// 服装加入购物车 if (ac.equals("tocar")) { String gid = request.getParameter("gid"); int sl = Integer.valueOf(request.getParameter("sl")); if (member != null) { String mid = member.get("id").toString(); // 检查该人的购物车是否有该物品 ArrayList<HashMap> cklist = (ArrayList<HashMap>) dao .select("select * from car where mid='" + mid + "' and gid='" + gid + "'"); if (cklist.size() > 0) { dao.commOper("update car set sl=sl+" + sl + " where mid='" + mid + "' and gid='" + gid + "' "); } else { dao.commOper("insert into car (gid,sl,mid) values ('" + gid + "','" + sl + "','" + mid + "')"); } out.print("true"); } else { out.print("false"); }

Java中equals与==的区别深度解析

但是，为了实现更精细的比较，许多类（如String, Integer, Date等）都重写了equals()方法，使其比较的是对象的内容或状态是否相等。例如，对于字符串，equals()方法会逐字符比较两个字符串的每个字符是否相同...

Java面试深度解析：equals()与==，int与Integer的区别

"Java面试题集，包含关于equals()和==的使用，以及int与Integer的区别" 面试题1深入解析：在Java编程中，equals() 和 == 是两个非常重要的比较操作符，但它们的用法和含义有所不同。== 操作符用于比较两个...

// 服装入库 if (ac.equals("goodskcadd")) { String gid = request.getParameter("gid"); String happennum = request.getParameter("happennum"); String type = "in"; String savetime = Info.getDateStr();

这段代码看起来像是一个 Java Servlet 中的一个处理请求的方法，其中 "ac" 可能是一个表示请求操作类型的参数。如果 "ac" 的值等于 "goodskcadd"，则会执行下面的代码。这段代码中的变量 "gid"、"happennum"、"type...

if (ac.equals("tobuy")) { String gid = request.getParameter("gid"); int sl = Integer.valueOf(request.getParameter("sl")); //需要的数量（将传入的字符串类型的 sl 参数转换为整数类型） String ddno = Info.getAutoNo(); String shrname = ""; String shrtel = ""; String shraddr = request.getParameter("addr"); double ddprice = 0.0; String fhstatus = "待发货"; String shstatus = "待收货"; String fkstatus = "待付款"; String wlinfo = "暂无物流信息"; String savetime = Info.getDateStr();

其中，需要传入三个参数：gid 表示购买的物品编号，sl 表示需要的数量，addr 表示收货地址。首先，通过判断参数 ac 是否等于 "tobuy"，确定是生成订单的请求。然后，通过执行 SQL 语句查询该物品的相关信息，包括...

// 服装评论 if (ac.equals("goodpj")) { String goodid = request.getParameter("id"); String memberid = member.get("id").toString(); String note = request.getParameter("note"); String savetime = Info.getDateStr();

这段代码看起来也是一个 Java Servlet 中的处理请求的方法，其中变量 "ac" 可能是一个表示请求操作类型的参数。如果 "ac" 的值等于 "goodpj"，则会执行下面的代码。这段代码中的变量 "goodid"、"memberid"、"note" ...

public void save() { String title = request.getParameter("title"); String pubren = request.getParameter("pubren"); String pubtime = request.getParameter("pubtime"); String laiyuan=request.getParameter("laiyuan"); String dcontent = request.getParameter("dcontent"); String tupian2 = request.getParameter("tupian2"); String lanmuid = request.getParameter("lanmuid"); String lanmuming = request.getParameter("lanmuming"); String tuijian=request.getParameter("tuijian"); String hot=request.getParameter("hot"); String zuixin=request.getParameter("zuixin"); String zhaiyao=request.getParameter("zhaiyao"); String style=request.getParameter("style"); SimpleDateFormat sdfxinxi = new SimpleDateFormat("yyyy-MM-dd"); Xinxi xinxi = new Xinxi(); xinxi.setTitle(title == null ? "" : title); xinxi.setPubren(pubren == null ? "" : pubren); xinxi.setPubtime(new Date()); xinxi.setHot(hot!=null?1:0); xinxi.setTuijian(tuijian!=null?1:0); xinxi.setZuixin(zuixin!=null?1:0); xinxi.setClickcount(0); xinxi.setZhaiyao(zhaiyao==null?"":zhaiyao); xinxi.setDcontent(dcontent == null ? "" : dcontent); xinxi.setTupian2(tupian2 == null ? "" : tupian2); xinxi.setAgainstcount(0); xinxi.setAgreecount(0); xinxi.setLanmuid(new Integer(lanmuid)); xinxi.setLanmuming(lanmuming == null ? "" : lanmuming); DALBase.save(xinxi); try { if(style!=null&&style.equals("admin")) response.sendRedirect("xinximanager.do?actiontype=get&seedid=201&lanmuid="+xinxi.getLanmuid()); if(style!=null&&style.equals("huiyuan")) response.sendRedirect("../e/myxinximanager.jsp?seedid=m2"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } /************************************ * 内部附件支持public void attachements(HttpServletRequest request, HttpServletResponse response, String belongid) { DALBase.delete("attachement", MessageFormat.format( " where belongid=''{0}'' and belongtable=''xinxi'' ", belongid)); String[] photos = request.getParameterValues("fileuploaded"); if (photos == null) return; for (int i = 0; i < photos.length; i++) { Attachement a = new Attachement(); a.setType("images"); a.setPubtime(new Date()); a.setBelongfileldname("id"); a.setFilename(photos[i]); a.setBelongid(belongid); a.setBelongtable("xinxi"); a.setUrl(SystemParam.getSiteRoot() + "/upload/temp/" + a.getFilename()); a.setTitle(a.getFilename()); DALBase.save(a); } }解释每一行代码 ***

通过request.getParameter()方法获取了一些参数，包括标题、发布人、发布时间、来源、内容、图片等等。然后创建了一个Xinxi对象，并设置了各个属性的值。最后通过DALBase.save()方法将该对象保存到数据库中。如果...

public void update() { String id = request.getParameter("id"); if (id == null) return; Xinxi xinxi = (Xinxi) DALBase.load(Xinxi.class, new Integer(id)); if (xinxi == null) return; String title = request.getParameter("title"); String pubren = request.getParameter("pubren"); String laiyuan=request.getParameter("laiyuan"); String clickcount = request.getParameter("clickcount"); String dcontent = request.getParameter("dcontent"); String tupian2 = request.getParameter("tupian2"); String lanmuid = request.getParameter("lanmuid"); String lanmuming = request.getParameter("lanmuming"); String tuijian=request.getParameter("tuijian"); String hot=request.getParameter("hot"); String zuixin=request.getParameter("zuixin"); String zhaiyao=request.getParameter("zhaiyao"); String style=request.getParameter("style"); SimpleDateFormat sdfxinxi = new SimpleDateFormat("yyyy-MM-dd"); xinxi.setZhaiyao(zhaiyao); xinxi.setTitle(title); xinxi.setPubren(pubren); xinxi.setLaiyuan(laiyuan); xinxi.setDcontent(dcontent); xinxi.setHot(hot!=null?1:0); xinxi.setTuijian(tuijian!=null?1:0); xinxi.setZuixin(zuixin!=null?1:0); xinxi.setTupian2(tupian2); xinxi.setLanmuid(new Integer(lanmuid)); xinxi.setLanmuming(lanmuming); DALBase.update(xinxi); //attachements(request, response, new Integer(xinxi.getId()).toString()); //binding(request, response); try { if(style!=null&&style.equals("admin")) response.sendRedirect("xinximanager.do?actiontype=get&seedid=201&lanmuid="+xinxi.getLanmuid()); if(style!=null&&style.equals("huiyuan")) response.sendRedirect("../e/myxinximanager.jsp?seedid=m2"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } /************************************ *解释每一行代码

2. String id = request.getParameter("id"); 获取HTTP请求中名为"id"的参数，并将其存储在一个名为"id"的字符串变量中。 3. if (id == null) return; 如果"id"为null，直接退出方法。 4. Xinxi xinxi = ...

if(ac.equals("adminlogin")) { String username = request.getParameter("username"); String password = request.getParameter("pwd"); String utype = request.getParameter("cx"); String pagerandom = request.getParameter("pagerandom")==null?"":request.getParameter("pagerandom"); String random = (String)request.getSession().getAttribute("random"); if(!pagerandom.equals(random)&&request.getParameter("a")!=null) { request.setAttribute("random", ""); go("/login.jsp", request, response); } else{ String sql1 = "select * from allusers where username='"+username+"' and pwd='"+password+"' "; List<HashMap> userlist1 = dao.select(sql1); if(userlist1.size()==1) { request.getSession(). setAttribute("username", userlist1.get(0).get("username")); request.getSession(). setAttribute("cx", userlist1.get(0).get("cx")); gor("main.jsp", request, response); }else{ request.setAttribute("error", ""); go("/login.jsp", request, response); } } }这段代码是什么意思

这段代码是一个Java Servlet中的一个if语句块，用于处理用户登录功能。首先，从请求中获取用户输入的用户名、密码、用户类型和验证码等信息。然后，将用户输入的验证码与系统生成的验证码进行比较，如果不相等并且...

public String encodeGet(String str){ if(str!=null){ try { str = new String(str.getBytes("iso8859-1"),"utf-8"); } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return str; } public String getRequestEncode(String key){ String str = request.getParameter(key); return encodeGet(str); } public Object getByRequest(Object model){ //Object model = c.getInterfaces(); Class c = model.getClass(); Map<String,String> map = new HashMap(); Map<String,String[]> parammap = request.getParameterMap(); for(Map.Entry<String, String[]> entry:parammap.entrySet()){ String[] value = entry.getValue(); if(value.length==1){ map.put(entry.getKey(),value[0]); } } Field[] fields = c.getDeclaredFields(); try { for(int i=0;i<fields.length;i++){ Field field = fields[i]; field.setAccessible(true); String fname = field.getName(); String mvalue = map.get(fname); if(mvalue != null && !mvalue.equals("") && !mvalue.equals("null")){ String ftype = field.getType().getSimpleName(); if(ftype.equals("String")){ field.set(model, mvalue); }else if(ftype.equals("Integer") || ftype.equals("int")){ field.set(model, Integer.parseInt(mvalue)); }else if(ftype.equals("Double")){ field.set(model, Double.parseDouble(mvalue)); }else if(ftype.equals("Timestamp")){ Timestamp timestamp = Timestamp.valueOf(mvalue); field.set(model,timestamp); } } } }catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } return model; }

支持的类型包括 String、Integer、Double 和 Timestamp。需要注意的是，这段代码存在一些问题。例如，它没有对参数的 key 进行空值判断，可能会导致空指针异常；它也没有处理参数值中包含特殊字符的情况，可能会...

// 服装出库 if (ac.equals("kcout")) { String pid = request.getParameter("pid"); String num = request.getParameter("num"); String type = request.getParameter("type"); String reason = request.getParameter("reason"); String savetime = Info.getDateStr(); int znum = 0; int innum = 0; int outnum = 0; ArrayList<HashMap> inlist = (ArrayList<HashMap>) dao .select("select * from kcrecord where type='in' and pid='" + pid + "' "); ArrayList<HashMap> outlist = (ArrayList<HashMap>) dao .select("select * from kcrecord where type='out' and pid='" + pid + "' "); if (inlist.size() > 0) { for (HashMap inmap : inlist) { innum += Integer.parseInt(inmap.get("num").toString());// 总入库量 } } if (outlist.size() > 0) { for (HashMap outmap : outlist) { outnum += Integer.parseInt(outmap.get("num").toString());// 总出库量 } } znum = innum - outnum;// 库存量 if (Integer.parseInt(num) > znum) { request.setAttribute("no", ""); go("/admin/kcout.jsp", request, response); } else { dao.commOper("insert into kcrecord (pid,num,type,reason,savetime) values" + " ('" + pid + "','" + Integer.parseInt(num) + "','" + type + "','" + reason + "','" + savetime + "') "); request.setAttribute("suc", ""); go("/admin/kcout.jsp", request, response); } }

这段代码实现了一个服装出库的功能。具体来说，如果用户提交了一个名为"kcout"的表单，程序会从请求参数中获取"pid"、"num"、"type"和"reason"的值。然后，它会查询数据库中"pid"对应的"kcrecord"表中的所有入库和...

public String kaoshilist4() { HttpServletRequest request = ServletActionContext.getRequest(); String truename = request.getParameter("truename"); String username = request.getParameter("username"); StringBuffer sb = new StringBuffer(); sb.append(" where "); StringBuffer sb2 = new StringBuffer(); sb2.append(" where "); if(username!=null&&!"".equals(username)){ sb.append(" user.username like '%"+username+"%'"); sb.append(" and "); sb2.append(" user.username like '%"+username+"%'"); sb2.append(" and "); request.setAttribute("username", username); } if(truename!=null&&!"".equals(truename)){ sb.append(" user.truename like '%"+truename+"%'"); sb.append(" and "); sb2.append(" user.truename like '%"+truename+"%'"); sb2.append(" and "); request.setAttribute("truename", truename); } sb.append(" 1=1 order by id desc"); String where = sb.toString(); sb2.append(" 1=1 "); String where2 = sb2.toString(); int currentpage = 1; int pagesize = 20; if (request.getParameter("pageNum") != null) { currentpage = Integer.parseInt(request.getParameter("pageNum")); pagesize = Integer.parseInt(request.getParameter("numPerPage")); } int total = kaoshiDao.selectBeanCount(where2); request.setAttribute("list", kaoshiDao.selectBeanList((currentpage - 1)* pagesize, pagesize, where)); request.setAttribute("totalCount", total); request.setAttribute("ps", pagesize); request.setAttribute("pn", currentpage); request.setAttribute("url", "method!kaoshilist4"); this.setUrl("kaoshi/kaoshilist4.jsp"); return SUCCESS; }解释此代码

主要实现逻辑是通过从 request 中获取参数，并拼接成查询语句，在数据库中查找对应的数据。其中，pageNum 和 numPerPage 是用于分页查询的参数，totalCount 是查询结果的总数，ps 和 pn 是分页需要的参数，url 是...

@WebServlet(name = "C_AddServlet", value = "/C_AddServlet") public class C_AddServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request,response); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); String id_clazz = request.getParameter("id_clazz"); String college = request.getParameter("college"); String major = request.getParameter("major"); Integer grade = Integer.parseInt(request.getParameter("grade")); Integer no = Integer.parseInt(request.getParameter("no")); String id_teacher = request.getParameter("id_teacher"); Clazz clazz = new Clazz(id_clazz,college,major,grade,no,id_teacher); ClazzService clazzService = new ClazzService(); try { clazzService.save(clazz); } catch (Exception e) { if (e.getClass().equals(SQLIntegrityConstraintViolationException.class)){ System.out.println("该班级号已存在！"); }else { e.printStackTrace(); } } response.sendRedirect("ListServlet"); } }

在doPost()方法中，代码首先设置请求的字符编码为utf-8，然后通过request.getParameter()方法获取表单中提交的各个参数，包括id_clazz（班级ID）、college（学院）、major（专业）、grade（年级）、no（班级号）和id...

public void getList(){ String replayname = request.getParameter("sreplayname"); String sort = request.getParameter("sort"); String order = request.getParameter("order"); Page page = new Page(); Map paramsMap = new HashMap(); paramsMap.put("replayname", replayname); paramsMap.put("sort", "order by "+sort+" "+order); String pageNo = (String) this.request.getParameter("page"); String pageSizes = (String) this.request.getParameter("rows"); if (pageNo == null) { page.setPageSize(10); page.setPageNo(1); } else { page.setPageSize(Integer.parseInt(pageSizes)); page.setPageNo(Integer.parseInt(pageNo)); } page = replayService.findByPage(page, paramsMap); Gson json = new Gson(); Map<String, Object> map = new HashMap<String, Object>(); map.put("total", page.getTotal()); map.put("rows", page.getList()); render(json.toJson(map)); } public void add(){ String action = request.getParameter("action"); if(replay != null){ if(action.equals("add")){ replayService.save(replay); render("操作成功!"); }else { String id = request.getParameter("id"); replay.setId(Integer.parseInt(id)); replayService.update(replay); render("操作成功!"); } } }

这是一个Java程序，包含两个方法getList()和add()。 getList()方法从请求中获取参数replayname、sort、order，然后使用这些参数和分页信息（pageNo和pageSizes）进行查询，最终返回查询结果。查询结果以JSON格式...

String uNo = request.getParameter("userno").trim(); if (uNo != null && !uNo.equals("")) { int num = Integer.parseInt(uNo); // do something with num } ResultSet rs = user.queryUser1(num);哪里有问题？

String uNo = request.getParameter("userno").trim(); if (uNo != null && !uNo.equals("")) { try { int num = Integer.parseInt(uNo); // do something with num ResultSet rs = user.queryUser1(num); } ...

<% request.setCharacterEncoding("UTF-8"); String usr = request.getParameter("username"); String pwd1 = request.getParameter("password1"); String pwd2 = request.getParameter("password2"); if (usr == null || usr.equals("") || pwd1 == null || pwd1.equals("") || pwd2 == null || pwd2.equals("")) { response.sendRedirect("register.jsp"); out.print("请完善你的信息"); }// 参数错误 else if (!pwd1.equals(pwd2)) { response.sendRedirect("register.jsp"); out.print("两次输入密码不一致"); // 两次输入密码不一致 } %>这段代码什么意思

这段代码是一个 Java Servlet/JSP 页面，用于处理用户注册信息。它首先从 HTTP 请求中获取用户名、密码1和密码2，然后检查这些参数是否为空。如果任何一个参数为空，它将重定向到注册页面并打印一个错误消息。...

public class XinxiAction extends PageActionBase { public void onLoad() { String actiontype = request.getParameter("actiontype"); System.out.println("actiontype=" + actiontype); if (actiontype == null) return ; // 获取combox if (actiontype.equals("agree")) { agree(); } if (actiontype.equals("against")) { against(); } } private void agree() { String id=request.getParameter("id"); if (id == null) return; Xinxi xinxi = (Xinxi) DALBase.load(Xinxi.class, new Integer(id)); if (xinxi == null) return; xinxi.setAgreecount(xinxi.getAgreecount()+1); DALBase.update(xinxi); try { response.getWriter().write(new Integer(xinxi.getAgreecount()).toString()); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private void against() { String id=request.getParameter("id"); if (id == null) return; Xinxi xinxi = (Xinxi) DALBase.load(Xinxi.class, new Integer(id)); if (xinxi == null) return; xinxi.setAgainstcount(xinxi.getAgainstcount()+1); DALBase.update(xinxi); try { response.getWriter().write(new Integer(xinxi.getAgainstcount()).toString()); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } /**************************************** 信息注销监听支持* *******************************************/ public void delete() { String id = request.getParameter("id"); DALBase.delete("xinxi", " where id=" + id); binding(); }每一行代码是什么意思

这是一个 Java 类，名为 XinxiAction，继承自 PageActionBase 类。其中包含了 onLoad()、agree()、against() 和 delete() 四...response 和 request 分别代表响应和请求对象。printStackTrace() 方法是打印异常信息的。

public class LoginServlet extends HttpServlet { @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //处理POST请求 String username = request.getParameter("username"); String password = request.getParameter("password"); boolean rememberMe = "on".equals(request.getParameter("remember-me")); try { if (username != null && !username.trim().isEmpty() && password != null && !password.trim().isEmpty()) { String hashedPasswd = hashPassword(password); if (authenticate(username, hashedPasswd)) { HttpSession session = request.getSession(); session.setAttribute("username", username); response.sendRedirect("mean1"); } else { response.sendRedirect("/login.html?error=1"); } } else { response.sendRedirect("/login.html?error=2"); } } catch (SQLException e) { throw new ServletException("Cannot connect to DB", e); } catch (NoSuchAlgorithmException e) { throw new ServletException("Cannot encrypt password", e); }如何修改代码，将其变为根据两个不同用户进入两个不同的页面代码

String username = request.getParameter("username"); String password = request.getParameter("password"); boolean rememberMe = "on".equals(request.getParameter("remember-me")); try { if (username !...

<% lv_writing_works.connect(); String id = request.getParameter("author_id").trim(); int num1 = -1; if (id!=null && !id .equals("")){ //把字符串转换为整形 num1 = Integer.parseInt(id); } ResultSet rs1 = lv_writing_works.queryAuthor(num1); while (rs1.next()){ %>第161行问题在哪里？

这段代码是一个 JSP 页面的代码片段，它首先连接了数据库，然后获取了请求参数中的作者 ID 并将其转换为整数类型。接着在第 165 行调用了 lv_writing_works 对象的 queryAuthor 方法查询数据库，并将查询结果...

找出一下代码中的错误：org.apache.jasper.JasperException: An exception occurred processing JSP page /do_loginstu.jsp at line 14 11: <body style="background-color:#E9D9CA;text-align:center;"> 12: <% 13: ReStu.connect(); 14: String stuno=new String(request.getParameter("StuNo")); 15: String password = new String(request.getParameter("Pswd")); 16: if(stuno==null || password==null || stuno.equals("") || password.equals("")){

代码中的错误是在第14行，应该将request.getParameter的返回值用trim()函数处理，这样可以去掉字符串的前后空格，以避免空格引起的问题，正确的代码如下所示： java String stuno = request.getParameter(...

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// 服装入库 if (ac.equals("goodskcadd")) { String gid = request.getParameter("gid"); String happennum = request.getParameter("happennum"); String type = "in"; String savetime = Info.getDateStr();

// 服装评论 if (ac.equals("goodpj")) { String goodid = request.getParameter("id"); String memberid = member.get("id").toString(); String note = request.getParameter("note"); String savetime = Info.getDateStr();

String uNo = request.getParameter("userno").trim(); if (uNo != null && !uNo.equals("")) { int num = Integer.parseInt(uNo); // do something with num } ResultSet rs = user.queryUser1(num);哪里有问题？

<% lv_writing_works.connect(); String id = request.getParameter("author_id").trim(); int num1 = -1; if (id!=null && !id .equals("")){ //把字符串转换为整形 num1 = Integer.parseInt(id); } ResultSet rs1 = lv_writing_works.queryAuthor(num1); while (rs1.next()){ %>第161行问题在哪里？

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