shiro框架源码解析与改造（八）---PermissionsAuthorizationFilter

PermissionsAuthorizationFilter是权限验证的关键过滤器。

@Override
    protected boolean onPreHandle(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {
        return this.isAccessAllowed(request, response,mappedValue) || this.onAccessDenied(request, response,mappedValue);
    }

具体验证方法如下：
委托subject验证，subject又委托authleam数据源进行验证，

public boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        Subject subject = this.getSubject(request, response);
        String[] perms = (String[])mappedValue;
        boolean isPermitted = true;
        if(perms != null && perms.length > 0) {
            if(perms.length == 1) {
                if(!subject.isPermitted(perms[0])) {
                    isPermitted = false;
                }
            } else if(!subject.isPermittedAll(perms)) {
                isPermitted = false;
            }
        }

        return isPermitted;
    }

 @Override
    public boolean isPermitted(PrincipalCollection principals, String permission) {
        this.assertRealmsConfigured();
        Iterator var3 = this.getRealms().iterator();

        Realm realm;
        do {
            if(!var3.hasNext()) {
                return false;
            }

            realm = (Realm)var3.next();
        } while(!(realm instanceof Authorizer) || !((Authorizer)realm).isPermitted(principals, permission));

        return true;
    }

这里调用AuthenAuthorityRealm的验证方法，AuthorizationInfo info = this.getAuthorizationInfo(principals);会调用用户自定义的数据源获取权限信息。

public boolean isPermitted(PrincipalCollection principals, String permission){
        Permission p = this.getPermissionResolver().resolvePermission(permission);
        AuthorizationInfo info = this.getAuthorizationInfo(principals);
        Collection<Permission> perms = this.getPermissions(info);
        if(perms != null && !perms.isEmpty()) {
            Iterator var4 = perms.iterator();

            while(var4.hasNext()) {
                Permission perm = (Permission)var4.next();
                if(perm.implies(p)) {
                    return true;
                }
            }
        }

        return false;
    }

而上面的this.onAccessDenied(request, response,mappedValue);这个方法则会在无权限的时候调用。
无权限时，则会重定向到无权限路径。

 protected boolean onAccessDenied(ServletRequest request, ServletResponse response, Object mappedValue) throws IOException {
        Subject subject = this.getSubject(request, response);
        if(subject.getPrincipal() == null) {
            this.saveRequestAndRedirectToLogin(request, response);
        } else {
            String unauthorizedUrl = this.getUnauthorizedUrl();
            HttpServletRequest httpRequest=WebUtils.toHttp(request);
            if (httpRequest.getHeader("X-Requested-With") == null || !httpRequest.getHeader("X-Requested-With").equals("XMLHttpRequest")) {
                if(StringUtils.hasText(unauthorizedUrl)) {
                    WebUtils.issueRedirect(request, response, unauthorizedUrl);
                } else {
                    WebUtils.toHttp(response).sendError(401);
                }
            }else {
                WebUtils.toHttp(response).sendError(401,"没有权限");
            }

        }

        return false;
    }