java 常用的代码
收集的java常用代码，共同分享（二）Java code
/**
* (#)ThrowableManager.java 1.0 Apr 10, 2008
*
* Copyright 2007- wargrey , Inc. All rights are reserved.
*/
package net.wargrey.application;
import java.awt.Component;
import javax.swing.JOptionPane;
/**
* This class <code>ExceptionManager</code> and its subclasses are a form of
* <code>Exception</code>. It is used to wrap all the <code>Throwable</code> instances
* and handle them in a unified way. It will show the information which consists of
* StackTraces and Messages by using JOptionPanel.
*
* @author Estelle
* @version 1.0
* @see java.lang.Exception
* @since jdk 1.5
*/
public class ExceptionManager extends Exception {
/**
* This field <code>alerter</code> is used to show the information the Class offered.
*
* @see javax.swing.JOptionPane
*/
private JOptionPane alerter;
/**
* This static method create an instance of the ExceptionManager by invoking the
* constructor <code>ExceptionManager(String msg)</code>.
*
* @param msg The message will pass the specified constructor
* @return An instance of the ExceptionManager created by invoking the constructor
* <code>ExceptionManager(String msg)</code>.
*/
public static ExceptionManager wrap(String msg){
return new ExceptionManager(msg);
}
/**
* This static method create an instance of the ExceptionManager by invoking the
* constructor <code>ExceptionManager(Throwable throwable)</code>.
*
* @param throwable The cause will pass the specified constructor
* @return An instance of the ExceptionManager created by invoking the constructor
* <code>ExceptionManager(Throwable throwable)</code>.
*/
public static ExceptionManager wrap(Throwable throwable){
return new ExceptionManager(throwable);
}
/**
* This static method create an instance of the ExceptionManager by invoking the
* constructor <code>ExceptionManager(String msg,Throwable throwable)</code>.
*
* @param msg The message will pass the specified constructor
* @param throwable The cause will pass the specified constructor
* @return An instance of the ExceptionManager created by invoking the constructor
* <code>ExceptionManager(String msg, Throwable throwable)</code>
*/
public static ExceptionManager wrap(String msg,Throwable throwable){
return new ExceptionManager(msg,throwable);
}
/**
* Constructs a new instance with the specified detail message. The concrete handler
* is its super class. This constructor always used to construct a custom exception
* not wrapping the exist exception.
*
* @param msg the detail message which is the part of the information will be
* shown.
*/
public ExceptionManager(String msg){
super(msg);
}
/**
* Constructs a new instance with the specified detail cause. The concrete handler
* is its super class. This constructor always used to wrap an exist exception.
*
* @param throwable the cause which has been caught. It's detail message and
* stacktrace are the parts the information will be shown.
*/
public ExceptionManager(Throwable throwable){
super(throwable);
}
/**
* Constructs a new instance with the specified detail message and cause. The
* concrete handler is its super class. This constructor always used to construct
* an exception wrapping the exist exception but requires a custom message.
*
* @param msg the detail message which is the part of the information will
* be shown.
* @param throwable the cause which has been caught. It's stacktrace is the parts
* the information will be shown.
*/
public ExceptionManager(String msg,Throwable throwable){
super(msg,throwable);
}
/**
* Show the information with everything is default.
*/
public synchronized void alert(){
alert((Component)null);
}
/**
* Show the information in a dialog with the specified title
* "ThrowableManager Alerter". The dialog belongs to the given component which
* default is the screen.
*
* @param parent The component cause the exception.
*/
public synchronized void alert(Component parent){
alert(parent,"ThrowableManager Alerter");
}
/**
* Show the information in a dialog with the specified title.
*
* @param title The title of the dialog.
*/
public synchronized void alert(String title){
alert((Component)null,title);
}
/**
* Show the information in a dialog which has the specified title and belongs to the
* specified component.
*
* @param parent The component cause the exception.
* @param title The title of the dialog.
*/
public synchronized void alert(Component parent,String title){
StringBuilder errorMessage=new StringBuilder();
errorMessage.append(this.toString());
for (StackTraceElement st:((this.getCause()==null)?this:this.getCause()).getStackTrace()){
errorMessage.append("\n\t at ");
errorMessage.append(st.toString());
}
alerter.showMessageDialog(parent, errorMessage, title ,JOptionPane.ERROR_MESSAGE);
}
}Java code
基础的java事件练习代码
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
public class ToolTipCtrl
{
private static boolean flag = true;
public static void main(String[] args)
{
JFrame frame = new JFrame();
final JButton btnSH = new JButton("Show or Hide");
final JButton btnS = new JButton("Show Only");
btnSH.setToolTipText(btnSH.getText());
btnS.setToolTipText(btnS.getText());
frame.add(btnSH, BorderLayout.WEST);
frame.add(btnS, BorderLayout.EAST);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 100);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
btnSH.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(flag)
{
postToolTip(btnSH);
}
else
{
hideToolTip(btnSH);
}
flag = !flag;
}
});
btnS.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
postToolTip(btnS);
}
});
}
public static void postToolTip(JComponent comp)
{
Action action = comp.getActionMap().get("postTip");
if(action != null)
{
ActionEvent ae = new ActionEvent(comp, ActionEvent.ACTION_PERFORMED, "postTip", EventQueue.getMostRecentEventTime(), 0);
action.actionPerformed(ae);
}
}
public static void hideToolTip(JComponent comp)
{
Action action = comp.getActionMap().get("hideTip");
if(action != null)
{
ActionEvent ae = new ActionEvent(comp, ActionEvent.ACTION_PERFORMED, "hideTip", EventQueue.getMostRecentEventTime(), 0);
action.actionPerformed(ae);
}
}
}
一些公共函数
Java code
//过滤特殊字符
public static String encoding(String src){
if (src==null)
return "";
StringBuilder result=new StringBuilder();
if (src!=null){
src=src.trim();
for (int pos=0;pos<src.length();pos++){
switch(src.charAt(pos)){
case '\"':result.append("&quot;");break;
case '<':result.append("&lt;");break;
case '>':result.append("&gt;");break;
case '\'':result.append("&apos;");break;
case '&':result.append("&amp;");break;
case '%':result.append("&pc;");break;
case '_':result.append("&ul;");break;
case '#':result.append("&shap;");break;
case '?':result.append("&ques;");break;
default:result.append(src.charAt(pos));break;
}
}
}
return result.toString();
}
//反过滤特殊字符
public static String decoding(String src){
if (src==null)
return "";
String result=src;
result=result.replace("&quot;", "\"").replace("&apos;", "\'");
result=result.replace("&lt;", "<").replace("&gt;", ">");
result=result.replace("&amp;", "&");
result=result.replace("&pc;", "%").replace("&ul", "_");
result=result.replace("&shap;", "#").replace("&ques", "?");
return result;
}
//利用反射调用一个继承层次上的函数族，比如安装程序，有安装数据库的，安装文件系统的等，命名均已“install”开始，你就可以将参数part设为“install”，src是其实类实例，root是终止父类
public static <T> void invokeMethods(String part,T src,Class root) throws ExceptionManager{
if (root!=null){
if (!root.isInstance(src))return;
root=(Class)root.getGenericSuperclass();
}
HashMap<String,Method> invokees=new HashMap<String,Method>();
Class target=src.getClass();
do{
Method [] methods=target.getDeclaredMethods();
for (Method method:methods){
String mn=method.getName();
Boolean isPass=mn.startsWith(part);
if (isPass){
Integer nopt=method.getParameterTypes().length;
Boolean isStatic=Modifier.isStatic(method.getModifiers());
if ((nopt==0)&&(!isStatic)){
if (!invokees.containsKey(mn))
invokees.put(mn, method);
}
}
}
target=(Class)target.getGenericSuperclass();
}while(target!=root);
Iterator<String> methods=invokees.keySet().iterator();
while (methods.hasNext()){
Method invokee=invokees.get(methods.next());
Boolean access=invokee.isAccessible();
invokee.setAccessible(true);
try {
invokee.invoke(src);
} catch (InvocationTargetException e) {
throw ExceptionManager.wrap(e.getTargetException());
}catch (Exception e){}
invokee.setAccessible(access);
}
}收藏的数据库联接，csdn上的
Java code
MySQL：
String Driver="com.mysql.jdbc.Driver"; //驱动程序
String URL="jdbc:mysql://localhost:3306/db_name"; //连接的URL,db_name为数据库名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).new Instance();
Connection con=DriverManager.getConnection(URL,Username,Password);
Microsoft SQL Server 2.0驱动(3个jar的那个):
String Driver="com.microsoft.jdbc.sqlserver.SQLServerDriver"; //连接SQL数据库的方法
String URL="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=db_name"; //db_name为数据库名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).new Instance(); //加载数据可驱动
Connection con=DriverManager.getConnection(URL,UserName,Password); //
Microsoft SQL Server 3.0驱动(1个jar的那个): // 老紫竹完善
String Driver="com.microsoft.sqlserver.jdbc.SQLServerDriver"; //连接SQL数据库的方法
String URL="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=db_name"; //db_name为数据库名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).new Instance(); //加载数据可驱动
Connection con=DriverManager.getConnection(URL,UserName,Password); //
Sysbase:
String Driver="com.sybase.jdbc.SybDriver"; //驱动程序
String URL="jdbc:Sysbase://localhost:5007/db_name"; //db_name为数据可名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).newInstance();
Connection con=DriverManager.getConnection(URL,Username,Password);
Oracle(用thin模式):
String Driver="oracle.jdbc.driver.OracleDriver"; //连接数据库的方法
String URL="jdbc:oracle:thin:@loaclhost:1521:orcl"; //orcl为数据库的SID
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).newInstance(); //加载数据库驱动
Connection con=DriverManager.getConnection(URL,Username,Password);
PostgreSQL:
String Driver="org.postgresql.Driver"; //连接数据库的方法
String URL="jdbc:postgresql://localhost/db_name"; //db_name为数据可名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).newInstance();
Connection con=DriverManager.getConnection(URL,Username,Password);
DB2：
String Driver="com.ibm.db2.jdbc.app.DB2.Driver"; //连接具有DB2客户端的Provider实例
//String Driver="com.ibm.db2.jdbc.net.DB2.Driver"; //连接不具有DB2客户端的Provider实例
String URL="jdbc:db2://localhost:5000/db_name"; //db_name为数据可名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).newInstance();
Connection con=DriverManager.getConnection(URL,Username,Password);
Informix:
String Driver="com.informix.jdbc.IfxDriver";
String URL="jdbc:Informix-sqli://localhost:1533/db_name:INFORMIXSER=myserver"; //db_name为数据可名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).newInstance();
Connection con=DriverManager.getConnection(URL,Username,Password);
JDBC-ODBC:
String Driver="sun.jdbc.odbc.JdbcOdbcDriver";
String URL="jdbc:odbc:dbsource"; //dbsource为数据源名
String Username="username"; //用户名
String Password="password"; //密码
Class.forName(Driver).newInstance();
Connection con=DriverManager.getConnection(URL,Username,Password);控制小数点的几个常用方法： Java code
import java.text.DecimalFormat;
public class NumberUtil {
public static double decimalFormatD(int num, double d){
String format = "0.";
String result = "";
double db;
for(int i=0;i<num;i++)
format = format.concat("0");
DecimalFormat decimal = new DecimalFormat(format);
result = decimal.format(d);
db = Double.parseDouble(result);
return db;
}
public static float decimalFormatF(int num, float f){
String format = "0.";
String result = "";
float fl;
for(int i=0;i<num;i++)
format = format.concat("0");
DecimalFormat decimal = new DecimalFormat(format);
result = decimal.format(f);
fl = Float.parseFloat(result);
return fl;
}
public static String doubleToString(double f){
String s = "";
double a = 0;
while(f >= 1) {
a = f%((double)10);
s = String.valueOf((int)a) + s;
f=(f - a)/10;
}
return s;
}
}
用一个for循环打印九九乘法表 Java code
/**
*一个for循环打印九九乘法表
*/
public void nineNineMultiTable()
{
for (int i = 1,j = 1; j <= 9; i++) {
System.out.print(i+"*"+j+"="+i*j+" ");
if(i==j)
{
i=0;
j++;
System.out.println();
}
}
}
jdbc连接sql server Java code
package util;
import java.sql.*;
public class JdbcUtil
{
public static void close(Statement st, Connection con)
{
try
{
st.close();
}catch(Exception e)
{
}
try
{
con.close();
}catch(Exception e)
{
}
}
public static void close(ResultSet rs, Statement st, Connection con)
{
try
{
rs.close();
}catch(Exception e)
{
}
close(st, con);
}
public static Connection getConnection() throws Exception
{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
return DriverManager.getConnection("jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=db", "sa", "54321");
}
}
简单的txt转换xml Java code
package com.liu;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.util.StringTokenizer;
public class TxtToXml {
private String strTxtFileName;
private String strXmlFileName;
public TxtToXml() {
strTxtFileName = new String();
strXmlFileName = new String();
}
public void createXml(String strTxt, String strXml) {
strTxtFileName = strTxt;
strXmlFileName = strXml;
String strTmp;
try {
BufferedReader inTxt = new BufferedReader(new FileReader(
strTxtFileName));
BufferedWriter outXml = new BufferedWriter(new FileWriter(
strXmlFileName));
outXml.write("<?xml version= \"1.0\" encoding=\"gb2312\"?>");
outXml.newLine();
outXml.write("<people>");
while ((strTmp = inTxt.readLine()) != null) {
StringTokenizer strToken = new StringTokenizer(strTmp, "，");
String arrTmp[];
arrTmp = new String;
for (int i = 0; i < 3; i++)
arrTmp = new String("");
int index = 0;
outXml.newLine();
outXml.write(" <students>");
while (strToken.hasMoreElements()) {
strTmp = (String) strToken.nextElement();
strTmp = strTmp.trim();
arrTmp = strTmp;
}
outXml.newLine();
outXml.write(" <name>" + arrTmp + "</name>");
outXml.newLine();
outXml.write(" <sex>" + arrTmp + "</sex>");
outXml.newLine();
outXml.write(" <age>" + arrTmp + "</age>");
outXml.newLine();
outXml.write(" </students>");
}
outXml.newLine();
outXml.write("</people>");
outXml.flush();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
String txtName = "testtxt.txt";
String xmlName = "testxml.xml";
TxtToXml thisClass = new TxtToXml();
thisClass.createXml(txtName, xmlName);
}
}
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