Integrating jCasbin Permission Management into Spring Boot Applications

As a backend developer, the author compares traditional Shiro permission management with the newer jCasbin library, noting Shiro's complexity in distributed Spring Cloud environments and introducing jCasbin as a simpler alternative.

1. Preparation

Add the jCasbin and JDBC adapter dependencies to your Maven pom.xml :

<dependency>
    <groupId>org.casbin</groupId>
    <artifactId>jcasbin</artifactId>
    <version>1.1.0</version>
</dependency>
<dependency>
    <groupId>org.casbin</groupId>
    <artifactId>jdbc-adapter</artifactId>
    <version>1.1.0</version>
</dependency>

Create a configuration class to bind properties from application.properties :

@Configuration
@ConfigurationProperties(prefix = "org.jcasbin")
public class EnforcerConfigProperties {
    private String url;
    private String driverClassName;
    private String username;
    private String password;
    private String modelPath;
    // getters and setters omitted for brevity
    @Override
    public String toString() {
        return "EnforcerConfigProperties [url=" + url + ", driverClassName=" + driverClassName + ", username=" + username + ", password=" + password + ", modelPath=" + modelPath + "]";
    }
}

Define the model and policy files ( model.conf and policy.csv ) and place them alongside the src directory. The policy can also be loaded from a database.

2. Initialize Permission Information

Implement a factory that creates a singleton Enforcer during Spring's startup by implementing InitializingBean :

@Component
public class EnforcerFactory implements InitializingBean {
    private static Enforcer enforcer;
    @Autowired
    private EnforcerConfigProperties enforcerConfigProperties;
    @Override
    public void afterPropertiesSet() throws Exception {
        // Load policy from DB via JDBCAdapter
        JDBCAdapter jdbcAdapter = new JDBCAdapter(
            enforcerConfigProperties.getDriverClassName(),
            enforcerConfigProperties.getUrl(),
            enforcerConfigProperties.getUsername(),
            enforcerConfigProperties.getPassword(), true);
        enforcer = new Enforcer(enforcerConfigProperties.getModelPath(), jdbcAdapter);
        enforcer.loadPolicy();
    }
    public static boolean addPolicy(Policy policy) {
        boolean added = enforcer.addPolicy(policy.getSub(), policy.getObj(), policy.getAct());
        enforcer.savePolicy();
        return added;
    }
    public static boolean removePolicy(Policy policy) {
        boolean removed = enforcer.removePolicy(policy.getSub(), policy.getObj(), policy.getAct());
        enforcer.savePolicy();
        return removed;
    }
    public static Enforcer getEnforcer() { return enforcer; }
}

Define a simple POJO to represent a policy entry:

public class Policy {
    private String sub; // user or role
    private String obj; // resource, e.g., /user/*
    private String act; // action, e.g., GET, POST
    public Policy() {}
    public Policy(String sub, String obj, String act) {
        this.sub = sub; this.obj = obj; this.act = act;
    }
    // getters and setters omitted
    @Override
    public String toString() {
        return "Policy[sub=" + sub + ", obj=" + obj + ", act=" + act + "]";
    }
}

3. Usage

3.1 Permission Filter

Create a servlet filter that checks each request against the Enforcer :

@WebFilter(urlPatterns = "/*", filterName = "JCasbinAuthzFilter")
@Order(Ordered.HIGHEST_PRECEDENCE)
public class JCasbinAuthzFilter implements Filter {
    private static final Logger log = LoggerFactory.getLogger(JCasbinAuthzFilter.class);
    private static Enforcer enforcer;
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        String user = request.getParameter("username");
        String path = request.getRequestURI();
        String method = request.getMethod();
        enforcer = EnforcerFactory.getEnforcer();
        if (path.contains("anon")) {
            chain.doFilter(request, response);
        } else if (enforcer.enforce(user, path, method)) {
            chain.doFilter(request, response);
        } else {
            log.info("Unauthorized access");
            Map
result = new HashMap<>();
            result.put("code", 1001);
            result.put("msg", "User lacks permission");
            result.put("data", null);
            response.setCharacterEncoding("UTF-8");
            response.setContentType("application/json");
            response.getWriter().write(JSONObject.toJSONString(result, SerializerFeature.WriteMapNullValue));
        }
    }
    // init and destroy omitted
}

3.2 Adding and Removing Permissions at Runtime

Expose REST endpoints that call the factory methods, allowing policies to be added or removed without restarting the service:

@PutMapping("/anon/role/per")
public ResultBO
addPer() {
    EnforcerFactory.addPolicy(new Policy("alice", "/user/list", "*"));
    return ResultTool.success();
}

@DeleteMapping("/anon/role/per")
public ResultBO
deletePer() {
    EnforcerFactory.removePolicy(new Policy("alice", "/user/list", "*"));
    return ResultTool.success();
}

Finally, the author notes that the same approach can be combined with Spring Cloud Zuul by implementing a custom ZuulFilter , achieving unified login and permission control across micro‑services.