir = " ${jsp.dir} " format = " java " destEncoding = " utf-8 " />
     </ target >

     
     < target name = " main " description = " 主任务 " >
         < antcall target = " replace " />
         < antcall target = " convert " />
     </ target >
</ project >

解释一下，首先这个任务进行jsp页编码形式的替换，接着进行内容编码的转换，其中可以指定目标目录，文件格式，目标编码形式。Ant Task主要用到了java的反射技术，我们自己的Task可以继承Task类，然后复写excute()方法，看看GBK2UTF8的源代码：

  1 import java.io.BufferedReader;
  2 import java.io.File;
  3 import java.io.FileOutputStream;
  4 import java.io.FileReader;
  5 import java.io.IOException;
  6 import java.io.OutputStreamWriter;
  7 import java.util.ArrayList;
  8 import java.util.List;
  9
10 import org.apache.tools.ant.BuildException;
11 import org.apache.tools.ant.Task;
12
13 public class GBK2UTF8 extends Task {
14    private String format = "";
15
16    private String destEncoding = "";
17
18    private String destDir = "";
19
20    private static List list = new ArrayList();
21
22    public String getDestDir() {
23        return destDir;
24    }
25    public void setDestDir(String destDir) {
26        this.destDir = destDir;
27    }
28    /**//*
29     * 复写execute()方法，实现自己的内容
30     */
31    public void execute() throws BuildException {
32        super.execute();
33        getAllFilesOfDir(getDestDir());
34        StringBuffer tempSb = new StringBuffer();
35        int hasRead = 0;
36        for (int i = 0; i < list.size(); i++) {
37            System.out.println(list.get(i));
38            try {
39                BufferedReader bfr = new BufferedReader(new FileReader(
40                        (File) list.get(i)));
41                String temp = bfr.readLine();
42                while (temp != null) {
43                    tempSb.append(temp);
44                    tempSb.append("\n");
45                    temp = bfr.readLine();
46                }
47                bfr.close();
48            // 文件内容编码转换
49                OutputStreamWriter osw = new OutputStreamWriter(
50                        new FileOutputStream((File) list.get(i)),
51                        getDestEncoding());
52                osw.write(tempSb.toString(), 0, tempSb.toString().length());
53                osw.flush();
54                osw.close();
55                tempSb = null;
56                tempSb = new StringBuffer();
57            } catch (IOException e) {
58            e.printStackTrace();
59            }
60        }
61    }
62
63    /**//*
64     * 判断后缀名是否满足条件
65     */
66    private boolean isProperFormat(File file) {
67        return (file.getName().endsWith(getFormat()));
68    }
69
70    /**//*
71     * 取得所有的文件列表
72     */
73    private List getAllFilesOfDir(String dir) {
74        File file = new File(dir);
75        if (!file.exists()) {
76            throw new RuntimeException("给出的目录不存在！");
77        }
78        File[] files = file.listFiles();
79        for (int i = 0; i < files.length; i++) {
80            if (files[i].isFile() && isProperFormat(files[i])) {
81                list.add(files[i].getAbsoluteFile());
82            } else if (files[i].isDirectory()) {
83                getAllFilesOfDir(files[i].getAbsolutePath());
84            } else {
85        // 那些不符合格式的文件将略去
86            }
87        }
88        return list;
89    }
90
91    public String getDestEncoding() {
92        return destEncoding;
93    }
94
95    public void setDestEncoding(String destEncoding) {
96        this.destEncoding = destEncoding;
97    }
98
99    public String getFormat() {
100        return format;
101    }
102
103    public void setFormat(String format) {
104        this.format = format;
105    }
106}
107

这样，就完成任务了。看看是不是很简单？
参考资料：http://ant.apache.org/manual/tutorial-writing-tasks.html

如何写自己的Ant Task?

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