servlet处理跨域请求

前言

我们要做的是让在一个不在当前项目文件夹的前端页面发送Ajax请求，由一个远程servlet处理

代码

创建一个web工程
导入所需的jar-> servlet-api.jar fastjson.jar
编写前端页面

 <html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input type="button" value="get" id='get'>
    <input type="button" value="POST" id='post'>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.js"></script>
    <script>
        let data = {
            name: '狗剩',
            age: 20
        }
        $("#get").on('click', function() {
            $.ajax({
                type: 'get',
                contentType:'application/json',  //data发送方式
                url: 'http://localhost/TestServlet',   //发送跨域请求
                data: data,
                success: (res) => {
                    console.log("res:", res)
                }
            })
        })
 
        $("#post").on('click', function() {
            $.ajax({
                type: 'post',
                contentType:'application/json',
                url: 'http://localhost/TestServlet',
                data: JSON.stringify(data),
                success: (res) => {
                    console.log("res:", res)
                }
            })
        })
    </script>
</body>
</html>

配置一个Filter处理跨域请求

 import javax.servlet.*;
import javax.servlet.http.HttpFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
 
public class Filter extends HttpFilter {
 
    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        //设置跨域请求
        System.out.println("Filter 过滤器 执行 了");
        HttpServletRequest request = (HttpServletRequest)req;
        HttpServletResponse response = (HttpServletResponse)resp;
        //允许跨域主机地址
        response.setHeader("Access-Control-Allow-Origin", "*");
        //允许跨域方法
        response.setHeader("Access-Control-Allow-Methods", "POST, DELETE,PUT,GET,OPTIONS");
        //缓存时间
        response.setHeader("Access-Control-Max-Age", "3600");
        //允许跨域的请求头
        response.setHeader("Access-Control-Allow-Headers", "*");
        //是否携带cookie
        response.setHeader("Access-Control-Allow-Credentials", "true");
        //允许放行
        chain.doFilter(request, response);
    }
 
}

编写servlet处理请求

 import com.alibaba.fastjson.JSON;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Map;
 
public class TestServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("请求已到达-> post");
        request.setCharacterEncoding("utf-8");
        ServletInputStream inputStream = request.getInputStream();
        BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
        StringBuilder sb = new StringBuilder();
        String str = null;
        while((str = br.readLine()) != null) {
            sb.append(str);
        }
        System.out.println(sb.toString());
        //转为map集合
		Map parseObject = JSON.parseObject(sb.toString(), Map.class);
        System.out.println("parseObject:" + parseObject);
 
    }
 
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("请求已到达-> get");
        request.setCharacterEncoding("UTF-8");
        String name = request.getParameter("name");
        int age = Integer.parseInt(request.getParameter("age"));
        System.out.println("name:" + name + ", age:" + age);
 
    }
 
}

配置web.xml

 <filter>
        <filter-name>Filter</filter-name>
        <filter-class>Filter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>Filter</filter-name>
        <!-- 配置需要进行跨域的接口 -->
        <url-pattern>/*</url-pattern>
    </filter-mapping>
 
    <servlet>
        <!--servlet名 -->
        <servlet-name>Test</servlet-name>
        <!-- servlet路径，包名.类名 -->
        <servlet-class>TestServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <!--servlet映射，必须与servlet-name同名 -->
        <servlet-name>Test</servlet-name>
        <!--浏览器中输入的访问该servlet的url-->
        <url-pattern>/TestServlet</url-pattern>
    </servlet-mapping>

部署项目，启动服务器，测试跨域请求

结语

 //需要注意的是前端Ajax请求的url
 url: 'http://localhost/TestServlet'
//servlet的web.xml配置
<url-pattern>/TestServlet</url-pattern>
//localhost后面的地址和xml配置的地址一致即可

posted @ 2021-03-25 23:28 DogLeftover 阅读(390) 评论(0) 编辑收藏举报

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servlet处理跨域请求

前言

代码

结语

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	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	</head>
	<body>
	<input type="button" value="get" id='get'>
	<input type="button" value="POST" id='post'>
	<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.js"></script>
	<script>
	let data = {
	name: '狗剩',
	age: 20
	}
	$("#get").on('click', function() {
	$.ajax({
	type: 'get',
	contentType:'application/json', //data发送方式
	url: 'http://localhost/TestServlet', //发送跨域请求
	data: data,
	success: (res) => {
	console.log("res:", res)
	}
	})
	})

	$("#post").on('click', function() {
	$.ajax({
	type: 'post',
	contentType:'application/json',
	url: 'http://localhost/TestServlet',
	data: JSON.stringify(data),
	success: (res) => {
	console.log("res:", res)
	}
	})
	})
	</script>
	</body>
	</html>

	import javax.servlet.*;
	import javax.servlet.http.HttpFilter;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;
	import java.io.IOException;

	public class Filter extends HttpFilter {

	@Override
	public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
	//设置跨域请求
	System.out.println("Filter 过滤器执行了");
	HttpServletRequest request = (HttpServletRequest)req;
	HttpServletResponse response = (HttpServletResponse)resp;
	//允许跨域主机地址
	response.setHeader("Access-Control-Allow-Origin", "*");
	//允许跨域方法
	response.setHeader("Access-Control-Allow-Methods", "POST, DELETE,PUT,GET,OPTIONS");
	//缓存时间
	response.setHeader("Access-Control-Max-Age", "3600");
	//允许跨域的请求头
	response.setHeader("Access-Control-Allow-Headers", "*");
	//是否携带cookie
	response.setHeader("Access-Control-Allow-Credentials", "true");
	//允许放行
	chain.doFilter(request, response);
	}

	}

	import com.alibaba.fastjson.JSON;
	import javax.servlet.ServletException;
	import javax.servlet.ServletInputStream;
	import javax.servlet.http.HttpServlet;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;
	import java.io.BufferedReader;
	import java.io.IOException;
	import java.io.InputStreamReader;
	import java.util.Map;

	public class TestServlet extends HttpServlet {
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	System.out.println("请求已到达-> post");
	request.setCharacterEncoding("utf-8");
	ServletInputStream inputStream = request.getInputStream();
	BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
	StringBuilder sb = new StringBuilder();
	String str = null;
	while((str = br.readLine()) != null) {
	sb.append(str);
	}
	System.out.println(sb.toString());
	//转为map集合
	Map parseObject = JSON.parseObject(sb.toString(), Map.class);
	System.out.println("parseObject:" + parseObject);

	}

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	System.out.println("请求已到达-> get");
	request.setCharacterEncoding("UTF-8");
	String name = request.getParameter("name");
	int age = Integer.parseInt(request.getParameter("age"));
	System.out.println("name:" + name + ", age:" + age);

	}

	}

	<filter>
	<filter-name>Filter</filter-name>
	<filter-class>Filter</filter-class>
	</filter>
	<filter-mapping>
	<filter-name>Filter</filter-name>
	<!-- 配置需要进行跨域的接口 -->
	<url-pattern>/*</url-pattern>
	</filter-mapping>

	<servlet>
	<!--servlet名 -->
	<servlet-name>Test</servlet-name>
	<!-- servlet路径，包名.类名 -->
	<servlet-class>TestServlet</servlet-class>
	</servlet>
	<servlet-mapping>
	<!--servlet映射，必须与servlet-name同名 -->
	<servlet-name>Test</servlet-name>
	<!--浏览器中输入的访问该servlet的url-->
	<url-pattern>/TestServlet</url-pattern>
	</servlet-mapping>

	//需要注意的是前端Ajax请求的url
	url: 'http://localhost/TestServlet'
	//servlet的web.xml配置
	<url-pattern>/TestServlet</url-pattern>
	//localhost后面的地址和xml配置的地址一致即可