用Java写脚本，常用的一些方法

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本文介绍了使用Java进行脚本编程的一些实用技巧，包括运行外部程序、获取类路径、读写文件、删除目录及操作环境变量等。这些方法有助于提高开发效率，简化日常任务。

用Java写脚本，常用的一些方法

平时用的一些小方法，总结之

1.运行一个可执行程序

比如，你如果想运行如下命令

C://test//aapt.exe -f params1 -M params2

try {
        ProcessBuilder pb = new ProcessBuilder("C://test//aapt.exe","-f","params1","-M","params2");
        pb.redirectErrorStream(true);
        Process process = pb.start();
        InputStream inputStream = process.getInputStream();
        BufferedReader bufferedReader = new BufferedReader(
                new InputStreamReader(inputStream));
        String line = "";
        while ((line = bufferedReader.readLine()) != null) {
            System.out.println(INFO + line);
        }
        int exit = process.waitFor();
        if (exit == 0) {
            System.out.println("finished...");
        } else {
            System.out.println("error...");
        }
    } catch (Exception e) {
        e.printStackTrace();
        System.exit(-1);
    }

注意：
1.调用ProcessBuilder的start()方法，开始执行命令。
2.通过process.getInputStream，把执行命令过程中的日志打印出来。
3.通过调用process.waitFor()，阻塞当前线程，直到命令执行完毕后，获得返回码

2.获取当前Class在运行时的路径(亦适用于jar)

比如，获取TestMain这个类在运行时的路径。

URL location = TestMain.class.getProtectionDomain().getCodeSource()
            .getLocation();
String path = location.getFile();

3.获取系统的环境变量

比如，获取系统的JAVA_HOME这个环境变量的值

String path = System.getenv("JAVA_HOME");

4.删除目录

public static boolean deleteDirectory(File directory) {
    if (directory.exists()) {
        File[] files = directory.listFiles();
        if (null != files) {
            for (int i = 0; i < files.length; i++) {
                if (files[i].isDirectory()) {
                    deleteDirectory(files[i]);
                } else {
                    files[i].delete();
                }
            }
        }
    }
    return (directory.delete());
}

5.读写文件

/**
 * 写文件
 *
 * @param filePath
 * @param sets
 * @throws IOException
 */
public synchronized void writeFile(String filePath, String content)
        throws IOException {
    FileWriter fw = new FileWriter(filePath);
    PrintWriter out = new PrintWriter(fw);
    out.write(content);
    out.println();
    fw.close();
    out.close();
}

/**
 * 读文件
 *
 * @param filename
 * @return
 */
public static String readFile(String filepath) {
    File file = new File(filepath);
    InputStream inputStream = null;
    BufferedReader bufferedReader = null;
    try {
        inputStream = new FileInputStream(file);
        String content = "";
        if (inputStream != null) {
            bufferedReader = new BufferedReader(new InputStreamReader(
                    inputStream));
            String line = "";
            while ((line = bufferedReader.readLine()) != null) {
                content += line;
            }
        }
        return content;
    } catch (Exception e) {
        System.out.println(e.toString());
    } finally {
        try {
            if (bufferedReader != null) {
                bufferedReader.close();
                bufferedReader = null;
            }
            if (inputStream != null) {
                inputStream.close();
                inputStream = null;
            }
        } catch (Exception e) {
            System.out.println(e.toString());
        }
    }

    return null;
}

public static byte[] readByte(final InputStream in) throws IOException {
    ByteArrayOutputStream output = null;
    try {
        if (in == null) {
            return null;
        }
        output = new ByteArrayOutputStream(1024 * 2);
        byte[] buffer = new byte[1024];
        int len;
        while ((len = in.read(buffer)) != -1) {
            output.write(buffer, 0, len);
        }
        return output.toByteArray();
    } finally {
        if (output != null) {
            try {
                output.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (in != null) {
            try {
                in.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

public static boolean saveObject(Serializable serializable,
        String filePath) {
    try {
        FileOutputStream fout = new FileOutputStream(filePath);
        ObjectOutputStream oos = new ObjectOutputStream(fout);
        oos.writeObject(serializable);
        oos.close();
        return true;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return false;
}