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個(gè)人整理非商業(yè)用途，歡迎探討與指正！！

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11.模塊化Controller層

將對應(yīng)模塊的Servlet寫入到一個(gè)指定的模塊中,模塊化編程

使用switch方式

package com.qf.servlet;import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import sun.rmi.transport.proxy.HttpReceiveSocket;/*** Servlet implementation class EmpServlet*/
@WebServlet("/emp/*")
public class EmpServlet extends HttpServlet {private static final long serialVersionUID = 1L;/*** @see HttpServlet#HttpServlet()*/public EmpServlet() {super();// TODO Auto-generated constructor stub}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//		請求的urlString requestURL = request.getRequestURL().toString();System.out.println(requestURL);String[] split = requestURL.split("/");
//		System.out.println(Arrays.toString(split));
//		獲取到需要執(zhí)行得Servlet方法String method = split[split.length-1];switch (method) {case "insert":insert(request,response);break;case "delete":delete(request,response);break;default:return;}}public void delete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("我是刪除方法");}public void insert(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("我是添加方法");}/*** @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoGet(request, response);}
}

使用反射

@WebServlet("/dept/*")
public class DeptServlet extends HttpServlet {private static final long serialVersionUID = 1L;public DeptServlet() {super();}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String requestURL = request.getRequestURL().toString();String[] split = requestURL.split("/");String method = split[split.length-1];//		當(dāng)前類對象Class<? extends DeptServlet> clazz = this.getClass();
//		獲取當(dāng)前對象的方法try {
//			獲取需要執(zhí)行的方法Method declaredMethod = clazz.getDeclaredMethod(method, HttpServletRequest.class,HttpServletResponse.class);
//			啟動(dòng)暴力反射declaredMethod.setAccessible(true);
//			方法的反向執(zhí)行declaredMethod.invoke(this, request, response);} catch (Exception e) {System.out.println("沒有對應(yīng)的方法");}}public void insert(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException  {System.out.println("添加方法");}private void delete(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException  {System.out.println("刪除方法");}private void update(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException  {System.out.println("修改方法");}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoGet(request, response);}
}

12.AJAX

異步的JS與XML技術(shù),可以實(shí)現(xiàn)JS和服務(wù)器之間的異步交互
異步交互:在不刷新網(wǎng)頁的前提下,局部代碼與服務(wù)器進(jìn)行交互
AJAX不是新技術(shù),也不是編程語言,就是一個(gè)使用JS和后端進(jìn)行交互的技術(shù)

AJAX的優(yōu)點(diǎn):用戶體驗(yàn)非常好;缺點(diǎn):開發(fā)改錯(cuò)困難,不可回退

12.1使用場景

場景1:AJAX驗(yàn)證用戶名是否重復(fù)

package com.qf.servlet;import java.io.IOException;
import java.util.ArrayList;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;/*** Servlet implementation class CheckNameServlet*/
@WebServlet("/check")
public class CheckNameServlet extends HttpServlet {private static final long serialVersionUID = 1L;public CheckNameServlet() {super();}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String name = request.getParameter("name");
//		模擬從數(shù)據(jù)庫中獲取數(shù)據(jù)ArrayList<String> list = new ArrayList<>();list.add("張三");list.add("李四");list.add("王五");list.add("tom");list.add("jack");list.add("rose");//		何如判斷name在list中boolean contains = list.contains(name);
//		false是可用 true是不可用
//		System.out.println(contains);
//		0不可用 1可用response.getWriter().print(contains?0:1);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoGet(request, response);}
}

<!DOCTYPE html>
<html><head><meta charset="utf-8"><title></title></head><body><input type="text" id="username"><span id="msg"></span><script>window.onload = function(){let username = document.querySelector("#username");let msg = document.querySelector("#msg");username.onblur = function(){// 發(fā)送ajax請求// 1.創(chuàng)建AJAX對象let xhr = new XMLHttpRequest();// 2.封裝AJAX的請求數(shù)據(jù)(形式為:xxxxServlet?xxxx=xxxx&xxx=xxx)xhr.open("GET","check?name="+username.value);// 3.發(fā)送請求xhr.send();// 4.AJAX的請求狀態(tài)判斷// readyState// 0:ajax創(chuàng)建但未初始化// 1:ajax創(chuàng)建完成但未發(fā)送請求// 2:ajax發(fā)送請求到服務(wù)器端// 3:ajax請求正在被處理// 4:ajax請求處理完成,可以使用ajax獲取服務(wù)器響應(yīng)的數(shù)據(jù)xhr.onreadystatechange = function(){if(xhr.status == 200 && xhr.readyState == 4){// 5.獲取響應(yīng)的數(shù)據(jù)let result = xhr.responseText;if(result == 0){msg.innerHTML = '用戶名已存在';msg.style.color = 'red';}else{msg.innerHTML = '√';msg.style.color = 'green';}}}}}</script></body>
</html>

13.JSON

配合AJAX進(jìn)行分離式開發(fā)中，數(shù)據(jù)的交互形式之一
JSON可以實(shí)現(xiàn)不同系統(tǒng),不同語言之間的數(shù)據(jù)交互
JSON是一種數(shù)據(jù)格式,類似于JS中的{}對象

語法:
??{
???“key”:“value”,
???“key”:“value”,
???…
??}

數(shù)據(jù)體量小,可以做為數(shù)據(jù)傳入的載體

13.1如何使用后端發(fā)送JSON數(shù)據(jù)

使用第三方工具(jar、依賴)
Gson
?谷歌發(fā)布
Jackson
?Springn內(nèi)置的
FastJson
?阿里發(fā)布的

package com.qf.test;import java.util.ArrayList;
import java.util.HashMap;import org.junit.Test;import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.gson.Gson;public class TestJSON {@Testpublic void test01() {System.out.println("helloworld");}@Testpublic void test02() {Gson gson = new Gson();String json = gson.toJson("helloworld");System.out.println(json);}@Testpublic void test03() {Gson gson = new Gson();String json = gson.toJson(new Dog(1,"李四"));System.out.println(json);}@Testpublic void test04() {ArrayList<Dog> dogs = new ArrayList<>();dogs.add(new Dog(1,"1"));dogs.add(new Dog(2,"2"));dogs.add(new Dog(3,"3"));dogs.add(new Dog(4,"4"));String json = new Gson().toJson(dogs);System.out.println(json);}@Testpublic void test05() {ArrayList<Dog> dogs = new ArrayList<>();dogs.add(new Dog(1,"1"));dogs.add(new Dog(2,"2"));dogs.add(new Dog(3,"3"));dogs.add(new Dog(4,"4"));int currPage = 10;HashMap<String,Object> map = new HashMap<>();map.put("dogs", dogs);map.put("page", currPage);String json = new Gson().toJson(map);System.out.println(json);}@Testpublic void test06() throws Exception {Dog dog = new Dog(1,"1");ObjectMapper objectMapper = new ObjectMapper();String json = objectMapper.writeValueAsString(dog);System.out.println(json);}
}