使用HttpClient发送http请求，并解析从服务器端返回的数据

使用Apache的httpclient包可以模拟HTTP请求的发送， get和post均可以。最方便的地方就是请求struts等web框架进行测试，省去了做测试页面的差事。

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

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.BufferedHttpEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

public class Client {
	
	public String sendGet(String url) throws ClientProtocolException, IOException{
		String result = null;
		HttpClient httpClient = new DefaultHttpClient();
		HttpGet get = new HttpGet(url);
		InputStream in = null;
		try {
			HttpResponse response = httpClient.execute(get);
			HttpEntity entity = response.getEntity();
			if (entity != null) {
				entity = new BufferedHttpEntity(entity);
				in = entity.getContent();
				byte[] read = new byte[1024];
				byte[] all = new byte[0];
				int num;
				while ((num = in.read(read)) > 0) {
					byte[] temp = new byte[all.length + num];
					System.arraycopy(all, 0, temp, 0, all.length);
					System.arraycopy(read, 0, temp, all.length, num);
					all = temp;
				}
				result = new String(all, "UTF-8");
			}
		} finally {
			if (in != null) in.close();
			get.abort();
		}
		
		return result;
	}
	
	public String sendPost(String url, Map<String, String> params) throws ClientProtocolException, IOException{
		String result = null;
		HttpClient httpClient = new DefaultHttpClient();
		
		HttpPost get = new HttpPost(url);
		
		// 创建表单参数列表  
		List<NameValuePair> qparams = new ArrayList<NameValuePair>(); 
		Set<String> keys = params.keySet();
		for (String key : keys) {
			qparams.add(new BasicNameValuePair(key, params.get(key)));
		}
		
		// 填充表单  
		get.setEntity(new UrlEncodedFormEntity(qparams,"UTF-8"));
		
		HttpResponse response = httpClient.execute(get);
		HttpEntity entity = response.getEntity();
		if (entity != null) {
			entity = new BufferedHttpEntity(entity);
			
			InputStream in = entity.getContent();
			byte[] read = new byte[1024];
			byte[] all = new byte[0];
			int num;
			while ((num = in.read(read)) > 0) {
				byte[] temp = new byte[all.length + num];
				System.arraycopy(all, 0, temp, 0, all.length);
				System.arraycopy(read, 0, temp, all.length, num);
				all = temp;
			}
			result = new String(all,"UTF-8");
			if (null != in) {
				in.close();
			}
		}
		get.abort();
		
		return result;
	}
	
	public String sendGet(String url, Map<String, String> params) throws ClientProtocolException, IOException {
		Set<String> keys = params.keySet();
		StringBuilder urlBuilder = new StringBuilder(url + "?");
		for (String key : keys) {
			urlBuilder.append(key).append("=").append(params.get(key)).append("&");
		}
		urlBuilder.delete(urlBuilder.length() - 1, urlBuilder.length());
		return this.sendGet(urlBuilder.toString());
	}
}

如果服务器返回的是XML，上面的方法返回的就是xml的字符串，如"<XML><student>......</student></XML>"。在处理xml非常管用。

上面的例子，如果使用第二种或者第三种方法，需要将参数放在Map<String, String>中