HttpClient的使用

最新推荐文章于 2024-06-25 14:35:48 发布

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本文介绍了如何使用HttpClient进行文件的上传和下载操作，并提供了具体的代码实现。包括如何发送POST请求携带表单数据和文件，以及如何从指定URL获取图片和HTML内容。

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今天学到了HttpClient的使用，里面最关键的就是将表单和文件已Post方式提交到Java EE的项目中。

再做项目HttpClientDemo前，先写工具类，为以后的项目开发提供方便。

今天学到了HttpClient的使用，里面最关键的就是将表单和文件已Post方式提交到Java EE的项目中。

package com.example.httpclientdemo.util;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.multipart.FilePart;
import org.apache.commons.httpclient.methods.multipart.MultipartRequestEntity;
import org.apache.commons.httpclient.methods.multipart.Part;
import org.apache.commons.httpclient.methods.multipart.StringPart;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;

public class NetUtil {
	/**
	 * 该方法可以根据一个url返回一个图片
	 * 
	 * @param address
	 *            得到图片的统一资源定位器地址
	 * @param flag
	 *            是否写入缓存
	 * @return 图片
	 * @throws Exception
	 */
	public static Bitmap getImg(String address, boolean flag) throws Exception {
		// 声明 URL
		URL url = new URL(address);
		// 得到打开的链接
		URLConnection conn = url.openConnection();
		conn.setRequestProperty("method", "get");
		conn.setReadTimeout(5000);
		InputStream is = conn.getInputStream();

		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		byte[] bytes = new byte[1024];
		int len = 0;
		while ((len = is.read(bytes)) != -1) {
			bos.write(bytes, 0, len);
		}

		byte[] imgBytes = bos.toByteArray();
		OutputStream fos = null;
		if (flag) {
			// 1.根据请求地址得到图片文件名
			int start = address.lastIndexOf("/");
			String iconName = address.substring(start + 1);
			File iconfile = new File(Environment.getExternalStorageDirectory(),
					iconName);

			fos = new FileOutputStream(iconfile);
			fos.write(imgBytes);
			fos.flush();
			fos.close();
		}
		return BitmapFactory.decodeByteArray(imgBytes, 0, imgBytes.length);

	}

	public static String getHtml(String address) throws Exception {
		// 声明 URL
		URL url = new URL(address);
		// 得到打开的链接
		URLConnection conn = url.openConnection();
		conn.setRequestProperty("method", "get");
		conn.setReadTimeout(5000);
		InputStream is = conn.getInputStream();
		// 得到网页编码类型
		String contentType = conn.getContentType();
		// 截取等号 = 得到结果如：utf-8、GBK
		String type = contentType.split("=")[1];
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		byte[] bytes = new byte[1024];
		int len = 0;
		while ((len = is.read(bytes)) != -1) {
			bos.write(bytes, 0, len);
		}

		byte[] imgBytes = bos.toByteArray();

		return new String(imgBytes, type);
	}

	public static String getJson(String address) throws Exception {
		// 声明 URL
		URL url = new URL(address);
		// 得到打开的链接
		URLConnection conn = url.openConnection();

		conn.setRequestProperty("method", "get");
		conn.setReadTimeout(5000);
		InputStream is = conn.getInputStream();
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		byte[] bytes = new byte[1024];
		int len = 0;
		while ((len = is.read(bytes)) != -1) {
			bos.write(bytes, 0, len);
		}
		byte[] imgBytes = bos.toByteArray();

		return new String(imgBytes);
	}

	public static HttpResponse clientPost(String path,
			NameValuePair... nameValuePairs) throws Exception {
		// 得到模拟http客户端
		HttpClient client = new DefaultHttpClient();
		HttpPost post = new HttpPost(path);
		List<NameValuePair> parameters = Arrays.asList(nameValuePairs);
		HttpEntity entity = new UrlEncodedFormEntity(parameters, "utf-8");

		post.setEntity(entity);
		HttpResponse response = client.execute(post);
		return response;

	}

	public static String clientPostFile(String path, String filepath)
			throws Exception {
		// 得到模拟http客户端
		File file = new File(filepath);

		org.apache.commons.httpclient.HttpClient httpClient = new org.apache.commons.httpclient.HttpClient();
		Part[] parts = { new StringPart("name", "小王子"),
				new StringPart("password", "xiaowangzi"),
				new FilePart("file", file) };

		PostMethod postMethod = new PostMethod(path);
		postMethod.setRequestEntity(new MultipartRequestEntity(parts,
				postMethod.getParams()));
		httpClient.getHttpConnectionManager().getParams()
				.setConnectionTimeout(5000);
		int status = httpClient.executeMethod(postMethod);
		if (status == 200) {
			return new String(postMethod.getResponseBody());
		} else {
			throw new IllegalArgumentException("文件不存在，或者文件不存在。。。");
		}

	}

	public static String getStringbyInputStream(InputStream is, String charset)
			throws IOException {
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		int len = 0;
		byte[] bytes = new byte[1024];

		while ((len = is.read(bytes)) != -1) {
			bos.write(bytes, 0, len);
		}

		return new String(bos.toByteArray(), charset);

	}

	public static String getStringbyInputStream(InputStream is)
			throws IOException {

		return getStringbyInputStream(is, "utf-8");

	}
}