Technical / Gaurang Jadia / Page 6

Here is small piece of java code to generate binary stream which tells browser to save file as attachment. I believe that this code will help java beginners to understand HttpServletResponse of the Servlets.

package com.gaurangjadia.code.controllers;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Download extends HttpServlet {

	private static final long serialVersionUID = 1L;

    public Download() {
        super();
    }

	public void init(ServletConfig config) throws ServletException {

	}

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		try{
			String fileName = request.getParameter("name");
			String path = request.getSession().getServletContext().getRealPath("/WEB-INF/upload/");
			
			//strFileName: Name of the file which is being downloaded and which exist under /WEB-INF/upload/ path
			if(fileName.equals("strFileName")){
				path += "/" + fileName;

				File file = new File(path);
				Integer intFileLength = (int)(file.length() / 1024) + 1;

				response.setContentType(new MimetypesFileTypeMap().getContentType(file));
				response.setHeader("Content-Disposition", "attachment; filename=" + fileName);

				FileInputStream in = new FileInputStream(path);
				OutputStream out = response.getOutputStream();

				byte buf[] = new byte[intFileLength];
				int bytesRead = 0;

				while( (bytesRead = in.read(buf)) &gt; 0 ){
					out.write(buf, 0, bytesRead);
				}
				out.close();
				in.close();
			}
			else{
				request.getRequestDispatcher("/WEB-INF/download.jsp").forward(request, response);
			}
		}
		catch(Exception ex){
			request.getRequestDispatcher("/WEB-INF/download.jsp").forward(request, response);
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}

package com.gaurangjadia.code.controllers;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.OutputStream;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class Download extends HttpServlet {

private static final long serialVersionUID = 1L;

public Download() {

super();

}

public void init(ServletConfig config) throws ServletException {

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

try{

String fileName = request.getParameter("name");

String path = request.getSession().getServletContext().getRealPath("/WEB-INF/upload/");

//strFileName: Name of the file which is being downloaded and which exist under /WEB-INF/upload/ path

if(fileName.equals("strFileName")){

path += "/" + fileName;

File file = new File(path);

Integer intFileLength = (int)(file.length() / 1024) + 1;

response.setContentType(new MimetypesFileTypeMap().getContentType(file));

response.setHeader("Content-Disposition", "attachment; filename=" + fileName);

FileInputStream in = new FileInputStream(path);

OutputStream out = response.getOutputStream();

byte buf[] = new byte[intFileLength];

int bytesRead = 0;

while( (bytesRead = in.read(buf)) > 0 ){

out.write(buf, 0, bytesRead);

}

out.close();

in.close();

}

else{

request.getRequestDispatcher("/WEB-INF/download.jsp").forward(request, response);

}

catch(Exception ex){

request.getRequestDispatcher("/WEB-INF/download.jsp").forward(request, response);

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doGet(request, response);

}

I was trying to find some example to connect MySQL database with my Java Shared Hosting Plan on GoDaddy.com but I could not. Well, I don’t want to say that GoDaddy has the best plan for hosting Java application. I still can not figure out how to use JSTL, custom url-pattens in the web.xml and forward requests from a servlet to JSP page. Also, we have to put http://<domain_name>/servlet/<servlet_name> to access servlet. But, here is simple working example to show you database connection from hosting to MySQL server on GoDaddy Shared Hosting.

Take a look at the example at link : GoDaddyJavaMySQL

DBConnector.java

package com.gaurangjadia.code.base;

import java.sql.Connection;
import java.sql.DriverManager;

public class DBConnector {

	private String host = "";
	private int port = 3306;
	private String databasename = "";
	private String username = "";
	private String password = "";
	private String connectionstring = "";
	
	public DBConnector(String hostname, int port, String db, String username, String password){
		this.setHost(hostname);
		this.setPort(port);
		this.setDatabasename(db);
		this.setUsername(username);
		this.setPassword(password);
		
		this.setConnectionstring("jdbc:mysql://" + getHost() + ":" + getPort() + "/" + getDatabasename());
	}

	public Connection connect() throws Exception{
		Class.forName("com.mysql.jdbc.Driver");

		Connection objConnection = DriverManager.getConnection(this.getConnectionstring(), this.getUsername(), this.getPassword());
		return objConnection;
	}

	public String getHost() {
		return host;
	}
	public void setHost(String host) {
		this.host = host;
	}

	public int getPort() {
		return port;
	}
	public void setPort(int port) {
		this.port = port;
	}

	public String getDatabasename() {
		return databasename;
	}
	public void setDatabasename(String databasename) {
		this.databasename = databasename;
	}

	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}

	public String getConnectionstring() {
		return connectionstring;
	}
	public void setConnectionstring(String connectionstring) {
		this.connectionstring = connectionstring;
	}
}

package com.gaurangjadia.code.base;

import java.sql.Connection;

import java.sql.DriverManager;

public class DBConnector {

private String host = "";

private int port = 3306;

private String databasename = "";

private String username = "";

private String password = "";

private String connectionstring = "";

public DBConnector(String hostname, int port, String db, String username, String password){

this.setHost(hostname);

this.setPort(port);

this.setDatabasename(db);

this.setUsername(username);

this.setPassword(password);

this.setConnectionstring("jdbc:mysql://" + getHost() + ":" + getPort() + "/" + getDatabasename());

}

public Connection connect() throws Exception{

Class.forName("com.mysql.jdbc.Driver");

Connection objConnection = DriverManager.getConnection(this.getConnectionstring(), this.getUsername(), this.getPassword());

return objConnection;

}

public String getHost() {

return host;

}

public void setHost(String host) {

this.host = host;

}

public int getPort() {

return port;

}

public void setPort(int port) {

this.port = port;

}

public String getDatabasename() {

return databasename;

}

public void setDatabasename(String databasename) {

this.databasename = databasename;

}

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

}

public String getConnectionstring() {

return connectionstring;

}

public void setConnectionstring(String connectionstring) {

this.connectionstring = connectionstring;

}

GoDaddyJavaMySQL.java

package com.gaurangjadia.code.controllers;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.gaurangjadia.code.base.DBConnector;

@WebServlet(description = "Main Controller to handle all requests", urlPatterns = { "/index.html" })
public class GoDaddyJavaMySQL extends HttpServlet {
	
	private static final long serialVersionUID = 1L;
	private DBConnector objDBConnector;
	
	public GoDaddyJavaMySQL() {
        	super();
	}
    
	public void init(ServletConfig config) throws ServletException {
		try {
			objDBConnector = new DBConnector("server_ip", 3306, "database_name", "user_name", "password");
		}
		catch (Exception ex) {
			ex.printStackTrace();
		}
	}
	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		PrintWriter out = response.getWriter();
		try {
			response.setContentType("text/html; charset=ISO-8859-1");
			Connection conn = objDBConnector.connect();
			
			Statement strQuery = conn.createStatement();
			ResultSet rs = strQuery.executeQuery("SELECT * FROM table_name");
			
			out.write("<html><head><title>Connect JavaEE Application to MySQL Database on GoDaddy Shared Linux Hosting Server </title></head><body>");
			out.write("<h2>Connect JavaEE Application to MySQL Database on GoDaddy Shared Linux Hosting Server.</h2>");
			out.write("<table border=\"1\">");
			while(rs.next()){
				out.write("<tr><td>" + rs.getString("Column_1") + "</td><td>" + rs.getString("Column_2") + "</td><td>" + rs.getString("Column_3") + "</td></tr>");
			}
			out.write("</table>");
			out.write("</body></html>");
			
		}
		catch (Exception ex) {
			ex.printStackTrace(out);
		}
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}

}

package com.gaurangjadia.code.controllers;

import java.io.IOException;

import java.io.PrintWriter;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.Statement;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.gaurangjadia.code.base.DBConnector;

@WebServlet(description = "Main Controller to handle all requests", urlPatterns = { "/index.html" })

public class GoDaddyJavaMySQL extends HttpServlet {

private static final long serialVersionUID = 1L;

private DBConnector objDBConnector;

public GoDaddyJavaMySQL() {

super();

}

public void init(ServletConfig config) throws ServletException {

try {

objDBConnector = new DBConnector("server_ip", 3306, "database_name", "user_name", "password");

}

catch (Exception ex) {

ex.printStackTrace();

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

PrintWriter out = response.getWriter();

try {

response.setContentType("text/html; charset=ISO-8859-1");

Connection conn = objDBConnector.connect();

Statement strQuery = conn.createStatement();

ResultSet rs = strQuery.executeQuery("SELECT * FROM table_name");

out.write("<html><head><title>Connect JavaEE Application to MySQL Database on GoDaddy Shared Linux Hosting Server </title></head><body>");

out.write("<h2>Connect JavaEE Application to MySQL Database on GoDaddy Shared Linux Hosting Server.</h2>");

out.write("<table border=\"1\">");

while(rs.next()){

out.write("<tr><td>" + rs.getString("Column_1") + "</td><td>" + rs.getString("Column_2") + "</td><td>" + rs.getString("Column_3") + "</td></tr>");

}

out.write("</table>");

out.write("</body></html>");

}

catch (Exception ex) {

ex.printStackTrace(out);

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doGet(request, response);

}

web.xml

< ?xml version="1.0" encoding="UTF-8"?>
<web -app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display -name>GoDaddyJavaMySQL</display>
  <welcome -file-list>
    </welcome><welcome -file>index.html</welcome>
    <welcome -file>index.htm</welcome>
    <welcome -file>index.jsp</welcome>
    <welcome -file>default.html</welcome>
    <welcome -file>default.htm</welcome>
    <welcome -file>default.jsp</welcome>
  
  <servlet>
    <description></description>
    <display -name>GoDaddyJavaMySQL</display>
    </servlet><servlet -name>GoDaddyJavaMySQL</servlet>
    <servlet -class>com.gaurangjadia.code.controllers.GoDaddyJavaMySQL</servlet>
  
  <servlet -mapping>
    </servlet><servlet -name>GoDaddyJavaMySQL</servlet>
    <url -pattern>/GoDaddyJavaMySQL</url>
  
</web>

< ?xml version="1.0" encoding="UTF-8"?>

<display -name>GoDaddyJavaMySQL</display>

</welcome><welcome -file>index.html</welcome>

<welcome -file>index.htm</welcome>

<welcome -file>index.jsp</welcome>

<welcome -file>default.html</welcome>

<welcome -file>default.htm</welcome>

<welcome -file>default.jsp</welcome>

<display -name>GoDaddyJavaMySQL</display>

</servlet><servlet -name>GoDaddyJavaMySQL</servlet>

<servlet -class>com.gaurangjadia.code.controllers.GoDaddyJavaMySQL</servlet>

</servlet><servlet -name>GoDaddyJavaMySQL</servlet>

<url -pattern>/GoDaddyJavaMySQL</url>

</web>

Gaurang Jadia

Nothing is permanent except change

Category Archives: Technical

How to enable Root User on Mac OS X

Step 1: Go to System Preferences

Step 2: Select Users & Groups under System Tab

Step 3: Select Login Options

Step 4: Click Join next to Network Account Server. It will open Directory Utility dialog box

Step 5: Click Edit Menu from the Menu Bar and click Enable Root User. System will ask you to enter password and it will enable Root User.

Download Controller – JavaEE Servlet

Connect JavaEE Application to MySQL Database on GoDaddy Shared Linux Hosting Server