基于JAAS实现登录

JAAS：Java Authentication and Authorization Service，提供了认证和授权框架。

本例是认证的实现，JAAS定义了可插拔的认证机制，使认证逻辑独立开来，可通过修改配置文件切换认证模块。

官方参考：
http://java.sun.com/products/archive/jaas/
http://java.sun.com/j2se/1.4.2/docs/guide/security/jaas/JAASRefGuide.html
security.pdf

一、配置文件及设置

1. 配置文件（假设为D:/jaas.conf）：


Sample{


com.fastunit.samples.jaas.SampleLoginModule required debug=false;


};
此文件定义了一个“Sample”验证模块，使用SampleLoginModule来进行验证。

2. 启用配置文件：
-Djava.security.auth.login.config=D:/jaas.conf

二、客户端调用

import javax.security.auth.login.LoginContext;
import javax.security.auth.login.LoginException;
import javax.servlet.http.HttpServletRequest;

public class LoginManager {

public static boolean login(HttpServletRequest request) {
try {
String username = request.getParameter("username");
String password = request.getParameter("password");
//此处指定了使用配置文件的“Sample”验证模块，对应的实现类为SampleLoginModule
LoginContext lc = new LoginContext("Sample", new SampleCallbackHandler(
username, password));
lc.login();// 如果验证失败会抛出异常
return true;
} catch (LoginException e) {
e.printStackTrace();
return false;
} catch (SecurityException e) {
e.printStackTrace();
return false;
}
}

}

import java.io.IOException;

import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.UnsupportedCallbackException;

public class SampleCallbackHandler implements CallbackHandler {
private String username;
private String password;

public SampleCallbackHandler(final String username, final String password) {
this.username = username;
this.password = password;
}

public void handle(Callback[] callbacks) throws IOException,
UnsupportedCallbackException {
for (int index = 0; index < callbacks.length; index++) {
if (callbacks[index] instanceof NameCallback) {
NameCallback ncb = (NameCallback) callbacks[index];
ncb.setName(username);
}
if (callbacks[index] instanceof PasswordCallback) {
PasswordCallback pcb = (PasswordCallback) callbacks[index];
pcb.setPassword(password.toCharArray());
}
}
}
}

三、验证实现

import java.io.IOException;
import java.util.Map;

import javax.security.auth.Subject;
import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.UnsupportedCallbackException;
import javax.security.auth.login.LoginException;
import javax.security.auth.spi.LoginModule;

public class SampleLoginModule implements LoginModule {
private boolean isAuthenticated = false;
private CallbackHandler callbackHandler;
private Subject subject;
private SamplePrincipal principal;

public void initialize(Subject subject, CallbackHandler callbackHandler,
Map sharedState, Map options) {
this.subject = subject;
this.callbackHandler = callbackHandler;
}

public boolean login() throws LoginException {
try {
NameCallback nameCallback = new NameCallback("username");
PasswordCallback passwordCallback = new PasswordCallback("password",
false);
final Callback[] calls = new Callback[] { nameCallback, passwordCallback };

// 获取用户数据
callbackHandler.handle(calls);
String username = nameCallback.getName();
String password = String.valueOf(passwordCallback.getPassword());

// TODO 验证，如：查询数据库、LDAP。。。

if (true) {// 验证通过
principal = new SamplePrincipal(username);
isAuthenticated = true;
} else {
throw new LoginException("user or password is wrong");
}

} catch (IOException e) {
throw new LoginException("no such user");
} catch (UnsupportedCallbackException e) {
throw new LoginException("login failure");
}
return isAuthenticated;
}

/**
* 验证后的处理,在Subject中加入用户对象
*/
public boolean commit() throws LoginException {
if (isAuthenticated) {
subject.getPrincipals().add(principal);
} else {
throw new LoginException("Authentication failure");
}
return isAuthenticated;
}

public boolean abort() throws LoginException {
return false;
}

public boolean logout() throws LoginException {
subject.getPrincipals().remove(principal);
principal = null;
return true;
}
}

import java.security.Principal;

public final class SamplePrincipal implements Principal {

private String name;

public SamplePrincipal(String name) {
this.name = name;
}

public String getName() {
return name;
}

public boolean equals(Object o) {
return (o instanceof SamplePrincipal)
&& this.name.equalsIgnoreCase(((SamplePrincipal) o).name);
}

public int hashCode() {
return name.toUpperCase().hashCode();
}

}