一、Java调用Linux系统的命令非常简单
这是一个非常常用的调用方法示例：
public String executeLinuxCmd(String cmd) {
System.out.println("got cmd job : " + cmd);
Runtime run = Runtime.getRuntime();
try {
Process process = run.exec(cmd);
InputStream in = process.getInputStream();
BufferedReader bs = new BufferedReader(new InputStreamReader(in));
// System.out.println("[check] now size \n"+bs.readLine());
StringBuffer out = new StringBuffer();
byte[] b = new byte[8192];
for (int n; (n = in.read(b)) != -1;) {
out.append(new String(b, 0, n));
}
System.out.println("job result [" + out.toString() + "]");
in.close();
// process.waitFor();
process.destroy();
return result;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
二、含有管道符（|）多级命令串联查询
public List<String> executeLinuxCmd(String cmd) {
System.out.println("got cmd job : " + cmd);
Runtime run = Runtime.getRuntime();
try {
// Process process = run.exec(cmd);
Process process = run.exec(new String[] {"/bin/sh", "-c", cmd});
InputStream in = process.getInputStream();
BufferedReader bs = new BufferedReader(new InputStreamReader(in));
List<String> list = new ArrayList<String>();
String result = null;
while ((result = bs.readLine()) != null) {
System.out.println("job result [" + result + "]");
list.add(result);
}
in.close();
// process.waitFor();
process.destroy();
return list;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
三、含有cd操作的方法示例
1. 问题背景
1.1 java程序运行在/home/lings目录下；
1.2 希望删除/home/test目录下的文件proxy.log；
1.3 调用上面的接口两次？
executeLinuxCmd("cd /home/test");
executeLinuxCmd("rm -fr /home/proxy.log");
是不行的！
1.4 这个接口的调用是单次事务型的，就是每次调用都是独立的事务或者说操作，没有关联的。
那这种“复杂”一点的操作流程怎么办呢？
1.5 方法a: 可以写一个独立的脚本，然后一次运行脚本，这样多复杂的逻辑都没问题。
1.6 方法b: 可以启动一个shell长连接，保持连接，发送多条命令，最后释放连接。
示例逻辑代码：
public void executeNewFlow() {
Runtime run = Runtime.getRuntime();
File wd = new File("/bin");
System.out.println(wd);
Process proc = null;
try {
proc = run.exec("/bin/bash", null, wd);
} catch (IOException e) {
e.printStackTrace();
}
if (proc != null) {
BufferedReader in = new BufferedReader(new InputStreamReader(proc.getInputStream()));
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(proc.getOutputStream())), true);
out.println("cd /home/test");
out.println("pwd");
out.println("rm -fr /home/proxy.log");
out.println("exit");//这个命令必须执行，否则in流不结束。
try {
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
proc.waitFor();
in.close();
out.close();
proc.destroy();
} catch (Exception e) {
e.printStackTrace();
}
}
}
三的优化和演进（返回值）
public List<String> executeNewFlow(List<String> commands) {
List<String> rspList = new ArrayList<String>();
Runtime run = Runtime.getRuntime();
try {
Process proc = run.exec("/bin/bash", null, null);
BufferedReader in = new BufferedReader(new InputStreamReader(proc.getInputStream()));
PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(proc.getOutputStream())), true);
for (String line : commands) {
out.println(line);
}
// out.println("cd /home/test");
// out.println("pwd");
// out.println("rm -fr /home/proxy.log");
out.println("exit");// 这个命令必须执行，否则in流不结束。
String rspLine = "";
while ((rspLine = in.readLine()) != null) {
System.out.println(rspLine);
rspList.add(rspLine);
}
proc.waitFor();
in.close();
out.close();
proc.destroy();
} catch (IOException e1) {
e1.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
return rspList;
}