1. 字符串有整型的相互转换，下面我们就来说一说关于java程序员必备20个技术?我们一起去了解并探讨一下这个问题吧!
java程序员必备20个技术
1. 字符串有整型的相互转换
String a = String.valueOf(2); //integer to numeric stringint i = Integer.parseInt(a); //numeric string to an int
2. 向文件末尾添加内容BufferedWriter out = null;try {out = new BufferedWriter(new FileWriter(”filename”, true));out.write(”aString”);} catch (IOException e) {// error processing code} finally {if (out != null) {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Oraclepublic class OracleJdbcTest {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();}public static void main(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 == null) {// Either dir does not exist or is not a directory} else {for (int i=0; i < children.length; i ) {// Get filename of file or directoryString 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 objectsFile[] files = dir.listFiles();// This filter only returns directoriesFileFilter 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1 public class PageBean { 2 private int curPage; //当前页3 private int pageCount; //总页数4 private int rowsCount; //总行数5 private int pageSize=10; //每页多少行678 9 public PageBean(int rows){1011 this.setRowsCount(rows);12 if(this.rowsCount % this.pageSize == 0){13 this.pageCount=this.rowsCount / this.pageSize;14 }15 else if(rows<this.pageSize){16 this.pageCount=1;17 }18 else{19 this.pageCount=this.rowsCount / this.pageSize 1;20 }21 }222324 public int getCurPage() {25 return curPage;26 }27 public void setCurPage(int curPage) {28 this.curPage = curPage;29 }30 public int getPageCount() {31 return pageCount;32 }33 public void setPageCount(int pageCount) {34 this.pageCount = pageCount;35 }36 public int getPageSize() {37 return pageSize;38 }39 public void setPageSize(int pageSize) {40 this.pageSize = pageSize;41 }42 public int getRowsCount() {43 return rowsCount;44 }45 public void setRowsCount(int rowsCount) {46 this.rowsCount = rowsCount;47 }48 }
分页展示如下1 List clist=adminbiz.queryNotFullCourse();//将查询结果存放在List集合里2 PageBean pagebean=new PageBean(clist.size());//初始化PageBean对象3 //设置当前页4 pagebean.setCurPage(page); //这里page是从页面上获取的一个参数，代表页数5 //获得分页大小6 int pagesize=pagebean.getPageSize();7 //获得分页数据在list集合中的索引8 int firstIndex=(page-1)*pagesize;9 int toIndex=page*pagesize;10 if(toIndex>clist.size()){11 toIndex=clist.size();12 }13 if(firstIndex>toIndex){14 firstIndex=0;15 pagebean.setCurPage(1);16 }17 //截取数据集合，获得分页数据18 List courseList=clist.subList(firstIndex, toIndex);
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