How to Handle Proxy Setting using Selenium Webdriver .

Mozilla FireFox:
FirefoxProfile profile = new FirefoxProfile();

profile.setPreference("network.proxy.type", 1);

profile.setPreference("network.proxy.http", "localhost");

profile.setPreference("network.proxy.http_port", 3128);

WebDriver driver = new FirefoxDriver(profile);

or
String PROXY = "localhost:8080";

org.openqa.selenium.Proxy proxy = new org.openqa.selenium.Proxy();
proxy.setHttpProxy(PROXY)
     .setFtpProxy(PROXY)
     .setSslProxy(PROXY);
DesiredCapabilities cap = new DesiredCapabilities();
cap.setCapability(CapabilityType.PROXY, proxy);
WebDriver driver = new FirefoxDriver(cap);

 Internet Explorer:

String PROXY = "localhost:8080";

org.openqa.selenium.Proxy proxy = new org.openqa.selenium.Proxy();
proxy.setHttpProxy(PROXY)
     .setFtpProxy(PROXY)
     .setSslProxy(PROXY);
DesiredCapabilities cap = new DesiredCapabilities();
cap.setCapability(CapabilityType.PROXY, proxy);

WebDriver driver = new InternetExplorerDriver(cap);

Chrome:
String PROXY = "localhost:8080";

org.openqa.selenium.Proxy proxy = new org.openqa.selenium.Proxy();
proxy.setHttpProxy(PROXY)
     .setFtpProxy(PROXY)
     .setSslProxy(PROXY);
DesiredCapabilities cap = new DesiredCapabilities();
cap.setCapability(CapabilityType.PROXY, proxy);

WebDriver driver = new ChromeDriver(cap);