java process

java process是什么？一起來(lái)看看小編今天的分享吧！

在項(xiàng)目開發(fā)中，經(jīng)常會(huì)遇到調(diào)用其它程序功能的業(yè)務(wù)需求，在java中通常有兩種實(shí)現(xiàn)方法，包括：

Runtime?runtime?=?Runtime.getRuntime()；
Process?p?=runtime.exec(cmd);

和

Process?p=new?ProcessBuilder(cmd).start();

在這里就需要認(rèn)識(shí)一下process類，process是一個(gè)抽象的類，它包含6個(gè)抽象的方法：

abstract??voiddestroy()?
??????????殺掉子進(jìn)程。
abstract??intexitValue()?
??????????返回子進(jìn)程的出口值。
abstract??InputStreamgetErrorStream()?
??????????獲取子進(jìn)程的錯(cuò)誤流。
abstract??InputStreamgetInputStream()?
??????????獲取子進(jìn)程的輸入流。
abstract??OutputStreamgetOutputStream()?
??????????獲取子進(jìn)程的輸出流。
abstract??intwaitFor()?
??????????導(dǎo)致當(dāng)前線程等待，如有必要，一直要等到由該?Process?對(duì)象表示的進(jìn)程已經(jīng)終止。

以“ping?百度網(wǎng)址”為例：

import?java.io.IOException;
?
public?class?ProcessDemo?{
????????public?static?void?main(String[]?args)?{
????????????????try?{
?????????????????????????Process?process?=?Runtime.getRuntime().exec("ping?www.baidu.com");
?????????????????????????System.out.println("任務(wù)執(zhí)行完畢！");
??????????????}?catch?(IOException?e)?{
???????????????????????????????????????//?TODO?Auto-generated?catch?block
???????????????????????????????????????e.printStackTrace();
??????????????}
???????}
}

由于Process提供了WaitFor和getInputStream兩個(gè)方法，這兩個(gè)方法都阻塞java線程，使調(diào)用ping被掛到后臺(tái)運(yùn)行，程序直接打印“任務(wù)執(zhí)行完畢！”，而我們想要的效果是先把ping操作執(zhí)行完成后，再輸出“任務(wù)執(zhí)行完畢！”，可以等待腳本返回或結(jié)束后，再繼續(xù)執(zhí)行java程序：

import?java.io.BufferedReader;
import?java.io.IOException;
import?java.io.InputStreamReader;
?
public?class?ProcessDemo?{
?????????public?static?void?main(String[]?args)?{
???????????????????try?{
????????????????????????Process?process?=?Runtime.getRuntime().exec("ping?www.baidu.com");
????????????????????????BufferedReader?bufferedReader?=?new?BufferedReader(
??????????????????????????????????new?InputStreamReader(process.getInputStream(),"gbk"));
????????????????????????String?line;
????????????????????????while?((line?=?bufferedReader.readLine())?!=?null)?{
????????????????????????????System.out.println(line);
????????????????????????}
????????????????????????System.out.println("任務(wù)執(zhí)行完畢！");
?????????????????????}?catch?(IOException?e)?{
????????????????????????//?TODO?Auto-generated?catch?block
???????????????????????e.printStackTrace();
??????????????????????}
???????????}
}

import?java.io.IOException;
?
public?class?ProcessDemo?{
?????public?static?void?main(String[]?args)?{
??????????try?{
??????????????Process?process?=?Runtime.getRuntime().exec("ping?www.baidu.com");
??????????????process.waitFor();
??????????????System.out.println("任務(wù)執(zhí)行完畢！");
??????????}?catch?(IOException?e)?{
??????????????//?TODO?Auto-generated?catch?block
??????????????e.printStackTrace();
??????????}?catch?(InterruptedException?e)?{
??????????????????????????????????????????????????????????//?TODO?Auto-generated?catch?block
??????????????e.printStackTrace();
??????????}
?????}
}

這樣就完成了process的Java程序操作。

以上就是小編今天的分享了，希望可以幫助到大家。