Runtime.exec()调用imageMagick实现图片缩放

直接上代码

public class PictureZoomUtils {
	private static Log logger = LogFactory.getLog(PictureZoomUtils.class);
	
	/**
	 * image magick convert.exe的绝对路径
	 */
	private String convertExe;

	public void zoom(File input, File output, int width, int height) throws Exception {
		StringBuilder command = new StringBuilder();
		command.append(convertExe).append(" ").append(input.getAbsolutePath()).append(" -resize ").append(width)
				.append("x").append(height)// 改变尺寸 -resize 120x120
				.append(" -colors").append(" 100") // 颜色数：设定图片采用的颜色数，如果是生成png或gif图片应指定这个参数
				.append(" +profile \"*\" ") // 图片中不存储附加信息，必须使用，否则生成图片过大
				.append(output.getAbsolutePath());

		try{
			Process process = Runtime.getRuntime().exec(command.toString());

			// any error message?
			StreamGobbler errorGobbler = new StreamGobbler(process.getErrorStream(), "ERROR");
			// any output?
			StreamGobbler outputGobbler = new StreamGobbler(process.getInputStream(), "OUTPUT");

			errorGobbler.start();
			outputGobbler.start();

			process.waitFor(); // 永远要先从标准错误流中读取，然后再读取标准输出流， 最后在执行waitFor
		}catch(Throwable t){
			logger.error(t);
		}
		
	}

	public void setConvertExe(String convertExe) {
		this.convertExe = convertExe;
	}

	public String getConvertExe() {
		return convertExe;
	}

}

class StreamGobbler extends Thread {
	private static Log logger = LogFactory.getLog(StreamGobbler.class);
	
	private InputStream is;
	private String type; // 输出流的类型ERROR或OUTPUT

	public StreamGobbler(InputStream is, String type) {
		this.is = is;
		this.type = type;
	}

	public void run() {
		try {
			InputStreamReader isr = new InputStreamReader(is);
			BufferedReader br = new BufferedReader(isr);
			String line = null;
			while ((line = br.readLine()) != null) {
				System.out.println(type + ">" + line);
				System.out.flush();
			}
		} catch (IOException ioe) {
			logger.error(ioe);
		}
	}
}