java DateFormat类的.setTimeZone(TimeZone zone)怎样使用?

setTimeZone

public void setTimeZone(TimeZone zone)

为此 DateFormat 对象的日历设置时区。

参数：

zone - 给定的新时区。

TimeZone

getDefault

public static TimeZone getDefault()

获取此主机的默认 TimeZone。默认 TimeZone 的来源可能随实现的变化而变化。

返回：

默认的 TimeZone。

另请参见：

setDefault(java.util.TimeZone) getTimeZone

public static TimeZone getTimeZone(String ID)

获取给定 ID 的 TimeZone。

参数：

ID - TimeZone 的 ID，要么是缩写（如 "PST" ），要么是全名（如 "America/Los_Angeles"），要么是自定义 ID（如 "GMT-8:00"）。注意，对缩写的支持只是出于 JDK 1.1.x 兼容性的考虑，因此应该使用全名。

返回：

指定的 TimeZone，如果给定的 ID 无法理解，则返回 GMT 区域。  DateFormat dateFormat = new SimpleDateFormat()

        //dateFormat.setTimeZone(TimeZone.getDefault())

        dateFormat.setTimeZone(TimeZone.getTimeZone("EET"))

        System.out.println(dateFormat.format(new Date()))

//我实现一个时钟窗口程序给你了，好让你更容易理解，希望对你有帮助。

import java.awt.*

import java.awt.event.*

import java.util.*

//世界时钟

public class TimerTest {

public static void main(String[] args) {

new TimerTestFrame("世界时钟")

}

}

class TimerTestFrame extends Frame {

/**

*

*/

private static final long serialVersionUID = 1L

public TimerTestFrame(String s) {

super(s)

addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

dispose()

System.exit(0)

}

})

setLayout(new GridLayout(2, 6))

ClockCanvas clk1 = new ClockCanvas("北京", "GMT+8")// 创建时钟

ClockCanvas clk2 = new ClockCanvas("巴黎", "GMT+2")

ClockCanvas clk3 = new ClockCanvas("华盛顿", "GMT-4")

ClockCanvas clk4 = new ClockCanvas("洛衫矶", "GMT-7")

ClockCanvas clk5 = new ClockCanvas("伦敦", "GMT+1")

ClockCanvas clk6 = new ClockCanvas("芝加哥", "GMT-5")

add(clk1)

add(clk2)

add(clk3)

add(clk4)

add(clk5)

add(clk6)

setSize(500, 350)// 设置框架宽高

setVisible(true)

}

}

class ClockCanvas extends Canvas implements Runnable {

/**

*

*/

private static final long serialVersionUID = 1L

private int seconds = 0

private String city

private GregorianCalendar calendar

Thread t

public ClockCanvas(String c, String tz) {

city = c

//也可以通过TimeZone.setTimeZone(String n)函数改变时区，n为时区参数名。

calendar = new GregorianCalendar(TimeZone.getTimeZone(tz))

t = new Thread(this)

t.start()

setSize(125, 125)// 设置画布大小

setBackground(Color.black)

}

// 重写父类的方法绘制时钟图形

public void paint(Graphics g) {

Graphics2Dg2d = (Graphics2D) g

BasicStroke bstroke = new BasicStroke(2.0f)

g2d.setStroke(bstroke)

g2d.setColor(Color.green)

g2d.drawOval(0, 0, 100, 100)

bstroke = new BasicStroke(5.0f)

g2d.setStroke(bstroke)

g2d.drawLine(50, 0, 50, 5)

g2d.drawLine(0, 50, 5, 50)

g2d.drawLine(50, 95, 50, 98)

g2d.drawLine(95, 50, 98, 50)

double hourAngle = 2 * Math.PI * (seconds - 3 * 60 * 60)

/ (12 * 60 * 60)

double minuteAngle = 2 * Math.PI * (seconds - 15 * 60) / (60 * 60)

double secondAngle = 2 * Math.PI * (seconds - 15) / (60)

bstroke = new BasicStroke(5.0f)

g2d.setStroke(bstroke)

g2d.drawLine(50, 50, 50 + (int) (30 * Math.cos(hourAngle)),

50 + (int) (30 * Math.sin(hourAngle)))

bstroke = new BasicStroke(3.0f)

g2d.setStroke(bstroke)

g2d.drawLine(50, 50, 50 + (int) (40 * Math.cos(minuteAngle)),

50 + (int) (40 * Math.sin(minuteAngle)))

bstroke = new BasicStroke(1.0f)

g2d.setStroke(bstroke)

g2d.drawLine(50, 50, 50 + (int) (45 * Math.cos(secondAngle)),

50 + (int) (45 * Math.sin(secondAngle)))

g2d.setColor(Color.red)

g2d.drawString(city, 35, 115)

}

public void timeElapsed() {

//new Date()()获得当前时间

System.out.println(new Date()())

calendar.setTime(new Date()())

seconds = calendar.get(Calendar.HOUR) * 60 * 60

+ calendar.get(Calendar.MINUTE) * 60

+ calendar.get(Calendar.SECOND)

}

public void run() {

try {

while (true) {

Thread.sleep(300)

timeElapsed()

repaint()

}

} catch (InterruptedException e) {

}

}

}

---