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Java 常用代码汇总

Java

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 = ;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【Java 常用代码汇总】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 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 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6789publicPageBean(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 publicintgetCurPage {25 return curPage;26 }27publicvoidsetCurPage(int curPage) {28 this.curPage = curPage;29 }30publicintgetPageCount {31 return pageCount;32 }33publicvoidsetPageCount(int pageCount) {34 this.pageCount = pageCount;35 }36publicintgetPageSize {37 return pageSize;38 }39publicvoidsetPageSize(int pageSize) {40 this.pageSize = pageSize;41 }42publicintgetRowsCount {43 return rowsCount;44 }45publicvoidsetRowsCount(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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