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java切换数据源代码 java切换数据源代码怎么写
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Java web点击按钮切换数据源
如果要在Javaweb切换数据源，首先你需要新建数据源常量类，此类中的常量是通过spring-db.xml映射对应的，然后配置spring-db.xml，这个是spring链接数据库的配置文件，再进行动态数据源设置，这个类是用来切换数据源，再获取jdbcTemplate的管理类。最后测试动态数据源，一般会用Junit4做单元测试。
总结：这种切换比较规范和简单，麻烦的是必须先配置多个数据源，以前是参考网上资料，自己修改的，希望对你有参考作用！
相关问答
Q1: JAVA操作中，频繁的切换数据源会有什么不好的影响或后果吗
一般没什么问题。因为一般程序都是从数据源的连接池中取得连接java切换数据源代码，只要保证连接池安全java切换数据源代码，程序再怎么频繁切换数据源都是没问题的。
其实这个就和你平常用JDBC连接数据操作的时候是一样的，用完你就colse 连接，再用就再取。
Q2: 速求java编程：计算器能在科学型与标准型之间切换的源代码
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**********************Java计算器 主类*********************/
public class Calculator implements ActionListener {
JFrame f;
JMenu mEdit;
JMenu mView;
JMenu mHelp;
JMenuItem mCopy;
JMenuItem mPaste;
JTextField tResult;
JButton bNumber;
JButton bOperator;
JButton bOther;
JButton bM;
boolean isDouble=false;//是否为实数
int opFlag=-1;
static double t1=0,t2=0,t3=0,result=0;
static int opflag1=-1,opflag2=-1,flag=0,resflag=1;
int preOp,currentOp=0;//标准位
double op1=0,op2=0;//操作数
double n3;
StringBuffer buf=new StringBuffer(20);
StringBuffer copyBoard=new StringBuffer(20);//剪贴板
StringBuffer memory=new StringBuffer(20);//M系列
StringBuffer str=new StringBuffer();
//Java计算器 构造器
public Calculator()
{
f = new JFrame("计算器_刘亚会");
Container contentPane = f.getContentPane();
/**************************Java计算器 菜单的创建*****************************/
JMenuBar mBar = new JMenuBar();
mBar.setOpaque(true);
mEdit = new JMenu("编辑(E)");
mEdit.setMnemonic(KeyEvent.VK_E);
mCopy = new JMenuItem("复制(C)");
mEdit.add(mCopy);
mPaste = new JMenuItem("粘贴(P)");
mEdit.add(mPaste);
mView = new JMenu("查看(V)");
mView.setMnemonic(KeyEvent.VK_V);
mView.add(new JMenuItem("标准型"));
mView.add(new JMenuItem("科学型"));
mView.addSeparator();
mView.add(new JMenuItem("查看分组"));
mHelp = new JMenu("帮助(H)");
mHelp.setMnemonic(KeyEvent.VK_H);
mHelp.add(new JMenuItem("帮助主题"));
mHelp.addSeparator();
mHelp.add(new JMenuItem("关于计算器"));
mBar.add(mEdit);
mBar.add(mView);
mBar.add(mHelp);
f.setJMenuBar(mBar);
contentPane.setLayout(new BorderLayout());
JPanel pTop = new JPanel();
tResult = new JTextField("0.",26);
tResult.setHorizontalAlignment(JTextField.RIGHT);
tResult.setEditable(false);
pTop.add(tResult);
contentPane.add(pTop,BorderLayout.NORTH);
JPanel pBottom = new JPanel();
pBottom.setLayout(new BorderLayout());
JPanel pLeft = new JPanel();
pLeft.setLayout(new GridLayout(5,1,3,3));
bM = new JButton(" ");
bM.setEnabled(false);
pLeft.add(bM);
/*************************Java计算器 功能键定义***************************/
bOther = new JButton("MC");
bOther.addActionListener(this);
bOther.setForeground(Color.red);
bOther.setMargin(new Insets(3,2,3,2));
pLeft.add(bOther);
bOther = new JButton("MR");
bOther.addActionListener(this);
bOther.setForeground(Color.red);
bOther.setMargin(new Insets(3,2,3,2));
pLeft.add(bOther);
bOther = new JButton("MS");
bOther.addActionListener(this);
bOther.setForeground(Color.red);
bOther.setMargin(new Insets(3,2,3,2));
pLeft.add(bOther);
bOther = new JButton("M+");
bOther.addActionListener(this);
bOther.setForeground(Color.red);
bOther.setMargin(new Insets(3,2,3,2));
pLeft.add(bOther);
pBottom.add(pLeft,BorderLayout.WEST);
JPanel pRight = new JPanel();
pRight.setLayout(new BorderLayout());
JPanel pUp = new JPanel();
pUp.setLayout(new GridLayout(1,3,3,0));
bOther = new JButton("BackSpace");
bOther.addActionListener(this);
bOther.setForeground(Color.red);
bOther.setMargin(new Insets(3,0,3,5));
pUp.add(bOther);
bOther = new JButton("CE");
bOther.addActionListener(this);
bOther.setForeground(Color.red);
pUp.add(bOther);
bOther = new JButton("C");
bOther.addActionListener(this);
bOther.setForeground(Color.red);
pUp.add(bOther);
/***************************Java计算器 数字键盘区定义**************************/
JPanel pDown = new JPanel();
pDown.setLayout(new GridLayout(4,5,3,2));
bNumber = new JButton("7");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bNumber = new JButton("8");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bNumber = new JButton("9");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bOperator = new JButton("/");
bOperator.setForeground(Color.red);
bOperator.addActionListener(this);
bOperator.setMargin(new Insets(3,0,3,0));
pDown.add(bOperator);
bOperator = new JButton("sqrt");
bOperator.addActionListener(this);
bOperator.setForeground(Color.red);
bOperator.setMargin(new Insets(3,0,3,0));
pDown.add(bOperator);
bNumber = new JButton("4");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
bNumber.setHorizontalTextPosition(JButton.LEFT);
pDown.add(bNumber);
bNumber = new JButton("5");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bNumber = new JButton("6");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bOperator = new JButton("*");
bOperator.setForeground(Color.red);
bOperator.addActionListener(this);
bOperator.setMargin(new Insets(3,3,3,3));
pDown.add(bOperator);
bOperator = new JButton("%");
bOperator.setForeground(Color.blue);
bOperator.addActionListener(this);
bOperator.setMargin(new Insets(3,3,3,3));
pDown.add(bOperator);
bNumber = new JButton("1");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bNumber = new JButton("2");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bNumber = new JButton("3");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bOperator = new JButton("-");
bOperator.setForeground(Color.red);
bOperator.addActionListener(this);
bOperator.setMargin(new Insets(3,3,3,3));
pDown.add(bOperator);
bOperator = new JButton("1/x");
bOperator.setForeground(Color.blue);
bOperator.addActionListener(this);
pDown.add(bOperator);
bNumber = new JButton("0");
bNumber.setForeground(Color.blue);
bNumber.addActionListener(this);
bNumber.setMargin(new Insets(3,3,3,3));
pDown.add(bNumber);
bOperator = new JButton("+/-");
bOperator.setForeground(Color.blue);
bOperator.addActionListener(this);
bOperator.setMargin(new Insets(3,3,3,3));
pDown.add(bOperator);
bOperator = new JButton(".");
bOperator.setForeground(Color.blue);
bOperator.addActionListener(this);
bOperator.setMargin(new Insets(3,3,3,3));
pDown.add(bOperator);
bOperator = new JButton("+");
bOperator.setForeground(Color.blue);
bOperator.addActionListener(this);
bOperator.setMargin(new Insets(3,3,3,3));
pDown.add(bOperator);
bOperator = new JButton("=");
bOperator.setForeground(Color.blue);
bOperator.addActionListener(this);
bOperator.setMargin(new Insets(3,3,3,3));
pDown.add(bOperator);
pRight.add(pUp,BorderLayout.NORTH);
pRight.add(pDown,BorderLayout.SOUTH);
pBottom.add(pRight,BorderLayout.EAST);
contentPane.add(pBottom,BorderLayout.SOUTH);
f.setSize(new Dimension(320,256));
f.setResizable(false);
f.setVisible(true);
f.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
);
}
/************************Java计算器 计算方法区***************************/
public void actionPerformed(ActionEvent e)
{
String s = e.getActionCommand();
if(s.equals("复制(C)"))
{
String temp = tResult.getText().trim();
copyBoard.replace(0, copyBoard.length(), temp);
mPaste.setEnabled(true);
}
else if(s.equals("粘贴(p)"))
{
tResult.setText(copyBoard.toString());
}
else if(s.equals("CE"))
{
//如果是CE则清除文本框
tResult.setText("0.");
}
else if(s.equals("BackSpace"))
{
if(!tResult.getText().trim().equals("0."))
{
//如果文本框中有内容
if(str.length()!=1 str.length()!=0)
{
tResult.setText(str.delete(str.length()-1,str.length()).toString());
}
else
{
tResult.setText("0.");
str.setLength(0);
}
}
op2 = Double.parseDouble(tResult.getText().trim());
}
else if(s.equals("C"))
{
//如果是C删除当前计算
tResult.setText("0.");
op1 = op2 = 0;
str.replace(0, str.length(), " ");
preOp = currentOp = 0;
}
else if(s.equals("MC"))
{
//如果是MC则清除缓冲区
String temp = "";
memory.replace(0, memory.length(), temp);
bM.setText(" ");
}
else if(s.equals("MR"))
{
//如果按键为MR则恢复缓冲区的数到文本框
tResult.setText(memory.toString());
}
else if(s.equals("MS"))
{
//如果按键为MS则将文本框的数存入缓冲区
String s1 = tResult.getText().trim();
memory.replace(0, memory.length(), s1);
bM.setText("M");
}
else if(s.equals("M+"))
{
//如果按键为MS则将文本框值与缓冲区的数相加但不显示结果
String temp1 = tResult.getText().trim();
double dtemp = Double.parseDouble(temp1);
String temp2 = memory.toString();
dtemp += Double.parseDouble(temp2);
temp1 = String.valueOf(dtemp);
memory.replace(0, memory.length(), temp1);
}
else if(s.equals("1/x"))
{
//如果按键为1/x则将文本框中的数据为它的倒数
String temp = tResult.getText().trim();
double dtemp = Double.parseDouble(temp);
tResult.setText(""+1/dtemp);
}
else if(s.equals("sqrt"))
{
//如果按键为sqrt则将文本框中的内容求平方根
String temp = tResult.getText().trim();
double dtemp = Double.parseDouble(temp);
tResult.setText(""+Math.sqrt(dtemp));
}
else if(s.equals("+"))
{
str.setLength(0);
if(currentOp==0)
{
preOp = currentOp = 1;
op2 = 0;
tResult.setText(""+op1);
}
else
{
currentOp = preOp;
preOp = 1;
switch(currentOp){
case 1:
op1 += op2;
tResult.setText(""+op1);
break;
case 2:
op1 -= op2;
tResult.setText(""+op1);
break;
case 3:
op1 *= op2;
tResult.setText(""+op1);
break;
case 4:
op1 /= op2;
tResult.setText(""+op1);
break;
}
}
}
else if(s.equals("-")){
str.setLength(0);
if(currentOp==0)
{
preOp=currentOp=2;//op1=op2;op2=0;
tResult.setText(""+op1);
}
else
{
currentOp =preOp;
preOp =2;
switch(currentOp){
case 1:op1=op1+op2;tResult.setText(""+op1);break;
case 2:op1=op1-op2;tResult.setText(""+op1);break;
case 3:op1=op1*op2;tResult.setText(""+op1);break;
case 4:op1=op1/op2;tResult.setText(""+op1);break;
}
}
}
else if(s.equals("*"))//*
{
str.setLength(0);
if(currentOp==0)
{
preOp=currentOp=3;//op1=op2;op2=1;
tResult.setText(""+op1);//op1=op2;
}
else
{
currentOp =preOp;
preOp =3;
switch(currentOp){
case 1:op1=op1+op2;tResult.setText(""+op1);break;
case 2:op1=op1-op2;tResult.setText(""+op1);break;
case 3:op1=op1*op2;tResult.setText(""+op1);break;
case 4:op1=op1/op2;tResult.setText(""+op1);break;
}
}
}
else if(s.equals("/"))// /
{
str.setLength(0);
if(currentOp==0)
{
preOp=currentOp=4;//op2=1;
tResult.setText(""+op1);//op1=op2;
}
else
{
currentOp =preOp;
preOp =4;
switch(currentOp){
case 1:op1=op1+op2;tResult.setText(""+op1);break;
case 2:op1=op1-op2;tResult.setText(""+op1);break;
case 3:op1=op1*op2;tResult.setText(""+op1);break;
case 4:op1=op1/op2;tResult.setText(""+op1);break;
}
}
}
else if(s.equals("="))// =
{
if(currentOp==0)
{
str.setLength(0);
tResult.setText(""+op2);
}
else
{
str.setLength(0);
currentOp =preOp;
switch(currentOp){
case 1:op1=op1+op2;tResult.setText(""+op1);break;
case 2:op1=op1-op2;tResult.setText(""+op1);break;
case 3:op1=op1*op2;tResult.setText(""+op1);break;
case 4:op1=op1/op2;tResult.setText(""+op1);break;
}
currentOp=0;
op2=0;
}
}
else if(s.equals("."))
{
isDouble=true;
if(tResult.getText().trim().indexOf('.')!=-1);
else {
if(tResult.getText().trim().equals("0")) {
str.setLength(0);
tResult.setText((str.append("0"+s)).toString());
}
//else if(tResult.getText().trim().equals("")){}//如果初时显示为空则不做任何操作
else {
tResult.setText((str.append(s)).toString());
}
}
}
else if(s.equals("0"))//如果选择的是"0"这个数字键
{
if(tResult.getText().trim().equals("0.")){}
else{
tResult.setText(str.append(s).toString());
op2=Double.parseDouble(tResult.getText().trim());
}
}
else{
tResult.setText(str.append(s).toString());
op2=Double.parseDouble(tResult.getText().trim());
if(currentOp==0)
op1=op2;
}
}//end actionPerformed
public static void main(String[] args) {
new Calculator();
}
}
这个就是了，看看功能是否一样
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