大家好，又见面了，我是你们的朋友全栈君。
1.字符串和整型的相互转换
String a= String.valueOf(2);
int i = Integer.parseInt(a);2. 向文件末尾添加内容
BufferedWriter out=null;
try {
out=new BufferedWriter(new FileWriter("filename",true));
out.write("i am stringbuffer!");
} catch (IOException e) {
e.printStackTrace();
}3. 得到当前方法的名字
String methodName = Thread.currentThread().getStackTrace()[1].getMethodName();4. 转字符串到日期与日期到字符串
//日期到字符串
SimpleDateFormat sdf = new SimpleDateFormat( "yyyy年MM月dd日 ");
String str = sdf.format(new Date());
System.out.println(str);
//字符串到日期
Date date = sdf.parse(str);
System.out.println(date);5. 使用JDBC链接Oracle
public 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. 把 Java util.Date 转成 sql.Date
java.util.Date utilDate = new java.util.Date();
java.sql.Date sqlDate = new java.sql.Date(utilDate.getTime());
7. 使用NIO进行快速的文件拷贝
public static void fileCopy( File in, File out )
throws IOException {
FileChannel inChannel = new FileInputStream( in ).getChannel();
FileChannel outChannel = new FileOutputStream( out ).getChannel();
try{
// inChannel.transferTo(0, inChannel.size(), outChannel);
// original -- apparently has trouble copying large files on Windows
// magic number for Windows, 64Mb - 32Kb)
int maxCount = (64 * 1024 * 1024) - (32 * 1024);
long size = inChannel.size();
long position = 0;
while ( position < size ){
position += inChannel.transferTo(position, maxCount, outChannel );
}
}finally{
if (inChannel != null){
inChannel.close();
}
if (outChannel != null){
outChannel.close();
}
}
}
8. 发送代数据的HTTP 请求
try {
URL my_url = new URL("链接地址");
BufferedReader br = new BufferedReader(new InputStreamReader(my_url.openStream()));
String strTemp = "";
while(null != (strTemp = br.readLine())){
System.out.println(strTemp);
}
} catch (Exception ex) {
ex.printStackTrace();
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