在静态工具类中需要注入mapper

在xml中

<bean id="messageUtil" class="org.ldd.ssm.hangyu.utils.MessageUtil" init-method="init" >
</bean>

在MessageUtil.java中

public class MessageUtil {

    @Autowired
    private  ChatMapper chatMapper;  

    private static MessageUtil messageUtil;  

    @PostConstruct
    public void init() {
        messageUtil = this;
        messageUtil.chatMapper = this.chatMapper;
    }  

    public static String sendContent(String type, ChatDto chat) {
        Map<String,Object> userMap = new HashMap<String,Object>();
        PageBean<Chat> pbModifyList = null;
        List<Chat> modifyList=messageUtil.chatMapper.findModifyRecord(chat);
        int modifyTotalCount=messageUtil.chatMapper.getModifyRecordCount(chat);
        pbModifyList = new PageBean<Chat>(modifyTotalCount,modifyList,chat.getPageNo());
        userMap.put(MessageUtil.MODIFYLIST, pbModifyList);
        JSONObject json = JSONObject.fromObject(userMap);
        return json.toString();
    }