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[JAVA] 讀取檔案 與 輸出

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.OutputStreamWriter;

public class ReadFile {

 public static void main(String[] args) {
  System.out.println(">>>>> hello world... >>>>>");
  try( // JDK7 AutoClose
   //輸入來源為檔案
   BufferedReader br = new BufferedReader(new FileReader(new File("檔案路徑")));
   //輸出至Console
   BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
  ) {
   char[] buffer = new char[1024];
   int readCnt = 0; //讀取筆數
   while ((readCnt = br.read(buffer)) != -1) {
    System.out.println("========================================================");
    bw.write(buffer, 0, readCnt);
    bw.flush();
    System.out.println("");
   }
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

[SCJP 6.0] ch10 輸入輸出 筆記

RAM <= 輸入：開檔，打字
RAM => 輸出：存檔，顯示螢幕



java.io.
　　Console:
　　　　Console c = System.console();
　　　　%...格式字串
　　　　String: readLine()
　　　　char[]: 密碼
　　File: 檔案 or 目錄 (基本資訊)
　　　　File f = new File("路徑");
　　　　真正建立檔案/目錄：
　　　　　　f.createNewFile();
　　　　　　f.mkdirs();

讀取檔案"內容"： (close())
　　byte:
　　　　InputStream => FileInputStream(File).read();
　　　　　　讀取1byte(int)，用(char)轉型 read檔尾-1
　　　　OutputStream => FileOutputStream(File).write(byte[]);
　　　　　　byte[] => String.getBytes()
　　　　InputStream => ObjectInputStream(InputStream).readObject();
　　　　　　檔尾EOFException
　　　　OutputStream => ObjectOutputStream(OutputStream).writeObject(Object);
　　　　　　Object => Serializable
　　　　　　不想序列化的屬性：transient (直接套用預設值)

　　字元：
　　　　Reader => InputStreamReader => FileReader(File).read();
　　　　　　read檔尾-1
　　　　Writer => OutputStreamWriter => FileWriter(File).write(String);
　　　　Reader => BufferedReader(Reader).readLine();
　　　　　　null: 讀完
　　　　Writer => BufferedWriter(Writer).write(String);
　　　　                                                   .flush(); 強制寫檔，刷新緩衝區

new BufferedReader( new FileReader( new File(路徑) ) )
new ObjectOutputStream( new FileOutputStream( new File(路徑) ) )
也有 BufferedInputStream(InputStream).read()
new PrintWriter(BufferedWriter).printf(String format, Object... args)

JAVA日期處裡

簡單來說，如果要設定日期的話利用Calendar來處理
取今天日期用Date就可
至於日期格式就要利用SimpleDateFormat來處理了

package edu.test;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Test{
    
    public static void main(String args[]){
     //假設要處理民國101年2月的字串"10102", 取得西元年份與月份
     int year = Integer.parseInt("10102".substring(0, 3))+1911;
     int month = Integer.parseInt("10102".substring(3, 5))-1;
     
     Calendar cal = Calendar.getInstance();
     
     //end:截止日期為"10102"的最後一日
     Date end = null;
     cal.set(year,month, 01);
     cal.set(Calendar.DAY_OF_MONTH,cal.getActualMaximum(Calendar.DAY_OF_MONTH));
     end = cal.getTime();
     System.out.println("偷印看看cal長怎樣 => "+cal);
     
     //beg:起始日期為"10102"減五個月的最後一日
     Date beg = null;
     cal.add(Calendar.MONTH,-5);
     cal.set(Calendar.DAY_OF_MONTH,cal.getActualMaximum(Calendar.DAY_OF_MONTH));
     beg = cal.getTime();
     System.out.println("偷印看看cal長怎樣 => "+cal);
     
     System.out.println("西元年(Date) => "+beg+", "+end);
     
     //Date轉String, 並利用SimpleDateFormat
     SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
     System.out.println("西元年(String) => "+sdf.format(beg)+", "+sdf.format(end));
     
     //now:現在日期
     Date now = new Date();
     System.out.println("現在日期西元年(String) => "+sdf.format(now));
    }

}

OUTPUT:

偷印看看cal長怎樣 => java.util.GregorianCalendar[time=1330522727243,areFieldsSet=true,areAllFieldsSet=false,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Taipei",offset=28800000,dstSavings=0,useDaylight=false,transitions=42,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2012,MONTH=1,WEEK_OF_YEAR=9,WEEK_OF_MONTH=5,DAY_OF_MONTH=29,DAY_OF_YEAR=60,DAY_OF_WEEK=4,DAY_OF_WEEK_IN_MONTH=5,AM_PM=1,HOUR=9,HOUR_OF_DAY=21,MINUTE=38,SECOND=47,MILLISECOND=243,ZONE_OFFSET=28800000,DST_OFFSET=0]
偷印看看cal長怎樣 => java.util.GregorianCalendar[time=1317389927243,areFieldsSet=true,areAllFieldsSet=false,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Taipei",offset=28800000,dstSavings=0,useDaylight=false,transitions=42,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2011,MONTH=8,WEEK_OF_YEAR=40,WEEK_OF_MONTH=5,DAY_OF_MONTH=30,DAY_OF_YEAR=273,DAY_OF_WEEK=6,DAY_OF_WEEK_IN_MONTH=5,AM_PM=1,HOUR=9,HOUR_OF_DAY=21,MINUTE=38,SECOND=47,MILLISECOND=243,ZONE_OFFSET=28800000,DST_OFFSET=0]
西元年(Date) => Fri Sep 30 21:38:47 CST 2011, Wed Feb 29 21:38:47 CST 2012
西元年(String) => 2011/09/30, 2012/02/29
現在日期西元年(String) => 2013/01/09

製作表格細框線

直接在<table>加border="1"真的是有夠醜的啊
只好用CSS來美化一下...

預設表格框線是不重疊的，所以會變成1px+1px的粗框線
加上border-collapse: collapse;來允許表格框線重疊

table {
  border: 1px solid #000000;
  border-collapse: collapse;
  /*允許表格框線重疊，才能顯示出 1px 的細框線*/
}
tr, td {
  border: 1px solid #000000;
}

String, List 轉JSON與output格式

This code try to create JSONObject and JSONArray by String and List.

package edu.test;

import java.util.ArrayList;
import java.util.List;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;

public class Test{
    
    public static void main(String args[]){
     //Create JSONObject by String
     String jsonObjString1 = "{\"id\": \"12345\", \"value\": \"Good Job!\"}";
     System.out.println("jsonObjString1 = "+jsonObjString1);
     JSONObject jsonObj1 = (JSONObject) JSONSerializer.toJSON(jsonObjString1);
     System.out.println("jsonObj1 = "+jsonObj1);
     
     //Create JSONObject by put key and value
     JSONObject jsonObj2 = new JSONObject();
     jsonObj2.put("id", "67890");
     jsonObj2.put("value", "Oh Ya!");
     System.out.println("jsonObj2 = "+jsonObj2);
     
     //Create JSONArray by JSONObject
     JSONArray jsonArr1 = new JSONArray();
     jsonArr1.add(jsonObj1);
     jsonArr1.add(jsonObj2);
     System.out.println("jsonArr1 = "+jsonArr1);
     
     //Create JSONArray by List
     List<JSONObject> jsonObjList = new ArrayList<JSONObject>();
     jsonObjList.add(jsonObj1);
     jsonObjList.add(jsonObj2);
     System.out.println("jsonObjList = "+jsonObjList);
     JSONArray jsonArr2 = (JSONArray) JSONSerializer.toJSON(jsonObjList);
     System.out.println("jsonArr2 = "+jsonArr2);
     
     //Create a JSONArray List
     List<JSONArray> jsonArrList = new ArrayList<JSONArray>();
     jsonArrList.add(jsonArr1);
     jsonArrList.add(jsonArr2);
     System.out.println("jsonArrList = "+jsonArrList);
    }
    
}

OUTPUT:

jsonObjString1 = {"id": "12345", "value": "Good Job!"}
jsonObj1 = {"id":"12345","value":"Good Job!"}
jsonObj2 = {"id":"67890","value":"Oh Ya!"}
jsonArr1 = [{"id":"12345","value":"Good Job!"},{"id":"67890","value":"Oh Ya!"}]
jsonObjList = [{"id":"12345","value":"Good Job!"}, {"id":"67890","value":"Oh Ya!"}]
jsonArr2 = [{"id":"12345","value":"Good Job!"},{"id":"67890","value":"Oh Ya!"}]
jsonArrList = [[{"id":"12345","value":"Good Job!"},{"id":"67890","value":"Oh Ya!"}], [{"id":"12345","value":"Good Job!"},{"id":"67890","value":"Oh Ya!"}]]