http post 请求

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

public class postUtils {

private static String PATH = "网络请求地址";
private static URL url;

public postUtils() {
}

static {
try {
url = new URL(PATH);
} catch (Exception e) {
e.printStackTrace();
}
}

/**
* 通过给定的请求参数和编码格式，获取服务器返回的数据
* @param params 请求参数
* @param encode 编码格式
* @return 获得的字符串
*/
public static String sendPostMessage(Map<String, String> params,
String encode) {
StringBuffer buffer = new StringBuffer();
if (params != null && !params.isEmpty()) {
for (Map.Entry<String, String> entry : params.entrySet()) {
try {
buffer.append(entry.getKey())
.append("=")
.append(URLEncoder.encode(entry.getValue(), encode))
.append("&");

} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}

}
buffer.deleteCharAt(buffer.length() - 1);
System.out.println(buffer.toString());
try {
HttpURLConnection urlConnection = (HttpURLConnection) url
.openConnection();
urlConnection.setConnectTimeout(3000);
//设置允许输入输出
urlConnection.setDoInput(true);
urlConnection.setDoOutput(true);
byte[] mydata = buffer.toString().getBytes();
//设置请求报文头，设定请求数据类型
urlConnection.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
//设置请求数据长度
urlConnection.setRequestProperty("Content-Length",
String.valueOf(mydata.length));
//设置POST方式请求数据
urlConnection.setRequestMethod("POST");
OutputStream outputStream = urlConnection.getOutputStream();
outputStream.write(mydata);
int responseCode = urlConnection.getResponseCode();
if (responseCode == 200) {
return changeInputStream(urlConnection.getInputStream(),
encode);
}
} catch (IOException e) {
e.printStackTrace();
}
}
return "";
}

/**
* 把服务端返回的输入流转换成字符串格式
* @param inputStream 服务器返回的输入流
* @param encode 编码格式
* @return 解析后的字符串
*/
private static String changeInputStream(InputStream inputStream,
String encode) {
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
byte[] data = new byte[1024];
int len = 0;
String result="";
if (inputStream != null) {
try {
while ((len = inputStream.read(data)) != -1) {
outputStream.write(data,0,len);
}
result=new String(outputStream.toByteArray(),encode);

} catch (IOException e) {
e.printStackTrace();
}
}
return result;
}

/**
* @param args
*/
public static void main(String[] args) {
//通过Map设置请求字符串。
Map<String, String> params = new HashMap<String, String>();
params.put("username", "admin");
params.put("password", "admin");
String result=sendPostMessage(params, "utf-8");
System.out.println(result);
}

}