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一、简介
CustomRealm（自定义Realm）是通过仿造JdbcRealm，继承AuthrizingRealm，
重写doGetAuthenticationInfo(AuthenticationToken token)【认证】和 doGetAuthorizationInfo(PrincipalCollection principalCollection)【授权】方法
二、理解
自定义的Realm，主要注意一下几个步骤：
-
首先继承并实现类AuthorizingRealm的方法。其中方法
doGetAuthenticationInfo 主要做认证操作，即可以通过获取其中的
用户名，查询出相应的密码，然后将用户名与密码一并返回，shiro会自动根据传入的用户名与密码与此Realm返回的用户名和密码作比对，返回你想要的结果。同理doGetAuthorizationInfo主要是用来做角色与权限的验证，也是通过用户名，从数据库中查找到相应的角色或者权限的数据并返回一个Simple的授权类，授权系统会根据传入的参数与返回的结果集对比，存在返回true不存在则抛异常。
-
两者方法只能获取用户名称，通过用户名称连接数据库获取其他信息。这里只是做数据准备操作，并不做判断是否传入的值与其相符的操作，此操作在此之后进行。
-
根据两者的返回对象分别返回Simple类型的对象。认证的对象需要将你获取的用户名和密码放到构造方法中。授权的对象需要你set到相应的方法中。
三、代码（参考官方JdbcRealm的实现）
public class JdbcRealm extends AuthorizingRealm {
protected static final String DEFAULT_AUTHENTICATION_QUERY = "select password from users where username = ?";
protected static final String DEFAULT_SALTED_AUTHENTICATION_QUERY = "select password, password_salt from users where username = ?";
protected static final String DEFAULT_USER_ROLES_QUERY = "select role_name from user_roles where username = ?";
protected static final String DEFAULT_PERMISSIONS_QUERY = "select permission from roles_permissions where role_name = ?";
private static final Logger log = LoggerFactory.getLogger(JdbcRealm.class);
protected DataSource dataSource;
protected String authenticationQuery = "select password from users where username = ?";
protected String userRolesQuery = "select role_name from user_roles where username = ?";
protected String permissionsQuery = "select permission from roles_permissions where role_name = ?";
protected boolean permissionsLookupEnabled = false;
protected JdbcRealm.SaltStyle saltStyle;
public JdbcRealm() {
this.saltStyle = JdbcRealm.SaltStyle.NO_SALT;
}
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
public void setAuthenticationQuery(String authenticationQuery) {
this.authenticationQuery = authenticationQuery;
}
public void setUserRolesQuery(String userRolesQuery) {
this.userRolesQuery = userRolesQuery;
}
public void setPermissionsQuery(String permissionsQuery) {
this.permissionsQuery = permissionsQuery;
}
public void setPermissionsLookupEnabled(boolean permissionsLookupEnabled) {
this.permissionsLookupEnabled = permissionsLookupEnabled;
}
public void setSaltStyle(JdbcRealm.SaltStyle saltStyle) {
this.saltStyle = saltStyle;
if (saltStyle == JdbcRealm.SaltStyle.COLUMN && this.authenticationQuery.equals("select password from users where username = ?")) {
this.authenticationQuery = "select password, password_salt from users where username = ?";
}
}
protected AuthenticationInfo doGetAuthenticationInfo(AuthenticationToken token) throws AuthenticationException {
UsernamePasswordToken upToken = (UsernamePasswordToken)token;
String username = upToken.getUsername();
if (username == null) {
throw new AccountException("Null usernames are not allowed by this realm.");
} else {
Connection conn = null;
SimpleAuthenticationInfo info = null;
try {
String salt;
try {
conn = this.dataSource.getConnection();
String password = null;
salt = null;
switch(this.saltStyle) {
case NO_SALT:
password = this.getPasswordForUser(conn, username)[0];
break;
case CRYPT:
throw new ConfigurationException("Not implemented yet");
case COLUMN:
String[] queryResults = this.getPasswordForUser(conn, username);
password = queryResults[0];
salt = queryResults[1];
break;
case EXTERNAL:
password = this.getPasswordForUser(conn, username)[0];
salt = this.getSaltForUser(username);
}
if (password == null) {
throw new UnknownAccountException("No account found for user [" + username + "]");
}
info = new SimpleAuthenticationInfo(username, password.toCharArray(), this.getName());
if (salt != null) {
info.setCredentialsSalt(Util.bytes(salt));
}
} catch (SQLException var12) {
salt = "There was a SQL error while authenticating user [" + username + "]";
if (log.isErrorEnabled()) {
log.error(salt, var12);
}
throw new AuthenticationException(salt, var12);
}
} finally {
JdbcUtils.closeConnection(conn);
}
return info;
}
}
private String[] getPasswordForUser(Connection conn, String username) throws SQLException {
boolean returningSeparatedSalt = false;
String[] result;
switch(this.saltStyle) {
case NO_SALT:
case CRYPT:
case EXTERNAL:
result = new String[1];
break;
case COLUMN:
default:
result = new String[2];
returningSeparatedSalt = true;
}
PreparedStatement ps = null;
ResultSet rs = null;
try {
ps = conn.prepareStatement(this.authenticationQuery);
ps.setString(1, username);
rs = ps.executeQuery();
for(boolean foundResult = false; rs.next(); foundResult = true) {
if (foundResult) {
throw new AuthenticationException("More than one user row found for user [" + username + "]. Usernames must be unique.");
}
result[0] = rs.getString(1);
if (returningSeparatedSalt) {
result[1] = rs.getString(2);
}
}
} finally {
JdbcUtils.closeResultSet(rs);
JdbcUtils.closeStatement(ps);
}
return result;
}
protected AuthorizationInfo doGetAuthorizationInfo(PrincipalCollection principals) {
if (principals == null) {
throw new AuthorizationException("PrincipalCollection method argument cannot be null.");
} else {
String username = (String)this.getAvailablePrincipal(principals);
Connection conn = null;
Set<String> roleNames = null;
Set permissions = null;
try {
conn = this.dataSource.getConnection();
roleNames = this.getRoleNamesForUser(conn, username);
if (this.permissionsLookupEnabled) {
permissions = this.getPermissions(conn, username, roleNames);
}
} catch (SQLException var11) {
String message = "There was a SQL error while authorizing user [" + username + "]";
if (log.isErrorEnabled()) {
log.error(message, var11);
}
throw new AuthorizationException(message, var11);
} finally {
JdbcUtils.closeConnection(conn);
}
SimpleAuthorizationInfo info = new SimpleAuthorizationInfo(roleNames);
info.setStringPermissions(permissions);
return info;
}
}
protected Set<String> getRoleNamesForUser(Connection conn, String username) throws SQLException {
PreparedStatement ps = null;
ResultSet rs = null;
LinkedHashSet roleNames = new LinkedHashSet();
try {
ps = conn.prepareStatement(this.userRolesQuery);
ps.setString(1, username);
rs = ps.executeQuery();
while(rs.next()) {
String roleName = rs.getString(1);
if (roleName != null) {
roleNames.add(roleName);
} else if (log.isWarnEnabled()) {
log.warn("Null role name found while retrieving role names for user [" + username + "]");
}
}
} finally {
JdbcUtils.closeResultSet(rs);
JdbcUtils.closeStatement(ps);
}
return roleNames;
}
protected Set<String> getPermissions(Connection conn, String username, Collection<String> roleNames) throws SQLException {
PreparedStatement ps = null;
LinkedHashSet permissions = new LinkedHashSet();
try {
ps = conn.prepareStatement(this.permissionsQuery);
Iterator var6 = roleNames.iterator();
while(var6.hasNext()) {
String roleName = (String)var6.next();
ps.setString(1, roleName);
ResultSet rs = null;
try {
rs = ps.executeQuery();
while(rs.next()) {
String permissionString = rs.getString(1);
permissions.add(permissionString);
}
} finally {
JdbcUtils.closeResultSet(rs);
}
}
} finally {
JdbcUtils.closeStatement(ps);
}
return permissions;
}
protected String getSaltForUser(String username) {
return username;
}
public static enum SaltStyle {
NO_SALT,
CRYPT,
COLUMN,
EXTERNAL;
private SaltStyle() {
}
}
}