java对比php快速入门

最新推荐文章于 2024-04-07 19:24:42 发布

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最新推荐文章于 2024-04-07 19:24:42 发布

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分类专栏： java php

本文链接：https://blog.youkuaiyun.com/zzz_781111/article/details/103599770

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本文探讨了Java和PHP在变量、字符串、数组、条件判断、循环结构、函数使用、命令行参数处理、时间操作、文件操作及数组操作等方面的入门知识，旨在帮助初学者快速了解两者之间的差异和入门要点。

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比较方面：变量，字符串，数组，判断，循环，函数，命令行参数，时间，文件，数组操作，调试

比较项目

php

java

变量

弱类型语言，变量可以任意代表任何类型

$age = 13;

$name = "pengpeng";

$money = 150.53;

$isBoy = true;

这里等号前后空格是为了整齐好看。

例子

<?php

$age = 13;

print $age;

运行方式

php t.php

强类型语言

int age=13;

String name = "pengpeng";

double money= 150.33;

boolean isBoy = true;

例子

HelloWorld.java

public class HelloWorld {

/* 第一个Java程序

* 它将打印字符串 Hello World

public static void main(String []args) {

int age=13;

String sAge = String.valueOf(age);

System.out.println( sAge );

}

运行方式

[root@hz-netim-02 java]# javac HelloWorld.java

[root@hz-netim-02 java]# java HelloWorld

[root@hz-netim-02 java]#

字符串及连接

$str1 = "str1";

$str2 = "str2";

$str3 = $str1.$str2;

$str4 = $str1."test".$str2;

print $str3."\n";

print $str4."\n";

String str1="str1";

String str2="str2";

String str3=str1+str2;

String str4=str1+"test"+str2;

System.out.println( str3);

System.out.println( str4);

数组遍历

<?php

$colorArr = array('red','blue','green','yellow');

foreach ($colorArr as $color){

print $color."\n";

}

String[] colorArr = {"red","blue","green","yellow"};

for (int i = 0; i < colorArr.length; i++)

{

System.out.println( colorArr[i]);

}

String[] str=new String[4]

哈希数组及遍历

<?php

$ageArr = array('zhang'=>13,'li'=>14,'wang'=>15,'qian'=>12);

foreach ($ageArr as $name => $age){

print "$name = $age\n";

}

import java.util.Map;

import java.util.HashMap;

import java.util.Set;

import java.util.HashSet;

import java.util.Iterator;

import java.util.Hashtable;

import java.util.TreeMap;

public class HelloWorld {

public static void main(String []args) {

Map map=new HashMap();

map.put("zhang", "13");

map.put("li", "14");

map.put("wang", "15");

map.put("qian", "12");

for (Iterator iterator= map.keySet().iterator(); map.keySet().hasNext();) {

Object key = iterator.next();

String sKey = (String) key;

System.out.println("map.get("+sKey+") is :"+map.get(key));

}

//或者下面方法

Iterator iterator = map.keySet().iterator(); //取得迭代器

while (iterator.hasNext()) { //遍历迭代器

Object key = iterator.next();

String sKey = (String) key;

System.out.println("map.get("+sKey+") is :"+map.get(key));

}

JSONArray dataDisksArr = jsonobject.getJSONObject("result").getJSONObject("instance").getJSONArray("dataDisks");

Iterator iterator=dataDisksArr.iterator();

while(iterator.hasNext()) {

JSONObject job = (JSONObject)iterator.next();

String diskId = job.getJSONObject("cloudDisk").getString("diskId");

System.out.println("diskId="+diskId);

}

json

$arr = Array('one', 'two', 'three');

echo json_encode($arr);

$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';

var_dump(json_decode($json));

import net.sf.json.JSONObject;

JSONObject json = JSONObject.fromObject(queryMap);//json数组

JSONObject jsonobject = JSONObject.fromObject(str);//从字符串转json对象

//json合并相同的字段会被后一个覆盖

JSONObject oldjson1=new JSONObject();

oldjson1.put("name", "zhangsan");

JSONObject oldjson2=new JSONObject();

oldjson2.put("name", "lisi");

oldjson2.put("age", "20");

//合并后的json

JSONObject newjson=new JSONObject();

newjson.putAll(oldjson1);

newjson.putAll(oldjson2);

//jsonArr遍历

JSONArray idsJSONArray = JSONArray.fromObject(sub_instance_arr_str);

System.out.println("sub_instance_arr_str="+sub_instance_arr_str);

System.out.println(idsJSONArray.toString());

Iterator iterator=idsJSONArray.iterator();

while(iterator.hasNext()){

String sub_instance_id = iterator.next().toString();

}

条件判断

<?php

$user=`whoami`;

if($user != "work" || ! isset($argv[1]) )

{

echo "必须是work账户，同时为./release.sh snake 或者 ./release.sh hornbill";

exit ;

}

else

{

echo "no problem";

}

public class Test {

public static void main(String args[]){

String user="whoami";

if( user != "work" || args[1] == null )

{

System.out.println("必须是work账户");

System.exit(0);

}

else

{

System.out.println("no problem");

}

case

case $1 in

"snake")

back_snake;

snake;

reduction_snakenx;

other_snake;

virus_restart;

;;

"hornbill")

back_hornbill;

hornbill;

# hornbill_min;

# hornbill_restart;

reduction_nx;

other_hornbill;

hornbill_restart_again;

;;

"backup")

back_snake;

back_hornbill;

hornbill_restart;

exit;

;;

echo NULL;

;;

esac

希望函数 back_snake 往后变为 backSnake

public class Test {

public static void main(String args[]){

String expression = "";

if(args.length >0) expression = args[0];

switch(expression){

case "snake":

System.out.println("snake");

break;

case "hornbill":

System.out.println("hornbill");

break;

default :

System.out.println("default");

}

循环

<?php

for($i=0;$i<10;$i++)

{

print $i."\n";

}

public class Test {

public static void main(String args[]){

for(int i = 0; i < 10; i=i+1) {

System.out.println("value of i : " +i );

}

函数定义

或

方法定义

<?php

header ( "Content-Type:text/html;charset=utf-8" );

function send_content_mail($maillist, $subject, $content)

{

$headers = "MIME-Version: 1.0" . "\r\n";

$headers .= "Content-type:text/html;charset=utf-8" . "\r\n";

$headers .= 'From: stat@meilishuo.com' . "\r\n";

$subject = "=?UTF-8?B?" . base64_encode($subject) . "?=";

$content.="<center>如有疑问，咨询管理员曾文杰wenjiezeng@meilishuo.com</center";

mail($maillist, $subject, $content, $headers);

}

send_content_mail("wenjiezeng@meilishuo.com", "test", "testMail");

静态调用

public class Test {

public static void main(String args[]){

test();

}

private static void test()

{

for(int i = 0; i < 10; i=i+1) {

System.out.println("value of i : " +i );

}

动态调用需要先实例化

public class HelloWord {

/**

* @param args

public static void main(String[] args) {

// TODO Auto-generated method stub

String str="HelloWord!";

int a=0;

int b=a+1;

int result=0;

for(int i=0;i<20;i++)

{

//Add方法调用

//类的实例化

HelloWord helloword=new HelloWord();

//通过实例化的类进行Add方法调用

result=helloword.Add(a, b);

System.out.println(str+" "+ result);

a+=i;

}

/**

* 被调用方法,没被static修饰，不是静态方法。调用时需要通过类的实例化进行调用

* @param x

* @param y

* @return

private int Add(int x,int y)

{

return x+y;

}

命令行参数

$argv

<?php

print_r($argv);

php t.php 1 2 3

Array

(

[0] => t.php

[1] => 1

[2] => 2

[3] => 3

)

import java.lang.reflect.Array;

public class Test {

public static void main(String args[]){

helpFunc(args);

helpFunc(555);

}

public static void helpFunc(Object obj) {

String className = obj.getClass().getName();

System.out.println("className="+className);

boolean bArr = obj.getClass().isArray();

if(bArr)

{

int length = Array.getLength(obj);

for (int i = 0; i < length; i++) {

Object os = Array.get(obj, i);

System.out.println("----obj "+ String.valueOf(i)+" is "+os.toString());

}

else

{

System.out.println("----obj ="+obj.toString());

}

运行情况

java Test 1 2 3

className=[Ljava.lang.String;

----obj 0 is 1

----obj 1 is 2

----obj 2 is 3

className=java.lang.Integer

----obj =555

时间处理

date_default_timezone_set('PRC');

$today = date("Y-m-d",time());

$yesterday = date("Y-m-d",time()-86400);

$yesterday = date("Ymd",strtotime("-1 day"));

String timeStr = "2017-8-24 11:17:10"; // 字面时间

SimpleDateFormat bjSdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

bjSdf.setTimeZone(TimeZone.getTimeZone("Asia/Shanghai"));

Date date = bjSdf.parse(timeStr); // 将字符串时间按北京时间解析成Date对象

Date now=new Date();

　　SimpleDateFormat f=newSimpleDateFormat("今天是"+"yyyy年MM月dd日 E kk点mm分");

　　System.out.println(f.format(now));

// -2:前天 -1：昨天 0：今天 1：明天 2：后天

public int getDayString(Date startDate){

int offSet = Calendar.getInstance().getTimeZone().getRawOffset();

long today = (System.currentTimeMillis()+offSet)/86400000;

long start = (startDate.getTime()+offSet)/86400000;

return (start-today);

}

Date date = new Date();

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

String nowDateStr= sdf.format(date);

///加1天

Date endDate = sdf.parse(endTime);

Calendar c = Calendar.getInstance();

c.setTime(endDate);

c.add(Calendar.DAY_OF_MONTH, 1); //利用Calendar 实现 Date日期+1天

endDate = c.getTime();

小文件

按行处理

$cc = file_get_contents($file);

$tmpArr = preg_split('/\r|\n/',$cc,-1,PREG_SPLIT_NO_EMPTY);

foreach($tmpArr as $line)

{

//do with $line

}

public String readToString(String fileName) {

String encoding = "UTF-8";

File file = new File(fileName);

Long filelength = file.length();

byte[] filecontent = new byte[filelength.intValue()];

try {

FileInputStream in = new FileInputStream(file);

in.read(filecontent);

in.close();

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

try {

return new String(filecontent, encoding);

} catch (UnsupportedEncodingException e) {

System.err.println("The OS does not support " + encoding);

e.printStackTrace();

return null;

}

#################字符串拆行##################

import java.lang.reflect.Array;

public class Test {

public static void main(String args[]){

String str1 = "ui78\n8huh\njf87\nuie8\nujkdf90\nhu67ghj\n894ghk";

System.out.println("str1=" + str1);

String[] str2 = str1.split("\n|\r");

for(int i = 0;i<str2.length;i++)

{

System.out.println("第" + i + "个：" + str2[i]);

}

System.out.println("\n" + "---------------------------------" + "\n");

}

"2|33|4".split("|") 出来的结果是： "" 2 | 3 3 | 4 奇怪吧，不过注意看一下API说明还是知道原因的. 所以正常的写法是这样的： ①、如果用“.”作为分隔的话，

必须是如下写法：String.split("\\."),这样才能正确的分隔开，不能用String.split("."); ②、如果用“|”作为分隔的话，必须是如下写法：String.split("\\|"),

这样才能正确的分隔开，不能用String.split("|"); “.”和“|”都是转义字符，必须得加"\\"; ③、如果在一个字符串中有多个分隔符，可以用“|”作为连字符，比如：“a=1andb =2orc=3”,把三个都分隔出来，可以用String.split("and|or");

System.out.println("使用StringTokenizer的切分字符串");

long st3 = System.nanoTime();

StringTokenizer token=new StringTokenizer(orginStr,".");

System.out.println("StringTokenizer截取字符串用时:"+(System.nanoTime()-st3));

System.out.println("StringTokenizer截取字符串结果个数：" + token.countTokens());

System.out.println();

大文件逐行

<?php

$handle = @fopen("/tmp/inputfile.txt", "r");

if ($handle) {

while (!feof($handle)) {

$buffer = fgets($handle, 4096);

echo $buffer;

}

fclose($handle);

}

/**

* 以行为单位读取文件，常用于读面向行的格式化文件

public static void readFileByLines(String fileName) {

File file = new File(fileName);

BufferedReader reader = null;

try {

System.out.println("以行为单位读取文件内容，一次读一整行：");

reader = new BufferedReader(new FileReader(file));

String tempString = null;

int line = 1;

// 一次读入一行，直到读入null为文件结束

while ((tempString = reader.readLine()) != null) {

// 显示行号

System.out.println("line " + line + ": " + tempString);

line++;

}

reader.close();

} catch (IOException e) {

e.printStackTrace();

} finally {

if (reader != null) {

try {

reader.close();

} catch (IOException e1) {

}

数组函数

arsort() asort() count() krsort() ksort()

String[] s1={"a","b","c","d","e"};

　　　　for(int i=0;i<s1.length;i++)

　　　　{

　　　　　　System.out.print(s1[i]+" ");//输出a b c d e，获取字符串数组

　　　　}

System.out.println("升序排序如下：");

int[] arr1 = {6,4,5,2};

Arrays.sort(arr1);

for(int i:arr1)

System.out.println(i);

System.out.println("将数组倒序排序如下：");

ArrayList<Integer> list2=new ArrayList<Integer>();

for(int i=1;i<=5;i++){

list2.add(i);

}

Collections.reverse(list2);

//list2.size(); 表示数组的长度

for(int i:list2)

System.out.println(i);

package collection;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

public class CollectionsTest {

public static void main(String[] args) {

ArrayList nums = new ArrayList();

nums.add(8);

nums.add(-3);

nums.add(2);

nums.add(9);

nums.add(-2);

System.out.println(nums);

Collections.reverse(nums);

System.out.println(nums);

Collections.sort(nums);

System.out.println(nums);

Collections.shuffle(nums);

System.out.println(nums);

//下面只是为了演示定制排序的用法，将int类型转成string进行比较

Collections.sort(nums, new Comparator() {

@Override

public int compare(Object o1, Object o2) {

// TODO Auto-generated method stub

String s1 = String.valueOf(o1);

String s2 = String.valueOf(o2);

return s1.compareTo(s2);

}

});

System.out.println(nums);

}

调试函数

var_dump()

print_r()

import java.lang.reflect.Array;

public class Test {

public static void main(String args[]){

helpFunc(args);

helpFunc(555);

}

public static void helpFunc(Object obj) {

String className = obj.getClass().getName();

System.out.println("className="+className);

boolean bArr = obj.getClass().isArray();

if(bArr)

{

int length = Array.getLength(obj);

for (int i = 0; i < length; i++) {

Object os = Array.get(obj, i);

System.out.println("----obj "+ String.valueOf(i)+" is "+os.toString());

}

else

{

System.out.println("----obj ="+obj.toString());

}

字符替换

$file = preg_replace('/\.less$/','.css',$file);

String replace(char oldChar, char newChar)

返回一个新的字符串，它是通过用 newChar 替换此字符串中出现的所有 oldChar 得到的。

String replaceAll(String regex, String replacement

发送邮件

// 文件名 SendEmail.java

import java.util.*;

import javax.mail.*;

import javax.mail.internet.*;

import javax.activation.*;

public class SendEmail

{

public static void main(String [] args)

{

// 收件人电子邮箱

String to = "abcd@gmail.com";

// 发件人电子邮箱

String from = "web@gmail.com";

// 指定发送邮件的主机为 localhost

String host = "localhost";

// 获取系统属性

Properties properties = System.getProperties();

// 设置邮件服务器

properties.setProperty("mail.smtp.host", host);

// 获取默认session对象

Session session = Session.getDefaultInstance(properties);

try{

// 创建默认的 MimeMessage 对象

MimeMessage message = new MimeMessage(session);

// Set From: 头部头字段

message.setFrom(new InternetAddress(from));

// Set To: 头部头字段

message.addRecipient(Message.RecipientType.TO,

new InternetAddress(to));

// Set Subject: 头部头字段

message.setSubject("This is the Subject Line!");

// 设置消息体

message.setText("This is actual message");

// 发送消息

Transport.send(message);

System.out.println("Sent message successfully....");

}catch (MessagingException mex) {

mex.printStackTrace();

}

写日志

function addLog($msg)

{

$now_date_day = date("Ymd", time());

$logtime = date("Ymd H:i:s", time());

$fileLog = "data/logs/tmp_myLogRS" . $now_date_day . ".txt";

file_put_contents($fileLog, "[" . $logtime . "]" . $msg . "\n", FILE_APPEND);

}