java 访问url

public class HttpUtils {

public static void main(String[] args) {
System.out.println(SMS("", "https://www.baidu.com/"));
}

private static String SMS(String postData, String postUrl) {
try {
// 发送POST请求
URL url = new URL(postUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");//修改发送方式
conn.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setUseCaches(false);
conn.setDoOutput(true);

conn.setRequestProperty("Content-Length", "" + postData.length());
OutputStreamWriter out = new OutputStreamWriter(
conn.getOutputStream(), "UTF-8");
out.write(postData);
out.flush();
out.close();

// 获取响应状态
if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
return "";
}
// 获取响应内容体
String line, result = "";
BufferedReader in = new BufferedReader(new InputStreamReader(
conn.getInputStream(), "utf-8"));
while ((line = in.readLine()) != null) {
result += line + "\n";
}
in.close();
return result;
} catch (IOException e) {
}
return "";
}
}

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.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;

public class HttpUtils {

private static final int TIME_OUT = 5;
/**
* 通过HTTP GET 发送参数
*
* @param httpUrl
* @param parameter
* @param httpMethod
*/
public static String sendGet(String httpUrl, Map<String, String> parameter) {
if (parameter == null || httpUrl == null) {
return null;
}

StringBuilder sb = new StringBuilder();
Iterator<Map.Entry<String, String>> iterator = parameter.entrySet().iterator();
while (iterator.hasNext()) {
if (sb.length() > 0) {
sb.append('&');
}
Entry<String, String> entry = iterator.next();
String key = entry.getKey();
String value;
try {
value = URLEncoder.encode(entry.getValue(), "UTF-8");
} catch (UnsupportedEncodingException e) {
value = "";
}
sb.append(key).append('=').append(value);
}
String urlStr = null;
if (httpUrl.lastIndexOf('?') != -1) {
urlStr = httpUrl + '&' + sb.toString();
} else {
urlStr = httpUrl + '?' + sb.toString();
}

HttpURLConnection httpCon = null;
String responseBody = null;
try {
URL url = new URL(urlStr);
httpCon = (HttpURLConnection) url.openConnection();
httpCon.setDoOutput(true);
httpCon.setRequestMethod("GET");
httpCon.setConnectTimeout(TIME_OUT * 1000);
httpCon.setReadTimeout(TIME_OUT * 1000);
// 开始读取返回的内容
InputStream in = httpCon.getInputStream();
byte[] readByte = new byte[1024];
// 读取返回的内容
int readCount = in.read(readByte, 0, 1024);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
while (readCount != -1) {
baos.write(readByte, 0, readCount);
readCount = in.read(readByte, 0, 1024);
}
responseBody = new String(baos.toByteArray(), "UTF-8");
baos.close();
} catch (Exception e) {
} finally {
if (httpCon != null)
httpCon.disconnect();
}
return responseBody;
}

/**
* 使用HTTP POST 发送文本
*
* @param httpUrl
*            发送的地址
* @param postBody
*            发送的内容
* @return 返回HTTP SERVER的处理结果,如果返回null,发送失败
*/
public static String sentPost(String httpUrl, String postBody) {
return sentPost(httpUrl, postBody, "UTF-8", null);
}

/**
* 使用HTTP POST 发送文本
*
* @param httpUrl
*            发送的地址
* @param postBody
*            发送的内容
* @return 返回HTTP SERVER的处理结果,如果返回null,发送失败
*/
public static String sentPost(String httpUrl, String postBody, String encoding) {
return sentPost(httpUrl, postBody, encoding, null);
}

/**
* 使用HTTP POST 发送文本
* @param httpUrl   目的地址
* @param postBody  post的包体
* @param headerMap 增加的Http头信息
* @return
*/
public static String sentPost(String httpUrl, String postBody, Map<String, String> headerMap) {
return sentPost(httpUrl, postBody, "UTF-8", headerMap);
}

/**
* 使用HTTP POST 发送文本
*
* @param httpUrl
*            发送的地址
* @param postBody
*            发送的内容
* @param encoding
*            发送的内容的编码
* @param headerMap 增加的Http头信息
* @return 返回HTTP SERVER的处理结果,如果返回null,发送失败
* .................
*/
public static String sentPost(String httpUrl, String postBody, String encoding, Map<String, String> headerMap) {
HttpURLConnection httpCon = null;
String responseBody = null;
URL url = null;
try {
url = new URL(httpUrl);
} catch (MalformedURLException e1) {
return null;
}
try {
httpCon = (HttpURLConnection) url.openConnection();
} catch (IOException e1) {
return null;
}
if (httpCon == null) {
return null;
}
httpCon.setDoOutput(true);
httpCon.setConnectTimeout(TIME_OUT * 1000);
httpCon.setReadTimeout(TIME_OUT * 1000);
httpCon.setDoOutput(true);
httpCon.setUseCaches(false);
try {
httpCon.setRequestMethod("POST");
} catch (ProtocolException e1) {
return null;
}
if (headerMap != null) {
Iterator<Entry<String, String>> iterator = headerMap.entrySet().iterator();
while (iterator.hasNext()) {
Entry<String, String> entry = iterator.next();
httpCon.addRequestProperty(entry.getKey(), entry.getValue());
}
}
OutputStream output;
try {
output = httpCon.getOutputStream();
} catch (IOException e1) {
return null;
}
try {
output.write(postBody.getBytes(encoding));
} catch (UnsupportedEncodingException e1) {
return null;
} catch (IOException e1) {
return null;
}
try {
output.flush();
output.close();
} catch (IOException e1) {
return null;
}
// 开始读取返回的内容
InputStream in;
try {
in = httpCon.getInputStream();
} catch (IOException e1) {
return null;
}
/**
* 这个方法可以在读写操作前先得知数据流里有多少个字节可以读取。
* 需要注意的是，如果这个方法用在从本地文件读取数据时，一般不会遇到问题，
* 但如果是用于网络操作，就经常会遇到一些麻烦。
* 比如，Socket通讯时，对方明明发来了1000个字节，但是自己的程序调用available()方法却只得到900，或者100，甚至是0，
* 感觉有点莫名其妙，怎么也找不到原因。
* 其实，这是因为网络通讯往往是间断性的，一串字节往往分几批进行发送。
* 本地程序调用available()方法有时得到0，这可能是对方还没有响应，也可能是对方已经响应了，但是数据还没有送达本地。
* 对方发送了1000个字节给你，也许分成3批到达，这你就要调用3次available()方法才能将数据总数全部得到。
*
* 经常出现size为0的情况，导致下面readCount为0使之死循环(while (readCount != -1) {xxxx})，出现死机问题
*/
int size = 0;
try {
size = in.available();
} catch (IOException e1) {
return null;
}
if (size == 0) {
size = 1024;
}
byte[] readByte = new byte[size];
// 读取返回的内容
int readCount = -1;
try {
readCount = in.read(readByte, 0, size);
} catch (IOException e1) {
return null;
}
ByteArrayOutputStream baos = new ByteArrayOutputStream();
while (readCount != -1) {
baos.write(readByte, 0, readCount);
try {
readCount = in.read(readByte, 0, size);
} catch (IOException e) {
return null;
}
}
try {
responseBody = new String(baos.toByteArray(), encoding);
} catch (UnsupportedEncodingException e) {
return null;
} finally {
if (httpCon != null) {
httpCon.disconnect();
}
if (baos != null) {
try {
baos.close();
} catch (IOException e) {
}
}
}

return responseBody;
}
}

import java.io.IOException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

/**
* 根据httpclient进行访问
* @author Administrator
*
*/
public class HttpUtils {

/**
* 访问url方法
*
* @param url
* @return
*/
public static String callOnHttp(String url) {

String address = "";
CloseableHttpClient httpclient = HttpClients.createDefault();
try {
HttpGet httpget = new HttpGet(url);
ResponseHandler<String> responseHandler = new ResponseHandler<String>() {
public String handleResponse(final HttpResponse response)
throws ClientProtocolException, IOException {
int status = response.getStatusLine().getStatusCode();
if (status >= 200 && status < 300) {
HttpEntity entity = response.getEntity();
return entity != null ? EntityUtils.toString(entity)
: null;
} else {
throw new ClientProtocolException(
"Unexpected response status: " + status);
}
}
};
address = httpclient.execute(httpget, responseHandler);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
httpclient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return address;
}
}