Runtime.getRuntime.exec(String)
这个方法传入的是字符串，JAVA内部处理时会对字符串进行分割成数据，然后调用exec(String[],null,null)方法
public Process exec(String command) throws IOException { return exec(command, null, null); }public Process exec(String command, String[] envp, File dir) throws IOException { if (command.length() == 0) throw new IllegalArgumentException("Empty command"); StringTokenizer st = new StringTokenizer(command); String[] cmdarray = new String[st.countTokens()]; for (int i = 0; st.hasMoreTokens(); i++) cmdarray[i] = st.nextToken(); return exec(cmdarray, envp, dir); public Process exec(String[] cmdarray, String[] envp, File dir) throws IOException { return new ProcessBuilder(cmdarray) .environment(envp) .directory(dir) .start(); }
Runtime.getRuntime.exec(String[])
该方法会最后也是执行exec(String[],null,null)
public Process exec(String cmdarray[]) throws IOException { return exec(cmdarray, null, null); } public Process exec(String[] cmdarray, String[] envp, File dir) throws IOException { return new ProcessBuilder(cmdarray) .environment(envp) .directory(dir) .start(); }
从上面可以看出，如果执行一整条已经拼接好的命令时，可以用exec(String);如果命令参数分开时，可以用exec(String[]);如果把一条已经拼接好的字符串执行第二个方法，就会报命令找不到。