blocks|key|880917|text|您只能通过以root或管理员身份运行命令行工具来设置系统时间。命令有所不同，但您可以先检查操作系统，然后针对该操作系统运行相应的命令。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|880918|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You can only set the system time by running a command line tool as root or Adminstrator. The command are different but you can check the OS first and run the appropriate command for that OS.

blocks|key|663989|text|您可以使用JNI来设置系统时间。这在Windows上是可行的。你需要知道JNI和C。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|663990|这是JNI函数，原型将由javah实用程序生成|663991|JNIEXPORT+void+JNICALL+Java_TimeSetter_setSystemTime
++(JNIEnv+*env,+jobject+obj,+jshort+hour,+jshort+minutes)+{

++++SYSTEMTIME+st;
++++GetLocalTime(&st);++
++++st.wHour+=+hour;++++++
++++st.wMinute+=+minutes;++
++++SetLocalTime(&st);+++
}|code-block|syntax|javascript|663992|Java+JNI包装器应该是|663993|class+TimeSetter+{

++++public+native+void+setSystemTime(+short+hour,+short+minutes);

++++static+{
++++++++System.loadLibrary("TimeSetter");
++++}
}|663994|最后，为了使用它|663995|public+class+JNITimeSetter+{

++++public+static+void+main(String[]+args)+{

++++++++short+hour+=+8;
++++++++short+minutes+=+30;

++++++++//+Set+the+system+at+8h+30m

++++++++TimeSetter+ts+=+new+TimeSetter();
++++++++ts.setSystemTime(hour,+minutes);
++++}
}|663996|entityMap^0|5|3|10|3|14|1|0|C|5|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|16|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|17|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|18|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|19|8|@]|D|@]|E|$]]|$1|S|3|T|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|U|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|V|$]]

You can use <code>JNI</code> for setting the system time. This would work on Windows. You need to know <code>JNI</code> and <code>C</code>.

This is the JNI function, the prototype will be generated by the <code>javah</code> utility 

<pre><code>JNIEXPORT void JNICALL Java_TimeSetter_setSystemTime
 (JNIEnv *env, jobject obj, jshort hour, jshort minutes) {

 SYSTEMTIME st;
 GetLocalTime(&amp;st); 
 st.wHour = hour; 
 st.wMinute = minutes; 
 SetLocalTime(&amp;st); 
}
</code></pre>

The Java JNI wrapper would be

<pre><code>class TimeSetter {

 public native void setSystemTime( short hour, short minutes);

 static {
 System.loadLibrary("TimeSetter");
 }
}
</code></pre>

And finally, to use it

<pre><code>public class JNITimeSetter {

 public static void main(String[] args) {

 short hour = 8;
 short minutes = 30;

 // Set the system at 8h 30m

 TimeSetter ts = new TimeSetter();
 ts.setSystemTime(hour, minutes);
 }
}
</code></pre>

blocks|key|664037|text|package+myTestProject;

import+java.text.DateFormat;
import+java.text.SimpleDateFormat;
import+java.util.Date;

public+class+LocalTimeChangeTest+{

++++private+static+DateFormat+dateFormat+=+new+SimpleDateFormat("yyyy-MM-dd+HH:mm:ss");

++++public+static+void+main(String[]+args)+{
++++++++try+{
++++++++++++String+value+=+"2014-12-12+00:26:14";
++++++++++++Date+date+=+dateFormat.parse(value);
++++++++++++value+=+dateFormat.format(date);
++++++++++++final+Process+dateProcess+=+Runtime.getRuntime().exec("cmd+/c+date+"%2Bvalue.substring(0,+value.lastIndexOf('+')));
++++++++++++dateProcess.waitFor();
++++++++++++dateProcess.exitValue();
++++++++++++final+Process+timeProcess+=+Runtime.getRuntime().exec("cmd+/c+time+"%2Bvalue.substring(value.lastIndexOf('+')%2B1));
++++++++++++timeProcess.waitFor();
++++++++++++timeProcess.exitValue();
++++++++}+catch+(Exception+exception)+{
++++++++++++throw+new+RuntimeException(exception);
++++++++}
++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|664038|在windows管理员模式下运行此代码。|unstyled|664039|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>package myTestProject;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

public class LocalTimeChangeTest {

 private static DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

 public static void main(String[] args) {
 try {
 String value = "2014-12-12 00:26:14";
 Date date = dateFormat.parse(value);
 value = dateFormat.format(date);
 final Process dateProcess = Runtime.getRuntime().exec("cmd /c date "+value.substring(0, value.lastIndexOf(' ')));
 dateProcess.waitFor();
 dateProcess.exitValue();
 final Process timeProcess = Runtime.getRuntime().exec("cmd /c time "+value.substring(value.lastIndexOf(' ')+1));
 timeProcess.waitFor();
 timeProcess.exitValue();
 } catch (Exception exception) {
 throw new RuntimeException(exception);
 }
 }
}
</code></pre>

Run this code under windows administrator model.

blocks|key|881099|text|在某些情况下，进程不使用管理员权限运行，但仍具有设置系统时间的权限。可以使用Java+Native+Access更改系统时间，并拥有所有所需的Java源代码(与JNI相比更简单)。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|881100|package+github.jna;

import+com.sun.jna.Native;
import+com.sun.jna.platform.win32.WinBase.SYSTEMTIME;
import+com.sun.jna.win32.StdCallLibrary;

/**
+*+Provides+access+to+the+Windows+SetSystemTime+native+API+call.
+*+This+class+is+based+on+examples+found+in
+*+<a+href="https://github.com/twall/jna/blob/master/www/GettingStarted.md">JNA+Getting+Started</a>
+*/
public+class+WindowsSetSystemTime+{

++++/**
+++++*+Kernel32+DLL+Interface.
+++++*+kernel32.dll+uses+the+__stdcall+calling+convention+(check+the+function+
+++++*+declaration+for+"WINAPI"+or+"PASCAL"),+so+extend+StdCallLibrary
+++++*+Most+C+libraries+will+just+extend+com.sun.jna.Library,
+++++*/
++++public+interface+Kernel32+extends+StdCallLibrary+{

++++++++boolean+SetLocalTime(SYSTEMTIME+st);

++++++++Kernel32+instance+=+(Kernel32)+Native.loadLibrary("kernel32.dll",+Kernel32.class);

++++}

++++public+boolean+SetLocalTime(SYSTEMTIME+st)+{
++++++++return+Kernel32.instance.SetLocalTime(st);
++++}

++++public+boolean+SetLocalTime(short+wYear,+short+wMonth,+short+wDay,+short+wHour,+short+wMinute,+short+wSecond)+{
++++++++SYSTEMTIME+st+=+new+SYSTEMTIME();
++++++++st.wYear+=+wYear;
++++++++st.wMonth+=+wMonth;
++++++++st.wDay+=+wDay;
++++++++st.wHour+=+wHour;
++++++++st.wMinute+=+wMinute;
++++++++st.wSecond+=+wSecond;
++++++++return+SetLocalTime(st);
++++}+++++++
}|code-block|syntax|javascript|881101|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/twall/jna%2520Java%2520Native%2520Access%2520(JNA)^0|12|I|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

There are cases where the process does not run with admin rights, but it still has the permissions to set the system time. It is possible to use <a href="https://github.com/twall/jna%20Java%20Native%20Access%20(JNA)" rel="nofollow">Java Native Access</a> to change the system time and have all the required sources in Java (simpler compared with JNI). 

<pre><code>package github.jna;

import com.sun.jna.Native;
import com.sun.jna.platform.win32.WinBase.SYSTEMTIME;
import com.sun.jna.win32.StdCallLibrary;

/**
 * Provides access to the Windows SetSystemTime native API call.
 * This class is based on examples found in
 * &lt;a href="https://github.com/twall/jna/blob/master/www/GettingStarted.md"&gt;JNA Getting Started&lt;/a&gt;
 */
public class WindowsSetSystemTime {

 /**
 * Kernel32 DLL Interface.
 * kernel32.dll uses the __stdcall calling convention (check the function 
 * declaration for "WINAPI" or "PASCAL"), so extend StdCallLibrary
 * Most C libraries will just extend com.sun.jna.Library,
 */
 public interface Kernel32 extends StdCallLibrary {

 boolean SetLocalTime(SYSTEMTIME st);

 Kernel32 instance = (Kernel32) Native.loadLibrary("kernel32.dll", Kernel32.class);

 }

 public boolean SetLocalTime(SYSTEMTIME st) {
 return Kernel32.instance.SetLocalTime(st);
 }

 public boolean SetLocalTime(short wYear, short wMonth, short wDay, short wHour, short wMinute, short wSecond) {
 SYSTEMTIME st = new SYSTEMTIME();
 st.wYear = wYear;
 st.wMonth = wMonth;
 st.wDay = wDay;
 st.wHour = wHour;
 st.wMinute = wMinute;
 st.wSecond = wSecond;
 return SetLocalTime(st);
 } 
}
</code></pre>

blocks|key|664143|text|package+com.test;

public+class+Exec+{

++++public+static+void+main(String[]+args)+{
++++++++try+{
++++++++++++String[]+cmd+=+{"/bin/bash","-c","echo+yourPassword+%7C+sudo+-S+date+--set='2017-05-13+21:59:10'"};
++++++++++++Runtime.getRuntime().exec(cmd);
++++++++}+catch+(Exception+e)+{
++++++++++++e.printStackTrace();
++++++++}
++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|664144|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>package com.test;

public class Exec {

 public static void main(String[] args) {
 try {
 String[] cmd = {"/bin/bash","-c","echo yourPassword | sudo -S date --set='2017-05-13 21:59:10'"};
 Runtime.getRuntime().exec(cmd);
 } catch (Exception e) {
 e.printStackTrace();
 }
 }
}
</code></pre>

blocks|key|881261|text|您可以使用以下代码更改日期或在当前日期中添加日期。它在windows中工作得很好：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|881262|Calendar+cal+=+Calendar.getInstance();
cal.add(Calendar.DATE,+1);
SimpleDateFormat+s+=+new+SimpleDateFormat("MM-dd-yyyy");++++
String+strExpectedDate+=+s.format(new+Date(cal.getTimeInMillis()));
Runtime+rt+=+Runtime.getRuntime();
rt.exec("cmd+/C+date+"+%2B+strExpectedDate);|code-block|syntax|javascript|881263|在上面的代码中，我将1天添加到当前日期，您可以为strExpectedDate传递任何日期，这将仅适用于windows|881264|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can change the date or add the date in current date using below code. It is working perfectly in windows:

<pre><code>Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, 1);
SimpleDateFormat s = new SimpleDateFormat("MM-dd-yyyy"); 
String strExpectedDate = s.format(new Date(cal.getTimeInMillis()));
Runtime rt = Runtime.getRuntime();
rt.exec("cmd /C date " + strExpectedDate);
</code></pre>

In above code I have added 1 day to current date, You can pass any date for strExpectedDate and this will only work on windows

blocks|key|881342|text|我是通过捷径做到的。快捷方式通过命令链接到cmd，可更改时间或使时间与服务器时间同步。由于更改系统设置快捷方式应以管理员权限调用，因此有一种自动设置快捷方式标志Run+as+administrator的方法。为了确保同步成功，有一个方法safeSynchronize将时间更改为假时间，之后才询问服务器时间。对我来说，它工作得很完美。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|881343|package+system;

import+mslinks.ShellLink;
import+org.apache.commons.io.FileUtils;
import+org.apache.commons.lang3.time.DateUtils;

import+java.io.*;
import+java.nio.file.Files;
import+java.text.DateFormat;
import+java.text.SimpleDateFormat;
import+java.time.Instant;
import+java.util.Calendar;
import+java.util.Date;
import+java.util.Random;

public+class+TimeSynchronizer+{

++++Random+random+=+new+Random();

++++private+int+WAIT_LAG+=+1000;

++++private+DateFormat+dateFormat+=+new+SimpleDateFormat("dd-MM-yy");
++++private+DateFormat+timeFormat+=+new+SimpleDateFormat("HH:mm:ss");

++++public+void+synchronize()+throws+IOException,+InterruptedException+{
++++++++File+file+=+getFile();
++++++++makeShortcut(file,+"/c+net+start+w32time");
++++++++callShortcut(file);
++++++++makeShortcut(file,+"/c+w32tm+/resync");
++++++++callShortcut(file);
++++++++if+(file.exists())+file.delete();
++++}

++++public+void+safeSynchronize()+throws+IOException,+InterruptedException+{
++++++++Calendar+rightNow+=+Calendar.getInstance();
++++++++int+minute+=+rightNow.get(Calendar.MINUTE);
++++++++boolean+isForward+=+minute+<+30;
++++++++Date+date+=+DateUtils.addMinutes(Date.from(Instant.now()),+10+*+(isForward+?+1+:+-1));

++++++++setTime(date);
++++++++synchronize();
++++}

++++public+void+setTime(Date+date)+throws+IOException,+InterruptedException+{
++++++++setTime(date,+false);
++++}

++++public+void+setTime(Date+date,+boolean+withDate)+throws+IOException,+InterruptedException+{
++++++++File+file+=+getFile();
++++++++if+(withDate)+{
++++++++++++makeShortcut(file,+"/c+date+"+%2B+dateFormat.format(date));
++++++++++++callShortcut(file);
++++++++}
++++++++makeShortcut(file,+"/c+time+"+%2B+timeFormat.format(date));
++++++++callShortcut(file);
++++++++if+(file.exists())+file.delete();
++++}

++++private+void+callShortcut(File+file)+throws+IOException,+InterruptedException+{
++++++++Process+process+=+Runtime.getRuntime().exec(
++++++++++++getSystem32Path()+%2B+"\\cmd.exe+/c+start+/wait+\"\"+\""+%2B+file.getAbsolutePath()+%2B+"\""
++++++++);
++++++++process.waitFor();
++++++++process.exitValue();
++++}

++++private+String+getSystem32Path()+{
++++++++return+System.getenv("SystemRoot")+%2B+"\\system32";
++++}

++++private+File+getFile()+{
++++++++return+new+File(random.nextInt()+%2B+"shortcut.lnk");
++++}

++++private+void+makeShortcut(File+file,+String+command)+throws+IOException,+InterruptedException+{
++++++++String+system32Path+=+getSystem32Path();
++++++++ShellLink+s+=+new+ShellLink();
++++++++s.setTarget(system32Path+%2B+"\\cmd.exe");
++++++++s.setCMDArgs(command);
++++++++s.saveTo(file.getAbsolutePath());
++++++++Thread.sleep(WAIT_LAG);

++++++++setRunAsAdmin(file);
++++}

++++private+void+setRunAsAdmin(File+file)+throws+IOException+{
++++++++byte[]+fileContent+=+Files.readAllBytes(file.toPath());
++++++++fileContent[21]+=+(char)32;
++++++++FileUtils.writeByteArrayToFile(file,+fileContent);
++++}
}|code-block|syntax|javascript|881344|entityMap^0|L|3|28|K|3A|F|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

I did it with shortcuts. Shortcut has link to <code>cmd</code> with commands, changing time or synchronize time with server time. As changing system settings shortcut should be called with admin permission there is a method automatically setting shortcut flag <code>Run as administrator</code>. To be sure that synchronization was succesfull there is a method <code>safeSynchronize</code> changing time to fake time and only after that ask the server time. For me it works perfectly.
<pre><code>package system;

import mslinks.ShellLink;
import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.time.DateUtils;

import java.io.*;
import java.nio.file.Files;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.time.Instant;
import java.util.Calendar;
import java.util.Date;
import java.util.Random;

public class TimeSynchronizer {

 Random random = new Random();

 private int WAIT_LAG = 1000;

 private DateFormat dateFormat = new SimpleDateFormat(&quot;dd-MM-yy&quot;);
 private DateFormat timeFormat = new SimpleDateFormat(&quot;HH:mm:ss&quot;);

 public void synchronize() throws IOException, InterruptedException {
 File file = getFile();
 makeShortcut(file, &quot;/c net start w32time&quot;);
 callShortcut(file);
 makeShortcut(file, &quot;/c w32tm /resync&quot;);
 callShortcut(file);
 if (file.exists()) file.delete();
 }

 public void safeSynchronize() throws IOException, InterruptedException {
 Calendar rightNow = Calendar.getInstance();
 int minute = rightNow.get(Calendar.MINUTE);
 boolean isForward = minute &lt; 30;
 Date date = DateUtils.addMinutes(Date.from(Instant.now()), 10 * (isForward ? 1 : -1));

 setTime(date);
 synchronize();
 }

 public void setTime(Date date) throws IOException, InterruptedException {
 setTime(date, false);
 }

 public void setTime(Date date, boolean withDate) throws IOException, InterruptedException {
 File file = getFile();
 if (withDate) {
 makeShortcut(file, &quot;/c date &quot; + dateFormat.format(date));
 callShortcut(file);
 }
 makeShortcut(file, &quot;/c time &quot; + timeFormat.format(date));
 callShortcut(file);
 if (file.exists()) file.delete();
 }

 private void callShortcut(File file) throws IOException, InterruptedException {
 Process process = Runtime.getRuntime().exec(
 getSystem32Path() + &quot;\\cmd.exe /c start /wait \&quot;\&quot; \&quot;&quot; + file.getAbsolutePath() + &quot;\&quot;&quot;
 );
 process.waitFor();
 process.exitValue();
 }

 private String getSystem32Path() {
 return System.getenv(&quot;SystemRoot&quot;) + &quot;\\system32&quot;;
 }

 private File getFile() {
 return new File(random.nextInt() + &quot;shortcut.lnk&quot;);
 }

 private void makeShortcut(File file, String command) throws IOException, InterruptedException {
 String system32Path = getSystem32Path();
 ShellLink s = new ShellLink();
 s.setTarget(system32Path + &quot;\\cmd.exe&quot;);
 s.setCMDArgs(command);
 s.saveTo(file.getAbsolutePath());
 Thread.sleep(WAIT_LAG);

 setRunAsAdmin(file);
 }

 private void setRunAsAdmin(File file) throws IOException {
 byte[] fileContent = Files.readAllBytes(file.toPath());
 fileContent[21] = (char)32;
 FileUtils.writeByteArrayToFile(file, fileContent);
 }
}
</code></pre>

Is it possible to change the System Time in Java? 

It should run under Windows and Linux. I've tried it with the <code>Runtime</code> Class in but there is a problem with the permissions.

This is my code:

<pre><code>String cmd="date -s \""+datetime.format(ntp_obj.getDest_Time())+"\"";
try {
 Runtime.getRuntime().exec(cmd);
} catch (IOException e1) {
// TODO Auto-generated catch block
 e1.printStackTrace();
}
System.out.println(cmd);
</code></pre>

The output of <code>cmd</code> is:

<pre><code>date -s "06/01/2011 17:59:01"
</code></pre>

But the System time is the same as before.

I will set the time because I am writing an NTP-Client and there I get the time from a NTP-Server and will set it.

How can I set the System Time in Java?

命令行工具

服务器

Windows

Linux

Java

可以在Java中更改系统时间吗？它应该可以在Windows和Linux下运行。我已经用中的Runtime类尝试过了，但是权限有问题。这是我的代码：String cmd="date -s \""+datetime.format(ntp_obj.getDest_Time())+"\"";try {    Runtime.g...

问如何在Java中设置系统时间？
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