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文章目录
11.模块化Controller层12.AJAX12.1使用场景
13.JSON13.1如何使用后端发送JSON数据
11.模块化Controller层
将对应模块的Servlet写入到一个指定的模块中,模块化编程
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 {
// 请求的url
String requestURL = request.getRequestURL().toString();
System.out.println(requestURL);
String[] split = requestURL.split("/");
// System.out.println(Arrays.toString(split));
// 获取到需要执行得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("我是删除方法");
}
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 stub
doGet(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];
// 当前类对象
Class clazz = this.getClass();
// 获取当前对象的方法
try {
// 获取需要执行的方法
Method declaredMethod = clazz.getDeclaredMethod(method, HttpServletRequest.class,HttpServletResponse.class);
// 启动暴力反射
declaredMethod.setAccessible(true);
// 方法的反向执行
declaredMethod.invoke(this, request, response);
} catch (Exception e) {
System.out.println("没有对应的方法");
}
}
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("删除方法");
}
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 stub
doGet(request, response);
}
}
12.AJAX
异步的JS与XML技术,可以实现JS和服务器之间的异步交互 异步交互:在不刷新网页的前提下,局部代码与服务器进行交互 AJAX不是新技术,也不是编程语言,就是一个使用JS和后端进行交互的技术
AJAX的优点:用户体验非常好;缺点:开发改错困难,不可回退
12.1使用场景
场景1:AJAX验证用户名是否重复
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");
// 模拟从数据库中获取数据
ArrayList
list.add("张三");
list.add("李四");
list.add("王五");
list.add("tom");
list.add("jack");
list.add("rose");
// 何如判断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 stub
doGet(request, response);
}
}
13.JSON
配合AJAX进行分离式开发中，数据的交互形式之一 JSON可以实现不同系统,不同语言之间的数据交互 JSON是一种数据格式,类似于JS中的{}对象
语法: { “key”:“value”, “key”:“value”, … }
数据体量小,可以做为数据传入的载体
13.1如何使用后端发送JSON数据
使用第三方工具(jar、依赖) Gson 谷歌发布 Jackson Springn内置的 FastJson 阿里发布的
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 {
@Test
public void test01() {
System.out.println("helloworld");
}
@Test
public void test02() {
Gson gson = new Gson();
String json = gson.toJson("helloworld");
System.out.println(json);
}
@Test
public void test03() {
Gson gson = new Gson();
String json = gson.toJson(new Dog(1,"李四"));
System.out.println(json);
}
@Test
public void test04() {
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);
}
@Test
public void test05() {
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
map.put("dogs", dogs);
map.put("page", currPage);
String json = new Gson().toJson(map);
System.out.println(json);
}
@Test
public void test06() throws Exception {
Dog dog = new Dog(1,"1");
ObjectMapper objectMapper = new ObjectMapper();
String json = objectMapper.writeValueAsString(dog);
System.out.println(json);
}
}
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