Java调用系统命令学习(3)
2016-02-25 11:02
513 查看
学习了两篇的Runtime类，现在对它有了更深一层的了解，那么我们来看看下面的代码：
Java代码
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader ;
import java.io.BufferedReader;
public class Exec_Output{
public static void main(String []args)throws IOException,InterruptedException{
Runtime rt = Runtime.getRuntime();
Process p = rt.exec("dir");
//int exitValue = p.exitValue();
//int exitValue = p.waitFor();
InputStream is = p.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line = null;
System.out.println("<OUTPUT>");
while((line = br.readLine())!=null){
System.out.println(line);
System.out.println("</OUTPUT>");
int exitValue = p.waitFor();
System.out.println("Process exitValue="+exitValue);
}
}
}
//执行结果（在Ubuntu9.10下执行）
<OUTPUT>
class CUtil.java Exec.java Exec_Javac.java Exec_Output.java Str.java
</OUTPUT>
[java] view
plain copy
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader ;
import java.io.BufferedReader;
public class Exec_Output{
public static void main(String []args)throws IOException,InterruptedException{
Runtime rt = Runtime.getRuntime();
Process p = rt.exec("dir");
//int exitValue = p.exitValue();
//int exitValue = p.waitFor();
InputStream is = p.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line = null;
System.out.println("<OUTPUT>");
while((line = br.readLine())!=null){
System.out.println(line);
System.out.println("</OUTPUT>");
int exitValue = p.waitFor();
System.out.println("Process exitValue="+exitValue);
}
}
}
//执行结果（在Ubuntu9.10下执行）
<OUTPUT>
class CUtil.java Exec.java Exec_Javac.java Exec_Output.java Str.java
</OUTPUT>
因为以上代码，我使用了Ubuntu9.10下执行，是一点问题都没有，但当我在windows xp下执行，意外却发生了。
E:classescomjavaworldjpitfallsarticle2>java BadExecWinDir
java.io.IOException: CreateProcess: dir error=2
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Unknown Source)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at BadExecWinDir.main(BadExecWinDir.java:12)
也许大家觉得奇怪，其实我也很奇怪，为什么呢。好好在Linux下，咋到XP就有问题了呢。
以下引用了别人的话：
说实在的，这个错误还真是让我摸不着头脑，我觉得在windows中返回2应该是没有找到这个文件的缘故，可能windows 2000中只有cmd命令，dir命令不是当前环境变量能够解释的吧。我也不知道了，慢慢往下看吧。
嘿，果然和作者想的一样，就是因为dir命令是由windows中的解释器解释的，直接执行dir时无法找到 dir.exe这个命令，所以会出现文件未找到这个2的错误。如果我们要执行这样的命令，就要先根据操作系统的不同执行不同的解释程序 command.com 或者cmd.exe。
到这里，大家明白了吧。
因此，别人还作了一些改进：
Java代码
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader ;
import java.io.BufferedReader;
public class Exec_Output_Win{
public static void main(String []args)throws IOException,InterruptedException{
if(args.length < 1){
System.out.println("USAGE:java Exec_Output_Win <cmd>");
System.exit(1);
}
try{
String osName = System.getProperty("os.name");
String []cmd = new String[3];
if(osName.equals("Windows NT")){
cmd[0] = "cmd.exe";
cmd[1] = "/C";
cmd[2] = args[0];
}else if(osName.equals("Windows 95")){
cmd[0] = "command.com";
cmd[1] = "/C";
cmd[2] = args[0];
}else if(osName.equals("Linux")){
System.out.println("Os:"+osName);
System.exit(0);
}
Runtime rt = Runtime.getRuntime();
System.out.println("Execing "+cmd[0]+" "+cmd[1]+" "+cmd[2]);
Process p = rt.exec(cmd);
//any error message?
StreamGobbler err = new StreamGobbler(p.getErrorStream(),"ERROR");
//any output?
StreamGobbler out= new StreamGobbler(p.getInputStream(),"OUTPUT");
//kick them off
err.start();
out.start();
//any error?
int exitValue = p.waitFor();
System.out.println("Process exitValue="+exitValue);
}catch(Exception e){
e.printStackTrace();
}
}
}
class StreamGobbler extends Thread{
InputStream is;
String type;
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);
}
}catch(IOException e){
e.printStackTrace();
}
}
}
//执行结果：
（Linux 环境下）
Os:Linux
（windows XP环境下）
E:classescomjavaworldjpitfallsarticle2>java GoodWindowsExec "dir *.java"
Execing cmd.exe /C dir *.java
OUTPUT> Volume in drive E has no label.
OUTPUT> Volume Serial Number is 5C5F-0CC9
OUTPUT>
OUTPUT> Directory of E:classescomjavaworldjpitfallsarticle2
OUTPUT>
OUTPUT>10/23/00 09:01p 805 BadExecBrowser.java
OUTPUT>10/22/00 09:35a 770 BadExecBrowser1.java
OUTPUT>10/24/00 08:45p 488 BadExecJavac.java
OUTPUT>10/24/00 08:46p 519 BadExecJavac2.java
OUTPUT>10/24/00 09:13p 930 BadExecWinDir.java
OUTPUT>10/22/00 09:21a 2,282 BadURLPost.java
OUTPUT>10/22/00 09:20a 2,273 BadURLPost1.java
... (some output omitted for brevity)
OUTPUT>10/12/00 09:29p 151 SuperFrame.java
OUTPUT>10/24/00 09:23p 1,814 TestExec.java
OUTPUT>10/09/00 05:47p 23,543 TestStringReplace.java
OUTPUT>10/12/00 08:55p 228 TopLevel.java
OUTPUT> 22 File(s) 46,661 bytes
OUTPUT> 19,678,420,992 bytes free
ExitValue: 0
[java] view
plain copy
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader ;
import java.io.BufferedReader;
public class Exec_Output_Win{
public static void main(String []args)throws IOException,InterruptedException{
if(args.length < 1){
System.out.println("USAGE:java Exec_Output_Win <cmd>");
System.exit(1);
}
try{
String osName = System.getProperty("os.name");
String []cmd = new String[3];
if(osName.equals("Windows NT")){
cmd[0] = "cmd.exe";
cmd[1] = "/C";
cmd[2] = args[0];
}else if(osName.equals("Windows 95")){
cmd[0] = "command.com";
cmd[1] = "/C";
cmd[2] = args[0];
}else if(osName.equals("Linux")){
System.out.println("Os:"+osName);
System.exit(0);
}
Runtime rt = Runtime.getRuntime();
System.out.println("Execing "+cmd[0]+" "+cmd[1]+" "+cmd[2]);
Process p = rt.exec(cmd);
//any error message?
StreamGobbler err = new StreamGobbler(p.getErrorStream(),"ERROR");
//any output?
StreamGobbler out= new StreamGobbler(p.getInputStream(),"OUTPUT");
//kick them off
err.start();
out.start();
//any error?
int exitValue = p.waitFor();
System.out.println("Process exitValue="+exitValue);
}catch(Exception e){
e.printStackTrace();
}
}
}
class StreamGobbler extends Thread{
InputStream is;
String type;
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);
}
}catch(IOException e){
e.printStackTrace();
}
}
}
//执行结果：
（Linux 环境下）
Os:Linux
（windows XP环境下）
E:classescomjavaworldjpitfallsarticle2>java GoodWindowsExec "dir *.java"
Execing cmd.exe /C dir *.java
OUTPUT> Volume in drive E has no label.
OUTPUT> Volume Serial Number is 5C5F-0CC9
OUTPUT>
OUTPUT> Directory of E:classescomjavaworldjpitfallsarticle2
OUTPUT>
OUTPUT>10/23/00 09:01p 805 BadExecBrowser.java
OUTPUT>10/22/00 09:35a 770 BadExecBrowser1.java
OUTPUT>10/24/00 08:45p 488 BadExecJavac.java
OUTPUT>10/24/00 08:46p 519 BadExecJavac2.java
OUTPUT>10/24/00 09:13p 930 BadExecWinDir.java
OUTPUT>10/22/00 09:21a 2,282 BadURLPost.java
OUTPUT>10/22/00 09:20a 2,273 BadURLPost1.java
... (some output omitted for brevity)
OUTPUT>10/12/00 09:29p 151 SuperFrame.java
OUTPUT>10/24/00 09:23p 1,814 TestExec.java
OUTPUT>10/09/00 05:47p 23,543 TestStringReplace.java
OUTPUT>10/12/00 08:55p 228 TopLevel.java
OUTPUT> 22 File(s) 46,661 bytes
OUTPUT> 19,678,420,992 bytes free
ExitValue: 0
因为我在linux下运行，得不到想要的结果。
以下引用作者的话：
这里作者教了一个windows中很有用的方法，呵呵，至少我是不知道的，就是cmd.exe /C +一个windows中注册了后缀的文档名，windows会自动地调用相关的程序来打开这个文档，我试了一下，的确很好用，但是好像文件路径中有空格的话就有点问题，我加上引号也无法解决。
这里作者强调了一下，不要假设你执行的程序是可执行的程序，要清楚自己的程序是单独可执行的还是被解释的，本章的结束作者会介绍一个命令行工具来帮助我们分析。
这里还有一点，就是得到process的输出的方式是getInputStream，这是因为我们要从Java 程序的角度来看，外部程序的输出对于Java来说就是输入，反之亦然。
最后的一个漏洞的地方就是错误的认为exec方法会接受所有你在命令行或者Shell中输入并接受的字符串。这些错误主要出现在命令作为参数的情况下，程序员错误的将所有命令行中可以输入的参数命令加入到exec中（这段翻译的不好，凑合看吧）。下面的例子中就是一个程序员想重定向一个命令的输出。
Java代码
import java.util.*;
import java.io.*;
// StreamGobbler omitted for brevity
public class BadWinRedirect
{
public static void main(String args[])
{
try
{
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java jecho 'Hello World' > test.txt");
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
Running BadWinRedirect produces:
E:classescomjavaworldjpitfallsarticle2>java BadWinRedirect
OUTPUT>'Hello World' > test.txt
ExitValue: 0
[java] view
plain copy
import java.util.*;
import java.io.*;
// StreamGobbler omitted for brevity
public class BadWinRedirect
{
public static void main(String args[])
{
try
{
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java jecho 'Hello World' > test.txt");
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
Running BadWinRedirect produces:
E:classescomjavaworldjpitfallsarticle2>java BadWinRedirect
OUTPUT>'Hello World' > test.txt
ExitValue: 0
程序员的本意是将Hello World这个输入重订向到一个文本文件中，但是这个文件并没有生成，jecho仅仅是将命令行中的参数输出到标准输出中，用户觉得可以像dos中重定向一样将输出重定向到一个文件中，但这并不能实现，用户错误的将exec认为是一个shell解释器，但它并不是，如果你想将一个程序的输出重定向到其他的程序中，你必须用程序来实现他。可用java.io中的包。
Java代码
import java.util.*;
import java.io.*;
class StreamGobbler extends Thread
{
InputStream is;
String type;
OutputStream os;
StreamGobbler(InputStream is, String type)
{
this(is, type, null);
}
StreamGobbler(InputStream is, String type, OutputStream redirect)
{
this.is = is;
this.type = type;
this.os = redirect;
}
public void run()
{
try
{
PrintWriter pw = null;
if (os != null)
pw = new PrintWriter(os);
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line=null;
while ( (line = br.readLine()) != null)
{
if (pw != null)
pw.println(line);
System.out.println(type + ">" + line);
}
if (pw != null)
pw.flush();
} catch (IOException ioe)
{
ioe.printStackTrace();
}
}
}
public class GoodWinRedirect
{
public static void main(String args[])
{
if (args.length < 1)
{
System.out.println("USAGE java GoodWinRedirect <outputfile>");
System.exit(1);
}
try
{
FileOutputStream fos = new FileOutputStream(args[0]);
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java jecho 'Hello World'");
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT", fos);
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
fos.flush();
fos.close();
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
Running GoodWinRedirect produces:
E:classescomjavaworldjpitfallsarticle2>java GoodWinRedirect test.txt
OUTPUT>'Hello World'
ExitValue: 0
[java] view
plain copy
import java.util.*;
import java.io.*;
class StreamGobbler extends Thread
{
InputStream is;
String type;
OutputStream os;
StreamGobbler(InputStream is, String type)
{
this(is, type, null);
}
StreamGobbler(InputStream is, String type, OutputStream redirect)
{
this.is = is;
this.type = type;
this.os = redirect;
}
public void run()
{
try
{
PrintWriter pw = null;
if (os != null)
pw = new PrintWriter(os);
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line=null;
while ( (line = br.readLine()) != null)
{
if (pw != null)
pw.println(line);
System.out.println(type + ">" + line);
}
if (pw != null)
pw.flush();
} catch (IOException ioe)
{
ioe.printStackTrace();
}
}
}
public class GoodWinRedirect
{
public static void main(String args[])
{
if (args.length < 1)
{
System.out.println("USAGE java GoodWinRedirect <outputfile>");
System.exit(1);
}
try
{
FileOutputStream fos = new FileOutputStream(args[0]);
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java jecho 'Hello World'");
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT", fos);
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
fos.flush();
fos.close();
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
Running GoodWinRedirect produces:
E:classescomjavaworldjpitfallsarticle2>java GoodWinRedirect test.txt
OUTPUT>'Hello World'
ExitValue: 0
这里就不多说了，看看就明白，紧接着作者给出了一个监测命令的小程序
Java代码
import java.util.*;
import java.io.*;
// class StreamGobbler omitted for brevity
public class TestExec
{
public static void main(String args[])
{
if (args.length < 1)
{
System.out.println("USAGE: java TestExec "cmd"");
System.exit(1);
}
try
{
String cmd = args[0];
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec(cmd);
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
//对这个程序进行运行:
E:classescomjavaworldjpitfallsarticle2>java TestExec "e:javadocsindex.html"
java.io.IOException: CreateProcess: e:javadocsindex.html error=193
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Unknown Source)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at TestExec.main(TestExec.java:45)
[java] view
plain copy
import java.util.*;
import java.io.*;
// class StreamGobbler omitted for brevity
public class TestExec
{
public static void main(String args[])
{
if (args.length < 1)
{
System.out.println("USAGE: java TestExec "cmd"");
System.exit(1);
}
try
{
String cmd = args[0];
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec(cmd);
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
//对这个程序进行运行:
E:classescomjavaworldjpitfallsarticle2>java TestExec "e:javadocsindex.html"
java.io.IOException: CreateProcess: e:javadocsindex.html error=193
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Unknown Source)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at TestExec.main(TestExec.java:45)
193在windows中是说这不是一个win32程序，这说明路径中找不到这个网页的关联程序，下面作者决定用一个绝对路径来试一下。
E:classescomjavaworldjpitfallsarticle2>java TestExec
"e:program filesnetscapeprogramnetscape.exe e:javadocsindex.html"
ExitValue: 0
好用了，这个我也试了一下，用的是IE。
最后，作者总结了几条规则，防止我们在进行Runtime.exec()调用时出现错误。
在一个外部进程执行完之前你不能得到他的退出状态
在你的外部程序开始执行的时候你必须马上控制输入、输出、出错这些流。
你必须用Runtime.exec()去执行程序
你不能象命令行一样使用Runtime.exec()。
Java代码
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader ;
import java.io.BufferedReader;
public class Exec_Output{
public static void main(String []args)throws IOException,InterruptedException{
Runtime rt = Runtime.getRuntime();
Process p = rt.exec("dir");
//int exitValue = p.exitValue();
//int exitValue = p.waitFor();
InputStream is = p.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line = null;
System.out.println("<OUTPUT>");
while((line = br.readLine())!=null){
System.out.println(line);
System.out.println("</OUTPUT>");
int exitValue = p.waitFor();
System.out.println("Process exitValue="+exitValue);
}
}
}
//执行结果（在Ubuntu9.10下执行）
<OUTPUT>
class CUtil.java Exec.java Exec_Javac.java Exec_Output.java Str.java
</OUTPUT>
[java] view
plain copy
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader ;
import java.io.BufferedReader;
public class Exec_Output{
public static void main(String []args)throws IOException,InterruptedException{
Runtime rt = Runtime.getRuntime();
Process p = rt.exec("dir");
//int exitValue = p.exitValue();
//int exitValue = p.waitFor();
InputStream is = p.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line = null;
System.out.println("<OUTPUT>");
while((line = br.readLine())!=null){
System.out.println(line);
System.out.println("</OUTPUT>");
int exitValue = p.waitFor();
System.out.println("Process exitValue="+exitValue);
}
}
}
//执行结果（在Ubuntu9.10下执行）
<OUTPUT>
class CUtil.java Exec.java Exec_Javac.java Exec_Output.java Str.java
</OUTPUT>
因为以上代码，我使用了Ubuntu9.10下执行，是一点问题都没有，但当我在windows xp下执行，意外却发生了。
E:classescomjavaworldjpitfallsarticle2>java BadExecWinDir
java.io.IOException: CreateProcess: dir error=2
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Unknown Source)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at BadExecWinDir.main(BadExecWinDir.java:12)
也许大家觉得奇怪，其实我也很奇怪，为什么呢。好好在Linux下，咋到XP就有问题了呢。
以下引用了别人的话：
说实在的，这个错误还真是让我摸不着头脑，我觉得在windows中返回2应该是没有找到这个文件的缘故，可能windows 2000中只有cmd命令，dir命令不是当前环境变量能够解释的吧。我也不知道了，慢慢往下看吧。
嘿，果然和作者想的一样，就是因为dir命令是由windows中的解释器解释的，直接执行dir时无法找到 dir.exe这个命令，所以会出现文件未找到这个2的错误。如果我们要执行这样的命令，就要先根据操作系统的不同执行不同的解释程序 command.com 或者cmd.exe。
到这里，大家明白了吧。
因此，别人还作了一些改进：
Java代码
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader ;
import java.io.BufferedReader;
public class Exec_Output_Win{
public static void main(String []args)throws IOException,InterruptedException{
if(args.length < 1){
System.out.println("USAGE:java Exec_Output_Win <cmd>");
System.exit(1);
}
try{
String osName = System.getProperty("os.name");
String []cmd = new String[3];
if(osName.equals("Windows NT")){
cmd[0] = "cmd.exe";
cmd[1] = "/C";
cmd[2] = args[0];
}else if(osName.equals("Windows 95")){
cmd[0] = "command.com";
cmd[1] = "/C";
cmd[2] = args[0];
}else if(osName.equals("Linux")){
System.out.println("Os:"+osName);
System.exit(0);
}
Runtime rt = Runtime.getRuntime();
System.out.println("Execing "+cmd[0]+" "+cmd[1]+" "+cmd[2]);
Process p = rt.exec(cmd);
//any error message?
StreamGobbler err = new StreamGobbler(p.getErrorStream(),"ERROR");
//any output?
StreamGobbler out= new StreamGobbler(p.getInputStream(),"OUTPUT");
//kick them off
err.start();
out.start();
//any error?
int exitValue = p.waitFor();
System.out.println("Process exitValue="+exitValue);
}catch(Exception e){
e.printStackTrace();
}
}
}
class StreamGobbler extends Thread{
InputStream is;
String type;
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);
}
}catch(IOException e){
e.printStackTrace();
}
}
}
//执行结果：
（Linux 环境下）
Os:Linux
（windows XP环境下）
E:classescomjavaworldjpitfallsarticle2>java GoodWindowsExec "dir *.java"
Execing cmd.exe /C dir *.java
OUTPUT> Volume in drive E has no label.
OUTPUT> Volume Serial Number is 5C5F-0CC9
OUTPUT>
OUTPUT> Directory of E:classescomjavaworldjpitfallsarticle2
OUTPUT>
OUTPUT>10/23/00 09:01p 805 BadExecBrowser.java
OUTPUT>10/22/00 09:35a 770 BadExecBrowser1.java
OUTPUT>10/24/00 08:45p 488 BadExecJavac.java
OUTPUT>10/24/00 08:46p 519 BadExecJavac2.java
OUTPUT>10/24/00 09:13p 930 BadExecWinDir.java
OUTPUT>10/22/00 09:21a 2,282 BadURLPost.java
OUTPUT>10/22/00 09:20a 2,273 BadURLPost1.java
... (some output omitted for brevity)
OUTPUT>10/12/00 09:29p 151 SuperFrame.java
OUTPUT>10/24/00 09:23p 1,814 TestExec.java
OUTPUT>10/09/00 05:47p 23,543 TestStringReplace.java
OUTPUT>10/12/00 08:55p 228 TopLevel.java
OUTPUT> 22 File(s) 46,661 bytes
OUTPUT> 19,678,420,992 bytes free
ExitValue: 0
[java] view
plain copy
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader ;
import java.io.BufferedReader;
public class Exec_Output_Win{
public static void main(String []args)throws IOException,InterruptedException{
if(args.length < 1){
System.out.println("USAGE:java Exec_Output_Win <cmd>");
System.exit(1);
}
try{
String osName = System.getProperty("os.name");
String []cmd = new String[3];
if(osName.equals("Windows NT")){
cmd[0] = "cmd.exe";
cmd[1] = "/C";
cmd[2] = args[0];
}else if(osName.equals("Windows 95")){
cmd[0] = "command.com";
cmd[1] = "/C";
cmd[2] = args[0];
}else if(osName.equals("Linux")){
System.out.println("Os:"+osName);
System.exit(0);
}
Runtime rt = Runtime.getRuntime();
System.out.println("Execing "+cmd[0]+" "+cmd[1]+" "+cmd[2]);
Process p = rt.exec(cmd);
//any error message?
StreamGobbler err = new StreamGobbler(p.getErrorStream(),"ERROR");
//any output?
StreamGobbler out= new StreamGobbler(p.getInputStream(),"OUTPUT");
//kick them off
err.start();
out.start();
//any error?
int exitValue = p.waitFor();
System.out.println("Process exitValue="+exitValue);
}catch(Exception e){
e.printStackTrace();
}
}
}
class StreamGobbler extends Thread{
InputStream is;
String type;
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);
}
}catch(IOException e){
e.printStackTrace();
}
}
}
//执行结果：
（Linux 环境下）
Os:Linux
（windows XP环境下）
E:classescomjavaworldjpitfallsarticle2>java GoodWindowsExec "dir *.java"
Execing cmd.exe /C dir *.java
OUTPUT> Volume in drive E has no label.
OUTPUT> Volume Serial Number is 5C5F-0CC9
OUTPUT>
OUTPUT> Directory of E:classescomjavaworldjpitfallsarticle2
OUTPUT>
OUTPUT>10/23/00 09:01p 805 BadExecBrowser.java
OUTPUT>10/22/00 09:35a 770 BadExecBrowser1.java
OUTPUT>10/24/00 08:45p 488 BadExecJavac.java
OUTPUT>10/24/00 08:46p 519 BadExecJavac2.java
OUTPUT>10/24/00 09:13p 930 BadExecWinDir.java
OUTPUT>10/22/00 09:21a 2,282 BadURLPost.java
OUTPUT>10/22/00 09:20a 2,273 BadURLPost1.java
... (some output omitted for brevity)
OUTPUT>10/12/00 09:29p 151 SuperFrame.java
OUTPUT>10/24/00 09:23p 1,814 TestExec.java
OUTPUT>10/09/00 05:47p 23,543 TestStringReplace.java
OUTPUT>10/12/00 08:55p 228 TopLevel.java
OUTPUT> 22 File(s) 46,661 bytes
OUTPUT> 19,678,420,992 bytes free
ExitValue: 0
因为我在linux下运行，得不到想要的结果。
以下引用作者的话：
这里作者教了一个windows中很有用的方法，呵呵，至少我是不知道的，就是cmd.exe /C +一个windows中注册了后缀的文档名，windows会自动地调用相关的程序来打开这个文档，我试了一下，的确很好用，但是好像文件路径中有空格的话就有点问题，我加上引号也无法解决。
这里作者强调了一下，不要假设你执行的程序是可执行的程序，要清楚自己的程序是单独可执行的还是被解释的，本章的结束作者会介绍一个命令行工具来帮助我们分析。
这里还有一点，就是得到process的输出的方式是getInputStream，这是因为我们要从Java 程序的角度来看，外部程序的输出对于Java来说就是输入，反之亦然。
最后的一个漏洞的地方就是错误的认为exec方法会接受所有你在命令行或者Shell中输入并接受的字符串。这些错误主要出现在命令作为参数的情况下，程序员错误的将所有命令行中可以输入的参数命令加入到exec中（这段翻译的不好，凑合看吧）。下面的例子中就是一个程序员想重定向一个命令的输出。
Java代码
import java.util.*;
import java.io.*;
// StreamGobbler omitted for brevity
public class BadWinRedirect
{
public static void main(String args[])
{
try
{
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java jecho 'Hello World' > test.txt");
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
Running BadWinRedirect produces:
E:classescomjavaworldjpitfallsarticle2>java BadWinRedirect
OUTPUT>'Hello World' > test.txt
ExitValue: 0
[java] view
plain copy
import java.util.*;
import java.io.*;
// StreamGobbler omitted for brevity
public class BadWinRedirect
{
public static void main(String args[])
{
try
{
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java jecho 'Hello World' > test.txt");
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
Running BadWinRedirect produces:
E:classescomjavaworldjpitfallsarticle2>java BadWinRedirect
OUTPUT>'Hello World' > test.txt
ExitValue: 0
程序员的本意是将Hello World这个输入重订向到一个文本文件中，但是这个文件并没有生成，jecho仅仅是将命令行中的参数输出到标准输出中，用户觉得可以像dos中重定向一样将输出重定向到一个文件中，但这并不能实现，用户错误的将exec认为是一个shell解释器，但它并不是，如果你想将一个程序的输出重定向到其他的程序中，你必须用程序来实现他。可用java.io中的包。
Java代码
import java.util.*;
import java.io.*;
class StreamGobbler extends Thread
{
InputStream is;
String type;
OutputStream os;
StreamGobbler(InputStream is, String type)
{
this(is, type, null);
}
StreamGobbler(InputStream is, String type, OutputStream redirect)
{
this.is = is;
this.type = type;
this.os = redirect;
}
public void run()
{
try
{
PrintWriter pw = null;
if (os != null)
pw = new PrintWriter(os);
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line=null;
while ( (line = br.readLine()) != null)
{
if (pw != null)
pw.println(line);
System.out.println(type + ">" + line);
}
if (pw != null)
pw.flush();
} catch (IOException ioe)
{
ioe.printStackTrace();
}
}
}
public class GoodWinRedirect
{
public static void main(String args[])
{
if (args.length < 1)
{
System.out.println("USAGE java GoodWinRedirect <outputfile>");
System.exit(1);
}
try
{
FileOutputStream fos = new FileOutputStream(args[0]);
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java jecho 'Hello World'");
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT", fos);
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
fos.flush();
fos.close();
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
Running GoodWinRedirect produces:
E:classescomjavaworldjpitfallsarticle2>java GoodWinRedirect test.txt
OUTPUT>'Hello World'
ExitValue: 0
[java] view
plain copy
import java.util.*;
import java.io.*;
class StreamGobbler extends Thread
{
InputStream is;
String type;
OutputStream os;
StreamGobbler(InputStream is, String type)
{
this(is, type, null);
}
StreamGobbler(InputStream is, String type, OutputStream redirect)
{
this.is = is;
this.type = type;
this.os = redirect;
}
public void run()
{
try
{
PrintWriter pw = null;
if (os != null)
pw = new PrintWriter(os);
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line=null;
while ( (line = br.readLine()) != null)
{
if (pw != null)
pw.println(line);
System.out.println(type + ">" + line);
}
if (pw != null)
pw.flush();
} catch (IOException ioe)
{
ioe.printStackTrace();
}
}
}
public class GoodWinRedirect
{
public static void main(String args[])
{
if (args.length < 1)
{
System.out.println("USAGE java GoodWinRedirect <outputfile>");
System.exit(1);
}
try
{
FileOutputStream fos = new FileOutputStream(args[0]);
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("java jecho 'Hello World'");
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT", fos);
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
fos.flush();
fos.close();
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
Running GoodWinRedirect produces:
E:classescomjavaworldjpitfallsarticle2>java GoodWinRedirect test.txt
OUTPUT>'Hello World'
ExitValue: 0
这里就不多说了，看看就明白，紧接着作者给出了一个监测命令的小程序
Java代码
import java.util.*;
import java.io.*;
// class StreamGobbler omitted for brevity
public class TestExec
{
public static void main(String args[])
{
if (args.length < 1)
{
System.out.println("USAGE: java TestExec "cmd"");
System.exit(1);
}
try
{
String cmd = args[0];
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec(cmd);
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
//对这个程序进行运行:
E:classescomjavaworldjpitfallsarticle2>java TestExec "e:javadocsindex.html"
java.io.IOException: CreateProcess: e:javadocsindex.html error=193
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Unknown Source)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at TestExec.main(TestExec.java:45)
[java] view
plain copy
import java.util.*;
import java.io.*;
// class StreamGobbler omitted for brevity
public class TestExec
{
public static void main(String args[])
{
if (args.length < 1)
{
System.out.println("USAGE: java TestExec "cmd"");
System.exit(1);
}
try
{
String cmd = args[0];
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec(cmd);
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
int exitVal = proc.waitFor();
System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
{
t.printStackTrace();
}
}
}
//对这个程序进行运行:
E:classescomjavaworldjpitfallsarticle2>java TestExec "e:javadocsindex.html"
java.io.IOException: CreateProcess: e:javadocsindex.html error=193
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Unknown Source)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at TestExec.main(TestExec.java:45)
193在windows中是说这不是一个win32程序，这说明路径中找不到这个网页的关联程序，下面作者决定用一个绝对路径来试一下。
E:classescomjavaworldjpitfallsarticle2>java TestExec
"e:program filesnetscapeprogramnetscape.exe e:javadocsindex.html"
ExitValue: 0
好用了，这个我也试了一下，用的是IE。
最后，作者总结了几条规则，防止我们在进行Runtime.exec()调用时出现错误。
在一个外部进程执行完之前你不能得到他的退出状态
在你的外部程序开始执行的时候你必须马上控制输入、输出、出错这些流。
你必须用Runtime.exec()去执行程序
你不能象命令行一样使用Runtime.exec()。
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