作者: zgh149

使用 url 來取得網頁原始碼相當簡單,也能藉此加上其他自動化的功能如自動偵測股票網站的數值等等

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
public class PageData {
    /**
     * 取得網頁資料
     * @return : 回傳string型態的網頁資料
     */
    public static String getPageData(String http){
        URL u = null;
        InputStream in = null;
        InputStreamReader r = null;
        BufferedReader br = null;
        StringBuffer message = null;
        try {
           u = new URL(http);
           in = u.openStream();
           r = new InputStreamReader(in, "UTF-8");
           br = new BufferedReader(r);
           String tempstr = null;
           message = new StringBuffer();
           while ((tempstr = br.readLine()) != null) {
               message.append(tempstr);
           }
        } catch (Exception e) {
           e.getStackTrace();
           System.out.println(e.getMessage());
        } finally {
           try {
              u = null;
              in.close();
              r.close();
              br.close();
           } catch (Exception e) {
           }
    }
        return message.toString();
    }
}

 
接著再根據 getPageData() 回傳的字串做處理

System.getProperties() 可以取得各種特性

import java.util.Iterator;
import java.util.Properties;
import java.util.Set;
public class GetExecProperty {
    static String execSimerPath = "";
    public static void showSupplyProperties() {
        Properties pros = System.getProperties();
        Set s = pros.keySet();
        Iterator it = s.iterator();
        while (it.hasNext()) {
            String keystr = it.next().toString();
            String tempstr2 = System.getProperty(keystr);
            System.out.println("key: " + keystr + " ,value: " + tempstr2);
        }
    }
    /**
     * return path of jar
     */
    public static String getExecPath() {
        String tempstr = "";
        String local = System.getProperty("user.dir");
        System.out.println("System.getProperty user.dir: " + local);
        String[] spilttemp = local.split("\\");
        for (int i = 0; i < spilttemp.length; i++) {
            tempstr = tempstr + spilttemp[i] + "\\";
        }
        System.out.println("tempstr: " + tempstr);
        return tempstr;
    }
}

資料的儲存方式除了database之外,還有 properties 可以選擇，優點是使用簡單，但是相對的儲存資料類型較少。

package fothers;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Properties;
import java.util.Set;
public class PropertiesExample {
    public static void main(String[] args){
        storeProperties();
        loadProperties();
        storePropertiesWithXml();
        loadPropertiesWithXml();
    }
    public static void storeProperties(){
        Properties proper = new Properties();
        proper.setProperty("key1", "value1");
        try {
            proper.store(new FileWriter("d:\testproperties\"+"testpro.properties"), "ps");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void loadProperties(){
        Properties proper = new Properties();
        try {
            proper.load(new FileReader("d:\testproperties\"+"testpro.properties"));
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void storePropertiesWithXml(){
        Properties proper = new Properties();
        proper.setProperty("keyxml", "valuexml");
        try {
            proper.storeToXML(new FileOutputStream("d:\testproperties\"+"testpro.xml"), "ps");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    public static void loadPropertiesWithXml(){
        Properties proper = new Properties();
        try {
            proper.loadFromXML(new FileInputStream("d:\testproperties\"+"testpro.xml"));
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

使用JDBC連接資料庫的範例,先準備連結 postgresql 需要的 jar檔(postgresql-8.4-701.jdbc4.jar)

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Types;
import java.util.ArrayList;
public class ConnToPostgresql {
    //show all tables in database
    public static String COMM_SHOW_ALLTABLES = "select * from information_schema.tables" +
            " where table_schema not in ('information_schema','pg_catalog')";
    //show all databases
    public static String COMM_SHOW_ALLDATABASE = "select * from pg_database";
    //show size of databases(pg_database_size() support PostgreSQL 8.1)
    public static String COMM_SHOW_DB_SIZE = "SELECT pg_database.datname," +
            " pg_size_pretty(pg_database_size(pg_database.datname)) AS size" +
            " FROM pg_database;";
    Connection conn;
    String driver = "org.postgresql.Driver";
    String url;
    String ipNum;
    String portNum;
    String dbName;
    String userName;
    String passWord;
    public ConnToPostgresql(String ipnum,String portnum,
            String dbname,String username,String password){
        ipNum = ipnum;
        portNum = portnum;
        dbName = dbname;
        userName = username;
        passWord = password;
        try {
            Class.forName(driver);
            // String url = "jdbc:postgresql://localhost:5432/test1225";
            url = "jdbc:postgresql://" + ipNum + ":" + portNum + "/"
                    + dbName;
            try {
                if (userName == null && passWord == null) {
                    conn = DriverManager.getConnection(url);
                } else {
                    conn = DriverManager.getConnection(url, userName, passWord);
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    public Connection getConn(){
        return conn;
    }
}

只要建立 ConnToPostgresql 物件,在建構子中傳入帳號和密碼,就能建立和資料庫連線

讀取 csv 檔 ,輸出成 ArrayList

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class ReadCSVtoArrayList {
    /**
     * Read csv file
     * @param csvpath path of csv file
     * @return ArrayList, element is data of column
     */
    public static ArrayList<ArrayList> readCSVToArrayList(String csvpath) {
        ArrayList<ArrayList> dataAL = new ArrayList<ArrayList>();
        BufferedReader reader;
        try {
            reader = new BufferedReader(new FileReader(csvpath));
            reader.readLine();// read first line in csv
            String line = null;
            while ((line = reader.readLine()) != null) {
                ArrayList<String> ticketStr = new ArrayList<String>();
                String item[] = line.split(",");
                ticketStr.clear();
                for(int i=0; i<item.length; i++){
                    ticketStr.add(i, item[i]);
                }
                dataAL.add(ticketStr);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return dataAL;
    }
}

接著就能操作 ArrayList 中的資料,完成需要的功能