裸奔编程之使用Servlet实现REST风格单纯使用Servlet进行完成REST解析

最新推荐文章于 2022-07-20 20:45:58 发布

nieyong

最新推荐文章于 2022-07-20 20:45:58 发布

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文章标签： servlet rest 编程 function url delete

本文链接：https://blog.youkuaiyun.com/nieyong/article/details/2101075

本文介绍如何通过Servlet实现RESTful风格的URL解析，并演示get、put、post、delete四种请求方式的处理流程。

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其实单纯使用Servlet已经可以完成对REST风格URL的解析任务。
我们今天就尝试着写一个简单的DEMO程序，使用一个Servlet 完成 get，put，post，delete 四种请求。
在编写前，先叙述一下编程环境：
JDK 1.5 + TOMCAT 5.5 + Eclipse 3.2

我们今天模拟在客户端使用AJAX或直接FORM提交，对同一个URL地址： http://你的域名/game/1234
使用get、put、post、delete四种不同的方式进行请求。
并演示如何在服务端如何解析传递过来的参数（id为1234），获取/game请求附加的的id参数。

首先建立一个Servlet，我们这里起名为 OneGameHandle ，见下面代码：

package com.game.servlet;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.util.logging.*;

public class OneGameHandle extends javax.servlet.http.HttpServlet implements

javax.servlet.Servlet {

private Logger logger = Logger.getLogger(this.getClass().getName());

public OneGameHandle() {

super();

}

protected void doGet(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

logger.log(Level.INFO, "doGet method is runing...");

logger.log(Level.INFO, "received id = " + getID(request));

}

protected void doPost(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

logger.log(Level.INFO, "doPost method is runing...");

logger.log(Level.INFO, "received id = " + getID(request));

}

protected void doPut(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

super.doPut(request, response);

logger.log(Level.INFO, "doPut method is runing...");

logger.log(Level.INFO, "received id = " + getID(request));

}

protected void doDelete(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

super.doDelete(request, response);

logger.log(Level.INFO, "doDelete method is runing...");

logger.log(Level.INFO, "received id = " + getID(request));

}

public void init() throws ServletException {

super.init();

}

//只是作为演示使用，不处理异常

private String getID(HttpServletRequest request) {

String url = request.getRequestURL().toString();

String id = null;

if (url.endsWith("/"))

url = url.substring(0, url.length() - 1);

id = url.substring(url.lastIndexOf('/') + 1);

return id;

}

在web.xml 中配置如下：

<servlet-name>OneGameHandle</servlet-name>

<servlet-class>com.game.servlet.OneGameHandle</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>OneGameHandle</servlet-name>

<url-pattern>/game/*</url-pattern>

</servlet-mapping>

你看到了没有，Servlet OneGameHandle 解析地址为 /game/* 。

下面，我们建立一个JSP文件，在该页面上，我们显示有关不同方式请求的按钮：

<%@ page language="java" contentType="text/html; charset=GBK"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

function doPutData(){

var url = "game/1234";

put_request(url,theAdd);

}

function theAdd(){

if (http_request.readyState == 4) {

if (http_request.status == 200) {

alert( http_request.responseText );

} else {

alert("connect the server wrong!");

}

function doDeleteData(){

var url = "game/2332";

delete_request(url,theAdd);

}

</script>

</head>

<body>

POST 方式提交数据....

</form>

<br>

GET 方式提交数据 ...<br>

<a href="game/2355">直接GET方式请求</a>

<br>

DELETE 方式请求...<br>

<br>

PUT 方式提交 ...<br>

</body>

</html>

对应于该页面牵涉到JS -request.js 贴图如下：

var http_request = false;

function init_request(){

http_request = false;

if(window.XMLHttpRequest) { //Mozilla

http_request = new XMLHttpRequest();

if (http_request.overrideMimeType) {//MiME

http_request.overrideMimeType("text/xml");

}

else if (window.ActiveXObject) { // IE

try {

http_request = new ActiveXObject("Msxml2.XMLHTTP");

} catch (e) {

try {

http_request = new ActiveXObject("Microsoft.XMLHTTP");

} catch (e) {}

}

if (!http_request) { //

window.alert("XMLHttpRequest.");

return false;

}

function get_request( url ){

init_request();

http_request.onreadystatechange = processRequest;

http_request.open("GET", url, true);

http_request.send(null);

}

function get_request( url, type ){

init_request();

if( type == "text" )

http_request.onreadystatechange = processRequest;

else if( type == "xml" )

http_request.onreadystatechange = processXmlRequest;

http_request.open("GET", url, true);

http_request.send(null);

}

//the user can custom the function

function get_request2( url, myProcess ){

init_request();

http_request.onreadystatechange = myProcess;

http_request.open("GET", url, true);

http_request.send(null);

}

function post_request( url, sinfo ) {

init_request();

http_request.onreadystatechange = processRequest;

http_request.open("POST", url, true);

http_request.setRequestHeader("Content-Length",sinfo.length);

http_request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");

http_request.send(sinfo);

}

function post_request( url, sinfo, type ) {

init_request();

if( type == "text" )

http_request.onreadystatechange = processRequest;

else if( type == "xml" )

http_request.onreadystatechange = processXmlRequest;

http_request.open("POST", url, true);

http_request.setRequestHeader("Content-Length",sinfo.length);

http_request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");

http_request.send(sinfo);

}

//this function gave the user too much free to write his method

function post_request2( url, sinfo, myProcess ) {

init_request();

http_request.onreadystatechange = myProcess;

http_request.open("POST", url, true);

http_request.setRequestHeader("Content-Length",sinfo.length);

http_request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");

http_request.send(sinfo);

}

// text

function processRequest() {

if (http_request.readyState == 4) {

if (http_request.status == 200) {

pageChange( http_request.responseText );

} else {

alert("connect the server wrong!");

}

//xml

function processXmlRequest() {

if (http_request.readyState == 4) {

if (http_request.status == 200) {

pageChange( http_request.responseXml );

} else {

alert("connect the server wrong!");

}

function put_request( url, myProcess ) {

init_request();

http_request.onreadystatechange = myProcess;

http_request.open("PUT", url, true);

http_request.send(null);

}

function delete_request( url, myProcess ) {

init_request();

http_request.onreadystatechange = myProcess;

http_request.open("DELETE", url, true);

http_request.send(null);

}

尝试点击JSP页面上的各个按钮，AJAX方式进行请求服务器，服务器端Servlet解析。
JSP页面效果图如下：
JSP页面内容
点击上图的各个按钮，然后观察一下tomcat的console输入看一下吧，是否已经处理了各种请求。

小结：
本例简单，只是获取一个参数。
本例方式使用Servlet来解析地址中含有/game/的字样的URL请求，自然很容易得到game 后面附加的参数。
缺点是，不能使用request方式来接收参数。
如果使用原生态的servlet来处理rest方式的请求，那么可以使用request.getParameter()。
那么该怎么办呢？明天，我们继续吧。