在java应用中如何用Process和ProcessBuilder 执行命令？ 博客分类： 知识点滴 javacommandprocess
2，如果调用外部java服务，如何在销毁进程的同时关闭它开启的外部服务？
3，如何获得执行进程的PID？
1，如何执行，如何用ProcessBuilder来简化操作
在ProcessBuilder(http://java.sun.com/j2se/1.5.0/docs/api/java/lang/ProcessBuilder.html)有个简单的例子。
ProcessBuilder pb = new ProcessBuilder("myCommand", "myArg1", "myArg2");
Map<String, String> env = pb.environment();
env.put("VAR1", "myValue");
env.remove("OTHERVAR");
env.put("VAR2", env.get("VAR1") + "suffix");
pb.directory("myDir");
Process p = pb.start();
这个例子描述了如何执行一个命令，但是如果你想从命令行读取输入输出呢？
假设我们想执行如下命令
Ipconfig –all
我们可以做如下改进
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class ProcessExec {
private Process process;
public void execute()
throws InterruptedException, IOException {
List<String> command = new ArrayList<String>();
command.add( "cmd.exe" );
command.add( "/c" );
command.add( "ipconfig -all" );
// 执行命令
ProcessBuilder pb = new ProcessBuilder( ( command ) );
process = pb.start();
// 异步读取输出
InputStream inputStream = process.getInputStream();
InputStream errorStream = process.getErrorStream();
ExecutorService service = Executors.newFixedThreadPool( 2 );
ResultStreamHandler inputStreamHandler = new ResultStreamHandler( inputStream );
ResultStreamHandler errorStreamHandler = new ResultStreamHandler( errorStream );
service.execute( inputStreamHandler );
service.execute( errorStreamHandler );
process.waitFor();
service.shutdownNow();
}
class ResultStreamHandler
implements Runnable {
private InputStream inputStream;
ResultStreamHandler( InputStream inputStream ) {
this.inputStream = inputStream;
}
public void run() {
BufferedReader bufferedReader = null;
try {
bufferedReader = new BufferedReader( new InputStreamReader( inputStream ) );
String line = null;
while ( ( line = bufferedReader.readLine() ) != null ) {
System.out.println( line );
}
}
catch ( Throwable t ) {
}
finally {
try {
bufferedReader.close();
}
catch ( IOException e ) {
}
}
}
}
}
现在我们可以异步读取输出了，但其方式比较单一，我们可不可以直接输出到一个指定文件呢？
自jdk1.7起，ProcessBuilder增加Redirect来方便我们处理这个问题
1，输出有output, error两个流，输入有input流，相应的在这我们要创建3个文件
File errors = new File("C:/error.log");
File input = new File("C:/input.txt");
2创建input.txt文件，输入一下命令
Ipconfig –all
确定all后面有回车符
3 创建一个ProcessBuilder实例，指定“cmd”作为参数，表示我们想执行一个window命令
4 Redirect输入输出流到不同的文件
pb.redirectError(errors);
pb.redirectOutput(output);
5 最后，执行命令
需要注意的是start必须在redirct设定后才调用
ProcessBuilder还有一些使用的方法
比如ProcessBuilder.Redirect.appendTo
这样每次输出到指定文件都追加到后面而不是覆盖
比较有用的还有inheritIO(), 调用这个方法可以redirect被执行命令的输入输出流到当前java进程的输入输出流，也就是说，如果你用eclipse执行，你在console里就可以看到输入输出。
2，如果调用外部java服务，如何在销毁进程的同时关闭它开启的外部服务？
有时候或许我们会执行一个外部的java应用
如：java –jar D:\\test.jar
假设test.jar 一旦启动会一直运行，那么问题来了，当process被销毁时，如何关闭这个外部进程呢？
有个bug专门描述了这个问题
http://bugs.java.com/bugdatabase/view_bug.do?bug_id=4770092
可以看出没有什么好的解决办法
但有时我们就想用这个功能，怎么办？
或许我们可以使用jdk自带的tools.jar
这个程序遍历虚拟机上所有的java程序，提取他们main class名，如果和指定的main class名匹配，则返回pid值
import sun.jvmstat.monitor.MonitorException;
import sun.jvmstat.monitor.MonitoredHost;
import sun.jvmstat.monitor.MonitoredVm;
import sun.jvmstat.monitor.MonitoredVmUtil;
import sun.jvmstat.monitor.VmIdentifier;
public class GetOwnPid {
public static void main(String[] args) {
new GetOwnPid().run();
}
public void run() {
System.out.println(getPid(this.getClass()));
}
public Integer getPid(Class<?> mainClass) {
MonitoredHost monitoredHost;
Set<Integer> activeVmPids;
try {
monitoredHost = MonitoredHost.getMonitoredHost(new HostIdentifier((String) null));
activeVmPids = monitoredHost.activeVms();
MonitoredVm mvm = null;
for (Integer vmPid : activeVmPids) {
try {
mvm = monitoredHost.getMonitoredVm(new VmIdentifier(vmPid.toString()));
String mvmMainClass = MonitoredVmUtil.mainClass(mvm, true);
if (mainClass.getName().equals(mvmMainClass)) {
return vmPid;
}
} finally {
if (mvm != null) {
mvm.detach();
}
}
}
} catch (java.net.URISyntaxException e) {
throw new InternalError(e.getMessage());
} catch (MonitorException e) {
throw new InternalError(e.getMessage());
}
return null;
}
}
3, 如何获得执行进程的PID?
如果process因为未知的原因阻塞了，我们想直接kill它，如何获得该进程的pid呢？
在Unix,我们可以用反射，因为UnixProcess类有pid属性
/* 获取pid */
try {
Field f = process.getClass().getDeclaredField("pid");
f.setAccessible(true);
pid = f.getInt(p);
} catch (Throwable e) {
}
}
在这里我们可以利用它的handle属性
首先下载jna.jar
process.getClass().getName().equals("java.lang.ProcessImpl")) {
/* determine the pid on windows plattforms */
try {
Field f = p.getClass().getDeclaredField("handle");
f.setAccessible(true);
long handl = f.getLong(p);
Kernel32 kernel = Kernel32.INSTANCE;
W32API.HANDLE handle = new W32API.HANDLE();
handle.setPointer(Pointer.createConstant(handl));
pid = kernel.GetProcessId(handle);
} catch (Throwable e) {
}
}
/* https://jna.dev.java.net/ */
public interface Kernel32 extends W32API {
Kernel32 INSTANCE = (Kernel32) Native.loadLibrary("kernel32", Kernel32.class, DEFAULT_OPTIONS);
/* http://msdn.microsoft.com/en-us/library/ms683179(VS.85).aspx */
HANDLE GetCurrentProcess();
/* http://msdn.microsoft.com/en-us/library/ms683215.aspx */
int GetProcessId(HANDLE Process);
}
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
import java.util.HashMap;
import java.util.Map;
import com.sun.jna.FromNativeContext;
import com.sun.jna.Pointer;
import com.sun.jna.PointerType;
import com.sun.jna.win32.StdCallLibrary;
import com.sun.jna.win32.W32APIFunctionMapper;
import com.sun.jna.win32.W32APITypeMapper;
/** Base type for most W32 API libraries. Provides standard options
* for unicode/ASCII mappings. Set the system property w32.ascii
* to true to default to the ASCII mappings.
*/
public interface W32API extends StdCallLibrary, W32Errors {
/** Standard options to use the unicode version of a w32 API. */
Map UNICODE_OPTIONS = new HashMap() {
{
put(OPTION_TYPE_MAPPER, W32APITypeMapper.UNICODE);
put(OPTION_FUNCTION_MAPPER, W32APIFunctionMapper.UNICODE);
}
};
/** Standard options to use the ASCII/MBCS version of a w32 API. */
Map ASCII_OPTIONS = new HashMap() {
{
put(OPTION_TYPE_MAPPER, W32APITypeMapper.ASCII);
put(OPTION_FUNCTION_MAPPER, W32APIFunctionMapper.ASCII);
}
};
Map DEFAULT_OPTIONS = Boolean.getBoolean("w32.ascii") ? ASCII_OPTIONS : UNICODE_OPTIONS;
public class HANDLE extends PointerType {
@Override
public Object fromNative(Object nativeValue, FromNativeContext context) {
Object o = super.fromNative(nativeValue, context);
if (INVALID_HANDLE_VALUE.equals(o))
return INVALID_HANDLE_VALUE;
return o;
}
}
/** Constant value representing an invalid HANDLE. */
HANDLE INVALID_HANDLE_VALUE = new HANDLE() {
{ super.setPointer(Pointer.createConstant(-1)); }
@Override
public void setPointer(Pointer p) {
throw new UnsupportedOperationException("Immutable reference");
}
};
}
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
public interface W32Errors {
int NO_ERROR = 0;
int ERROR_INVALID_FUNCTION = 1;
int ERROR_FILE_NOT_FOUND = 2;
int ERROR_PATH_NOT_FOUND = 3;
}
String processName = rtb.getName();
Integer pid = tryPattern1(processName);
private static Integer tryPattern1(String processName) {
Integer result = null;
/* tested on: */
/* - windows xp sp 2, java 1.5.0_13 */
/* - mac os x 10.4.10, java 1.5.0 */
/* - debian linux, java 1.5.0_13 */
/* all return pid@host, e.g 2204@antonius */
Pattern pattern = Pattern.compile("^([0-9]+)@.+$", Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(processName);
if (matcher.matches()) {
result = new Integer(Integer.parseInt(matcher.group(1)));
}
return result;
}
相关信息还可以参照http://bugs.sun.com/view_bug.do?bug_id=4244896