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常用Java编程代码大全

更新时间:2022-09-23 10:36:25 来源:动力节点 浏览61次

1. 字符串有整型的相互转换

String a = String.valueOf(2); //integer to numeric string
int i = Integer.parseInt(a); //numeric string to an int

2. 向文件末尾添加内容

BufferedWriter out = ;
try {
out = new BufferedWriter(new FileWriter(”filename”, true));
out.write(”aString”);
} catch (IOException e) {
// error processing code
} finally {
if (out != ) {
out.close;
}
}

3. 得到当前方法的名字

String methodName = Thread.currentThread.getStackTrace[1].getMethodName;

4. 转字符串到日期

java.util.Date = java.text.DateFormat.getDateInstance.parse(date String);
或者是:SimpleDateFormat format = new SimpleDateFormat( "yyyy-MM-dd" );
Date date = format.parse( myString );

5. 使用JDBC链接Oracle

public classOracleJdbcTest
{String driverClass = "oracle.jdbc.driver.OracleDriver";
Connection con;public void init(FileInputStream fs) throws ClassNotFoundException, SQLException, FileNotFoundException, IOException
{Properties props = new Properties;
props.load(fs);String url = props.getProperty("db.url");
String userName = props.getProperty("db.user");
String password = props.getProperty("db.password");
Class.forName(driverClass);con=DriverManager.getConnection(url, userName, password);}public void fetch throws SQLException, IOException
{PreparedStatement ps = con.prepareStatement("select SYSDATE from dual");
ResultSet rs = ps.executeQuery;while (rs.next)
{// do the thing you do
}
rs.close;
ps.close;
}
publicstaticvoidmain(String[] args)
{
OracleJdbcTest test = new OracleJdbcTest;
test.init;
test.fetch;
}
}

6.列出文件和目录

File dir = new File("directoryName");
String children = dir.list;
if (children == ) {
// Either dir does not exist or is not a directory
} else {
for (int i=0; i < children.length; i++) {
// Get filename of file or directory
String filename = children[i];
}
}
// It is also possible to filter the list of returned files.
// This example does not return any files that start with `.'.
FilenameFilter filter = new FilenameFilter {
public boolean accept(File dir, String name) {
return !name.startsWith(".");
}
};
children = dir.list(filter);
// The list of files can also be retrieved as File objects
File files = dir.listFiles;
// This filter only returns directories
FileFilter fileFilter = new FileFilter {
public boolean accept(File file) {
return file.isDirectory;
}
};
files = dir.listFiles(fileFilter);

7.解析/读取XML 文件

<?xml version="1.0"?>
<students>
<student>
<name>John</name>
<grade>B</grade>
<age>12</age>
</student>
<student>
<name>Mary</name>
<grade>A</grade>
<age>11</age>
</student>
<student>
<name>Simon</name>
<grade>A</grade>
<age>18</age>
</student>
</students>

8. java分页代码实现

public class PageBean {
private int curPage; //当前页
private int pageCount; //总页数
private int rowsCount; //总行数
private int pageSize=10; //每页多少行
publicPageBean(int rows){
this.setRowsCount(rows);
if(this.rowsCount % this.pageSize == 0){
this.pageCount=this.rowsCount / this.pageSize;
}
else if(rows<this.pageSize){
this.pageCount=1;
}
else{
this.pageCount=this.rowsCount / this.pageSize +1;
}
}
publicintgetCurPage {
return curPage;
}
publicvoidsetCurPage(int curPage) {
this.curPage = curPage;

 

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