HttpClient3.x之Get请求和Post请求示例

HttpClient的支持在HTTP/1.1规范中定义的所有的HTTP方法：GET, HEAD, POST, PUT, DELETE, TRACE 和 OPTIONS。每有一个方法都有一个对应的类：HttpGet，HttpHead，HttpPost，HttpPut，HttpDelete，HttpTrace和HttpOptions。所有的这些类均实现了HttpUriRequest接口，故可以作为execute的执行参数使用。请求URI是能够应用请求的统一资源标识符。 HTTP请求的URI包含一个协议计划protocol scheme，主机名host name,，可选的端口optional port，资源的路径resource path，可选的查询optional query和可选的片段optional fragment。

head，put，delete，trace HttpClient支持这些方法，
大多数浏览器不支持这些方法，原因是Html 4中对 FORM 的method方法只支持两个get和post，很多浏览器还都依然是基于html4的。

通常会在JAVA中通过代码调用URL进行远端方法调用，这些方法有的是Get请求方式的，有的是POST请求方式的，为此，总结一例，贴出以便查阅。

依赖JAR包有：commons-codec.jar,commons-httpclient.jar,commons-logging.jar。

package com.wujintao.httpclient;

import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;
import org.junit.Test;

public class TestCase {

	@Test
	public void testGetRequest() throws IllegalStateException, IOException {
		HttpClient client = new HttpClient();
		StringBuilder sb = new StringBuilder();
		InputStream ins = null;
		// Create a method instance.
		GetMethod method = new GetMethod("http://www.baidu.com");
		// Provide custom retry handler is necessary
		method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
				new DefaultHttpMethodRetryHandler(3, false));
		try {
			// Execute the method.
			int statusCode = client.executeMethod(method);
			System.out.println(statusCode);
			if (statusCode == HttpStatus.SC_OK) {
				ins = method.getResponseBodyAsStream();
				byte[] b = new byte[1024];
				int r_len = 0;
				while ((r_len = ins.read(b)) > 0) {
					sb.append(new String(b, 0, r_len, method
							.getResponseCharSet()));
				}
			} else {
				System.err.println("Response Code: " + statusCode);
			}
		} catch (HttpException e) {
			System.err.println("Fatal protocol violation: " + e.getMessage());
		} catch (IOException e) {
			System.err.println("Fatal transport error: " + e.getMessage());
		} finally {
			method.releaseConnection();
			if (ins != null) {
				ins.close();
			}
		}
		System.out.println(sb.toString());
	}

	@Test
	public void testPostRequest() throws HttpException, IOException {
		HttpClient client = new HttpClient();
		PostMethod method = new PostMethod("http://www.baidu.com/getValue");
		method.setRequestHeader("Content-Type",
				"application/x-www-form-urlencoded;charset=gb2312");
		NameValuePair[] param = { new NameValuePair("age", "11"),
				new NameValuePair("name", "jay"), };
		method.setRequestBody(param);
		int statusCode = client.executeMethod(method);
		System.out.println(statusCode);
		method.releaseConnection();
	}

}