HttpClient -- HTTP工具

package com.http.demo;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.ProtocolException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

/**
 * http://www.cnblogs.com/not-NULL/p/5531866.html
 * http://www.cnblogs.com/loveyakamoz/archive/2011/07/21/2113252.html
 * HTTP工具
 */
public class HttpUtil {
    /**
     * 請求類型： GET
     */
    public final static String GET  = "GET";
    /**
     * 請求類型： POST
     */
    public final static String POST = "POST";

    /**
     * HttpURLConnection方式 模擬Http Get請求
     * @param urlStr請求路徑
     * @param paramMap 請求參數
     */
    public static String get(String urlStr, Map<String, String> paramMap) throws Exception {
        urlStr = urlStr + "?" + getParamString(paramMap);
        HttpURLConnection conn = null;
        try {
            //創建URL對象
            URL url = new URL(urlStr);
            //獲取URL連接
            conn = (HttpURLConnection) url.openConnection();
            //設置通用的請求屬性
            setHttpUrlConnection(conn, GET);
            //建立實際的連接
            conn.connect();
            //獲取響應的內容
            return readResponseContent(conn.getInputStream());
        } finally {
            if (null != conn)
                conn.disconnect();
        }
    }

    /**
     * HttpURLConnection方式 模擬Http Post請求
     * @param urlStr請求路徑
     * @param paramMap請求參數
     * @return
     */
    public static String post(String urlStr, Map<String, String> paramMap) throws Exception {
        HttpURLConnection conn = null;
        PrintWriter writer = null;
        try {
            //創建URL對象
            URL url = new URL(urlStr);
            //獲取請求參數
            String param = getParamString(paramMap);
            //獲取URL連接
            conn = (HttpURLConnection) url.openConnection();
            //設置通用請求屬性
            setHttpUrlConnection(conn, POST);
            //建立實際的連接
            conn.connect();
            //將請求參數寫入請求字符流中
            writer = new PrintWriter(conn.getOutputStream());
            writer.print(param);
            writer.flush();
            //讀取響應的內容
            return readResponseContent(conn.getInputStream());
        } finally {
            if (null != conn)
                conn.disconnect();
            if (null != writer)
                writer.close();
        }
    }

    /**
     * 讀取響應字節流並將之轉爲字符串
     * @param in要讀取的字節流
     */
    private static String readResponseContent(InputStream in) throws IOException {
        Reader reader = null;
        StringBuilder content = new StringBuilder();
        try {
            reader = new InputStreamReader(in);
            char[] buffer = new char[1024];
            int head = 0;
            while ((head = reader.read(buffer)) > 0) {
                content.append(new String(buffer, 0, head));
            }
            return content.toString();
        } finally {
            if (null != in)
                in.close();
            if (null != reader)
                reader.close();
        }
    }

    /**
     * 設置Http連接屬性
     * @param connhttp連接
     * @return
     * @throws ProtocolException
     * @throws Exception
     */
    private static void setHttpUrlConnection(HttpURLConnection conn,
                                             String requestMethod) throws ProtocolException {
        conn.setRequestMethod(requestMethod);
        conn.setRequestProperty("content-encoding", "utf8");
        conn.setRequestProperty("accept", "application/json");
        conn.setRequestProperty("Accept-Charset", "UTF-8");
        conn.setRequestProperty("Accept-Language", "zh-CN");
        conn.setRequestProperty("User-Agent",
            "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)");
        conn.setRequestProperty("Proxy-Connection", "Keep-Alive");

        System.out.println(conn.getRequestMethod());
        if (null != requestMethod && POST.equals(requestMethod)) {
            conn.setDoOutput(true);
            conn.setDoInput(true);
        }
    }

    /**
     * 將參數轉爲路徑字符串
     * @param paramMap 參數
     */
    private static String getParamString(Map<String, String> paramMap) {
        if (null == paramMap || paramMap.isEmpty()) {
            return "";
        }
        StringBuilder builder = new StringBuilder();
        for (String key : paramMap.keySet()) {
            builder.append("&").append(key).append("=").append(paramMap.get(key));
        }
        return new String(builder.deleteCharAt(0).toString());
    }

    public static void main(String[] args) {
    	 String url = "http:www.baidu.com";

         Map<String, String> params = new HashMap<>();

         /*params.put("name", "jerry");
         params.put("age", "18");
         params.put("sex", "man");*/

         try {
             //System.out.println(post(url, params));
             System.out.println(get(url,null));
         } catch (Exception e) {
             e.printStackTrace();
         }
	}
}

/**  jar包依賴：

<!-- httpclient -->
<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpcore</artifactId>
	<version>4.3</version>
</dependency>
<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpclient</artifactId>
	<version>4.3</version>
</dependency>
<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpmime</artifactId>
	<version>4.3</version>
</dependency>
<dependency>
	<groupId>org.apache.geronimo.bundles</groupId>
	<artifactId>commons-httpclient</artifactId>
	<version>3.1_2</version>
</dependency>

*/