Exception occurred during processing request: null java.lang.NullPointerExceptio
@SuppressWarnings("serial")
public class RoleAction extends ActionSupport{
	private RoleService roleService;
	private Yuangong yuanGong;
	private List<Yuangong>yuangList = new ArrayList<Yuangong>(0);
	private String keyWord;
	public RoleService getRoleService() {
		return roleService;
	}
	public void setRoleService(RoleService roleService) {
		this.roleService = roleService;
	}
	
	public Yuangong getYuanGong() {
		return yuanGong;
	}
	public void setYuanGong(Yuangong yuanGong) {
		this.yuanGong = yuanGong;
	}
	public List<Yuangong> getYuangList() {
		return yuangList;
	}
	public void setYuangList(List<Yuangong> yuangList) {
		this.yuangList = yuangList;
	}
	public String getKeyWord() {
		return keyWord;
	}
	public void setKeyWord(String keyWord) {
		this.keyWord = keyWord;
	}
	/**
	 * 添加角色
	 * @return
	 */
	public String addRole(){
		Yuangong yg = roleService.insertYG(yuanGong);
		if(yg!=null){
			return "success";
		}	
		return "input";
public interface RoleService {
	public Yuangong insertYG(Yuangong yuanGong);
	public Yuangong deleteYG(Yuangong yuanGong);
	public Yuangong upateYG(Yuangong yuanGong);
	public Yuangong findByYgBH(String ygbh);
	public List<Yuangong> findByKeyWord(String keyWord);
}
public class RoleServiceImpl implements RoleService {
	
	private RoleDao roleDao;
	public void setRoleDao(RoleDao roleDao) {
		this.roleDao = roleDao;
	}
	@Override
	public Yuangong insertYG(Yuangong yuanGong) {
		
		return roleDao.insert(yuanGong);
	}
public interface RoleDao {
	
	public Yuangong insert(Yuangong yuanGong);
	public Yuangong update(Yuangong yuanGong);
	public Yuangong delete(Yuangong yuanGong);
	public Yuangong findByYgBH(String ygbh);
	public List<Yuangong> findByKeyWord(String keyWord);
	
	
	
}
public class RoleDaoImpl implements RoleDao {
	/**
	 * 插入员工信息
	 * @param yuanGong
	 * @return
	 */
	@SuppressWarnings("unused")
	@Override
	public Yuangong insert(Yuangong yuanGong) {
		
		//创建连接对象
		DBMangger dbMangger = new DBMangger();
		//SQL语句
		String sql = "insert into YuanGong values("+yuanGong.getYgbh()+","+yuanGong.getYgxm()+"," +
				""+yuanGong.getYgzh()+","+yuanGong.getYgmm()+","+yuanGong.getYgmm()+","
				+yuanGong.getBmbh()+","+yuanGong.getStatus()+",sysdate)";
		
			int i = dbMangger.executeUpdate(sql);
		if(i>0){
			System.out.println("执行成功");
			return yuanGong;
		}else{
			System.out.println("保存失败");
			return null;