java 后台发送http请求

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;


import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


public class HttpRequestUtil {

private Logger logger;

public HttpRequestUtil(){
logger = LoggerFactory.getLogger(HttpRequestUtil.class);
}

/**
* 向指定URL发送GET方法的请求
* 
* @param url
*            发送请求的URL
* @param param
*            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
* @return URL 所代表远程资源的响应结果
*/
public String sendGet(String url, String param) {
String result = "";
BufferedReader bufferedReader = null;
try {

// 设置通用的请求属性
URLConnection connection = initConnection(url, param, "get");

// 建立实际的连接
connection.connect();
// 获取所有响应头字段
Map<String, List<String>> map = connection.getHeaderFields();
// 遍历所有的响应头字段
for (String key : map.keySet()) {
System.out.println(key + "--->" + map.get(key));
}
// 定义 BufferedReader输入流来读取URL的响应
InputStream inputStream = connection.getInputStream();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");
bufferedReader = new BufferedReader(inputStreamReader);
String line;
while (null != (line = bufferedReader.readLine())) {
result += line;
}
} catch (Exception e) {
String message = "发送GET请求出现异常！请求地址：" + url; 
logger.error(message, e);

}
// 使用finally块来关闭输入流
finally {
try {
if (null != bufferedReader) {
bufferedReader.close();
}
} catch (Exception e2) {
String message = "http get请求关闭输入流异常！请求地址：" + url; 
logger.error(message, e2);
}
}
return result;
}


/**
* 向指定 URL 发送POST方法的请求
* 
* @param url
*            发送请求的 URL
* @param param
*            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
* @return 所代表远程资源的响应结果
*/
public String sendPost(String url, String param) {
PrintWriter out = null;
BufferedReader bufferedReader = null;
String result = "";
try {

            URLConnection conn = initConnection(url, param, "post");
            
// 发送POST请求必须设置如下两行
conn.setDoOutput(true);
conn.setDoInput(true);
// 获取URLConnection对象对应的输出流
out = new PrintWriter(conn.getOutputStream());
// 发送请求参数
out.print(param);
// flush输出流的缓冲
out.flush();
// 定义BufferedReader输入流来读取URL的响应
InputStream inputStream = conn.getInputStream();
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");
bufferedReader = new BufferedReader(inputStreamReader);
String line;
while (null != (line = bufferedReader.readLine())) {
result += line;
}
} catch (Exception e) {

String message = "发送 POST 请求出现异常！请求地址：" + url;
logger.error(message, e);
}
// 使用finally块来关闭输出流、输入流
finally {
try {
if (null != out) {
out.close();
}
if (null != bufferedReader) {
bufferedReader.close();
}
} catch (IOException ex) {
String message = "http post请求关闭输入流异常！请求地址：" + url;
logger.error(message, ex);
}
}
return result;
}

private URLConnection initConnection(String url, String param, String method) throws IOException {
String urlNameString;
if(method.equals("get")){
urlNameString = url + "?" + param;
}else{
urlNameString = url;
}

URL realUrl = new URL(urlNameString);
// 打开和URL之间的连接

URLConnection connection = realUrl.openConnection();

connection.setRequestProperty("accept", "*/*");
connection.setRequestProperty("connection", "Keep-Alive");
connection.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
connection.setRequestProperty("Accept-Charset", "utf-8");
connection.setRequestProperty("contentType", "utf-8");
return connection;
}
}