java改时区

code:

package com.soofound.framework.util;

import java.io.IOException;
import java.io.InputStream;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.TimeZone;

/**
 * 设置时区
 * 
 * @author zxf
 * @date 2015-11-4
 */
// java -classpath . com.linux.test.base.SetTimeZone
public class SetTimeZone {

    public static void main(String[] args) {
        setTimeZone();
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String time1 = df.format(Calendar.getInstance().getTime());
        System.out.println(time1);
    }

    /**
     * 设置时区 <br>
     * 
     * 注：xx:59:59时，可能有问题。可以循环2次验证后再设置
     */
    public static void setTimeZone() {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH");
        String time = df.format(Calendar.getInstance().getTime());
        /**
         * 如果当前java获取的时间与linux的'date'命令获取的时间一致，则不修改时区
         */
        String osTime = time();
        System.out.println("def java time: " + time + ", os time: " + osTime);
        if ( time.equals(osTime) ) {
            return;
        }

        /**
         * 先获取往前减的时区
         */
        TimeZone correct = getCorrect("GMT-%d");// 如: GMT-8 ()
        /**
         * 往前减的时区没有，则获取往后加的时区
         */
        if ( correct == null ) {
            correct = getCorrect("GMT+%d");// 如: GMT+8
        }
        /**
         * 如果找到正确的时区，则设置为默认时区
         */
        if ( correct != null ) {
            System.out.printf("set TimeZone: %s %n", correct.getID());
            osTime = time();
            SimpleDateFormat df1 = new SimpleDateFormat("yyyy-MM-dd HH");
            String time1 = df1.format(Calendar.getInstance().getTime());
            System.out.println("set . java time: " + time1 + ", os time: " + osTime);
            TimeZone.setDefault(correct);
        }
    }

    /**
     * 时区区间：1-16，一般1-12就可以了
     * 
     * @param format
     * @return
     */
    private static TimeZone getCorrect(String format) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH");
        for ( int i = 1; i <= 16; i++ ) {
            String tzName = String.format(format, i);// 减 | 加
            TimeZone tz = TimeZone.getTimeZone(tzName);
            df.setTimeZone(tz);
            String time = df.format(Calendar.getInstance().getTime());

            String linexTime = time();
            if ( time.equals(linexTime) ) {
                return tz;
            }
        }
        return null;
    }

    /**
     * 获取系统时间
     * 
     * @return
     */
    private static String time() {
        try {
            String cmd = "date '+%F %H'";
            Process pro = Runtime.getRuntime().exec(new String[] { "sh", "-c", cmd });
            InputStream is = pro.getInputStream();
            byte[] bs = new byte[1024];
            int len = is.read(bs, 0, 1024);
            String time = new String(bs, 0, len);
            if ( time != null )
                time = time.trim();
            return time;
        } catch ( IOException e ) {
            return null;
            // return "2015-11-04 19";// windows test
        } catch ( Exception e ) {
            e.printStackTrace();
            return null;
        }
    }

}