spring MVC 管理HttpClient---实现在java中直接向Controller发送请求

在spring MVC中，大多数时候是由客户端的页面通过ajax等方式向controller发送请求，但有时候需要在java代码中直接向controller发送请求，这时可以使用HttpCilent实现。

首先用到的包是httpclient-4.3.5.jar和httpcore-4.3.2.jar

先看下面代码：

package module.system.common;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

/**
 * 在java中处理http请求.
 * @author nagsh
 *
 */
public class HttpDeal {
    /**
     * 处理get请求.
     * @param url  请求路径
     * @return  json
     */
	public String get(String url){
		//实例化httpclient
		CloseableHttpClient httpclient = HttpClients.createDefault();
		//实例化get方法
		HttpGet httpget = new HttpGet(url);
		//请求结果
		CloseableHttpResponse response = null;
		String content ="";
		try {
			//执行get方法
			response = httpclient.execute(httpget);
			if(response.getStatusLine().getStatusCode()==200){
				content = EntityUtils.toString(response.getEntity(),"utf-8");
				System.out.println(content);
			}
		} catch (ClientProtocolException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return content;
	}
	/**
	 * 处理post请求.
	 * @param url  请求路径
	 * @param params  参数
	 * @return  json
	 */
	public String post(String url,Map<String, String> params){
		//实例化httpClient
		CloseableHttpClient httpclient = HttpClients.createDefault();
		//实例化post方法
		HttpPost httpPost = new HttpPost(url);
		//处理参数
		List<NameValuePair> nvps = new ArrayList <NameValuePair>();
        Set<String> keySet = params.keySet();
	    for(String key : keySet) {
	        nvps.add(new BasicNameValuePair(key, params.get(key)));
	    }
		//结果
		CloseableHttpResponse response = null;
		String content="";
		try {
			//提交的参数
			UrlEncodedFormEntity uefEntity  = new UrlEncodedFormEntity(nvps, "UTF-8");
			//将参数给post方法
			httpPost.setEntity(uefEntity);
			//执行post方法
			response = httpclient.execute(httpPost);
			if(response.getStatusLine().getStatusCode()==200){
				content = EntityUtils.toString(response.getEntity(),"utf-8");
				System.out.println(content);
			}
		} catch (ClientProtocolException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return content;
	}
	public static void main(String[] args) {
		HttpDeal hd = new HttpDeal();
        hd.get("http://localhost:8080/springMVC/userType/getAll.do");
        Map<String,String> map = new HashMap();
        map.put("id","1");
        hd.post("http://localhost:8080/springMVC/menu/getChildren.do",map);
	}

}

这个类里的get和post方法分别可以实现get请求和post请求，如果单单在一个java测试类里边运行是没问题的，但在controller或jsp中调用，会抛异常。为什么呢？由于是在springMVC中，所以，我们应该把它交给spring来管理。

首先是：httpClient-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:p="http://www.springframework.org/schema/p"
	xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
	http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
	http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
	http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd">
    <!-- 配置占位符 -->
	<bean
		class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
		<property name="location" value="classpath:/httpclient.properties" />
	</bean>
	<!-- 定义httpclient连接池 -->
	<bean id="httpClientConnectionManager" class="org.apache.http.impl.conn.PoolingHttpClientConnectionManager" destroy-method="close">
		<!-- 设置连接总数 -->
		<property name="maxTotal" value="${http.pool.maxTotal}"></property>
		<!-- 设置每个地址的并发数 -->
		<property name="defaultMaxPerRoute" value="${http.pool.defaultMaxPerRoute}"></property>
	</bean>

	<!-- 定义 HttpClient工厂，这里使用HttpClientBuilder构建-->
	<bean id="httpClientBuilder" class="org.apache.http.impl.client.HttpClientBuilder" factory-method="create">
		<property name="connectionManager" ref="httpClientConnectionManager"></property>
	</bean>

	<!-- 得到httpClient的实例 -->
	<bean id="httpClient" factory-bean="httpClientBuilder" factory-method="build"/>

	<!-- 定期清理无效的连接 -->
	<bean class="module.system.common.IdleConnectionEvictor" destroy-method="shutdown">
		<constructor-arg index="0" ref="httpClientConnectionManager" />
		<!-- 间隔一分钟清理一次 -->
		<constructor-arg index="1" value="60000" />
	</bean>

	<!-- 定义requestConfig的工厂 -->
	<bean id="requestConfigBuilder" class="org.apache.http.client.config.RequestConfig.Builder">
		<!-- 从连接池中获取到连接的最长时间 -->
		<property name="connectionRequestTimeout" value="${http.request.connectionRequestTimeout}"/>
		<!-- 创建连接的最长时间 -->
		<property name="connectTimeout" value="${http.request.connectTimeout}"/>
		<!-- 数据传输的最长时间 -->
		<property name="socketTimeout" value="${http.request.socketTimeout}"/>
		<!-- 提交请求前测试连接是否可用 -->
		<property name="staleConnectionCheckEnabled" value="${http.request.staleConnectionCheckEnabled}"/>
	</bean>	

	<!-- 得到requestConfig实例 -->
	<bean id="requestConfig" factory-bean="requestConfigBuilder" factory-method="build" />

</beans>

httpclient.properties：

#从连接池中获取到连接的最长时间
http.request.connectionRequestTimeout=500
#5000
http.request.connectTimeout=5000
#数据传输的最长时间
http.request.socketTimeout=30000
#提交请求前测试连接是否可用
http.request.staleConnectionCheckEnabled=true

#设置连接总数
http.pool.maxTotal=200
#设置每个地址的并发数
http.pool.defaultMaxPerRoute=100

一个必须的类，几记得修改xml里的该类的路径：

package module.system.common;

import org.apache.http.conn.HttpClientConnectionManager;

/**
 * 定期清理无效的http连接
 */
public class IdleConnectionEvictor extends Thread {

    private final HttpClientConnectionManager connMgr;

    private Integer waitTime;

    private volatile boolean shutdown;

    public IdleConnectionEvictor(HttpClientConnectionManager connMgr,Integer waitTime) {
        this.connMgr = connMgr;
        this.waitTime = waitTime;
        this.start();
    }

    @Override
    public void run() {
        try {
            while (!shutdown) {
                synchronized (this) {
                    wait(waitTime);
                    // 关闭失效的连接
                    connMgr.closeExpiredConnections();
                }
            }
        } catch (InterruptedException ex) {
            // 结束
        }
    }

    /**
     * 销毁释放资源
     */
    public void shutdown() {
        shutdown = true;
        synchronized (this) {
            notifyAll();
        }
    }
}

重新部署一下，就可以在controller里实例化HttpDeal类并调用它的方法了。我的spring MVC整合了json,所以返回值是json数据，比如：

[{"id":1,"type":"管理员","menu":"1,2,3"},{"id":2,"type":"操作员","menu":"1,2,"}]
[{"id":4,"attributes":null,"children":[],"text":"用户管理","pid":1,"url":"../user/getPage.do","title":null,"ptext":"系统管理"},{"id":5,"attributes":null,"children":[],"text":"部门管理","pid":1,"url":"../department/getPage.do","title":null,"ptext":"系统管理"},{"id":10,"attributes":null,"children":[],"text":"权限管理","pid":1,"url":"../userType/getPage.do","title":null,"ptext":"系统管理"}]

可以通过我另一篇文章http://blog.csdn.net/u012116457/article/details/24371877里的方法将json转为map等。

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