1.最简单的doGet
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
res.setContentType("text/html;charset=GB2312");
PrintWriter out = res.getWriter();
out.println("<html><head><title>HelloServlet</title></head>");
out.println("<body>");
out.println("你好:kinco");
out.println("</body></html>");
}
2.最简单的读取web项目下的文件
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
ServletContext context = getServletContext();
BufferedReader reader = new BufferedReader(new InputStreamReader(context.getResourceAsStream("/main.html")));
PrintWriter out = res.getWriter();
String temp = "";
StringBuffer sb = new StringBuffer();
while((temp = reader.readLine()) != null) {
sb.append(temp);
}
out.println(sb.toString());
reader.close();
out.close();
}
3.最简单的读取数据库
package cn.hackywit.jdbc;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JdbcUtil {
private static String className;
private static String url;
private static String user;
private static String password;
static{
try {
InputStream in = JdbcUtil.class.getClassLoader().getResourceAsStream("dbinfo.properties");
Properties props = new Properties();
props.load(in);
className = props.getProperty("className");
url = props.getProperty("url");
user = props.getProperty("user");
password = props.getProperty("password");
Class.forName(className);
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection getConnection() throws Exception{
return DriverManager.getConnection(url,user,password);
}
public static void release(ResultSet rs,Statement stmt,Connection conn){
if(rs!=null){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
rs = null;
}
if(stmt!=null){
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
stmt = null;
}
if(conn!=null){
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}
}
}
package cn.hackywit.jdbc;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
public class mysql {
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = JdbcUtil.getConnection();
// 3.创建sql语句对象Statement
stmt = conn.createStatement();
// 4.将sql语句对象发送给数据库处理并得到返回结果ResultSet
rs = stmt.executeQuery("select password from user where username='hackywit'");
// 5.遍历结果
while(rs.next()){
String pwd = (String) rs.getObject("password");
if(pwd.equals("123456")){
System.out.println(pwd);
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
} finally {
// 6.释放所有的连接
JdbcUtil.release(rs, stmt, conn);
}
}
}
dbinfo.properties
className=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/kincodb?characterEncoding=utf8&useSSL=false
user=root
password=123
4.读取.properties配置文件
//利用ServletContext读取a1.properties
private void test1() throws IOException, FileNotFoundException {
ServletContext sc = getServletContext();
String path = sc.getRealPath("/WEB-INF/a1.properties");
Properties props = new Properties();
props.load(new FileInputStream(path));
String value = props.getProperty("username");
System.out.println(value);
}
//利用ServletContext读取a2.properties
private void test2() throws IOException, FileNotFoundException {
ServletContext sc = getServletContext();
String path = sc.getRealPath("/WEB-INF/classes/a2.properties");
Properties props = new Properties();
props.load(new FileInputStream(path));
String value = props.getProperty("username");
System.out.println(value);
}
//利用ServletContext读取a3.properties
private void test3() throws IOException, FileNotFoundException {
ServletContext sc = getServletContext();
String path = sc.getRealPath("/WEB-INF/classes/cn/itcast/resources/a3.properties");
Properties props = new Properties();
props.load(new FileInputStream(path));
String value = props.getProperty("username");
System.out.println(value);
}
//------------------------------------------------------------------
//利用ResourceBundle读取配置文件a2.properties
private void test4() throws IOException, FileNotFoundException {
ResourceBundle rb = ResourceBundle.getBundle("a2");//基名
String value = rb.getString("username");
System.out.println(value);
}
//利用ResourceBundle读取配置文件a3.properties
private void test5() throws IOException, FileNotFoundException {
ResourceBundle rb = ResourceBundle.getBundle("cn.itcast.resources.a3");//基名
String value = rb.getString("username");
System.out.println(value);
}
//------------------------------------------------------------------
//利用类加载器读取配置文件a2.properties
private void test6() throws IOException, FileNotFoundException {
ClassLoader cl = ServletDemo7.class.getClassLoader();//得到ServletDemo7的类加载器
InputStream in = cl.getResourceAsStream("a2.properties");
Properties props = new Properties();
props.load(in);
String value = props.getProperty("username");
System.out.println(value);
}
//利用类加载器读取配置文件a3.properties
private void test7() throws IOException, FileNotFoundException {
ClassLoader cl = ServletDemo7.class.getClassLoader();//得到ServletDemo7的类加载器
InputStream in = cl.getResourceAsStream("cn/itcast/resources/a3.properties");
Properties props = new Properties();
props.load(in);
String value = props.getProperty("username");
System.out.println(value);
}
